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,
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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.

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... Quercetin contains four phenolic groups, which make it a strong scavenger of the reactive oxygen species (ROS), antioxidant, immune booster, and anti-inflammatory substance [18]. Quercetin is also an excellent metal ionophore (antioxidative, anti-inflammatory, and immunomodulatory zinc ionophore) [19], and also increases the glutathione (antioxidant) level in the body [20]. These properties make quercetin an important therapeutic agent to prevent/treat many diseases caused by oxidative stress and the release of pro-inflammatory substances in the body ( Figure 1) [18,21,22]. ...
... Accordingly, the authors trust that the physicochemical and metabolic drug interactions of quercetin must be understood before making a combination of quercetin with other drugs/compounds. Further, quercetin is also an established metal ionophore [19]. It binds with beneficial metals like zinc, which provides a synergistic effect. ...
... The literature has highlighted interactions of quercetin Table 2. metabolic drug interactions of quercetin must be understood before making a combination of quercetin with other drugs/compounds. Further, quercetin is also an established metal ionophore [19]. It binds with beneficial metals like zinc, which provides a synergistic effect. ...
Article
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Quercetin is a phenolic flavonol compound with established antioxidant, anti-inflammatory, and immuno-stimulant properties. Recent studies demonstrate the potential of quercetin against COVID-19. This article highlighted the prophylactic/therapeutic potential of quercetin against COVID-19 in view of its clinical studies, inventions, and patents. The literature for the subject matter was collected utilizing different databases, including PubMed, Sci-Finder, Espacenet, Patentscope, and USPTO. Clinical studies expose the potential of quercetin monotherapy, and also its combination therapy with other compounds, including zinc, vitamin C, curcumin, vitamin D3, masitinib, hydroxy- chloroquine, azithromycin, and ivermectin. The patent literature also examines claims that quercetin containing nutraceuticals, pharmaceuticals, and dietary supplements, alone or in combination with other drugs/compounds, including favipiravir, remdesivir, molnupiravir, navitoclax, dasatinib, disulfiram, rucaparib, tamarixin, iota-carrageenan, and various herbal extracts (aloe, poria, rosemary, and sphagnum) has potential for use against COVID-19. The literature reveals that quercetin exhibits anti-COVID-19 activity because of its inhibitory effect on the expression of the human ACE2 receptors and the enzymes of SARS-CoV-2 (MPro, PLPro, and RdRp). The USFDA designated quercetin as a “Generally Recognized as Safe” substance for use in the food and beverage industries. It is also an inexpensive and readily available compound. These facts increase the possibility and foreseeability of making novel and economical drug combinations containing quercetin to prevent/treat COVID-19. Quercetin is an acidic compound and shows metabolic interaction with some antivirals, antibiotics, and anti-inflammatory agents. Therefore, the physicochemical and metabolic drug interactions between quercetin and the combined drugs/compounds must be better understood before developing new compositions.
... This analysis helped identify a range of compounds containing nitrogen, oxygen or sulphur functionalities ( Figure 2). In the literature, many of these compounds have hypothesised synergy with zinc, such as levamisole [30], quercetin [31], hydroxychloroquine [17] and clioquinol [32], or are currently formulated with zinc for therapeutic purposes, such as erythromycin (Zyneryt ® ), carnosine (Polaprezinc ® ), pyrithione (Head & Shoulders ® shampoo) and ascorbic acid (e.g., Beeline ® Vitamin C + Zinc). This analysis helped identify a range of compounds containing nitrogen, oxygen or sulphur functionalities ( Figure 2). ...
... This analysis helped identify a range of compounds containing nitrogen, oxygen or sulphur functionalities ( Figure 2). In the literature, many of these compounds have hypothesised synergy with zinc, such as levamisole [30], quercetin [31], hydroxychloroquine [17] and clioquinol [32], or are currently formulated with zinc for therapeutic purposes, such as erythromycin (Zyneryt ® ), carnosine (Polaprezinc ® ), pyrithione (Head & Shoulders ® shampoo) and ascorbic acid (e.g., Beeline ® Vitamin C + Zinc). ...
... The potency of CQL with respect to 8-HQ may be explained by the greater partition coefficient of CQL or indeed by the presence of the chlorine electron withdrawing groups on CQL. Figure 4 suggests that quercetin is a more potent zinc ionophore than naringenin, requiring concentrations of 0.1 and 1 mM respectively to produce the responses shown. This has been confirmed previously in liposomal assays prepared via a different methodology where quercetin again demonstrated significantly greater ionophoric activity than naringenin [21,31]. The lack of a hydroxyl group on naringenin may confer weaker affinity for zinc and may explain this difference in effect. ...
Article
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The importance of zinc in biology has gained greater recognition in recent years due to its essential contributions to the function of many endogenous enzymes. Disruption of zinc homeostasis may be useful in treating pathological conditions, such as Alzheimer’s, and for antiviral purposes. Despite the growth of knowledge and increased interest in zinc, little is known about the structure and function of zinc ionophores. In this study we analyse the Cambridge Structural Database and solution complexation studies found in the literature to identify key functional groups which may confer zinc ionophorism. Pharmaceuticals, nutraceuticals and amino acids with these functionalities were selected to enable us to explore the translatability of ionophoric activity from in vitro assays to cellular systems. We find that although certain species may complex to zinc in the solid and solution states, and may carry ions across simple membrane systems, this does not necessarily translate into ionophoric activity. We propose that the CSD can help refine key functionalities but that ionophoric activity must be confirmed in cellular systems.
