Article

Zinc Ionophore Activity of Quercetin and Epigallocatechin-gallate: From Hepa 1-6 Cells to a Liposome Model

Authors:
  • Vascular Biology Lab, Institute of Medicine and Experimental Biology of Cuyo (IMBECU) CONICET, School of Medical Sciences, National University of Cuyo, Mendoza, Argentina,
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Labile zinc - a tiny fraction of total intracellular zinc that is loosely bound to proteins and easily interchangeable - modulates the activity of numerous signalling and metabolic pathways. Dietary plant polyphenols such as the flavonoids quercetin and epigallocatechin-gallate act as antioxidants and as signalling molecules. Remarkably, the activities of numerous enzymes that are targeted by polyphenols are dependent on zinc. We have previously shown that these polyphenols chelate zinc cations and hypothesized that these flavonoids might be also acting as zinc ionophores, transporting zinc cations through the plasma membrane. To prove this hypothesis, herein we have demonstrated the capacity of quercetin and epigallocatechin-gallate to rapidly increase labile zinc in mouse hepatocarcinoma Hepa 1-6 cells as well as, for the first time, in liposomes. In order to confirm that the polyphenols transport of zinc cations across the plasma membrane independently of plasma membrane zinc transporters, quercetin, epigallocatechin-gallate or clioquinol, alone and combined with zinc, were added to unilamellar dipalmitoylphosphocholine/cholesterol liposomes loaded with membrane-impermeant FluoZin™-3. Only the combinations of the chelators with zinc triggered a rapid increase of FluoZin™-3 fluorescence within liposomes, thus demonstrating, the ionophore action of quercetin, epigallocatechin-gallate and clioquinol on lipid membrane systems. The ionophore activity of dietary polyphenols may underlay the raising of labile zinc levels triggered in cells by polyphenols and, thus, many of their biological actions.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... There is a debate in the literature regarding the efficacy of CQ and HCQ in the treatment of COVID-19 infection [9][10][11][12]. Adding azithromycin to CQ and HCQ was reported to reduce the complications and fatality rates, and reduce the viral load in COVID-19 patients [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. These reports resulted in emerged ideas calling for combining CQ and HCQ with other drugs in the treatment of COVID-19. ...
... Zinc is essential for different cellular and enzymatic activities, as well as being a necessary cofactor for many viral proteins [15][16][17][18][19][20][21][22][23][24][25]. Zinc was also proved to inhibit RNAdependent RNA polymerase of SARS-CoV in cell culture [17]. ...
... Remarkably, the activities of numerous enzymes that are targeted by polyphenols are dependent on zinc. Husam and his colleagues have previously shown that these polyphenols chelate zinc cations, and they hypothesized that these flavonoids might also be acting as zinc ionophores, transporting zinc cations through the plasma membrane [19]. ...
Article
Full-text available
No specific treatment for COVID-19 infection is available up till now, and there is a great urge for effective treatment to reduce morbidity and mortality during this pandemic. We aimed to evaluate the effect of combining chloroquine/hydroxychloroquine (CQ/HCQ) and zinc in the treatment of COVID-19 patients. This was a randomized clinical trial conducted at three major University hospitals in Egypt. One hundred ninety-one patients with a confirmed diagnosis of COVID-19 infection were randomized into two groups: group I (96) patients received both HCQ and zinc, and group II (95) received HCQ only. The primary endpoints were the recovery within 28 days, the need for mechanical ventilation, and death. The two groups were matched for age and gender. They had no significant difference regarding any of the baseline laboratory parameters or clinical severity grading. Clinical recovery after 28 days was achieved by 79.2% in the zinc group and 77.9% in zinc-free treatment group, without any significant difference (p = 0.969). The need for mechanical ventilation and the overall mortality rates did not show any significant difference between the 2 groups either (p = 0.537 and 0.986, respectively). The age of the patient and the need for mechanical ventilation were the only risk factors associated with the patients’ mortality by the univariate regression analysis (p = 0.001 and < 0.001, respectively). Zinc supplements did not enhance the clinical efficacy of HCQ. More randomized studies are needed to evaluate the value of adding zinc to other therapies for COVID 19. ClinicalTrials.gov Identifier: NCT04447534
... Quercetin antitumor effects have been described in different cancer types, including HCC [1]. In 25 of the articles included in the present review, quercetin efficacy as single treatment was evaluated employing different HCC study models [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]46,48,49,[51][52][53][54]57]. Antiproliferative effect of this flavonoid alone has been demonstrated in several researches with in vitro models [22][23][24][25][26][27][30][31][32][33]35,38,46,48,49,[51][52][53][54], highlighting the HepG2 cell line as the most used in 21 of the 25 articles [24,25,27,28,[30][31][32][33][35][36][37][38]46,[48][49][50][51][52][53][54]57]. ...
... This evidences an important need of suitable and uniform experiment design and performance to get consistent results. Among included articles, several of them determined effects of the flavonoid in different specific mechanisms [27][28][29]34,38]. These include inhibition of chymotrypsin-like activity of the proteasome, involved in proteasomal regulation of cancer signaling pathways [27,38]; rise of intracellular labile zinc, which has second messenger molecule activities in tumor cells [34]; and modulation of microRNAs expression, highly involved in cancer development and chemoresistance [63], leading to inhibition of the oncogenic RNA-binding proteins insulin-like growth factor-2 binding protein 1 and 3 (IGF2BP1 and IGF2BP3) through the upregulation of miR-1275 [29]. ...
... Among included articles, several of them determined effects of the flavonoid in different specific mechanisms [27][28][29]34,38]. These include inhibition of chymotrypsin-like activity of the proteasome, involved in proteasomal regulation of cancer signaling pathways [27,38]; rise of intracellular labile zinc, which has second messenger molecule activities in tumor cells [34]; and modulation of microRNAs expression, highly involved in cancer development and chemoresistance [63], leading to inhibition of the oncogenic RNA-binding proteins insulin-like growth factor-2 binding protein 1 and 3 (IGF2BP1 and IGF2BP3) through the upregulation of miR-1275 [29]. Another study published in 2018 employed quercetin to analyze adequacy of the cellular antioxidant (CAA) assay in HepG2 cells in order to determine the antioxidant activity of extracts from tree nuts [28]. ...
Article
Full-text available
Quercetin is a flavonoid present in fruits, vegetables and plants with antioxidant, anti-inflammatory and anticancer properties. Its beneficial activities have been demonstrated in different human pathologies, including hepatoprotective effects against liver disorders. High mortality and late diagnosis of the primary liver tumor hepatocarcinoma (HCC) makes this cancer an interesting target for the study of quercetin effects. Our aim was to systematically review antitumor activities of quercetin in HCC preclinical studies employing single, encapsulated, combined or derived quercetin forms. Literature search was conducted in PubMed, Scopus and Web of Science (WOS), and 39 studies were finally included. We found that 17 articles evaluated quercetin effects alone, six used encapsulated strategy, 10 combined this flavonoid, two decided to co-encapsulate it and only four studied effects of quercetin derivatives, highlighting that only nine included in vivo models. Results evidence the quercetin antiproliferative and proapoptotic properties against HCC either alone and with the mentioned strategies; nevertheless, few investigations assessed specific activities on different processes related with cancer progression. Overall, further studies including animal models are needed to deeper investigate the precise mechanisms of action of quercetin as antitumor agent, as well as the potential of novel strategies aimed to improve quercetin effects in HCC.
... Quercetin (QC) is a naturally occurring flavonoid having a zincionophore activity. It is lipid-soluble and chelates zinc on its carbonyl oxygen (C-3,4 O-) and the deprotonated (C-5 OH) to the intracellular compartment [24,25]. In COVID-19, quercetin was introduced in February 2020 by Eastern Virginia medical school team in combinations with essential immunity vitamins and minerals namely; vitamin C, vitamin D, Zinc, and Magnesium -if needed-in both the prevention and treatment protocols [26]. ...
... In advanced ARDS, with the loss of the regenerative ability of alveolar stem cells by the extensive alveolar damage, neither Quercetin Immune-modulatory Effects • Quercetin is a zinc ionophore: it concentrates zinc inside immune cells even in low serum zinc concentrations [24,25]. • It inhibits auto-immune and pro-inflammatory cytokines responses via the reduction of MHC class-II antigen presentation and TLR-signalling at the check point from activated dendritic cells [28]. ...
Article
Full-text available
In the Pandemic of COVID-19 infection caused by SARS-CoV-2, no longer the age and preliminary health status are barriers against this disease-associated morbidity and mortality. In COVID-19 a dysregulated immune response and an exaggerated pro-inflammatory cytokines release are reported. The loss of taste and smell as early alarming symptoms reflect acute serum zinc deficiency. The pathogenesis can be explained as a redistribution of zinc ion associated with acute immune cellular dysfunction. Zinc deficiency results in multiple immunological changes with a shift towards a predominantly innate immune response, which is not as effective in viral immune clearance as the adaptive immune response. Notably, micronutrients homeostasis plays a key role in maintaining a healthy immune response especially Vitamin C, Vitamin D, Zinc and Magnesium. Zinc is considered as the gatekeeper of the immune system. Current studies on zinc-ionophores especially, chloroquine and quercetin, reported an effectiveness in the reduction of COVID-19 morbidity and mortality with an early administration. These Zinc-ionophores are able to chelate zinc and concentrate it intra-cellularly. Concerns about chloroquine safety, its pH-dependent efficacy, response polymorphism, and drug-resistance were studied in malaria treatment. Quercetin is a lipid-soluble, naturally occurring flavonoid, available as a dietary supplement with chloroquine-like actions. It is postulated that zinc supplementation combined with zinc-ionophores may offer dual anti-viral and immune-modulatory effects in favor of both the maintenance and the resetting of an effective cell-mediated immune response. Visual Abstract Significance Statement With the worldwide reopening conditions after the lockdown restrictions. Still the virulence of the SARS-CoV-2 isn't attenuated and the vaccine trials aren't yet completed. A long-term supplementation with chloroquine as an immune supportive agent isn't recommended due to safety concerns. Quercetin is a dietary supplement having chloroquine-like actions. Quercetin plus essential immunity vitamins and minerals in their recommended doses may offer an adequate immune support.
... Nowadays. the worldwide considerable attention to the coronavirus (COVID- 19) epidemic has been largely limited to monitoring/containment and clinical trials should be dive into recent findings about possible and affordable treatment options in using plants as a sources of vitamins, phytochemical and bioactive compounds such as using zinc ionophore activity of quercetin, kaempferol and other polyphenols [37][38][39][40][41]. ...
... To prove that CQ is a Zn ionophore would require kinetic studies in a metabolically inert model system such as liposomes. Work by Dabbagh-Bazarbachi [124] et al. used this approach to establish that quercetin functions as a true Zn ionophore. If zinc combined with CQ/HCQ can clinically prevent replication of SARS-CoV-2 by inhibition of RNA-dependent RNA polymerase, such treatment would likely be most useful prophylactically or in the early phase of rapid viral replication and less useful in the late "cytokine storm", where host-damaging inflammatory responses give rise to severe pathophysiology. ...
Article
Full-text available
Chloroquine (CQ) and hydroxychloroquine (HCQ) have been proposed as treatments for COVID-19. These drugs have been studied for many decades, primarily in the context of their use as antimalarials, where they induce oxidative stress-killing of the malarial parasite. Less appreciated, however, is evidence showing that CQ/HCQ causes systemic oxidative stress. In vitro and observational data suggest that CQ/HCQ can be repurposed as potential antiviral medications. This review focuses on the potential health concerns of CQ/HCQ induced by oxidative stress, particularly in the hyperinflammatory stage of COVID-19 disease. The pathophysiological role of oxidative stress in acute respiratory distress syndrome (ARDS) has been well-documented. Additional oxidative stress caused by CQ/HCQ during ARDS could be problematic. In vitro data showing that CQ forms a complex with free-heme that promotes lipid peroxidation of phospholipid bilayers are also relevant to COVID-19. Free-heme induced oxidative stress is implicated as a systemic activator of coagulation, which is increasingly recognized as a contributor to COVID-19 morbidity. This review will also provide a brief overview of CQ/HCQ pharmacology with an emphasis on how these drugs alter proton fluxes in subcellular organelles. CQ/HCQ-induced alterations in proton fluxes influence the type and chemical reactivity of reactive oxygen species (ROS).
... Another zinc ionophore, quercetin, could be used instead of chloroquine. This agent has lower adverse effects, however, more experimental studies are required to support this hypothesis (Dabbagh-Bazarbachi et al., 2014). ...
Article
Full-text available
The global impact of the new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), infection that caused COVID-19 has been evident in the last few months from the unprecedented socioeconomic disruption to more than 600,000 deaths. The lack of vaccine and effective therapeutic agents for the disease prompted world-wide effort to test those antiviral therapeutics already in use for other diseases. Another interesting approach has been based on the pathological sequel of the disease that involve severe inflammatory reaction (or the cytokine storm) associated with pneumonia in critically ill patients. This article outlines the prophylaxis therapeutic potential of supplements vitamins and micronutrients in COVID-19. By ameliorating the inflammatory and oxidative stress associated with the disease and some direct antiviral effects, the application of these agents as adjuvants and other alternative approaches are discussed. Available clinical trials including those currently registered on these supplements are scrutinized.
... 137 It should be noted that both hydroxychloroquine and the plant phytochemical quercetin are Zinc ionophores. 138,139 However, the role of zinc with or without the addition of zinc ionophores in the treatment of COVID-19 remains speculative. 140 ...
Article
Full-text available
Introduction COVID-19 disease progresses through a number of distinct phases. The management of each phase is unique and specific. The pulmonary phase of COVID-19 is characterized by an organizing pneumonia with profound immune dysregulation, activation of clotting, and a severe microvascular injury culminating in severe hypoxemia. The core treatment strategy to manage the pulmonary phase includes the combination of methylprednisolone, ascorbic acid, thiamine, and heparin (MATH+ protocol). The rationale for the MATH+ protocol is reviewed in this paper. Areas covered We provide an overview on the pathophysiological changes occurring in patients with COVID-19 respiratory failure and a treatment strategy to reverse these changes thereby preventing progressive lung injury and death. Expert opinion While there is no single ‘Silver Bullet’ to cure COVID-19, we believe that the severely disturbed pathological processes leading to respiratory failure in patients with COVID-19 organizing pneumonia will respond to the combination of Methylprednisone, Ascorbic acid, Thiamine, and full anticoagulation with Heparin (MATH+ protocol).We believe that it is no longer ethically acceptable to limit management to ‘supportive care’ alone, in the face of effective, safe, and inexpensive medications that can effectively treat this disease and thereby reduce the risk of complications and death.
... In this perspective, zinc supplementation in the absence of CQ might produce similar effects without adverse sideeffects of CQ treatment [12]. A similar effect observed in a study using zinc ionophores [13], and it is also interesting to note that a combination of CQ with zinc has an inhibitory effect on autophagy by the influx of Zn2+ into the cell [14]. Hydroxychloroquine metaphorically make the cap on the vinegar, Greene says, preventing acid surroundings. ...