... Several studies have shown that certain dietary flavonoids, especially quercetin, affect zinc uptake [61], transport [62], and homeostasis [63]. Quercetin has shown ionophore effects on zinc ions [64,65]. Dabbagh-Bazarbachi et al. found that a complex of quercetin and zinc enhances its ionophore activity and promotes intracellular transport of zinc in Hepa 1-6 cells and liposomes. ...
... ZnAF ® -2 DA indicator (Goryo Chemical, Hokkaido, Japan) was used for fluorescent staining, and the available zinc ion in each cell was measured by using a modified method of Husam Dabbagh-Bazarbachi et al. [65]. Cells were treated with 40 µM each sample for 3 h and were washed three times with HBSS, then ZnAF-2 DA adjusted to 2 µM was added, incubated at 37 • C for 1 h. ...
Article
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Quercetin forms complexes with various metals due to its structural attributes. It predominantly exhibits chelating activity at the 3-hydroxy/4-carbonyl group. Previously, coordination in synthetically obtained quercetin–zinc (II) complexes has been limited to this group. However, the expanded coordination observed in quercetin–iron complexes has opened avenues for diverse applications. Thus, synthesizing novel quercetin–zinc complexes with different coordination positions is a significant advance. In our study, we not only synthesized and comprehensively characterized a new quercetin–zinc (II) complex, Zn-Q, but also evaluated the structure and bioactivity of chelate complexes (Q+Zn) derived from co-treatment in cell culture mediums. The structure of the new compound Zn-Q was comprehensively characterized using 1D 1H and 2D correlation spectroscopy (COSY), nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV-Vis), electrospray ionization mass spectrometer (ESI-MS), and X-ray diffraction analysis (XRD) analysis. Subcellular localization and absorption of these zinc (II) complexes were determined using the ZnAF-2 DA zinc ion fluorescence probe. Throughout the experiments, both Zn-Q and Q+Zn exhibited significant antioxidant, cell growth inhibitory, and anticancer effects in HepG2 and HCT116 cells, with Zn-Q showing the highest potential for inducing apoptosis via the caspase pathway. Tracking intracellular zinc complex absorption using zinc fluorescent probes revealed zinc (II) localization around the cell nucleus. Interestingly, there was a proportional increase in intracellular quercetin absorption in conjunction with zinc (II) uptake. Our research highlights the advantages of quercetin complexation with zinc (II): enhanced anticancer efficacy compared to the parent compound and improved bioavailability of both quercetin and zinc (II). Notably, our findings, which include enhanced intracellular uptake of both quercetin and zinc (II) upon complex formation and its implications in apoptosis, contribute significantly to the understanding of metal–polyphenol complexes. Moving forward, comprehensive functional assessments and insights into its mechanism of action, supported by animal studies, are anticipated.
... QUE is a flavonol compound with a variety of biological activities, which could not only chelate divalent copper ions [18], but also scavenge free radicals. It is mainly found in vegetables and fruits such as broccoli, apples, onions, etc. ...
... As an exogenous antioxidant, it may function with the endogenous antioxidant defense system [19]. Moreover, it could promote zinc into cells as an intracellular antioxidant and enhance antioxidant capacity [18]. Studies have shown that QUE could alleviate the toxic effects of the heavy metal cadmium on the kidney [20,21] and testis [22] of rats. ...
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CuSO4 is the most commonly used feed additive in pig production at present, but long-term ingestion of excessive copper would lead to chronic copper toxicity. High copper could reduce the reproductive efficiency of sows and seriously affect the development of the pig industry. Quercetin (QUE), a powerful antioxidant, reduces toxicity of a number of heavy metals. Porcine granulosa cells (pGCs) are crucial to the fate of follicle development. The present study found that high concentrations of CuSO4 induced ROS production, which resulted in decreased mRNA expression of antioxidant-related genes GPX4, CAT, and SOD2 and increased mRNA expression of SOD1, TRX, and HO-1. The protein expression of antioxidant enzymes SOD2 and HO-1 decreased. Moreover, the concentration of MDA increased, the activity of CAT decreased, and the content of GSH decreased. After high copper treatment, the mitochondrial membrane potential (MMP) was decreased and the morphological structure was changed. However, the combined treatment with Quercetin (QUE) reversed these changes, and the level of cellular oxidative stress decreased. Therefore, we conclude that high copper has oxidative toxicity to pGCs, and QUE could remove the ROS induced by high copper, protect mitochondria from oxidative stress damage, and improve the function of pGCs.
... Hypothetically, this eff ect can be achieved with the help of other zinc ionophores (complexing ligands), such as quercitin and epigallocatechingallate [14] with much lower toxicity, although clinical trials supported by in vitro experimental studies are needed to confi rm this hypothesis. ...
... Recent studies have shown the antiviral activity against SARS-CoV-2 of the zinc ionophore -chloroquine [11][12][13], which increases the intake of zinc into body cells [12]. Such an eff ect can be achieved with the help of other less toxic ionophores (ligand complexformers) of zinc, such as quercetin and epigallocatechin gallate [14]. ...