Article
Coronaviruses 2019 (Covid-19) is a massive family of viruses that causes respiratory illnesses ranging from the common cold to the most severe conditions such as Middle East Respiratory Syndrome and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that represents the humanitarian crisis on a global scale. Currently, there are no therapeutic strategies approved by the U.S.Food and Drug Administration (FDA) to cure or prevent COVID-19. Global research efforts from around the world extrapolate the updates focusing specifically on the biphasic nature of Covid-19 that involve both innate and acquired immunity. Even though researchers around the globe are racing to invent a life-saving therapeutics and vaccines to tackle COVID-19, the only available venture is a supportive approach in rendering treatment to patients with severe and non-severe cases of COVID-19. Supplementation of several vitamins and trace elements showed the expected favorable impact on enhancing immunity in viral infection. Numerous studies prompted the value of zinc (Zn) supplementation that prevents the virus from entering cells by binding with protein in potentiating antiviral immunity, which is realized through different mechanisms, including the improvement in markers of immune function. Zinc is also an associated factor for several enzymes (needed for the activity for over 300 enzymes), transcription factors, and replication factors. Interestingly, low-level zinc results in dysfunction of all immune cells, subjects with altered zinc state have a high risk for infectious disorders, autoimmune disorders, and cancer. Several assumptions regarding immunomodulators of zinc remain unresolved. This review aimed to explore the hypothetical association of Zinc supplementation (the key immunomodulator) in association with a preventive and therapeutic role of treating patients with COVID-19.
... Low-dose zinc supplementation together with small concentrations of the zinc ionophores pyrithione or hinokitol decreased RNA synthesis in influenza, poliovirus, picornavirus, the equine arteritis virus, and SARS-CoV by directly inhibiting the RNA-dependent RNA polymerase of the virus (34,41). There is evidence that zinc can enhance the effect of chloroquine, another known zinc ionophore, while zinc ionophores like epigallocatechingallate or quercetin remain to be tested (42)(43)(44)(45). There are close similarities of SARS-CoV2 and other coronaviridae like SARS-CoV and Middle East respiratory syndrome-related coronavirus (MERS-CoV) (46). ...
Article
Full-text available
During the current corona pandemic, new therapeutic options against this viral disease are urgently desired. Due to the rapid spread and immense number of affected individuals worldwide, cost-effective, globally available, and safe options with minimal side effects and simple application are extremely warranted. This review will therefore discuss the potential of zinc as preventive and therapeutic agent alone or in combination with other strategies, as zinc meets all the above described criteria. While a variety of data on the association of the individual zinc status with viral and respiratory tract infections are available, study evidence regarding COVID-19 is so far missing but can be assumed as was indicated by others and is detailed in this perspective, focusing on re-balancing of the immune response by zinc supplementation. Especially, the role of zinc in viral-induced vascular complications has barely been discussed, so far. Interestingly, most of the risk groups described for COVID-19 are at the same time groups that were associated with zinc deficiency. As zinc is essential to preserve natural tissue barriers such as the respiratory epithelium, preventing pathogen entry, for a balanced function of the immune system and the redox system, zinc deficiency can probably be added to the factors predisposing individuals to infection and detrimental progression of COVID-19. Finally, due to its direct antiviral properties, it can be assumed that zinc administration is beneficial for most of the population, especially those with suboptimal zinc status.
... In another investigation, both in vitro and in vivo experiments had shown that zinc ions can block hepatitis E virus replication by inhibiting the activity of viral RdRp [53]. The charged zinc ions require a transporter for the influx into the cell, and quercetin acts as an ionophore that mediates zinc influx into the cells through plasma membrane [54]. While correlating these results, it is evident that the combination of quercetin and zinc is a potential strategy against SARS-CoV-2, imparting greater antiviral efficacy at a lower cytotoxicity. ...
Article
Full-text available
Background The world pandemic COVID-19 caused by SARS-CoV-2 is currently claiming thousands of lives. Flavonoids abundantly present in the fruits and vegetables, especially quercetin, are shown to have antiviral activities. Main text This paper reviews the capability of the plant flavonoid quercetin to fight the novel coronavirus and the possibility for drug development based on this. The mode of action explaining the known pathways through which this molecule succeeds in the antiviral activity, action of quercetin on SARS-CoV-2 main protease 3CL pro , antiviral activities of its derivatives on human viruses, effect of combination of zinc co-factor along with quercetin in the COVID-19 treatment, and the regulation of miRNA genes involved in the viral pathogenesis are discussed. Proof for this concept is provided following the virtual screening using ten key enzymes of SARS-CoV-2 and assessing their interactions. Active residues in the 3D structures have been predicted using CASTp and were docked against quercetin. Key proteins 3CL pro , spike glycoprotein/ human ACE2-BOAT1 complex, RNA-dependent RNA polymerase, main peptidase, spike glycoprotein, RNA replicase, RNA binding protein, papain-like protease, SARS papain-like protease/ deubiquitinase, and complex of main peptidase with an additional Ala at the N-terminus of each protomer, have shown the binding energies ranging between − 6.71 and − 3.37 kcal/ Mol, showing that quercetin is a potential drug candidate inhibiting multiple SARS-CoV-2 enzymes. Conclusion The antiviral properties of flavonoid and the molecular mechanisms involved are reviewed. Further, proof for this concept is given by docking of key proteins from SARS-CoV-2 with quercetin. Graphical abstract
... The formulation of COVI-MXG would afford a synergistic effect, seeing as it contains Gongronema latifolium which has an appreciable amount of Zinc [23] and the zinc ionophore activity of quercetin [24] which showed a higher binding a nity ( Table 2). Zinc has been shown to play an important role in the inhibition of coronavirus RNA polymerase [25] . ...
Preprint
Full-text available
Background: COVID-19 pandemic disease, caused by coronavirus 2 (SARS-CoV-2) is expressed as severe acute respiratory syndrome. There are currently no proven effective therapeutic agents or vaccines against the virus. However clinical management includes infection prevention, control measures, supportive care using drug therapy based on previous scientific experience, pathophysiology and pharmacology of the drug. Some of the therapeutic agents exploited include; antiviral and antimalarial agents (remdesivir, hydroxychloroquine, chloroquine, lopinavir, umifenovir, favipiravir, and oseltamivir), Zinc and selenium. There are claims of herbal preparations with palliative or therapeutic effects. The novel formulation of herbal preparation, COVI-MXG for the management of Covid-19 contains a unique combination of five (5) plants. In silico studies was carried out using robust methods and software to evaluate the plant constituents to determine its possible antiviral activity, safety and pharmacokinetic profile. Results: Pharmacokinetic predictions showed phytochemicals with varying degrees of gastrointestinal absorption rates and blood brain barrier permeability. Toxicity class fall between 3 and 5 with high LD50 values. Conclusions: When compared with the listed therapeutic agents, the phytochemical compounds present in COVI-MXG showed varying degrees of binding affinities for SARS-CoV-2 (7BV2.pdb) better than the drugs currently in use at the target sites. The preparation contains high concentration of Zinc and other micronutrients.
... Cellular Zn intake can be improved by ionophores including chloroquine and some of its derivatives such as hydroxychloroquine [64]. Alternatively, natural ionophores of potential use with a good tolerability profile are quercetin and epigallocatechin gallate [79]. ...
Article
Full-text available
Coronavirus disease-2019 (COVID-19) pandemic continues to threaten patients, societies, and economic and healthcare systems around the world. Like many other diseases, the host immune system determines the progress of COVID-19 and fatality. Modulation of inflammatory response and cytokine production using immunonutrition is a novel concept that has been applied to other diseases as well. Zinc, one of the anti-inflammatory and antioxidant micronutrient found in food with well-established role in immunity, is currently being used in some clinical trials against COVID-19. This review integrates the contemporary studies of role of zinc in antiviral immunity along with discussing its potential role against COVID-19, and ongoing COVID-19 clinical trials using zinc.
... While a significant increase of Zn was found in quercetin-fortified beef soup and a significant decrease of Zn was observed in cinnamaldehyde fortified beef soup. Previous study has shown that some polyphenols could chelate zinc cations and act as zinc ionophores (Dabbagh-Bazarbachi et al., 2014). The increasing of zinc in quercetin fortified beef soup might due to the soluble chelate formed between quercetin and zinc ions. ...
Article
Full-text available
The effects of quercetin and cinnamaldehyde, two popular dietary phytochemicals from vegetables and spices on the general nutrient content and whole chemical profile of beef soup during stewing were investigated by routine chemical analysis and an UPLC-MS/MS based untargeted metabolomics analysis. It was found that quercetin decreased the content of total sugar and methionine, and increased solid matters, unsaturated fatty acids and zinc content in beef soup. Cinnamaldehyde decreased total sugar, aspartic acid and zinc content, but increased total fatty acids in beef soup. Metabolomics results showed that a total of 204 metabolites were assigned to putative molecular classes. 12 metabolite species were summarized based on the chemical structure using HMDB. Cinnamaldehyde decreased the content of most of the molecule species in beef soup while quercetin did not have significant effect. In general, cinnamaldehyde decreased the nutritional value of beef soup, thus spices rich in cinnamaldehyde may not be suitable used for preparing meat soup due to its negative effect on nutrient contents in beef soup. This work could help to fully understand the effects of quercetin and cinnamaldehyde on the nutritional value of beef soup.
... • The antiviral activity in vitro of Zn SARS-CoV-1 is potentiated by the ionophore pyrithione 60 • In addition to their antioxidant properties, plant polyphenol flavonoids (quercetin 69 , green tea 69, 70 and punicalagin -pomegranate extract 71 ) are less toxic Zn ionophores. Catechin, quercetin or its derivatives were active against to Influenza Virus (or complications) in clinical or laboratory settings 72,73 and against murine norovirus in vitro. ...
Preprint
Full-text available
Wiseman, DM. Rapid deployment reduce load & secondary peak, low risk, multi stage COVID-19 Strategy. V9.6. Synechion, Inc., Dallas, TX. 2020 synechion.com/COVID/RapidDeploymentReduceLoadCOVIDStrategyLATEST.pdf Background: As COVID-19 lockdowns are relaxed, there are indications of secondary peaking. Although their reintroduction is economically unsustainable there are few medical interventions for widespread use on the immediate horizon to reduce healthcare resource overload. Objective: To execute a rapidly deployable low-risk multi-stage COVID-19 strategy to: a) reduce resource load; b) reduce secondary peaks; c) protect essential workers, high-risk disease and minority groups; d) reduce escalation of exposed or early stage patients; e) improve the speed and quality of treatment guideline making; f) accelerate medical and economic recovery. Methods: This strategy was formulated using the method adopted by NIH (COVID-19 Treatment Guidelines) consisting of a critical review and synthesis of medical literature, observational studies, case reports and clinical judgments of front-line physicians. Results: A low-risk, rapidly deployable multi-stage strategy was devised: 1. For moderate and severe hospitalized patients. early use of methylprednisolone and LMW heparin may reduce death rate from >25% to <10%, along with reductions in intubation and hospital load. 2. For moderate cases, zinc must be added to low dose hydroxychloroquine (possibly with azithromycin), and administered early to produce similarly favorable outcomes. 3. For pre-exposed, exposed and mildly symptomatic cases, use of zinc is proposed in a low risk strategy for prevention, pre-emption and treatment of mild symptoms. Zinc’s antiviral and other actions may be enhanced with natural, antioxidant, antiviral agents that are also ionophores (“door openers”) that help zinc get to where it is needed. These agents are inexpensive, readily available and used within current indications as nutritional supplements. 4. Zinc status may partly determine COVID-19 severity associated with high risk conditions such as diabetes, obesity, heart disease and old age and may play an additional role in high-risk African-American and Hispanic communities. Zinc supplementation may be provided along with intensive medical and dietary efforts to assist these high-risk groups, reduce their risks for serious COVID-19, and contribution to healthcare workload. 5. Our analysis of a recently devised machine-learning algorithm to predict COVID-19 outcomes suggests that this may be widely adapted to reduce confounding in observational data, enhancing their utility and accelerating the formulation of treatment guidelines before results of randomized clinical trials are known. 6. Novel screening and tele-medicine technology will further contribute to economic and medical recovery. Conclusion: Currently available observational, front-line and other data support this low risk strategy to accelerate medical and economic recovery from COVID-19. The strategy includes clinical study protocol outlines for tracking with methods for rapid data collection. These may be implemented at a government or community level, or by businesses wishing to protect their employee, customers and to drive economic recovery from COVID-19. We seek: Government, business or community (city, faith- or condition-based) partners to implement this strategy and to track outcomes using scientifically established tools and systems for rapid data collection, analysis and dissemination of treatment guidelines that will accelerate medical and economic recovery from COVID-19.
... Our docking results showed Epigallocatechin with the lowest ICM score of around -26 while Chebulagic, a benzopyran tannin, had the lowest mfscore of -117 [ Fig 13 and Table 6]. Epigallocatechin (found in black tea) has been shown to be an effective antioxidant in several studies (50) while Chebulagic acid has been shown to be inhibiting enterovirus 71 replication in some studies (51). Cimicifugic acid, Scutellarin and Rosemarinic acid were other compounds with lower ICM and mfscores. ...
Preprint
Full-text available
Background The current Novel Coronavirus (SARS-CoV-2) pandemic is the third major outbreak of the 21st century which emerged in December 2019 from Wuhan, China. At present there are no known treatments or vaccines to cure or prevent the illness.Objective The objective of this study was to explore a list of potential drugs (herbal and antivirals) for their role in inhibiting activity and or replication of SARS-CoV-2 by using molecular docking onto the crystal structures of key viral proteins.MethodologyIn this study, we used molecular docking to estimate the binding affinities of 3699 drugs on the potential active sites of the 6 main SARS-CoV-2 proteins (Papain like protease, Main protease, ADP Ribose phosphatase, Spike protein, NSP-9 and NSP-10 to 16 complex). While other studies have mostly been performed on the homology models, we obtained the most recently submitted crystal structures of all 6 proteins from the protein data bank for this analysis.ResultsOur results showed the top ligands as Theasinensin A, Epigallocatechin, Theaflavin, Theasinensin A, Epigallocatechin and Favipiravir showing the highest binding affinities against papain-like protease, ADP ribose phosphatase, main protease, spike protein, RNA replicase (NSP-9) and methyl-transferase (NSP-16) respectively.Conclusion We show that the compounds from our list with the greatest inhibitory potential against SARS-CoV-2 activity or replication include Theasinensin A, Epigallocatechin-3-gallate, Theaflavin, Favipiravir, Curucumin, Quercetin, Mitoxantrone, Amentoflavone, Colistin, Cimicifugic acid, Theaflavin, Silymarin and Chebulagic. We recommend further wet-lab and clinical testing of these compounds to further explore their role against SARS-CoV-2.
... Another reason for using hydroxychloroquine is that it can function as a zinc ionophore to transport zinc ions into cells and cell organelles 113 . However, quercetin, a natural polyphenol and anti-oxidant (abundant in food such as onions) with very low toxicity 114 , is also a zinc ionophore 115 . ...