Article
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Within the conditions of the ongoing COVID-19 pandemic, when many questions regarding prevention and treatment strategies remain unsolved and the search for the best antiviral agents is underway, attention should be paid to the role of trace elements zinc and selenium in increasing the body’s resistance to viral infections and their direct antiviral activity against SARS-CoV-2. Experimental data show that trace elements zinc and selenium not only act through regulating the immune response at all levels of humoral and cellular immunity, but also can play a significant role in adjuvant therapy for viral diseases. This is especially relevant in the case of COVID-19. Studies of the direct antiviral effect of these microelements testify to its 3 main ways to SARS-CoV-2: I — counteraction to virus replication and its transcription through: (i) their covalent binding to the SH-group of the cysteine of the main protease M(Pro) of the virus; (ii) inhibition of its RNA polymerase activity by zinc; II — preventing the penetration of the virus into cells due to blocking SH-groups of protein disulfide isomerase (RDI) of the protein of its spikes (peplomers); III — decreasing the adsorption capacity of the virus due to the blocking of the electrostatic interaction of SARS-CoV-2 peplomers and angiotensin-converting enzyme (ACE-2) in ultra-low, uncharacteristic oxidation states (Zn+1 and Se-2). The intensity of the antiviral action of these trace elements may depend on their chemical form. It was found that zinc citrate (a five-membered complex of zinc with citric acid) and monoselenium citric acid obtained with the help of nanotechnology have a greater intensity of action and higher chemical purity. Taking into account the immunostimulating and direct antiviral effect of zinc and selenium, their use in the form of pharmaceuticals and dietary supplements should be considered as adjunctive therapy for SARS-CoV-2 in patients, or as a preventive strategy for uninfected people from risk groups during the spread of COVID-19.
... In hindsight, it is now known that influenza viruses also use the RDRP protein to replicate [36], which can be inhibited with intracellular zinc ions [28,29]. Consequently, there is a mechanism of action that can explain why we should anticipate the combination of zinc with a zinc ionophore (i.e., hydroxychloroquine, or quercetin [37], or EGCG (Epigallocatechin Gallate) [38]) to inhibit the replication of the influenza viruses. Other RNA viruses, including the respiratory syncytial virus (hereafter RSV) [39] and the highly pathogenic Marburg and Ebola viruses [40,41], are also using the RDRP protein to replicate, raising the question of whether the zinc/zinc ionophore concept could also play a useful role against them. ...
... McCullough's therapeutic recommendations for handling the cytokine injury phase and the thrombosis phase of the COVID-19 illness are, for the most part, standard on-label treatments for treating hyper-inflammation and preventing blood clots. The most noteworthy innovations to the antiviral part of the protocol are the addition of ivermectin [43][44][45][46][47][48], which has 20 known mechanisms of action against COVID-19 [49], to be used as an alternative or in conjunction with hydroxychloroquine, the addition of a nutraceutical bundle [50][51][52] combined with a zinc ionophore (quercetin [37] or EGCG [38]) for both low-risk and high-risk patients, and lowering the age threshold for high-risk patients to 50 years. The MATH+ protocol [6,7], developed for hospitalized patients by Marik's group, follows the same principles of a sequenced multidrug treatment. ...
Article
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When confronted with a public health emergency, significant innovative treatment protocols can sometimes be discovered by medical doctors at the front lines based on repurposed medications. We propose a statistical framework for analyzing the case series of patients treated with such new protocols, that enables a comparison with our prior knowledge of expected outcomes, in the absence of treatment. The goal of the proposed methodology is not to provide a precise measurement of treatment efficacy, but to establish the existence of treatment efficacy, in order to facilitate the binary decision of whether the treatment protocol should be adopted on an emergency basis. The methodology consists of a frequentist component that compares a treatment group against the probability of an adverse outcome in the absence of treatment, and calculates an efficacy threshold that has to be exceeded by this probability, in order to control the corresponding p-value and reject the null hypothesis. The efficacy threshold is further adjusted with a Bayesian technique, in order to also control the false positive rate. A random selection bias threshold is then calculated from the efficacy threshold to control for random selection bias. Exceeding the efficacy threshold establishes the existence of treatment efficacy by the preponderance of evidence, and exceeding the more demanding random selection bias threshold establishes the existence of treatment efficacy by the clear and convincing evidentiary standard. The combined techniques are applied to case series of high-risk COVID-19 outpatients that were treated using the early Zelenko protocol and the more enhanced McCullough protocol.
... In hindsight, it is now known that influenza viruses also use the RDRP protein to replicate [36], which can be inhibited with intracellular zinc ions [28,29]. Consequently, there is a mechanism of action that can explain why we should anticipate the combination of zinc with a zinc ionophore (i.e., hydroxychloroquine, or quercetin [37], or EGCG (Epigallocatechin Gallate) [38]) to inhibit the replication of the influenza viruses. Other RNA viruses, including the respiratory syncytial virus (hereafter RSV) [39] and the highly pathogenic Marburg and Ebola viruses [40,41], are also using the RDRP protein to replicate, raising the question of whether the zinc/zinc ionophore concept could also play a useful role against them. ...
... McCullough's therapeutic recommendations for handling the cytokine injury phase and the thrombosis phase of the COVID-19 illness are, for the most part, standard on-label treatments for treating hyper-inflammation and preventing blood clots. The most noteworthy innovations to the antiviral part of the protocol are the addition of ivermectin [43][44][45][46][47][48], which has 20 known mechanisms of action against COVID-19 [49], to be used as an alternative or in conjunction with hydroxychloroquine, the addition of a nutraceutical bundle [50][51][52] combined with a zinc ionophore (quercetin [37] or EGCG [38]) for both low-risk and high-risk patients, and lowering the age threshold for high-risk patients to 50 years. The MATH+ protocol [6,7], developed for hospitalized patients by Marik's group, follows the same principles of a sequenced multidrug treatment. ...