Preprint
Full-text available
The Coronavirus Disease 2019 (COVID-19) is a respiratory disease characterized by acute respiratory distress syndrome (ARDS) in severe cases, with liquid from inflammatory response filling air sacs of the lung and blocking air exchange. The pathogen for COVID-19 is a novel coronavirus called SARS-CoV-2. However, it is still unclear how the virus causes such pathologies. Here, I review evidence that leads to my hypothesis that the pulmonary pathologies of COVID-19 is the result of the immune system failing to recognize the infection as a viral infection and the virus actively misleading the immune system to initiate a response against bacteria, fungi and parasitic worms so that the virus can replicate without being attacked and easily spread under the disease conditions such as cough. Such a mechanistic understanding has profound implications for therapeutic strategies. I will also propose and discuss a therapy for COVID-19 by IL-12 and/or synthetic double-stranded RNAs (dsRNAs) such as poly IC or poly IC:LC to switch the immune response to an antiviral type 1 T helper (Th1) cell response, combined with Vitamin D3 (VD3) and B3 to modulate the inflammatory response and simultaneously boost innate immune functions, and with anti-viral drugs to suppress viral replication. Such a therapeutic strategy centered around activating antiviral Th1 response is crucial for the successful recovery of COVID-19 patients.
... Results showed that only the combination of EGCG-QTLSs triggered the transport of Zn cation across the membrane, as compared to individual Zn chelators. Although, it showed the ionophore action EGCG-QTLSs and hence could be used in cancer identification and pre-diagnosis [50]. Caddeo et al., fabricated LSs of succinylated chitosan (SCS) coated QT and Resveratrol (RVT) (SCS-QT/RVT LSs) and evaluated their antioxidant and anti-inflammatory activities. ...
Article
Quercetin (QT, 3,3′,4′,5,7-pentahydroxyflavone), is a natural flavonoid with nutritional value and potentially acts as a free-radical scavenger (antioxidant). QT has also been explored for its anti-cancer as well as anti-proliferative activities against numerous cancerous cells. Moreover, QT exhibits significant pro-apoptotic activity against tumor cells and well established to control the growth of different carcinoma cells at various phases of cell cycle. Hence, it can reduce the burden of human solid cancer and metastasis. Both these activities have been established in a diverse class of human cell lines in-vitro as well as in animal models (in-vivo). Apart from the promising therapeutic activities of QT molecule, their applications have been limited due to some major concerns including low oral bioavailability and poor aqueous solubility. Also, rapid gastrointestinal digestion of QT seems to be a key barrier for its clinical translations for oral drug delivery in conventional dosage form. Henceforth, to overcome these drawbacks, QT is loaded with liposomal systems, which exhibits promising outcomes in the upregulation of QT by the epithelial system and also improved its targeting at the site of action. Further, Liposomes based Drug Delivery Systems (LDDS) have showed significant therapeutic activity with conjugated drug moiety and exhibits safety, biocompatibility, biodegradability and mitigated toxicity despite having certain limitations associated with physiological and biological barriers. Herein, in this review we have focused on the mechanism related with the chemotherapeutic activity of QT and also discussed the promising activity of QT-loaded LDDS as a potent chemotherapeutic agent for cancer therapy
... We assessed free and labile zinc cations in microglia 1-6 h after treatment with 10 ng mL À1 IL-4 in the presence or absence of 1 mM TPEN or 100 mM CaEDTA, using the cell permeable zinc-specific fluorescence dye FluoZin-3AM (Molecular Probes, Eugene, OR). 29 Following treatment, the culture media were replaced with fresh media containing 3 mM FluoZin-3AM and incubated for 30 min. Cells were washed with prewarmed culture medium and then fixed in 4% paraformaldehyde. ...
Article
Microglia, the resident immune cells of the central nervous system, can display a pro-inflammatory M1 phenotype or an anti-inflammatory M2 phenotype. Arginase (Arg)-1 expressed in interleukin-4 (IL-4)-induced M2 microglia reduces nitric oxide (NO) production by competing with inducible NO synthase for L-arginine, which contributes to the attenuation of brain inflammation. Although previous studies have indicated that brain zinc promotes M1 activation, the effect of zinc on M2 microglial activation remains to be determined. In the present study, murine primary microglia treated with 10 ng/mL IL-4 exhibited increased Arg-1 mRNA expression and levels of intracellular free zinc. Chelation of this increased intracellular free zinc by the cell permeable zinc chelator N,N,N',N'-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN) aggravated the IL-4-induced mRNA expression and enzymatic activity of Arg-1. However, the cell impermeable zinc chelator CaEDTA had no effect on Arg-1 expression or cytosolic levels of free zinc in IL-4-induced M2-polarized microglia. Furthermore, treatment with IL-4 resulted in upregulation of phagocytic activity in microglia, while administration of TPEN abolished IL-4-induced phagocytic activity. Moreover, this effect was reversed via L-arginine supplementation. These findings suggest that IL-4 induces an increase in intracellular free zinc in microglia, which may act as a negative regulator of IL-4-induced Arg-1 expression, and that such negative regulation is essential for microglial phagocytic activity.
... Nowadays. the worldwide considerable attention to the coronavirus (COVID- 19) epidemic has been largely limited to monitoring/containment and clinical trials should be dive into recent findings about possible and affordable treatment options in using plants as a sources of vitamins, phytochemical and bioactive compounds such as using zinc ionophore activity of quercetin, kaempferol and other polyphenols [37][38][39][40][41]. ...
Article
Full-text available
Pomegranate (Punica granatum L.) and their derivative parts contain various phytochemical compounds. The pomegranate peels had the highest antioxidant activity as compared to other parts of pomegranate fruit. HPLC-UV technique was used to identify and quantify the individual ascorbic acid and bioactive compounds (i.e. gallic acid, procatachouic acid, quercetin, and kaempferol) in solvents extract of peels of pomegranate cultivated in Yemen, while scavenging assay of DPPH of dried and undried peel extracts were used to measure antioxidant capacity expression as EC 50 value. The resulted findings by HPLC analysis showed that the amount of ascorbic acid was higher than the phenolic acids (gallic acid and protocatechuic acid), and flavonoids (quercetin and kaempferol) in all extracts and the highest amount of ascorbic acid was found in aqueous extract followed by methanolic whereas the last one was in ethanol solvent. While the phenolic acids were higher than the flavonoids in all extracts, the amount of protocatechuic acid in aqueous extract was higher than the amount of other polyphenols, and the quercetin amount was the lowest one. To compare the anti-oxidative activity of dried and undried peel extract by acetone and water, the EC 50 value of dried and undried peel acetonic extracts were 1.2±0.35 and 5±1.8 µg/ml, respectively, which were higher than aqueous extracts of dried and undried peel (8.1±0.66 and 7.9 ±0.08 µg/ml) respectively.
... Quercetin is a zinc ionophore and could have similar antiviral activity of chloroquine but described as safe choice in the treatment of viral infections [16]. ...
Article
Full-text available
ABSTRACT COVID-19 emerged in Wuhan, China in December 2019, reached epidemic proportions and spread globally as a serious life-threatening pandemic. SARS- Cov-2 is the causative virus that causes severe acute respiratory distress, pneumonia, respiratory failure, and septic shock leading to increased mortality. High risk patients include those with chronic non-communicable diseases such as diabetes, hypertension, coronary heart disease and cancers. No speci􀏐ic treatment is available and supportive care all that could be done to rescue patients. Quadriple therapy consisting of Zinc, Quercetin, Bromelain and Vitamin C showed promising results in improving clinical outcome among COVID-19 patients. Keywords: COVID-19, Cytokines, zinc, Quercetin, Bromelain, Vitamin C.
... 10,11 In this phase, antiviral agents such as quercetin or zinc may be beneficial. 12,13,14,15,16 Infectivity is the highest in symptom-free individuals, during the incubation period, and in the beginning of the early symptomatic phase. 17,18 Masks reduce the inoculum size. ...
... Quercetin is a polyphenol that has a theoretical mechanism of action that could reduce the activity of a SARS-CoV-2 entry through the ACE2 receptor, inhibit viral proteases via conveyance of zinc, and attenuate inflammatory responses mediated through interleukin-6 (Bastaminejad and Bakhtiyari, 2020; Cione et al., 2019;Dabbagh-Bazarbachi et al., 2014;Derosa et al., 2020). The mechanisms of action favorably affect viral replication and immune response, so it is conceivable that this agent taken in combination with others discussed could play an assistive role in reducing early viral amplification and tissue damage (Colunga Biancatelli et al., 2020). ...
Article
Full-text available
The SARS-CoV-2 virus spreading across the world has led to surges of COVID-19 illness, hospitalizations, and death. The complex and multifaceted pathophysiology of life-threatening COVID-19 illness including viral mediated organ damage, cytokine storm, and thrombosis warrants early interventions to address all components of the devastating illness. In countries where therapeutic nihilism is prevalent, patients endure escalating symptoms and without early treatment can succumb to delayed in-hospital care and death. Prompt early initiation of sequenced multidrug therapy (SMDT) is a widely and currently available solution to stem the tide of hospitalizations and death. A multipronged therapeutic approach includes 1) adjuvant nutraceuticals, 2) combination intracellular anti-infective therapy, 3) inhaled/oral corticosteroids, 4) antiplatelet agents/anticoagulants, 5) supportive care including supplemental oxygen, monitoring, and telemedicine. Randomized trials of individual, novel oral therapies have not delivered tools for physicians to combat the pandemic in practice. No single therapeutic option thus far has been entirely effective and therefore a combination is required at this time. An urgent immediate pivot from single drug to SMDT regimens should be employed as a critical strategy to deal with the large numbers of acute COVID-19 patients with the aim of reducing the intensity and duration of symptoms and avoiding hospitalization and death.
... Thereby, it facilitates Zn's entry across a cell's lipid membrane and considerably increases Zn's intracellular levels, particularly in the endosomallysosomal section. 142,[188][189][190][191] Raised concentration intracellular Zn 2+ demonstrates antiviral activity, including COVID-19 involving three distinct antiviral mechanisms of action [ Figure 3]. 142,190,192 The exact mode of action of hydroxychloroquine remains elusive to date. ...
... Thereby, it facilitates Zn's entry across a cell's lipid membrane and considerably increases Zn's intracellular levels, particularly in the endosomallysosomal section. 142,[188][189][190][191] Raised concentration intracellular Zn 2+ demonstrates antiviral activity, including COVID-19 involving three distinct antiviral mechanisms of action [ Figure 3]. 142,190,192 The exact mode of action of hydroxychloroquine remains elusive to date. ...
Article
Full-text available
Abstract: The global pandemic from COVID-19 infection has generated significant public health concerns, both health-wise and economically. There is no specific pharmacological antiviral therapeutic option to date available for COVID-19 management. Also, there is an urgent need to discover effective medicines, prevention, and control methods because of the harsh death toll from this novel coronavirus infection. Acute respiratory tract infections, significantly lower respiratory tract infections, and pneumonia are the primary cause of millions of deaths worldwide. The role of micronutrients, including trace elements, boosted the human immune system and was well established. Several vitamins such as vitamin A, B6, B12, C, D, E, and folate; microelement including zinc, iron, selenium, magnesium, and copper; omega-3 fatty acids as eicosapentaenoic acid and docosahexaenoic acid plays essential physiological roles in promoting the immune system. Furthermore, zinc is an indispensable microelement essential for a thorough enzymatic physiological process. It also helps regulate gene-transcription such as DNA replication, RNA transcription, cell division, and cell activation in the human biological system. Subsequently, zinc, together with natural scavenger cells and neutrophils, are also involved in developing cells responsible for regulating nonspecific immunity. The modern food habit often promotes zinc deficiency; as such, quite a few COVID-19 patients presented to hospitals were frequently diagnosed as zinc deficient. Earlier studies documented that zinc deficiency predisposes patients to a viral infection such as herpes simplex, common cold, hepatitis C, severe acute respiratory syndrome coronavirus (SARS-CoV-1), the human immunodeficiency virus (HIV) because of reducing antiviral immunity. This manuscript aimed to discuss the various roles played by zinc in the management of COVID-19 infection.
... Thereby, it facilitates Zn's entry across a cell's lipid membrane and considerably increases Zn's intracellular levels, particularly in the endosomallysosomal section. 142,[188][189][190][191] Raised concentration intracellular Zn 2+ demonstrates antiviral activity, including COVID-19 involving three distinct antiviral mechanisms of action [ Figure 3]. 142,190,192 The exact mode of action of hydroxychloroquine remains elusive to date. ...
Article
Abstract: The global pandemic from COVID-19 infection has generated significant public health concerns, both health-wise and economically. There is no specific pharmacological antiviral therapeutic option to date available for COVID-19 management. Also, there is an urgent need to discover effective medicines, prevention, and control methods because of the harsh death toll from this novel coronavirus infection. Acute respiratory tract infections, significantly lower respiratory tract infections, and pneumonia are the primary cause of millions of deaths worldwide. The role of micronutrients, including trace elements, boosted the human immune system and was well established. Several vitamins such as vitamin A, B6, B12, C, D, E, and folate; microelement including zinc, iron, selenium, magnesium, and copper; omega-3 fatty acids as eicosapentaenoic acid and docosahexaenoic acid plays essential physiological roles in promoting the immune system. Furthermore, zinc is an indispensable microelement essential for a thorough enzymatic physiological process. It also helps regulate gene-transcription such as DNA replication, RNA transcription, cell division, and cell activation in the human biological system. Subsequently, zinc, together with natural scavenger cells and neutrophils, are also involved in developing cells responsible for regulating nonspecific immunity. The modern food habit often promotes zinc deficiency; as such, quite a few COVID-19 patients presented to hospitals were frequently diagnosed as zinc deficient. Earlier studies documented that zinc deficiency predisposes patients to a viral infection such as herpes simplex, common cold, hepatitis C, severe acute respiratory syndrome coronavirus (SARS-CoV-1), the human immunodeficiency virus (HIV) because of reducing antiviral immunity. This manuscript aimed to discuss the various roles played by zinc in the management of COVID-19 infection.
... Thereby, it facilitates Zn's entry across a cell's lipid membrane and considerably increases Zn's intracellular levels, particularly in the endosomallysosomal section. 142,[188][189][190][191] Raised concentration intracellular Zn 2+ demonstrates antiviral activity, including COVID-19 involving three distinct antiviral mechanisms of action [ Figure 3]. 142,190,192 The exact mode of action of hydroxychloroquine remains elusive to date. ...
Article
Full-text available
Nandeeta Samad,1 Temitayo Eniola Sodunke,2 Abdullahi Rabiu Abubakar,3 Iffat Jahan,4 Paras Sharma,5 Salequl Islam,6 Siddhartha Dutta,7 Mainul Haque8 1Department of Public Health, North South University, Dhaka, 1229, Bangladesh; 2Department of Anatomy, University of Ilorin, Ilorin, Kwara State, Nigeria; 3Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Bayero University, Kano, 700233, Nigeria; 4Department of Physiology, Eastern Medical College, Cumilla, Bangladesh; 5Department of Pharmacognosy, BVM College of Pharmacy, Gwalior, India; 6Department of Microbiology, Jahangirnagar University, Dhaka, 1342, Bangladesh; 7Department of Pharmacology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India; 8The Unit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan Nasional Malaysia (National Defence University of Malaysia), Kuala Lumpur, MalaysiaCorrespondence: Mainul HaqueUnit of Pharmacology, Faculty of Medicine and Defence Health, Universiti Pertahanan Nasional Malaysia (National Defence University of Malaysia), Kem Perdana Sungai Besi, Kuala Lumpur, 57000, MalaysiaTel +60 10 926 5543Email runurono@gmail.comAbstract: The global pandemic from COVID-19 infection has generated significant public health concerns, both health-wise and economically. There is no specific pharmacological antiviral therapeutic option to date available for COVID-19 management. Also, there is an urgent need to discover effective medicines, prevention, and control methods because of the harsh death toll from this novel coronavirus infection. Acute respiratory tract infections, significantly lower respiratory tract infections, and pneumonia are the primary cause of millions of deaths worldwide. The role of micronutrients, including trace elements, boosted the human immune system and was well established. Several vitamins such as vitamin A, B6, B12, C, D, E, and folate; microelement including zinc, iron, selenium, magnesium, and copper; omega-3 fatty acids as eicosapentaenoic acid and docosahexaenoic acid plays essential physiological roles in promoting the immune system. Furthermore, zinc is an indispensable microelement essential for a thorough enzymatic physiological process. It also helps regulate gene-transcription such as DNA replication, RNA transcription, cell division, and cell activation in the human biological system. Subsequently, zinc, together with natural scavenger cells and neutrophils, are also involved in developing cells responsible for regulating nonspecific immunity. The modern food habit often promotes zinc deficiency; as such, quite a few COVID-19 patients presented to hospitals were frequently diagnosed as zinc deficient. Earlier studies documented that zinc deficiency predisposes patients to a viral infection such as herpes simplex, common cold, hepatitis C, severe acute respiratory syndrome coronavirus (SARS-CoV-1), the human immunodeficiency virus (HIV) because of reducing antiviral immunity. This manuscript aimed to discuss the various roles played by zinc in the management of COVID-19 infection.Keywords: zinc therapy, microelement, immune-boosting, efficacy, COVID-19, viral infections, pneumonia, pandemic
... Ionophores are lipid soluble compounds that act by promoting intracellular transport of non-lipid soluble zinc, independent of zinc binding proteins present in the plasma membrane. Several compounds have been identi ed as zinc ionophores including pyrithione(4), pyrrolidine dithiocarbamate(4), hinokitiol (8), resveratrol (9), plant polyphenols such as quercetin and epigallocatechin-gallate (10), chloroquine and hydroxychloroquine (11). One randomized trial of hydroxychloroquine in non-hospitalized adults with early COVID-19 examined a subgroup of 63 patients (15% of the analyzed cohort of 423) who received zinc (12). ...
Preprint
Full-text available
Background: Zinc impairs replication of RNA viruses such as SARS-CoV-1, and may be effective against SARS-CoV-2. However, to achieve adequate intracellular zinc levels, administration with an ionophore, which increases intracellular zinc levels, may be necessary. We evaluated the impact of zinc with an ionophore (Zn+ionophore) on COVID-19 in-hospital mortality rates. Methods: A multicenter cohort study was conducted of 3,473 adult hospitalized patients with reverse-transcriptase-polymerase-chain-reaction (RT-PCR) positive SARS-CoV-2 infection admitted to four New York City hospitals between March 10 through May 20, 2020. Exclusion criteria were: death or discharge within 24h, comfort-care status, clinical trial enrollment, treatment with an IL-6 inhibitor or remdesivir. Patients who received Zn+ionophore were compared to patients who did not using multivariable time-dependent cox proportional hazards models for time to in-hospital death adjusting for confounders including age, sex, race, BMI, diabetes, week of admission, hospital location, sequential organ failure assessment (SOFA) score, intubation, acute renal failure, neurological events, treatment with corticosteroids, azithromycin or lopinavir/ritonavir and the propensity score of receiving Zn+ionophore. A sensitivity analysis was performed using a propensity score-matched cohort of patients who did or did not receive Zn+ionophore matched by age, sex and ventilator status. Results: Among 3,473 patients (median age 64, 1947 [56%] male, 522 [15%] ventilated, 545[16%] died), 1,006 (29%) received Zn+ionophore. Zn+ionophore was associated with a 24% reduced risk of in-hospital mortality (12% of those who received Zn+ionophore died versus 17% who did not; adjusted Hazard Ratio [aHR] 0.76, 95% CI 0.60-0.96, P=0.023). More patients who received Zn+ionophore were discharged home (72% Zn+ionophore vs 67% no Zn+ionophore, P=0.003) Neither Zn nor the ionophore alone were associated with decreased mortality rates. Propensity score-matched sensitivity analysis (N=1356) validated these results (Zn+ionophore aHR for mortality 0.63, 95%CI 0.44-0.91, P=0.015). There were no significant interactions for Zn+ionophore with other COVID-19 specific medications. Conclusions: Zinc with an ionophore was associated with increased rates of discharge home and a 24% reduced risk of in-hospital mortality among COVID-19 patients, while neither zinc alone nor the ionophore alone reduced mortality. Further randomized trials are warranted.
... Quercetin is a polyphenol that has a theoretical mechanism of action that could reduce the activity of a SARS-CoV-2 entry through the ACE2 receptor, inhibit viral proteases via conveyance of zinc, and attenuate inflammatory responses mediated through interleukin-6 (Bastaminejad and Bakhtiyari, 2020; Cione et al., 2019;Dabbagh-Bazarbachi et al., 2014;Derosa et al., 2020). The mechanisms of action favorably affect viral replication and immune response, so it is conceivable that this agent taken in combination with others discussed could play an assistive role in reducing early viral amplification and tissue damage (Colunga Biancatelli et al., 2020). ...
... Quercetin-3-beta-galactoside was identified as a natural inhibitor of the protease by molecular docking [43,44]. The benefits of quercetin might be also modulated by zinc actions; the ionophore actions of quercetin increase the levels of zinc [45]. The administration of quercetin and vitamin C might have synergic antiviral properties, as ascorbate might recycle quercetin increasing its efficacy [46]. ...
Article
Full-text available
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) disease (COVID-19) was declared a pandemic in March 2020, triggering important changes for the entire society and healthcare systems, as well as significant lockdown measures aimed to limit the disease spread. We herein intended to catch the dynamic of Romanian physicians’ perceptions of COVID-19 impact. For this purpose, after a literature review, a 30-item questionnaire was designed. The questionnaire was twice distributed online, about 1 month apart, during which partial relaxation measures were decreed in Romania. The questionnaire was voluntarily filled in by Romanian physicians who were willing to participate in the study. A total of 214 physicians answered the questionnaire upon its first release, and 199 respondents were registered upon its second release, most of whom (94.9%) were involved in clinical work, with one-third working in units dedicated to COVID-19 patients. In parallel with the relaxation of lockdown measures, along with increased confidence in the efficiency of protective measures (46.7% vs. 31.3%), separation from household members decreased from 36.9% to 22.1%. Nevertheless, the feeling of rejection felt by doctors remained similar (22.4% vs. 24.6%). Furthermore, answers regarding the clinical picture, diagnostic approach, and treatment options are discussed. Most of therapeutic options considered for SARS-CoV-2 treatment (e.g., lopinavir/ritonavir, oseltamivir, hydroxychloroquine, azithromycin, tocilizumab, and convalescent plasma) failed to confirm significant efficiency. On the contrary, vaccines for widescale use are already available despite the initial skepticism. In the beginning of the pandemic, 25.2% (18.2% vs. 32.2%) considered that there will not be an effective COVID-19 vaccine, while 41.6% (43.0% vs. 40.2%) thought that a vaccine would be available after at least 12 months. In conclusion, initially, following only a 1 month period, Romanian physicians’ intention to consider treatments such as hydroxychloroquine or lopinavir/ritonavir for COVID-19 decreased significantly. Moreover, confidence in the efficiency of available protective measures increased, and the rates of separation from household members decreased.
... including O 2 and ONOO − , and it facilitates zinc trafficking into cells, which in turn functions as an antioxidant [5,6]. However, quercetin has been reported to induce cell type-specific cytotoxicity in vitro, where quercetin was relatively harmless to murine thymocytes and human lung embryonic fibroblasts at 100 μM, but significantly increased cell death was observed in human umbilical vein endothelial cells (HUVECs) at the same concentration [7,8]. ...
Article
Full-text available
Quercetin has been reported to act as a senolytic by selectively removing senescent endothelial cells, and thus it would seem quercetin could revolutionize the field of gerontology. However, given quercetin's narrow therapeutic index reported in work done with human umbilical vein endothelial cells (HUVECs), we hypothesized that quercetin is not innocuous for non-senescent adult human vascular endothelial cells at concentrations that have been reported to be safe for proliferating HUVECs. Furthermore, we investigated quercetin 3-D-galactoside (Q3G; hyperoside), an inactive quercetin derivative that needs to be cleaved by beta-galactosidase overexpressed in senescent cells to release quercetin, as a potential safer senolytic. We compared the effectiveness of quercetin and Q3G in primary human coronary artery endothelial cells (HCAEC), which are adult microvascular cells. We found that quercetin caused cell death in non-senescent endothelial cells at a concentration that has been reported to selectively remove senescent cells, and that Q3G was not cytotoxic to either young or senescent cells. Thus, in primary adult human endothelial cells, quercetin and Q3G are not senolytics. Earlier work reporting positive results was done with HUVECs, and given their origin and the disparate findings from the current study, these may not be the best cells for evaluating potential senolytics in clinically relevant endothelial cells. New and noteworthy Previously, quercetin has been reported to be a senolytic, a drug that selectively removes senescent cells, in HUVECs. However, we found neither quercetin nor Q3G was effective as a senolytic for adult human endothelial cells.
... Quercetin is a polyphenol that has a theoretical mechanism of action that could reduce the activity of a SARS-CoV-2 entry through the ACE2 receptor, inhibit viral proteases via conveyance of zinc, and attenuate inflammatory responses mediated through interleukin-6 (Bastaminejad and Bakhtiyari, 2020; Cione et al., 2019;Dabbagh-Bazarbachi et al., 2014;Derosa et al., 2020). The mechanisms of action favorably affect viral replication and immune response, so it is conceivable that this agent taken in combination with others discussed could play an assistive role in reducing early viral amplification and tissue damage (Colunga Biancatelli et al., 2020). ...
Article
Full-text available
The SARS-CoV-2 virus spreading across the world has led to surges of COVID-19 illness, hospitalizations, and death. The complex and multifaceted pathophysiology of life-threatening COVID-19 illness including viral mediated organ damage, cytokine storm, and thrombosis warrants early interventions to address all components of the devastating illness. In countries where therapeutic nihilism is prevalent, patients endure escalating symptoms and without early treatment can succumb to delayed in-hospital care and death. Prompt early initiation of sequenced multidrug therapy (SMDT) is a widely and currently available solution to stem the tide of hospitalizations and death. A multipronged therapeutic approach includes 1) adjuvant nutraceuticals, 2) combination intracellular anti-infective therapy, 3) inhaled/oral corticosteroids, 4) antiplatelet agents/anticoagulants, 5) supportive care including supplemental oxygen, monitoring, and telemedicine. Randomized trials of individual, novel oral therapies have not delivered tools for physicians to combat the pandemic in practice. No single therapeutic option thus far has been entirely effective and therefore a combination is required at this time. An urgent immediate pivot from single drug to SMDT regimens should be employed as a critical strategy to deal with the large numbers of acute COVID-19 patients with the aim of reducing the intensity and duration of symptoms and avoiding hospitalization and death.
... 132 It should be noted that both hydroxychloroquine and the plant phytochemical quercetin are Zinc ionophores. 133,134 However, the role of zinc with or without the addition of zinc ionophores in the treatment of COVID-19 remains speculative. 135 ...
Article
Full-text available
In December 2019, COVID-19, a severe respiratory illness caused by the new coronavirus SARS-CoV-2 (COVID-19) emerged in Wuhan, China. The greatest impact that COVID-19 had was on intensive care units (ICUs), given that approximately 20% of hospitalized cases developed acute respiratory failure (ARF) requiring ICU admission. Based on the assumption that COVID-19 represented a viral pneumonia and no anti-coronaviral therapy existed, nearly all national and international health care societies’ recommended “supportive care only” avoiding other therapies outside of randomized controlled trials, with a specific prohibition against the use of corticosteroids in treatment. However, early studies of COVID-19-associated ARF reported inexplicably high mortality rates, with frequent prolonged durations of mechanical ventilation (MV), even from centers expert in such supportive care strategies. These reports led the authors to form a clinical expert panel called the Front-Line COVID-19 Critical Care Alliance (www.flccc.net ). The panel collaboratively reviewed the emerging clinical, radiographic, and pathological reports of COVID-19 while initiating multiple discussions among a wide clinical network of front-line clinical ICU experts from initial outbreak areas in China, Italy, and New York. Based on the shared early impressions of “ what was working and what wasn’t working,” the increasing medical journal publications and the rapidly accumulating personal clinical experiences with COVID-19 patients, a treatment protocol was created for the hospitalized patients based on the core therapies of methylprednisolone, ascorbic acid, thiamine, heparin and co-interventions (MATH+). This manuscript reviews the scientific and clinical rationale behind MATH+ based on published in-vitro, pre-clinical, and clinical data in support of each medicine, with a special emphasis of studies supporting their use in the treatment of patients with viral syndromes and COVID-19 specifically. The review concludes with a comparison of published multi-national mortality data with MATH+ center outcomes.
Article
Scope: Resveratrol (RSV) has been described as a potent antioxidant, anti-steatotic, and antitumor compound, and it has also been identified as a potent autophagy inducer. On the other hand, quercetin (QCT) is a dietary flavonoid with known antitumor, anti-inflammatory and antidiabetic effects. Additionally, QCT increases autophagy. To study the hypothetical synergistic effect of both compounds, we tested the combined effect of QCT and RSV on the autophagy process in HepG2 cells METHODS AND RESULTS: Autophagy was studied by western blotting, real-time RT-PCR, and cellular staining. Our results clearly indicate a bifunctional molecular effect of RSV. Both polyphenols were individually able to promote autophagy. Strikingly, when RSV was combined with QCT, it promoted a potent reduction of QCT-induced autophagy and influenced pro-apoptotic signaling. Conclusion: RSV acts differentially on the autophagic process depending on the cellular energetic state. We further characterized the molecular mechanisms related to this effect, and we observed that AMP-activated protein kinase (AMPK) phosphorylation, heme oxygenase 1 (HO-1) downregulation, lysosomal membrane permeabilization (LMP) and Zinc (Zn2+ ) dynamics could be important modulators of such RSV-related effects and could globally represent a promising strategy to sensitize cancer cells to QCT treatment. This article is protected by copyright. All rights reserved.
Article
Full-text available
Decreased uptake and cellular accumulation of zinc is a common characteristic in cancer of the liver, pancreas and prostate, because these malignant cells are intolerant to the physiological concentrations of zinc. A tea polyphenol, epigallocatechin-3-gallate (EGCG), can enhance the cytotoxicity of zinc ions to cancer, but the application of this is limited by the low stability of EGCG. In this work, we have prepared a material that can simultaneously preserve the EGCG stability and facilitate zinc uptake and accumulation in cancer cells, under conditions that are not harmful to normal cells. Thus, we co-crystallize zinc oxide with EGCG to obtain hybrid EGCG-ZnO crystalline nanoparticles of 16.5 ± 5.3 nm in diameter. The EGCG-ZnO particles effectively kill PC-3 prostate adenocarcinoma cells at concentrations that are not cytotoxic to normal cells, WI-38 human embryonic lung fibroblasts. The EGCG-ZnO particles are two times more cytotoxic against PC-3 cells than the standard ZnO particles. In PC-3 cells, the EGCG-ZnO particles are taken up by endocytosis, followed by lysosomal disruption to release zinc and EGCG into the cytoplasm, finally resulting in nuclear accumulation of zinc.