Preprint
Full-text available
When confronted with a public health emergency, significant innovative treatment protocols can sometimes be discovered by medical doctors at the front lines based on repurposed medications. We propose a statistical framework for analyzing the case series of patients treated with such new protocols, that enables a comparison with our prior knowledge of expected outcomes, in the absence of treatment. The goal of the proposed methodology is not to provide a precise measurement of treatment efficacy, but to establish the existence of treatment efficacy, in order to facilitate the binary decision of whether the treatment protocol should be adopted on an emergency basis. The methodology consists of a frequentist component that compares a treatment group against the probability of an adverse outcome in the absence of treatment, and calculates an efficacy threshold that has to be exceeded by this probability, in order to control the corresponding p-value, and reject the null hypothesis. The efficacy threshold is further adjusted with a Bayesian technique, in order to also control the false positive rate. A random selection bias threshold is then calculated from the efficacy threshold to control for random selection bias. Exceeding the efficacy threshold establishes the existence of treatment efficacy by the preponderance of evidence, and exceeding the more demanding random selection bias threshold establishes the existence of treatment efficacy by the clear and convincing evidentiary standard. The combined techniques are applied to case series of high-risk COVID-19 outpatients, that were treated using the early Zelenko protocol and the more enhanced McCullough protocol.
... Consequently, there is a mechanism of action that can explain why we should anticipate the combination of zinc with a zinc ionophore (i.e. hydroxychloroquine, or quercetin [66], or EGCG [67]) to inhibit the replication of the influenza viruses. Other RNA viruses, including the respiratory syncytial virus (RSV) [68] and the highly pathogenic Marburg and Ebola viruses [69,70], are also using the RDRP protein to replicate, raising the question of whether the zinc/zinc ionophore concept could also play a useful role against them. ...
... McCullough's therapeutic recommendations for handling the cytokine injury phase and the thrombosis phase of the COVID-19 illness are, for the most part, standard on-label treatments for treating hyper-inflammation and preventing blood clots. The most noteworthy innovations to the antiviral part of the protocol are the addition of ivermectin [72][73][74][75][76][77], which has 20 known mechanisms of action against COVID-19 [78], to be used as an alternative or in conjunction with hydroxychloroquine, the addition of a nutraceutical bundle [79][80][81] combined with a zinc ionophore (quercetin [66] or EGCG [67]) for both lowrisk and high-risk patients, and lowering the age threshold for high-risk patients to 50 years. The MATH+ protocol [6,7], developed for hospitalized patients by Marik's group, follows the same principles of a sequenced multi-drug treatment. ...
Preprint
Full-text available
When confronted with a public health emergency where the pre-existing standard of care is inadequate, significant innovative treatment protocols can sometimes be discovered by medical doctors at the front lines based on repurposed medications. We propose a statistical framework for analyzing the case series of patients treated with such new protocols, that enables a comparison with our prior knowledge of expected outcomes, in the absence of treatment. The goal of the proposed methodology is not to provide a precise measurement of treatment efficacy, but to establish the existence of treatment efficacy, in order to facilitate the binary decision of whether the treatment protocol should be adopted on an emergency basis. The methodology consists of a frequentist component that compares a treatment group against the probability of an adverse outcome in the absence of treatment, and calculates an efficacy threshold that has to be exceeded by this probability, in order to control the corresponding p-value, and reject the null hypothesis. The efficacy threshold is further adjusted with a Bayesian technique, in order to also control the false positive rate. A random selection bias threshold is then calculated from the efficacy threshold to control for random selection bias. Exceeding the efficacy threshold establishes the existence of efficacy by the preponderance of evidence, and exceeding the more demanding random selection bias threshold establishes the existence of efficacy by the clear and convincing evidentiary standard. The combined techniques are applied to case series of high-risk COVID-19 outpatients, that were treated using the early Zelenko protocol and the more enhanced McCullough protocol.
... One of the interesting characteristics of cyanorona-20 structure is its clear ability to serve as a multizincophore (zinc ion carriers or zinc ionophores, e.g., chloroquine [22], hydroxychloroquine [22], quercetin [23], epigallocatechin gallate [23], and CoViTris2020/ChloViD2020 [24], transport extracellular Zn 2+ ions across the hydrophobic cell membranes to enter the living cell, and have been studied mainly for their antiviral activities, as they have been shown to eff ectively inhibit the replication of various viruses in vitro [25]). Zn 2+ inhibits coronavirus RdRp activity (i.e., inhibits coronaviral replication and transcription) in vitro (Zn 2+ ion is the only known elemental cofactor and ligand present in the crystal structure of SARS-CoV-2 RdRp and, thus, it has an extremely important role in controlling/ regulating the activity of this COVID-19 RNA-synthesizing enzymatic machine) and, therefore, zinc ionophores have been shown to successfully hinder the replication process of coronaviruses intracellularly in cell cultures [26][27][28]. ...
... One of the interesting characteristics of cyanorona-20 structure is its clear ability to serve as a multizincophore (zinc ion carriers or zinc ionophores, e.g., chloroquine [22], hydroxychloroquine [22], quercetin [23], epigallocatechin gallate [23], and CoViTris2020/ChloViD2020 [24], transport extracellular Zn 2+ ions across the hydrophobic cell membranes to enter the living cell, and have been studied mainly for their antiviral activities, as they have been shown to eff ectively inhibit the replication of various viruses in vitro [25]). Zn 2+ inhibits coronavirus RdRp activity (i.e., inhibits coronaviral replication and transcription) in vitro (Zn 2+ ion is the only known elemental cofactor and ligand present in the crystal structure of SARS-CoV-2 RdRp and, thus, it has an extremely important role in controlling/ regulating the activity of this COVID-19 RNA-synthesizing enzymatic machine) and, therefore, zinc ionophores have been shown to successfully hinder the replication process of coronaviruses intracellularly in cell cultures [26][27][28]. ...