Article
Over the last years there has been an increasing interest in the possible beneficial effect of polyphenol consumption on neurodegenerative disorders. Since there is a clear impact of environmental factors on the onset and evolution of neurodegenerative conditions, food arises as a promising factor that might be influencing this group of pathologies. The mechanisms by which polyphenols can affect these processes can be through direct interaction with redox signalling or inflammatory pathways but can also be explained by the interaction of dietary polyphenols with either micro- and macronutrients that are known to have neurological effects or by interaction with food contaminants or food associated toxins avoiding their neuronal toxicity.
Article
Full-text available
Background Due to lack of approved drugs and vaccines, the medical world has resorted to older drugs, produced for viral infections and other diseases, as a remedy to combat COVID-19. The accumulating evidence from in vitro and in vivo studies for SARS-CoV and MERS-CoV have demonstrated that several polyphenols found in plants and zinc- polyphenol clusters have been in use as herbal medicines have antiviral activities against viruses with various mechanisms. Scope of review Curcumin, zinc and zinc-ionophores have been considered as nutraceuticals and nutrients showing great antiviral activities with their medicinal like activities. Major conclusions In this work, we discussed the potential prophylactic and/or therapeutic effects of curcumin, zinc and zinc-ionophores in treatment of viral infections including COVID-19. General significance Curcuminoids and Zinc classified as nutraceuticals under GRAS (Generally Recognized As Safe) by FDA can provide complementary treatment for COVID 19 patients with their immunity-boosting and antiviral properties.
Chapter
Phytochemicals as nutritional components have been explored for their anticancer properties. Quercetin (QT), being a chief component of different dietary products, has been widely explored for its anticancer and antiproliferative activities on numerous cancer cell lines. Also, it is an exceptional antioxidant which plays crucial role against various human cancers. QT shows significant pro-apoptotic activity against tumor cells and thus can impede the development of various cancers in humans. Moreover, the anticancer activities of QT have been recognized in various in vitro and in vivo studies on numerous cancer cell lines and animal models. Furthermore, the toxicity of QT against cancer cells is complemented with slight or no adverse effects to normal cells. Again QT molecules have been reported with major issues including low oral bioavailability and poor aqueous solubility which makes it to be an unideal moiety for therapeutic applications. Also, the frequent gastrointestinal digestion of QT seems to be a key barrier for its clinical translations. Henceforth, to overcome these drawbacks, QT-based nanoformulations (NFs) are developed which have shown favourable results in its upregulation by the epithelial system which also improved its targeted delivery at site. Herein, in this review, we have tried to focus on various promising roles of QT-based nanoformulations alone or modified with targeted nanocarriers as an ideal agent for oncotherapy.
Article
Full-text available
In view of the emerging COVID‑19 pandemic caused by SARS‑CoV‑2 virus, the search for potential protective and therapeutic antiviral strategies is of particular and urgent interest. Zinc is known to modulate antiviral and antibacterial immunity and regulate inflammatory response. Despite the lack of clinical data, certain indications suggest that modulation of zinc status may be beneficial in COVID‑19. In vitro experiments demonstrate that Zn2+ possesses antiviral activity through inhibition of SARS‑CoV RNA polymerase. This effect may underlie therapeutic efficiency of chloroquine known to act as zinc ionophore. Indirect evidence also indicates that Zn2+ may decrease the activity of angiotensin‑converting enzyme 2 (ACE2), known to be the receptor for SARS‑CoV‑2. Improved antiviral immunity by zinc may also occur through up‑regulation of interferon α production and increasing its antiviral activity. Zinc possesses anti‑inflammatory activity by inhibiting NF‑κB signaling and modulation of regulatory T‑cell functions that may limit the cytokine storm in COVID‑19. Improved Zn status may also reduce the risk of bacterial co‑infection by improving mucociliary clearance and barrier function of the respiratory epithelium, as well as direct antibacterial effects against S. pneumoniae. Zinc status is also tightly associated with risk factors for severe COVID‑19 including ageing, immune deficiency, obesity, diabetes, and atherosclerosis, since these are known risk groups for zinc deficiency. Therefore, Zn may possess protective effect as preventive and adjuvant therapy of COVID‑19 through reducing inflammation, improvement of mucociliary clearance, prevention of ventilator‑induced lung injury, modulation of antiviral and antibacterial immunity. However, further clinical and experimental studies are required.
Article
Full-text available
Background and aim The novel coronavirus disease (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is now become a worldwide pandemic bringing over 71 million confirmed cases, while the specific drugs and vaccines approved for this disease are still limited regarding their effectiveness and adverse events. Since virus incidences are still on rise, infectivity and mortality may also rise in the near future, natural products are highly considered to be valuable sources for the discovery of new antiviral drugs against SARS-CoV-2. This present review aims to comprehensively summarize the up-to-date scientific literatures on biological activities of plant- and mushroom-derived compounds relevant to mechanistic targets involved in SARS-CoV-2 infection and inflammatory-associated pathogenesis, including viral entry, replication and release, and the renin-angiotensin-aldosterone system (RAAS). Experimental procedure Data were retrieved from a literature search available on PubMed, Scopus and Google Scholar databases and collected until the end of May 2020. The findings from in vitro cell and non-cell based studies were considered, while the results of in silico studies were excluded. Results and Conclusion Based on the previous findings in SARS-CoV studies, except in silico molecular docking analysis, herein, we provide a total of 150 natural compounds as potential candidates for development of new anti-COVID-19 drugs with higher efficacy and lower toxicity than the existing therapeutic agents. Several natural compounds have showed their promising actions on multiple therapeutic targets, which should be further explored. Among them, quercetin, one of the most abundant of plant flavonoids, is proposed as a lead candidate with its ability on the virus side to inhibit SARS-CoV spike protein-angiotensin-converting enzyme 2 (ACE2) interaction, viral protease and helicase activities, as well as on the host cell side to inhibit ACE activity and increase intracellular zinc level.
Preprint
Full-text available
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a new strain of coronavirus. There are three phases of COVID-19: early infection stage, pulmonary stage and hyper-inflammation stage respectively. It is important to prevent lung or other organs injuries by preventing phase-II and phase-III via pharmacological or non-pharmacological treatments. This was a case series study done on twenty-two patients confirmed to be infected with SARS-CoV-2 and diagnosed with COVID-19. Patients in this study have been used quercetin 800 mg, bromelain 165 mg, zinc acetate 50 mg and ascorbic acid 1 g once daily as supplements for 3 to 5 days during SARS-CoV-2 infection. The aim of this study is to evaluate the safety and efficacy of quercetin, bromelain, zinc and ascorbic acid combination supplements on patients with COVID-19. The mean levels of WBC, ANC, ALC, AMC and AST were normal among all included patients before and after taking quercetin, bromelain, zinc and ascorbic acid supplements (P-value > 0.05). Quercetin 800 mg, bromelain 165 mg, zinc acetate 50 mg and ascorbic acid 1 g once daily supplements were safe for patients infected with SARS-CoV-2 and may prevent poor prognosis. Randomized clinical trials needed in the future to ensure the efficacy of quercetin, bromelain, zinc and vitamin c combination.
Article
Şiddetli akut solunum sendromu koronavirüs 2'nin (SARS-CoV-2) neden olduğu mevcut koronavirüs hastalığı 2019 (COVID-19) salgını, 2019 yılının son aylarında Çin’in Wuhan kentindeki toptancı pazarında ortaya çıkmış ve dünyanın hemen hemen tüm ülkelerine yayılmıştır. COVID-19’un şu anda spesifik bir tedavisi bulunmamakla birlikte, in vitro, in vivo çalışmalar ve randomize kontrollü çalışmalara dayalı olarak tüm dünyada belirli ilaçlar kullanılmaktadır. Bu derlemede, COVID-19 tedavisi için kullanılan bu ilaçlar hakkında kısa bilgiler, yapılan araştırmaların sonuçları ve ilaçların olası yan etkilerini özetlenmiştir. Hazırladığımız bu derlemenin, SARS-CoV-2'yi hedefleyen aşıların ve spesifik ilaçların onaylanmasına kadar COVID-19 hastalarını tedavi etmek ve hastalığı kontrol altına almak için kullanılan en güncel terapötik ilaçlar hakkında bir izlenim sağlayacağını umuyoruz.
Article
This paper presents an evidence-based strategy for improving clinical outcomes in COVID-19. Recommendations are based on the phases of the disease, because optimal interventions for one phase may not be appropriate for a different phase. The four phases addressed are: Prevention, Infection, Inflammation and Recovery. Underlying this phased approach is recognition of emerging evidence for two different components of pathophysiology, early infection and late stage severe complications. These two aspects of the disease suggest two different patterns of clinical emphasis that seem on the surface to be not entirely concordant. We describe the application of therapeutic strategies and appropriate tactics that address four main stages of disease progression for COVID-19. Emerging evidence in COVID-19 suggests that the SARS-CoV-2 virus may both evade the innate immune response and kill macrophages. Delayed innate immune response and a depleted population of macrophages can theoretically result in a blunted antigen presentation, delaying and diminishing activation of the adaptive immune response. Thus, one clinical strategy involves supporting patient innate and adaptive immune responses early in the time course of illness, with the goal of improving the timeliness, readiness, and robustness of both the innate and adaptive immune responses. At the other end of the disease pathology spectrum, risk of fatality in COVID-19 is driven by excessive and persistent upregulation of inflammatory mechanisms associated with cytokine storm. Thus, the second clinical strategy is to prevent or mitigate excessive inflammatory response to prevent the cytokine storm associated with high mortality risk. Clinical support for immune system pathogen clearance mechanisms involves obligate activation of immune response components that are inherently inflammatory. This puts the goals of the first clinical strategy (immune activation) potentially at odds with the goals of the second strategy(mitigation of proinflammatory effects). This creates a need for discernment about the time course of the illness and with that, understanding of which components of an overall strategy to apply at each phase of the time course of the illness. We review evidence from early observational studies and the existing literature on both outcomes and mechanisms of disease, to inform a phased approach to support the patient at risk for infection, with infection, with escalating inflammation during infection, and at risk of negative sequelae as they move into recovery.
Preprint
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a new strain of coronavirus. There are three phases of COVID-19: early infection stage, pulmonary stage and hyper-inflammation stage respectively. It is important to prevent lung or other organs injuries by preventing phase-II and phase-III via pharmacological or non-pharmacological treatments. This was a case series study done on twenty-two patients confirmed to be infected with SARS-CoV-2 and diagnosed with COVID-19. Patients in this study have been used quercetin 800 mg, bromelain 165 mg, zinc acetate 50 mg and ascorbic acid 1 g once daily as supplements for 3 to 5 days during SARS-CoV-2 infection. The aim of this study is to evaluate the safety and efficacy of quercetin, bromelain, zinc and ascorbic acid combination supplements on patients with COVID-19. The mean levels of WBC, ANC, ALC, AMC and AST were normal among all included patients before and after taking quercetin, bromelain, zinc and ascorbic acid supplements (P-value > 0.05). Quercetin 800 mg, bromelain 165 mg, zinc acetate 50 mg and ascorbic acid 1 g once daily supplements were safe for patients infected with SARS-CoV-2 and may prevent poor prognosis. Randomized clinical trials needed in the future to ensure the efficacy of quercetin, bromelain, zinc and vitamin c combination.
Article
Full-text available
Background Propolis is a resinous product that is collected from plants by bees to cover holes and crevices in their hives. Propolis has potent antibacterial, antiviral, anti-inflammatory, wound healing, and anticancer properties. Propolis has been used therapeutically by humans for centuries, including the treatment of dental caries and mouth infections. Highlight This review article attempts to analyze the potential use of propolis in general dentistry and oral health management. Conclusion Propolis is potentially useful in dentistry and oral health management based on available in vitro, in vivo, and ex vivo studies, as well as human clinical trials.
Research
Full-text available
Quercetin is a flavonoid present in fruits, vegetables and plants with beneficial effects in several human disorders, including liver cancer. The antioxidant and anti-inflammatory properties make quercetin an interesting drug to be evaluated in hepatocarcinoma (HCC), the major primary liver tumor with a high mortality rate. Moreover, increasing number of studies reported a high variety of antitumor actions which places quercetin as a promising antitumor agent, not only as single treatment but also improving current therapeutic options against advanced HCC.
Article
Full-text available
Coronavirus disease-19 (COVID-19)-induced severe acute respiratory syndrome is a global pandemic. As a preventive measure, human movement is restricted in most of the world. The Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), along with the WHO have laid out some therapeutic guidelines for the infected patients. However, other than handwashing and vigilance surrounding commonly encountered oronasal symptoms and fever, no useful prophylactic measure has yet been established. In a pandemic, the accessibility of a prophylactic biologically active substance is crucial. Ideally, it would be something readily available at a low price to a larger percentage of the population with minimal risk. Studies have demonstrated that zinc may reduce viral replication and increase immune responses. For example, in some studies, zinc supplementation used against the influenza virus has been shown to yield clinical benefits with reduced disease burden. While consuming zinc (within the recommended upper safety limits), as a prophylactic might provide an additional shield against the initiation and progression of COVID-19 would need clinical studies, the potential clearly exists.
Article
Full-text available
Fluorescent dyes are widely used in the detection of labile (free or exchangeable) Zn(2+) and Ca(2+) in living cells. However, their specificity over other cations and selectivity for detection of labile vs. protein-bound metal in cells remains unclear. We characterized these important properties for commonly used Zn(2+) and Ca(2+) dyes in a cellular environment. By tracing the fluorescence emission signal along with UV-Vis and size exclusion chromatography-inductively coupled plasma mass spectrometry (SEC-ICP-MS) in tandem, we demonstrated that among the dyes used for Zn(2+), Zinpyr-1 fluoresces in the low molecular mass (LMM) region containing labile Zn(2+), but also fluoresces in different molecular mass regions where zinc ion is detected. However, FluoZin™-3 AM, Newport Green™ DCF and Zinquin ethyl ester display weak fluorescence, lack of metal specificity and respond strongly in the high molecular mass (HMM) region. Four Ca(2+) dyes were studied in an unperturbed cellular environment, and two of these were tested for binding behavior under an intracellular Ca(2+) release stimulus. A majority of Ca(2+) was in the labile form as tested by SEC-ICP-MS, but the fluorescence from Calcium Green-1™ AM, Oregon Green® 488 BAPTA-1, Fura red™ AM and Fluo-4 NW dyes in cells did not correspond to free Ca(2+) detection. Instead, the dyes showed non-specific fluorescence in the mid- and high-molecular mass regions containing Zn, Fe and Cu. Proteomic analysis of one of the commonly seen fluorescing regions showed the possibility for some dyes to recognize Zn and Cu bound to metallothionein 2. These studies indicate that Zn(2+) and Ca(2+) binding dyes manifest fluorescence responses that are not unique to recognition of labile metals and bind other metals, leading to suboptimal specificity and selectivity.