Article
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Evident inhibition/blockade of the viral RNA-dependent RNA polymerase (RdRp) of the newly-emerged fatal Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is considered one of the most promising and efficient approaches for developing highly potent remedies for Coronavirus Disease 2019 (COVID-19). However, almost all of the reported viral RdRp inhibitors (either repurposed or new antiviral drugs) lack specific selectivity against the novel coronaviral-2 RdRp and still at a beginning phase of advancement. In this complementary research study, the new pyrazine derivative cyanorona-20 was revisited with an update about its synthetic and toxicological data. This promising selective specific anti-COVID-19 compound is deemed to be the first distinctive derivative of favipiravir. Cyanorona-20, the unrivalled nucleoside/nucleotide analog, was designed, synthesized, characterized, computationally studied, and biologically evaluated for its anti-COVID-19/cytotoxic actions. The results of the biological assay displayed that cyanorona-20 surprisingly exhibited very high and largely significant anti-COVID-19 activities (anti-SARS-CoV-2 EC50 = 0.45 μM), and, in addition, it could be also a very promising guide and lead compound for the design and synthesis of new anti-SARS-CoV-2 and anti-COVID-19 agents through structural modifications and further computational studies. Further appraisal for the improvement of cyanorona-20 medication, through performing deeper in vivo biological evaluations and extensive clinical trials, is a prerequisite requirement in the coming days. In this short communication paper, the comprehensive chemicobiological data and information about the "Corona Antidote", cyanorona-20 compound, were briefly and collectively revisited and the synthetic and pharmacotoxicological data were updated.
... In hindsight, it is now known that influenza viruses also use the RDRP protein to replicate [36], which can be inhibited with intracellular zinc ions [28,29]. Consequently, there is a mechanism of action that can explain why we should anticipate the combination of zinc with a zinc ionophore (i.e., hydroxychloroquine, or quercetin [37], or EGCG (Epigallocatechin Gallate) [38]) to inhibit the replication of the influenza viruses. Other RNA viruses, including the respiratory syncytial virus (hereafter RSV) [39] and the highly pathogenic Marburg and Ebola viruses [40,41], are also using the RDRP protein to replicate, raising the question of whether the zinc/zinc ionophore concept could also play a useful role against them. ...
... McCullough's therapeutic recommendations for handling the cytokine injury phase and the thrombosis phase of the COVID-19 illness are, for the most part, standard on-label treatments for treating hyper-inflammation and preventing blood clots. The most noteworthy innovations to the antiviral part of the protocol are the addition of ivermectin [43][44][45][46][47][48], which has 20 known mechanisms of action against COVID-19 [49], to be used as an alternative or in conjunction with hydroxychloroquine, the addition of a nutraceutical bundle [50][51][52] combined with a zinc ionophore (quercetin [37] or EGCG [38]) for both low-risk and high-risk patients, and lowering the age threshold for high-risk patients to 50 years. The MATH+ protocol [6,7], developed for hospitalized patients by Marik's group, follows the same principles of a sequenced multidrug treatment. ...
Preprint
When confronted with a public health emergency, significant innovative treatment protocols can sometimes be discovered by medical doctors at the front lines based on repurposed medications. We propose a very simple hybrid statistical framework for analyzing the case series of patients treated with such new protocols, that enables a comparison with our prior knowledge of expected outcomes, in the absence of treatment. The goal of the proposed methodology is not to provide a precise measurement of treatment efficacy, but to establish the existence of treatment efficacy, in order to facilitate the binary decision of whether the treatment protocol should be adopted on an emergency basis. The methodology consists of a frequentist component that compares a treatment group against the probability of an adverse outcome in the absence of treatment, and calculates an efficacy threshold that has to be exceeded by this probability, in order to control the corresponding p-value, and reject the null hypothesis. The efficacy threshold is further adjusted with a Bayesian technique, in order to also control the false positive rate. A selection bias threshold is then calculated from the efficacy threshold to control for random selection bias. Exceeding the efficacy threshold establishes efficacy by the preponderance of evidence, and exceeding the more demanding selection bias threshold establishes efficacy by the clear and convincing evidentiary standard. The combined techniques are applied to case series of high-risk COVID-19 outpatients, that were treated using the early Zelenko protocol and the more enhanced McCullough protocol. The resulting efficacy thresholds are then compared against our prior knowledge of mortality and hospitalization rates of untreated high-risk COVID-19 patients, as reported in the research literature.
... The host cell's Mx proteins act as "gatekeepers" against RNA viruses and other groups of viruses that reproduce within the host nucleus [63]. Zinc cation transport across the plasma membrane can be aided by polyphenols even without zinc transport proteins in the plasma membrane [64]. The viral RNA-dependent RNA polymerase can be inhibited by Zn cations [65]. ...
Chapter
Traditional medicine and nutritional supplements have long used propolis, a honeybee resin. However, recent preclinical studies have shown that propolis may have a wide range of therapeutic bioactivities, such as protecting neurons from damage, reducing inflammation, fighting cancer, and preventing the spread of viruses. There is encouraging preclinical evidence that propolis and its constituents can inhibit the growth of several viruses, including adenoviruses, influenza, respiratory tract viruses, herpes simplex virus types 1 and 2, HIV, and SARS-CoV-2. Terpenes, flavonoids, and phenolic acids are only a few of the more than 300 chemical components found in propolis; however, the exact composition varies greatly depending on the place of origin and the flora found there. Through influencing many pathogenic and antiviral pathways, propolis and its components have shown promise as a treatment for SARS-CoV-2.
... Other natural products such as the polyphenols epigallocatechin-3-gallate, quercetin, and resveratrol have been described as zinc ionophores. 170,171 Phytonutrients modulate zinc uptake in mammals, either enhancing it or competing with zinc uptake by virtue of their chelating properties, eg, phytate, a major competitor of zinc uptake. Serving as a chelating agent imparts additional bioactivity to some nutrients such as being bactericidal and fungicidal in our gut. ...
Article
Full-text available
Natural products include inorganic as well as organic compounds. Living organisms face constant challenges in acquiring essential metal ions and getting rid of non-essential ones with toxic actions. They employ an extracellular biochemistry in these tasks and use it to engage in a chemical warfare against invaders and competitors by either increasing or decreasing the availability of metal ions for maintaining their welfare in aquatic or terrestrial ecological niches. To control mutualistic, cambialistic or parasitic symbiosis with other organisms they use a remarkably rich suite of secreted bioactive molecules with ligand donor atoms for metal binding. This overview discusses the interactions of these extracellular natural products with a multitude of metal ions in the periodic system of the elements. It focuses mainly on metallophores and metal ionophores secreted from bacteria, fungi, and plants, but metal-carrying cofactors and other chelating agents will also be mentioned in the context of related functions and with an intent to categorize. The intracellular fate of the metal ions and the controlled pathways for the biosynthesis, secretion, uptake, biodegradation or recycling of the secreted natural products that interact with metal ions will not be covered. Metallophores make extracellular metal ions available via delivery to specific transporters and unavailable to competing organisms, especially pathogens, though some invaders have developed ways to compete efficiently for metal ions. The classic concept of siderophores, carriers of iron(III) ions, is extended here to specific and broad-band metallophores for metal ions such as copper (chalkophores), zinc (zincophores), and yet others. Metal ionophores, in contrast, transport metal ions through biological membranes. There is a wide variety of chemical structures for either metallophores or metal ionophores. Together with physicochemical investigations of metal complexation und conditions mimicking the natural environment, “omics” mining and mapping the diversity of chemotypes is an on-going effort with analytic, genetic, and bioinformatic tools and comes together in defining the metallometabolome, which combines the metabolome and the metallome. Investigations are highly multidisciplinary, include an important, but academically infrequently crossed bridge between the biosciences (biochemistry) and the earth sciences (geochemistry), define significant applications in the pharmaceutical/medical sciences regarding immune modulation and the control of virulence at the host-pathogen interface, and have implications for the nutritional/toxicological and environmental/ecological sciences.
... 17 It has also been shown to act as a zinc ionophore and increase the entry of zinc into cells to inhibit viral intracellular replication. 45 According to the results of a randomized controlled trial by Di Pierro et al. 22 discussed in the current review, they observed that the intake of 1500 mg/day of quercetin Phytosome® in the first week and 1000 mg/day of quercetin in the second week (corresponding to 600 mg and 400 mg of quercetin per day, respectively) in addition to standard treatment for 2 weeks disclosed the ability to clear the COVID-19 virus and improve clinical symptoms, and statistically shortened the rate of conversion of RT-PCR test from positive to negative. 22 The shortening of the conversion rate of the RT-PCR test from positive to negative was consistent with the recording of complete clinical remission in the quercetin and placebo groups on the 7 th and 17 th days, respectively, in the study of Rondanelli et al. 23 . ...
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Objectives: The COVID-19 pandemic has rapidly become a global health crisis. Currently, there are no proven, reliable, specific treatments for COVID-19. Alongside drug interventions, supportive treatments are implemented during the disease. Quercetin, recognized for its antiviral, anti-inflammatory, anti-aging, and antioxidant properties, is under evaluation in this study for its potential impact on preventing, influencing the course, and mitigating the severity of COVID-19. Methods: A thorough search was conducted across scientific databases, including PubMed, Embase, Web of Science, SAGEpub, Copernicus, Cochrane Library, ScienceDirect, Elsevier, Scopus, Google Scholar, EBSCOhost, Crossref, Ovid-LWW, and DergiPark databases, between 1 November 2021 and 1 April 2022 to ensure a comprehensive inclusion of relevant studies. Results: Thirteen randomized controlled clinical trials (five published, eight unpublished) were identified. Existing literature supports quercetin’s role as a potent free radical scavenger with robust antioxidant properties. It exhibits anti-inflammatory characteristics by inhibiting lipid peroxidation and restraining pro-inflammatory enzymes such as lipoxygenase and phospholipase A2. Scholarly discourse suggests that quercetin supplementation within the 500-1500 mg range leads to favorable outcomes, including quicker patient discharge, reduced inflammation, increased respiratory rate, accelerated viral clearance, and an improved disease prognosis. However, it is noted that intervention durations vary across studies. Conclusions: The analysis of the studies suggested that quercetin is a promising therapeutic agent that can cause a decrease in disease symptoms, frequency of hospitalization, hospital stay, need for non-invasive oxygen treatment, need for intensive care, and mortality. Nonetheless, more clinical studies are needed to better understand quercetin’s curative effects on COVID-19 infection.