Article
Full-text available
Flavonoids are among the most investigated phytochemicals due to their pharmacological and therapeutic activities. Their ability to chelate with metal ions has resulted in the emergence of a new category of molecules with a broader spectrum of pharmacological activities. However, the biological significance of these flavonoid-metal ion complexes is yet to be completely explored. Moreover, no concerted efforts have been made to elucidate their molecular targets and mechanisms of action. This review attempts to provide a snapshot of the various biological activities reported for flavonoid-metal ion complexes and their potential as therapeutic agents. Understanding the mechanism of action and the influence of structure will provide a strong basis to design novel flavonoid-metal ion complexes of therapeutic significance.
Article
Full-text available
Zinc is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Dysfunctional zinc signaling is associated with a number of chronic disease states including cancer, cardiovascular disease, Alzheimer's disease, and diabetes. Cellular homeostasis requires mechanisms that tightly control the uptake, storage, and distribution of zinc. This is achieved through the coordinated actions of zinc transporters and metallothioneins. Evidence on the role of these proteins in type 2 diabetes mellitus (T2DM) is now emerging. Zinc plays a key role in the synthesis, secretion and action of insulin in both physiological and pathophysiological states. Moreover, recent studies highlight zinc's dynamic role as a "cellular second messenger" in the control of insulin signaling and glucose homeostasis. This suggests that zinc plays an unidentified role as a novel second messenger that augments insulin activity. This previously unexplored concept would raise a whole new area of research into the pathophysiology of insulin resistance and introduce a new class of drug target with utility for diabetes pharmacotherapy.
Article
Full-text available
As key enzymes in the regulation of biological phosphorylations, protein-tyrosine phosphatases are central to the control of cellular signaling and metabolism. Zinc(II) ions are known to inhibit these enzymes, but the physiological significance of this inhibition has remained elusive. Employing metal buffering for strict metal control and performing a kinetic analysis, we now demonstrate that zinc(II) ions are reversible inhibitors of the cytoplasmic catalytic domain of the receptor protein-tyrosine phosphatase β (also known as vascular endothelial protein-tyrosine phosphatase). The Ki(Zn) value is 21 ± 7 pm, 6 orders of magnitude lower than zinc inhibition reported previously for this enzyme. It exceeds the affinity of the most potent synthetic small molecule inhibitors targeting these enzymes. Inhibition is in the range of cellular zinc(II) ion concentrations, suggesting that zinc regulates this enzyme, which is involved in vascular physiology and angiogenesis. Thus, for some enzymes that are not recognized as zinc metalloenzymes, zinc binding inhibits rather than activates as in classical zinc enzymes. Activation then requires removal of the inhibitory zinc.
Article
Full-text available
There is increasing interest in the potential health benefits of dietary flavonoids. Fruits and vegetables, tea, and cocoa are rich natural sources of flavonoids. Epidemiological studies have indicated that consumption of these foods is likely to be associated with a reduced risk of cardiovascular disease, but the etiology of this benefit is not yet clearly defined. Furthermore, in some acute interventions, a positive effect of tea and cocoa on vascular function has been reported. An alternative source of flavonoids is dietary supplements, which have become increasingly popular in the recent past. In this context, it needs to be critically evaluated whether vascular health-promoting and other positive properties of flavonoid-rich diets can be replaced by purified flavonoids as dietary supplements. Plant sources of flavonoids contain a complex mixture of secondary plant metabolites and not only flavonoids per se. This complex mixture of secondary plant metabolites cannot be simply exchanged by single purified compounds as dietary supplements. If flavonoids are given as dietary supplements, toxicity issues as well as nutrient drug interactions need to be taken into account. Purified flavonoids given in high doses as dietary supplements may affect trace element, folate, and vitamin C status. Furthermore, they may exhibit antithyroid and goitrogenic activities. In this review article, the available literature on the safety issues surrounding high dose supplemental flavonoid consumption has been summarized.
Article
Full-text available
The essential trace element zinc (Zn) is widely required in cellular functions, and abnormal Zn homeostasis causes a variety of health problems that include growth retardation, immunodeficiency, hypogonadism, and neuronal and sensory dysfunctions. Zn homeostasis is regulated through Zn transporters, permeable channels, and metallothioneins. Recent studies highlight Zn's dynamic activity and its role as a signaling mediator. Zn acts as an intracellular signaling molecule, capable of communicating between cells, converting extracellular stimuli to intracellular signals, and controlling intracellular events. We have proposed that intracellular Zn signaling falls into two classes, early and late Zn signaling. This review addresses recent findings regarding Zn signaling and its role in physiological processes and pathogenesis.
Article
Full-text available
Zinc, the most abundant trace metal in the brain, has numerous functions, both in health and in disease. Zinc is released into the synaptic cleft of glutamatergic neurons alongside glutamate from where it interacts and modulates NMDA and AMPA receptors. In addition, zinc has multifactorial functions in Alzheimer's disease (AD). Zinc is critical in the enzymatic nonamyloidogenic processing of the amyloid precursor protein (APP) and in the enzymatic degradation of the amyloid- β (A β ) peptide. Zinc binds to A β promoting its aggregation into neurotoxic species, and disruption of zinc homeostasis in the brain results in synaptic and memory deficits. Thus, zinc dyshomeostasis may have a critical role to play in the pathogenesis of AD, and the chelation of zinc is a potential therapeutic approach.
Article
Full-text available
Zinc is a vital element in maintaining the normal structure and physiology of cells. The fact that it has an important role in states of cardiovascular diseases has been studied and described by several research groups. It appears to have protective effects in coronary artery disease and cardiomyopathy. Intracellular zinc plays a critical role in the redox signaling pathway, whereby certain triggers such as ischemia and infarction lead to release of zinc from proteins and cause myocardial damage. In such states, replenishing with zinc has been shown to improve cardiac function and prevent further damage. Thus, the area of zinc homeostasis is emerging in cardiovascular disease research. The goal of this report is to review the current knowledge and suggest further avenues of research.
Article
Full-text available
Bioactive proanthocyanidins have been reported to have several beneficial effects on health in relation to metabolic syndrome, type 2 diabetes, and cardiovascular disease. We studied the effect of grape seed proanthocyanidin extract (GSPE) in rats fed a high fat diet (HFD). This is the first study of the effects of flavonoids on the liver proteome of rats suffering from metabolic syndrome. Three groups of rats were fed over a period of 13 weeks either a chow diet (control), an HFD, or a high fat diet supplemented for the last 10 days with GSPE (HFD + GSPE). The liver proteome was fractionated, using a Triton X-114-based two-phase separation, into soluble and membrane protein fractions so that total proteome coverage was considerably improved. The data from isobaric tag for relative and absolute quantitation (iTRAQ)-based nano-LC-MS/MS analysis revealed 90 proteins with a significant (p < 0.05) minimal expression difference of 20% due to metabolic syndrome (HFD versus control) and 75 proteins due to GSPE treatment (HFD + GSPE versus HFD). The same animals have previously been studied (Quesada, H., del Bas, J. M., Pajuelo, D., Díaz, S., Fernandez-Larrea, J., Pinent, M., Arola, L., Salvadó, M. J., and Bladé, C. (2009) Grape seed proanthocyanidins correct dyslipidemia associated with a high-fat diet in rats and repress genes controlling lipogenesis and VLDL assembling in liver. Int. J. Obes. 33, 1007-1012), and GSPE was shown to correct dyslipidemia observed in HFD-fed rats probably through the repression of hepatic lipogenesis. Our data corroborate those findings with an extensive list of proteins describing the induction of hepatic glycogenesis, glycolysis, and fatty acid and triglyceride synthesis in HFD, whereas the opposite pattern was observed to a large extent in GSPE-treated animals. GSPE was shown to have a wider effect than previously thought, and putative targets of GSPE involved in the reversal of the symptoms of metabolic syndrome were revealed. Some of these novel candidate proteins such as GFPT1, CD36, PLAA (phospholipase A(2)-activating protein), METTL7B, SLC30A1, several G signaling proteins, and the sulfide-metabolizing ETHE1 and SQRDL (sulfide-quinone reductase-like) might be considered as drug targets for the treatment of metabolic syndrome.
Article
Full-text available
To evaluate the influence of resveratrol on cellular zinc status, normal human prostate epithelial (NHPrE) cells were treated with resveratrol (0, 0.5, 1, 2.5, 5, and 10 microM) and zinc [0, 4, 16, and 32 microM, representing zinc-deficient (ZD), zinc-normal (ZN), zinc-adequate (ZA), and zinc-supplemented (ZS) conditions, respectively]. A progressive reduction in cell growth was observed in cells treated with increasing amounts of resveratrol (2.5-10 microM). Resveratrol at 5 and 10 microM resulted in a dramatic increase in cellular total zinc concentration, especially in ZS cells. Flow cytometry indicated that 10 microM resveratrol induced arrest of the cell cycle at the G(2)/M phase in association with the observed cell growth inhibition. Data from an in vitro experiment using zinquin as an indicator of intracellular free Zn(II) status demonstrated complex interactions between resveratrol and Zn(II). Fluorescence spectrofluorometry and fluorescence microscopic analyses revealed that intracellular free labile zinc was progressively elevated from nearly twofold in ZS cells with no resveratrol to multifold in ZA and ZS cells with 10 microM resveratrol compared with the corresponding ZN cells. Furthermore, increases in cellular zinc status were associated with elevated levels of reactive oxygen species and senescence, as evidenced by morphological and histochemical changes in cells treated with 2.5 or 10 microM resveratrol, especially in ZA and ZS cells. Taken together, the interaction between resveratrol and zinc in NHPrE cells increases total cellular zinc and intracellular free labile zinc status and, subsequently, reactive oxygen species production and senescence.
Article
Full-text available
To evaluate effects of epigallocatechin-3-gallate (EGCG) on the viability, membrane properties, and zinc distribution, with and without the presence of Zn(2+), in human prostate carcinoma LNCaP cells. We examined changes in cellular morphology and membrane fluidity of LNCaP cells, distribution of cellular zinc, and the incorporated portion of EGCG after treatments with EGCG, Zn(2+), and EGCG+Zn(2+). We observed an alteration in cellular morphology and a decrease in membrane fluidity of LNCaP cells after treatment with EGCG or Zn(2+). The proportion of EGCG incorporated into liposomes treated with the mixture of EGCG and Zn(2+) at the ratio of 1:1 was 90.57%, which was significantly higher than that treated with EGCG alone (30.33%). Electron spin resonance (ESR) studies and determination of fatty acids showed that the effects of EGCG on the membrane fluidity of LNCaP were decreased by Zn(2+). EGCG accelerated the accumulation of zinc in the mitochondria and cytosol as observed by atomic absorption spectrometer. These results show that EGCG interacted with cell membrane, decreased the membrane fluidity of LNCaP cells, and accelerated zinc accumulation in the mitochondria and cytosol, which could be the mechanism by which EGCG inhibits proliferation of LNCaP cells. In addition, high concentrations of Zn(2+) could attenuate the actions elicited by EGCG.
Article
Full-text available
We have previously demonstrated that clioquinol (5-chloro-7-iodo-8-hydroxyquinoline) acts as a zinc ionophore and induces apoptosis of human cancer cells; however, the mechanisms of clioquinol/zinc-induced apoptotic cell death remain to be elucidated further. Using fluorescence-labelled probes, the present study has examined intracellular zinc distribution after clioquinol treatment in human cancer cells in order to identify cellular targets for zinc ionophores. DU 145, a human prostate cancer line, was chosen as a model system for the present study, and results were confirmed in other human cancer cell lines. Although treatment of cancer cells with 50 microM ZnCl2 for 3 days had no effect on cell viability, addition of clioquinol dramatically enhanced the cytotoxicity, confirming our previous observations. The ionophore activity of clioquinol was confirmed using fluorescence microscopy. Intracellular free zinc was found to be concentrated in lysosomes, indicating that lysosomes are the primary target of zinc ionophores. Furthermore, lysosomal integrity was disrupted after addition of clioquinol and zinc to the cells, as shown by redistribution of both Acridine Orange and cathepsin D. Clioquinol plus zinc resulted in a cleavage of Bid (BH3-interacting domain death agonist), a hallmark of lysosome-mediated apoptotic cell death. Thus the present study demonstrates for the first time that clioquinol generates free zinc in lysosomes, leading to their disruption and apoptotic cell death.
Article
Full-text available
Wilson's disease, a genetic copper-overload condition, is currently treated with zinc because of the ability of zinc to induce metallothionein. We are interested in nonmetal chemicals that may alter intestinal copper metabolism and thus help to alleviate copper toxicity. Previously, we have shown that quercetin, a dietary flavonoid, can chelate copper. This study further examined the interaction of quercetin and copper in intestinal epithelial cells. We found that quercetin enhanced metallothoinein induction by copper and the effect was dose dependent. Quercetin also exerted a cumulative effect after repeated exposure. Repeated low-dose treatment (3-10 microM) of cells with quercetin can lead to the same effect on metallothoinein as one higher concentration treatment (100 microM). This property of quercetin is distinct from its chemical interaction with copper, but both can contribute to a reduction of copper toxicity. Among other flavonoids tested, two other copper chelators, catechin and rutin, did not increase copper induction of metallothionein, whereas genistein, an isoflavone that does not interact with copper chemically, increased copper induction of metallothionein. The effect of quercetin on copper metabolism is unique. Quercetin decreased zinc-stimulated metallothionein expression and had no effect on the cadmium induction of metallothionein. The clinical application of our observation needs to be explored.
Article
Full-text available
The influence of metal ions (Fe2+, Cu2+, Zn2+) on the hepatoprotective activity of epigallocatechin gallate (EGCG) against hepatotoxin-induced cell injury was investigated. Primary cultures of rat hepatocytes were treated with a well-known hepatotoxin, bromobenzene (BB), in the presence of EGCG only or EGCG plus each metal ion. After 24 h, 0.02 mM EGCG did not show protective activity on the cultured hepatocytes. In contrast, the hepatocytes were protected against BB in the presence of 0.02 mM EGCG and 0.02 mM zinc. The addition of only zinc could not protect hepatocytes against BB. These results suggest that the formation of the zinc-EGCG complex is very important in the enhancement of the hepatoprotective activity of EGCG. The complexation of EGCG with zinc was confirmed by UV-VIS absorption spectroscopy.
Article
Full-text available
Clioquinol, a metal chelator, has been used for many years as an antimicrobial agent and more recently as a potential treatment for Alzheimer's disease. Because it binds copper and zinc, metals essential for the activity of the enzyme superoxide dismutase-1 (SOD1), a potential target for anticancer drug development, we investigated its effects on human cancer cells. Treatment with clioquinol reduced the viability of eight different human cancer cell lines in a concentration-dependent manner, with IC(50) values in the low micromolar range. Biochemical analysis revealed that clioquinol induced cancer cell death through apoptotic pathways that require caspase activity. Although clioquinol induced modest inhibition of SOD1 activity in treated cells, comparable inhibition by a known SOD1 inhibitor, diethyldithiocarbamate, did not result in cytotoxicity. The addition of copper, iron, or zinc did not rescue cells from cliquinol-induced cytotoxicity but enhanced its killing, arguing against metal chelation as its major mechanism of action. To test if clioquinol might act as an ionophore, a fluorescent probe was used to monitor intracellular zinc concentrations. The addition of clioquinol resulted in elevated levels of intracellular zinc, indicating that clioquinol acts as a zinc ionophore. In an in vivo xenografts mouse model, clioquinol inhibited tumor growth of xenografts over a 6-week period, without inducing visible toxicity. Our results show that clioquinol has anticancer effects both in vitro and in vivo. Transition metal ionophores may be a subclass of metal chelators with anticancer activity deserving of further development.