... Epigallocatechin-gallate (EGCG) is a representative phytochemical known for its biological action owing to its ionophore activity in liposomes [50]. Along with EGCG, quercetin also shows high potency, such as increased Zn metabolism and accumulation of intracellular labile Zn by regulating Zn transporters [51]. The presence of Zn cations also regulates the bioactivity and stability of EGCG. ...
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Artemisia annua L. is a well-known therapeutic herb that is widely used in folk medicine in Asian and African countries. A. annua can alleviate fever, wounds, and inflammation and is also popular as an anti-malarial agent. Cu and Zn are essential nutrients for human wellness and are vital to plants; they sometimes act as elicitors and induce stress mechanisms in plants to stimulate the production of secondary metabolites, which have bioactivities. Therefore, we added Cu or Zn to a nutrient solution and cultivated A. annua to enhance the Cu or Zn content. The Cu or Zn treatment during A. annua cultivation elevated their accumulation, and Zn showed a dramatic accumulation level in harvests. The aerial part of Zn16X contained 35 times higher Zn content than that of the control. Although the Cu or Zn contents were elevated, the plant height and yield were not affected, indicating the absence of toxic effects. The Cu or Zn treatment decreased the artemisinin content; however, these treatments increased the amounts of phenolic acids and flavonoids in A. annua. In particular, Zn4X showed a notable increase in the phenolic acids and flavonoids amounts. Moreover, the contents of certain types of caffeoylquinic acids were also highly elevated in Zn4X. Overall, Cu or Zn treatment in A. annua increased Cu or Zn accumulation and stimulated phenolic acid and flavonoid synthesis, which may have enhanced the therapeutic efficacy of A. annua.
... In addition, Quercetin has been shown to reduce tumor necrosis factor-alpha (TNF-α) production with chronic inflammation [7]. Reduction in the ratio of CD4 + :CD8 + T cells and suppression of macrophages, dendritic, mast cells, and interleukin-6 (IL-6) levels were revealed after a specific tissue was treated with Quercetin in pre-clinical studies ( Figure 1) [8][9]. Besides, Quercetin is expected to have an antiviral activity by acting as a zinc chelator and zinc ionophore [10]. ...
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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.
... In addition, Quercetin has been shown to reduce tumor necrosis factor-alpha (TNF-α) production with chronic inflammation [7]. Reduction in the ratio of CD4 + :CD8 + T cells and suppression of macrophages, dendritic, mast cells, and interleukin-6 (IL-6) levels were revealed after a specific tissue was treated with Quercetin in pre-clinical studies ( Figure 1) [8][9]. Besides, Quercetin is expected to have an antiviral activity by acting as a zinc chelator and zinc ionophore [10]. ...
Article
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Coronavirus disease 2019 (COVID-19) is an infectious disease caused by a new strain of coronavirus, SARS-CoV-2. There are three phases of COVID-19: early infection stage, pulmonary stage, and hyper-inflammation stage. It is essential to prevent lung or other organ injuries by preventing phase-II and phase-III using pharmacological or non-pharmacological treatments. This case series study aims to evaluate the safety and efficacy of Quercetin, Bromelain, zinc, and vitamin C combination supplements in patients with COVID-19. In this study, twenty-two patients diagnosed (mean age 49.27, 68.18% male) with COVID-19 in Imam Abdulrahman Alfaisal Hospital in Riyadh have administrated Quercetin 800 mg, Bromelain 165 mg, zinc acetate 50 mg, and vitamin C 1 g once daily as supplements for 3 to 5 days. The mean levels of WBC, ANC, ALC, AMC, and AST, D dimer were measured to investigate the safety of the used treatment. we planned to measure how long stay at the hospital, Chemistry profiles like D dimer, serum ferritin, CRP, serum zinc, and interleukin 6 as planned in the protocol and measured not done for all parameters like zinc, and interleukin 6 were not done as unavailable facilities at lab of hospital Their mean values were normal among all included patients before and after taking the supplements. Therefore, the oncedaily administration of these supplements was found to be safe for patients infected with SARSCoV- 2 and may prevent the poor prognosis of the disease. Randomized clinical trials are needed in the future to ensure the efficacy of Quercetin, Bromelain, zinc, and vitamin C combination. The study was registered at clinicaltrials.gov with the identifier: NCT04468139.
... A study revealed a 50-95% decrease in viral genome replication by zinc picolinate combined with herbal polyphenols such as epigallocatechin-3-gallate (EGCG), quercetin (QCT) and taxifolin which act as zinc ionophores in HCoV-OC43 infected A549, H1299 and Vero cells [108]. Likewise, in liposomal model systems and Hepa 1-6 cells, quercetin and EGCG exhibited zinc ionophore activity by triggering a rapid uptake of FluoZin-3 within the liposomes and Hepa cells [109]. Using various plant polyphenols as zinc ionophores could inhibit SARS-CoV-2 infection and other emerging variants and are relatively safe. ...