Article
The canonical transient receptor potential 6 (TRPC6) protein is a non-selective cation channel able to transport essential trace elements like iron (Fe) and zinc (Zn) through the plasma membrane. Its over-expression in HEK-293 cells causes an intracellular accumulation of Zn, indicating that it could be involved in Zn transport. This finding prompted us to better understand the role played by TRPC6 in Zn homeostasis. Experiments done using the fluorescent probe FluoZin-3 showed that HEK cells possess an intracellular pool of mobilisable Zn present in compartments sensitive to the vesicular proton pump inhibitor Baf-A, which affects endo/lysosomes. TRPC6 over-expression facilitates the basal uptake of Zn and enhances the size of the pool of Zn sensitive to Baf-A. Quantitative RT-PCR experiments showed that TRPC6 over-expression does not affect the mRNA expression of Zn transporters (ZnT-1, ZnT-5, ZnT-6, ZnT-7, ZnT-9, Zip1, Zip6, Zip7, and Zip14); however it up-regulates the mRNA expression of metallothionein-I and -II. This alters the Zn buffering capacities of the cells as illustrated by the experiments done using the Zn ionophore Na pyrithione. In addition, HEK cells over-expressing TRPC6 grow slower than their parental HEK cells. This feature can be mimicked by growing HEK cells in a culture medium supplemented with 5 μM of Zn acetate. Finally, a proteomic analysis revealed that TRPC6 up-regulates the expression of the actin-associated proteins ezrin and cofilin-1, and changes the organisation of the actin cytoskeleton without changing the cellular actin content. Altogether, these data indicate that TRPC6 is participating in the transport of Zn and influences the Zn storage and buffering capacities of the cells.
Article
Osteoarthritis (OA), primarily characterized by cartilage degeneration, is caused by an imbalance between anabolic and catabolic factors. Here, we investigated the role of zinc (Zn(2+)) homeostasis, Zn(2+) transporters, and Zn(2+)-dependent transcription factors in OA pathogenesis. Among Zn(2+) transporters, the Zn(2+) importer ZIP8 was specifically upregulated in OA cartilage of humans and mice, resulting in increased levels of intracellular Zn(2+) in chondrocytes. ZIP8-mediated Zn(2+) influx upregulated the expression of matrix-degrading enzymes (MMP3, MMP9, MMP12, MMP13, and ADAMTS5) in chondrocytes. Ectopic expression of ZIP8 in mouse cartilage tissue caused OA cartilage destruction, whereas Zip8 knockout suppressed surgically induced OA pathogenesis, with concomitant modulation of Zn(2+) influx and matrix-degrading enzymes. Furthermore, MTF1 was identified as an essential transcription factor in mediating Zn(2+)/ZIP8-induced catabolic factor expression, and genetic modulation of Mtf1 in mice altered OA pathogenesis. We propose that the zinc-ZIP8-MTF1 axis is an essential catabolic regulator of OA pathogenesis.
Article
In this work, we have studied the formation of complexes between flavonols, (quercetin, rutin, quercitrin, kaempferol, luteolin, tamarixetin) and flavanols ((+)-catechin, (−)-epicatechin), flavanonol, (+)-taxifolin, and Zn acetate in two hydro-organic media at neutral pH in the absence of oxygen. The complexation was first studied by cyclic voltammetry. Then preparative electrolysis have been attempted followed by coulometry, UV–Vis optical absorption and circular dicroism spectroscopies for characterizing the oxidized compounds. Spectroelectrochemistries monitored either in the UV–Vis or in the EPR spectrometers at room temperature have been also used and we have identified o-semi-quinone intermediates in some cases. Different behaviour vis-à-vis the complexation by Zn2+ according to the molecular structures of these different families of polyphenols have been found. Some of them are more easily oxidizible.
Article
Several pathways increase the concentrations of cellular free zinc(II) ions. Such fluctuations suggest that zinc(II) ions are signalling ions used for the regulation of proteins. One function is the inhibition of enzymes. It is quite common that enzymes bind zinc(II) ions with micro- or nanomolar affinities in their active sites that contain catalytic dyads or triads with a combination of glutamate (aspartate), histidine and cysteine residues, which are all typical zinc-binding ligands. However, for such binding to be physiologically significant, the binding constants must be compatible with the cellular availability of zinc(II) ions. The affinity of inhibitory zinc(II) ions for receptor protein tyrosine phosphatase β is particularly high (K i = 21 pM, pH 7.4), indicating that some enzymes bind zinc almost as strongly as zinc metalloenzymes. The competitive pattern of zinc inhibition for this phosphatase implicates its active site cysteine and nearby residues in the coordination of zinc. Quantitative biophysical data on both affinities of proteins for zinc and cellular zinc(II) ion concentrations provide the basis for examining the physiological significance of inhibitory zinc-binding sites in proteins and the role of zinc(II) ions in cellular signalling. Regulatory functions of zinc(II) ions add a significant level of complexity to biological control of metabolism and signal transduction and embody a new paradigm for the role of transition metal ions in cell biology.
Article
The nutritional essentiality of zinc for the growth of living organisms had been recognized long before zinc biochemistry began with the discovery of zinc in carbonic anhydrase in 1939. Painstaking analytical work then demonstrated the presence of zinc as a catalytic and structural cofactor in a few hundred enzymes. In the 1980s, the field again gained momentum with the new principle of "zinc finger" proteins, in which zinc has structural functions in domains that interact with other biomolecules. Advances in structural biology and a rapid increase in the availability of gene/protein databases now made it possible to predict zinc-binding sites from metal-binding motifs detected in sequences. This procedure resulted in the definition of zinc proteomes and the remarkable estimate that the human genome encodes ∼3000 zinc proteins. More recent developments focus on the regulatory functions of zinc(II) ions in intra- and intercellular information transfer and have tantalizing implications for yet additional functions of zinc in signal transduction and cellular control. At least three dozen proteins homeostatically control the vesicular storage and subcellular distribution of zinc and the concentrations of zinc(II) ions. Novel principles emerge from quantitative investigations on how strongly zinc interacts with proteins and how it is buffered to control the remarkably low cellular and subcellular concentrations of free zinc(II) ions. It is fair to conclude that the impact of zinc for health and disease will be at least as far-reaching as that of iron.
Article
Aims: Clioquinol is emerging as a potential therapy for some diseases, such as Alzheimer disease and cancer. This agent is a lipophilic chelator of Zn(2+). In this study, the effect of clioquinol on the intracellular Zn(2+) level was examined in order to gain insights into the toxicological profile of clioquinol. Main methods: The effect of clioquinol was estimated using a flow cytometer and FluoZin-3, a fluorescent indicator for Zn(2+), in rat thymocytes. Key findings: Clioquinol, at concentrations ranging from 10 to 300 nM, augmented FluoZin-3 fluorescence in a concentration-dependent manner. However, the effect induced by 1 μM clioquinol was less than that by 300 nM clioquinol. Removal of extracellular Zn(2+), using the membrane impermeable Zn(2+)-chelator diethylenetriamine-N,N,N',N″,N″-pentaacetic acid (DTPA), abolished the clioquinol-induced augmentation of FluoZin-3 fluorescence. Clioquinol did not augment Fluo-3 fluorescence, an indicator of intracellular Ca(2+), in the presence of DTPA. The results suggested that clioquinol caused an extracellular Zn(2+)-dependent increase in the intracellular Zn(2+) concentration. However, in the presence of DTPA, clioquinol at micromolar concentrations (1-10 μM) attenuated FluoZin-3 fluorescence in a concentration-dependent manner. Clioquinol even at 10 μM did not affect FluoZin-3 fluorescence under cell-free condition. The concentration-response relationship for the clioquinol induced change in Zn(2+) level appeared to be bell-shaped. These results indicate that micromolar concentrations of clioquinol, without chelated Zn(2+), decrease intracellular Zn(2+) concentration. Significance: The effect of clioquinol on the intracellular Zn(2+) level varies, depending on the extracellular Zn(2+) concentration and the clioquinol concentration. Clioquinol may therefore exert various types of Zn(2+)-dependent cytotoxicity.
Article
Abstract Zinc (Zn) is one of the essential trace elements and has numerous physiological functions. Zn acts as an antioxidant and also as a part of other antioxidant related proteins, such as metallothionein (MT) and Zn-copper superoxide dismutase. Zn deficiency often occurs in patients with diabetes. Therefore, the effect of Zn deficiency or Zn supplementation on diabetes-induced cardiac and renal pathogeneses has been explored. Diabetes was induced by streptozotocin (STZ) in mice and rats. Zn deficiency was induced by chronic treatment of diabetic mice with Zn chelator N,N,N,N-Tetrakis(2-pyridylmethyl)-1,2 -ethylenediamine (TPEN) for four months. For Zn supplementation study, diabetic mice or rats were treated with Zn for three months. Inflammation, fibrosis, and histopathological changes in the heart and kidney of these diabetic mice and rats were examined by Western blotting assay, immunohistochemical and fluorescent staining. Results showed that diabetes induced cardiac and renal oxidative damage, inflammation and fibrosis, which were reversed by Zn supplementation that also induced cardiac and renal MT synthesis. Furthermore, Zn deficiency was found to significantly enhance the renal damage induced by diabetes. Several clinical observations also support the preventive effect of Zn in the development of diabetic cardiomyopathy and nephropathy. Therefore, Zn plays an important role in the protection of the heart and kidney against diabetes-induced oxidative damage, inflammation, and fibrosis. These studies suggested that diabetic patients should be monitored and treated for Zn deficiency to avoid the acceleration of diabetes-induced cardiac and renal injury.
Article
The deprivation of zinc, caused by malnutrition or as a consequence of aging or disease, strongly affects immune cell functions, causing higher frequency of infections. Among other effects, an increased production of reactive oxygen species (ROS) and proinflammatory cytokines has been observed in zinc-deficient patients, but the underlying mechanisms were unknown. The aim of the current study was to define mechanisms explaining the increase in proinflammatory cytokine production during zinc deficiency, focusing on the role of epigenetic and redox-mediated mechanisms. Interleukin (IL)-1β and tumor necrosis factor (TNF)α production was increased in HL-60 cells under zinc deficiency. Analyses of the chromatin structure demonstrated that the elevated cytokine production was due to increased accessibilities of IL-1β and TNFα promoters in zinc-deficient cells. Moreover, the level of nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) oxidase-produced ROS was elevated under zinc deficiency, subsequently leading to p38 mitogen-activated protein kinase (MAPK) phosphorylation. The increased activation of p38 MAPK appeared to be necessary for posttranscriptional processes in IL-1β and TNFα synthesis. These data demonstrate that IL-1β and TNFα expression under zinc deficiency is regulated via epigenetic and redox-mediated mechanisms. Assuming an important role of zinc in proinflammatory cytokine regulation, this should encourage research in the use of zinc supplementation for treatment of inflammatory diseases.
Article
The effects of various subclasses of flavonoids, Rose Bengal, and different styrylpyridinium dyes on the magnitude of the dipole potential of membranes composed of pure phospholipids and sterol-containing bilayers were investigated. Changes in the steady-state membrane conductance induced by cation-ionophore complexes were measured to examine the changes in the dipole potential of lipid bilayers. The characteristic parameters of the Langmuir adsorption isotherm for different flavonoids and Rose Bengal and the slope of the linear dependence of the dipole potential change on the aqueous concentrations of RH dyes were estimated. Chalcones (phloretin and phloridzin) and flavonols (quercetin and myricetin) strictly decrease the dipole potential of phospholipid- and sterol-containing membranes; the unsaturation of the C-ring and the hydrophobicity of the molecule contribute to the ability of the flavonoid to reduce the bilayer dipole potential. Rose Bengal decreases the magnitude of the bilayer dipole potential to a similar extent, but its affinity for membrane lipids is higher; the effects of RH dyes, chalcones, and phloroglucinol are determined by sterol concentration and type.
Article
Essentiality of zinc for humans and its deficiency was recognized in 1963. During the past 50 years, it has become apparent that deficiency of zinc in humans is prevalent. Nutritional deficiency of zinc may affect nearly 2 billion subjects in the developing world. Consumption of cereal proteins high in phytate decreases the availability of zinc for absorption. Conditioned deficiency of zinc is also very common. Growth retardation, hypogonadism in males, rough skin, impaired immunity, neuro-sensory disorder and cognitive impairment are some of the clinical manifestations of zinc deficiency. Zinc is involved in many biochemical functions. Over 300 enzymes require zinc for their activation and nearly 2000 transcription factors require zinc for gene expression. Zinc is essential for cell mediated immunity. Zinc is also an effective antioxidant and anti-inflammatory agent. In therapeutic dosages, zinc has been used for the treatment of acute diarrhea in infants and children, common cold, Wilson's disease, sickle cell disease and for prevention of blindness in patients with age related macular degeneration.
Article
Prevention of cancer through dietary intervention recently has received an increasing interest, and dietary polyphenols have become not only important potential chemopreventive, but also therapeutic, natural agents. Polyphenols have been reported to interfere at the initiation, promotion and progression of cancer. They might lead to the modulation of proteins in diverse pathways and require the integration of different signals for the final chemopreventive or therapeutic effect. Polyphenols have been demonstrated to act on multiple key elements in signal transduction pathways related to cellular proliferation, differentiation, apoptosis, inflammation, angiogenesis and metastasis; however, these molecular mechanisms of action are not completely characterized and many features remain to be elucidated. The aim of this review is to provide insights into the molecular basis of potential chemopreventive and therapeutic activities of dietary polyphenols with emphasis in their ability to control intracellular signalling cascades considered as relevant targets in a cancer preventive approach.
Article
Epidemiological studies have described the beneficial effects of dietary polyphenols (flavonoids) on the reduction of the risk of chronic diseases, including cancer. Moreover, it has been shown that flavonoids, such as quercetin in apples, epigallocatechin-3-gallate in green tea and genistein in soya, induce apoptosis. This programmed cell death plays a critical role in physiological functions, but there is underlying dysregulation of apoptosis in numerous pathological situations such as Parkinson's disease, Alzheimer's disease and cancer. At the molecular level, flavonoids have been reported to modulate a number of key elements in cellular signal transduction pathways linked to the apoptotic process (caspases and bcl-2 genes), but that regulation and induction of apoptosis are unclear. The aim of this review is to provide insights into the molecular basis of the potential chemopreventive activities of representative flavonoids, with emphasis on their ability to control intracellular signaling cascades responsible for regulating apoptosis, a relevant target in cancer-preventive approach.
Article
There is increasing evidence that the consumption of flavonoid-rich foods can beneficially influence normal cognitive function. In addition, a growing number of flavonoids have been shown to inhibit the development of Alzheimer disease (AD)-like pathology and to reverse deficits in cognition in rodent models, suggestive of potential therapeutic utility in dementia. The actions of flavonoid-rich foods (e.g., green tea, blueberry, and cocoa) seem to be mediated by the direct interactions of absorbed flavonoids and their metabolites with a number of cellular and molecular targets. For example, their specific interactions within the ERK and PI3-kinase/Akt signaling pathways, at the level of receptors or kinases, have been shown to increase the expression of neuroprotective and neuromodulatory proteins and increase the number of, and strength of, connections between neurons. Concurrently, their effects on the vascular system may also lead to enhancements in cognitive performance through increased brain blood flow and an ability to initiate neurogenesis in the hippocampus. Additional mechanisms have been suggested for the ability of flavonoids to delay the initiation of and/or slow the progression of AD-like pathology and related neurodegenerative disorders, including a potential to inhibit neuronal apoptosis triggered by neurotoxic species (e.g., oxidative stress and neuroinflammation) or disrupt amyloid β aggregation and effects on amyloid precursor protein processing through the inhibition of β-secretase (BACE-1) and/or activation of α-secretase (ADAM10). Together, these processes act to maintain the number and quality of synaptic connections in key brain regions and thus flavonoids have the potential to prevent the progression of neurodegenerative pathologies and to promote cognitive performance.
Article
Metal-binding compounds have been shown to have anticancer activity and are being evaluated clinically as anticancer agents. We have recently found that a zinc-binding compound, 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol), kills cancer cells by transporting zinc into the cells. We therefore compared the action of clioquinol with two other cytotoxic zinc-binding compounds, N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) and pyrrolidine dithiocarbamate (PDTC). We demonstrate that metal-binding compounds can be subclassified based upon the reversibility of their cytotoxicity by metal supplementation and their modes of action. Understanding the mechanisms whereby metal-binding compounds affect cell behavior may aid in their optimization for clinical use.
Article
Polyphenolic compounds are known to possess many beneficial health effects, including the antioxidative activities of scavenging reactive oxygen species and chelating metals, such as iron and zinc. Tea and red wine are thought to be important sources of these compounds. However, some polyphenolic compounds can also reduce the absorption of iron, and possibly other trace metals, when included in a diet. There is very little information on the effect of dietary polyphenolic compounds on the status of trace elements other than iron. The effects of epigallocatechin-3-gallate (EGCG), green tea extract (GT), and grape seed extract (GSE) on the absorption of (65)Zn were examined and compared with their effects on (55)Fe absorption in human intestinal Caco-2 cells grown on microporous membrane inserts. The levels of EGCG, GT, and GSE used in this study were within physiological ranges and did not affect the integrity of the Caco-2 cell monolayers. GSE significantly (P < 0.05) reduced zinc transport across the cell monolayer, and the decreased zinc transport was associated with a reduction in apical zinc uptake. However, EGCG and GT did not alter zinc absorption. In contrast, the polyphenolic compounds in EGCG, GT, and GSE almost completely blocked transepithelial iron transport across the cell monolayer. The effect of GSE on zinc absorption was very different from that on iron absorption. Whereas GSE decreased zinc absorption by reducing apical zinc uptake, the polyphenolic compounds inhibited iron absorption by enhancing apical iron uptake. GSE inhibited zinc absorption similarly to that observed for phytate. Phytate significantly (P < 0.05) decreased transepithelial zinc transport by reducing apical zinc uptake. The inhibition of zinc absorption may be due to the presence of procyanidins in GSE, which bind zinc with high affinity and block the transport of zinc across the apical membrane of enterocytes. Further research on the absorption of zinc as zinc-polyphenol complexes and free zinc should provide further insight into the process of dietary zinc absorption in the presence of GSE and other bioactive dietary polyphenols. The present study suggests that some individuals should consider their zinc status if they regularly consume procyanidin-containing foods in their diet. However, further studies, especially in vivo studies, are needed to confirm these results.
Article
Homeostatic control maintains essential transition metal ions at characteristic cellular concentrations to support their physiological functions and to avoid adverse effects. Zinc is especially widely used as a catalytic or structural cofactor in about 3000 human zinc proteins. In addition, the homeostatic control of zinc in eukaryotic cells permits functions of zinc(II) ions in regulation and in paracrine and intracrine signaling. Zinc ions are released from proteins through ligand-centered reactions in zinc/thiolate coordination environments, and from stores in cellular organelles, where zinc transporters participate in zinc loading and release. Muffling reactions allow zinc ions to serve as signaling ions (second messengers) in the cytosol that is buffered to picomolar zinc ion concentrations at steady-state. Muffling includes zinc ion binding to metallothioneins, cellular translocations of metallothioneins, delivery of zinc ions to transporter proteins, and zinc ion fluxes through cellular membranes with the result of removing the additional zinc ions from the cytosol and restoring the steady-state. Targets of regulatory zinc ions are proteins with sites for transient zinc binding, such as membrane receptors, enzymes, protein-protein interactions, and sensor proteins that control gene expression. The generation, transmission, targets, and termination of zinc ion signals involve proteins that use coordination dynamics in the inner and outer ligand spheres to control metal ion association and dissociation. These new findings establish critically important functions of zinc ions and zinc metalloproteins in cellular control.
Article
Clioquinol was produced as a topical antiseptic and marketed as an oral intestinal amebicide in 1934, being used to treat a wide range of intestinal diseases. In the early 1970s, it was withdrawn from the market as an oral agent because of its association with subacute myelo-optic neuropathy (SMON), a syndrome that involves sensory and motor disturbances in the lower limbs and visual changes. The first methods for determining plasma and tissue clioquinol (5-chloro-7-iodo-8-quinolinol) levels were set up in the 1970s and involved HPLC separation with UV detection, these were followed by a more sensitive GC method with electron capture detection and a gaschromatographic-massspectrometric (GC-MS) method. Finally, an HPLC method using electrochemical detection has proved to be as highly sensitive and specific as the GC-MS. In rats, mice, rabbits, and hamsters, clioquinol is rapidily absorbed and undergoes first-pass metabolization to glucuronate and sulfate conjugates; the concentrations of the metabolites are higher than those of free clioquinol. Bioavailabilty versus intraperitoneal dosing is about 12%. Dogs and monkeys form fewer conjugates. In man, single-dose concentrations are dose related, and the drug's half-life is 11-14 h. There is no accumulation, and the drug is much less metabolized to conjugates. Clioquinol acts as a zinc and copper chelator. Metal chelation is a potential therapeutic strategy for Alzheimer's disease (AD) because zinc and copper are involved in the deposition and stabilization of amyloid plaques, and chelating agents can dissolve amyloid deposits in vitro and in vivo. In general, the ability of clioquinol to chelate and redistribute metals plays an important role in diseases characterised by Zn, Cu, Fe dyshomeostasis, such as AD and Parkinson's disease, as it reduces oxidation and the amyloid burden. Zinc chelators may also act as anticancer agents. Animal toxicity studies have revealed species-specific differences in neurotoxic responses that are related to the serum levels of clioquinol and metabolites. This is also true in humans, who form fewer conjugates. The results of studies of Alzheimer patients are conflicting and need further confirmation. The potential therapeutic role of the two main effects of MPACs (the regulation of the distribution of metals and antioxidants) has not yet been fully explored.
Article
The effect of red wine (RW), red grape juice (RGJ), green tea (GT), and representative polyphenols on Caco-2 cell (65)Zn uptake was explored. RW, RGJ, and GT enhanced the uptake of zinc from rice matrix. Fractionation of RW revealed that enhancing activity of zinc uptake was exclusively resided in the polyphenol fraction. Among the polyphenols tested, only tannic acid and quercitin stimulated the uptake of zinc while others did not influence the uptake. In tune with these results, only tannic acid and quercitin competed with zinquin (a zinc selective fluorophore) for zinc in vitro. Although all the polyphenols tested appear to enhance the expression of metallothionein (MT), the induction was higher with tannic acid, quercitin, and RW extract. Furthermore, phytic acid abrogated the tannic acid-induced MT expression. These results suggest that polyphenol-rich beverages, tannic acid, and quercitin bind and stimulate the zinc uptake and MT expression in Caco-2 cells.
Article
Numerous methods have been reported for the preparation of liposomes, many of which, in addition to requiring time-consuming preparative steps and the use of organic solvents, result in heterogeneous liposome populations of incontrollable size. Taking into consideration the phenomenon of spontaneous vesiculation and the theory of curvature, here we present an extremely rapid and simple, solvent-free method for the preparation of monodisperse solutions of highly stable small unilamellar vesicles using both charged and zwitterionic lipids mixed with lyso-palmitoylphosphatidylcholine, exploiting a combination of a rapid pH change followed by a defined period of equilibration. Various experimental parameters and their interactions were evaluated in terms of their effect on resulting liposome size and shape, as well as on liposome stability and size distribution, with transmission electron microscope imaging being used to visualize the formed liposomes, and photon correlation spectroscopy to obtain statistical data on mean diameter and monodispersity of the liposome population. zeta potential measurements also provided information about the interpretation of vesiculation kinetics and liposome stability. The time interval of pH jump, operation temperature, equilibration time, and lipid type were shown to be the determining factors controlling the size, shape, and monodispersity of the liposomes. Buffer type was also found to be important for the long-term storage of the liposomes. Ongoing work is looking at the application of the developed method for encapsulation of bioactive molecules, such as drugs, genetic materials, and enzymes.
Article
Changes in the free zinc(II) concentration are closely related to cell proliferation and apoptosis, especially during the early apoptotic process. In the present paper, we demonstrated that zinc(II) probe FluoZin-3AM owns sensitive properties to distinguish different stages of apoptotic cell (induced by an anticancer agent, etoposide) according to trace intracellular zinc(II) fluorescence flux. When apoptosis in HeLa or K562 cells was artificially induced, FluoZin-3AM selectively and strongly stained apoptotic cells only at early and middle stages, which was attributed to significantly increased free zinc(II) flux during these stages. This conclusion was further verified by comparing it with the conventional apoptosis detector probe Annexin-V-FITC and PI. Furthermore, FluoZin-3AM was found cell permeable to detect the intracellular zinc(II) fluorescence enhancement to threefolds within 120 s with low cytotoxicity when zinc(II) was incorporated into the cell by zinc(II) ionophore pyrithione. All the above implied that monitoring intracellular zinc fluorescence flux was an effective method to distinguish cell apoptosis from necrosis, and FluoZin-3AM was found to be a suitable probe acting alone to fulfill the work.
Article
Cancer and cardiovascular disease (CVD) chemoprevention can be achieved by the use of natural, synthetic, or biologic compounds to reverse, suppress, or prevent the development of diseases. Chemoprevention is a potential anti-cancer approach, which has reduced secondary effects in comparison to classical prophylaxis. Natural compounds such as flavonoids reduce oxidative stress, which is the most likely mechanism in the protective effects of these compounds. Even though the exact mechanisms of action are not well understood another central action mechanism of polyphenolic flavonoids seems to be an induction of apoptosis as demonstrated in numerous cellular systems. Moreover, flavonoids may modulate protein and lipid kinase signaling pathways. Understanding the mechanism of these natural products will contribute to the development of more specific preventive strategies against cancer and CVD. Much of the research in the field is focused on epigallocatechin-3-O-gallate (EGCG), quercetin and curcumin, which were found to have beneficial effects against cancer and CVD. We review the chemoprotective mechanisms through which these natural compounds exert their beneficial effects against cancer and CVDs.
Article
Green tea and its major constituent epigallocatechin gallate (EGCG) are known for their chemopreventive effects including those against prostate cancer, which could be mediated by metal ions. Zn(2+) is an essential trace element that is required for human health and plays an important role in the normal function of the prostate gland. In the present study, the effect of EGCG on cell membrane and mitochondria of PC-3 (prostate carcinoma) cells in the presence and absence of Zn(2+) was studied. These studies revealed that EGCG, Zn(2+), or EGCG + Zn(2+) affected the morphology of PC-3 cells and induced apoptosis in PC-3 cells. It was observed that effects of treatment with EGCG, Zn(2+), or EGCG + Zn(2+)on mitochondria showed EGCG + Zn(2+) > Zn(2+) > EGCG, including cytochrome C release from the intermembrane space into the cytosol, inhibited the synthesis of ATP, loss of mitochondrial membrane potential, and activation of caspase-9. However, the order of effect on depressing membrane fluidity of PC-3 cells was EGCG > EGCG + Zn(2+) > Zn(2+). In summary, these findings suggest that EGCG, Zn(2+), and EGCG + Zn(2+) induce necrosis or apoptosis of PC-3 cells through mitochondria-mediated apoptotic pathway and free Zn(2+)-enhanced effects of EGCG on PC-3 cells due to its interactions with mitochondria.
Article
Zinc, which is essential for many cellular processes, is controlled by zinc transporters and through buffering by metallothioneins and glutathione. Although zinc is increasingly implicated in disease states, little is known about how zinc regulates cellular biochemical pathways. Recent seminal articles have revealed discrete zinc-trafficking pathways that are linked to signalling cascades, particularly those involving protein phosphatase inhibition and downstream activation of mitogen-activated protein kinases and tyrosine kinases. Here, we discuss the mechanisms of cellular zinc homeostasis, and we propose an important role for the zinc transporter solute carrier family 39, member 7 (SLC39A7; commonly referred to as ZIP7). ZIP7 releases zinc from the endoplasmic reticulum and might be required for tyrosine kinase activation. These observations position ZIP7 at a critical node in zinc-mediated tyrosine kinase signalling and suggest that this protein might form a novel target for diseases such as cancer where prevention of tyrosine kinase activation would be therapeutically advantageous.
Article
The interactions of carrier ionophores, nonactin, A23187, and lasalocid A with liposomes formed from the synthetic lipids dimyristoylphosphatidylcholine and dipalmitoylphosphatidylcholine are investigated by differential scanning calorimetry and 1H and 31P nuclear magnetic resonance techniques. The results indicate that the mode of interaction of these ionophores is dependent on the fluidity of the bilayer and on the chemical nature of these ionophores. The 31P NMR studies are suggestive of the formation of small particles that are probably intervesicular lipid-ionophore aggregates in multilamellar vesicles when they are incorporated with these ionophores at high concentrations. The results are interpreted on the basis of the chemical structure and conformations of the ionophores in membrane mimetic media. The 1H NMR line-width measurements indicate that the aromatic rings containing the carboxyl groups of lasalocid A and A23187 are located near the membrane interface while the rest of the molecule is buried in the membrane interior.
Article
This review discusses evidence from human studies on the effects of dietary phytate on zinc bioavailability. In vitro and animal experiments have implicated calcium as a potentiating factor because it reacts with phytate, and zinc binds to the precipitate. Magnesium also reacts similarly to calcium, but most studies have not considered this factor. Protein provides amino acids, some of which are able to desorb zinc from the precipitate and improve bioavailability. Some predictive ratios, derived from animal studies, have been directly applied to human studies. The studies reviewed included those on: zinc status of groups, apparent absorption of zinc in normal subjects and ileostomists, true absorption using a stable isotope, plasma tolerance, and the accumulation in the body of a radioisotope. It was concluded that detrimental effects of phytate could be demonstrated on zinc bioavailability, but that the studies had not been designed specifically to demonstrate whether the interactions found in animal studies also apply to humans. It is suggested that more targeted research is required before predictive ratios are used for humans.