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The emergence of SARS-CoV-2 and its variants have posed a significant threat to humankind in tackling the viral spread. Furthermore, currently repurposed drugs and frontline antiviral agents have failed to cure severe ongoing infections effectively. This insufficiency has fuelled research for potent and safe therapeutic agents to treat COVID-19. Nonetheless, various vaccine candidates have displayed a differential efficacy and need for repetitive dosing. The FDA-approved polyether ionophore veterinary antibiotic for treating coccidiosis has been repurposed for treating SARS-CoV-2 infection (as shown by both in vitro and in vivo studies) and other deadly human viruses. Based on selectivity index values, ionophores display therapeutic effects at sub-nanomolar concentrations and exhibit selective killing ability. They act on different viral targets (structural and non-structural proteins), host-cell components leading to SARS-CoV-2 inhibition, and their activity is further enhanced by Zn²⁺ supplementation. This review summarizes the anti-SARS-CoV-2 potential and molecular viral targets of selective ionophores like monensin, salinomycin, maduramicin, CP-80,219, nanchangmycin, narasin, X-206 and valinomycin. Ionophore combinations with Zn²⁺ are a new therapeutic strategy that warrants further investigation for possible human benefits.
... Glycyrrhizin, a component of licorice, has been shown to be functional as a broad-spectrum antiviral 28 . Quercetin ($188 US per patient) is an anti-oxidant found in many fruits and vegetables that has been shown to be active against COVID-19 29 ; it also has been shown to be a zinc ionophore 30 . Paxlovid (nirmatrelvir-ritonavir; $46,111 US per patient) was developed by Pfizer pharmaceuticals as a combination drug that interferes with SARS-CoV-2 replication by inhibition of the main viral protease (mPro) 31 ; it is now widely used but shows only modest activity against COVID-19 somewhat like remdesivir in therapeutic profile 25 . ...
Article
COVID-19 disease is caused by the Betacoronavirus, SARS-CoV-2. This virus gave rise to 676 million confirmed cases with 6.9 million deaths worldwide by early 2023. After first appearing in Wuhan, China in late 2019, the virus has mutated into seven successive major forms with progressive increases in infectivity: Alpha, Beta, Delta, Omicron, and Omicron variants BA.4, BA.5, and XBB.1.5. Liposomal mRNA vaccines have been developed against SARS-CoV-2. Many of these received Emergency-use Authorization, and all have been highly promoted by civil authorities and the media. On the other hand, therapeutics against COVID-19 have been developed, but some of these have been severely suppressed, even by reliance on retracted papers. Our laboratory found that chlorpheniramine maleate, an over-the- counter antihistamine, was active against the Coronavirus through drug-database searches, molecular modeling, and a preliminary retrospective clinical-study. The manuscript that described this work was rejected by several journal editors without peer review, thus providing further direct evidence for suppression of small-molecule therapeutics. Epidemiologic study of death statistics in the VAERS database showed that 19,710 people lost their lives after COVID-19 vaccination; mortality from all other common vaccines does not sum to even 20% of this staggering value. The vaccine has also been responsible for significant morbidity. A consensus has begun to develop among physicians and scientists that COVID-19 disease and vaccination both result in chronic symptoms in many people, now called “Long COVID” or “Long-hauler’s syndrome”. Thus, vaccination does not appear to be a reasonable approach to combat COVID-19 disease. In view of this, development, testing, and approval or repurposing of therapeutics is imperative, especially as we observe recent increases in mortality due to COVID-19 Omicron XBB.1.5. Chlorpheniramine maleate, an over-the-counter medication, is uniquely positioned to serve as a broad-spectrum antiviral against SARS-CoV-2 and other viruses in this post- pandemic age.
... There is evidence to suggest that green tea extract, with its major constituent EGCG, holds great potential in the prevention and treatment of COVID-19 and its sequelae [29]. EGCG has also been shown to act as a zinc ionophore and could improve the cellular utilization of zinc [30]. Symptoms of long COVID may resemble those seen in zinc and vitamin D defi ciency [31]. ...
Article
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Tea and ascorbic acid have antioxidative and anti-inflammatory effects, and vitamin D and zinc have immunomodulatory effects. This study investigated the effect of a nutraceutical prescription combining these four nutrients on the blood biochemical markers and the modified C19-YRS questionnaires in patients who had recovered from COVID-19 disease for four months. Analysis of six markers associated with long COVID symptoms, i.e., INR, d-dimer, hs-CRP, NT-ProBNP, IL-6 and IgA, indicated that the nutraceutical could positively affect the values, especially for the inflammatory markers. The physician’s clinical observation and questionnaire analysis reported significant improvements in post-exertional malaise, sleep quality and overall health of the patients. These results suggested that formulated nutraceutical could not only reduces or eliminates the symptom of long COVID, but potentially also prevents reinfection.
... One major off-target interaction of polyphenols is their ability to bind and inhibit the activity of certain drug metabolizing enzymes [220,221]. Some polyphenols have also been reported to modulate estrogen receptors and may exhibit estrogen-like effects [222][223][224][225]. Polyphenols also have the ability to interfere with nutrient absorption and metabolism in the body, especially, chelating iron and zinc, thereby inhibiting their absorption [226,227]. While this can be beneficial in preventing iron overload in patients with hemochromatosis, it can also lead to iron deficiency anemia in individuals with poor iron status. ...
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Altered RNA editing has been linked to several neurodevelopmental disorders, including autism spectrum disorder (ASD) and intellectual disability, in addition to depression, schizophrenia, some cancers, viral infections and autoimmune disorders. The human ADAR2 is a potential therapeutic target for managing these various disorders due to its crucial role in adenosine to inosine editing. This study applied consensus scoring to rank potential ADAR2 inhibitors after performing molecular docking with AutoDock Vina and Glide (Maestro), using a library of 35,161 compounds obtained from traditional Chinese medicine. A total of 47 compounds were predicted to be good binders of the human ADAR2 and had insignificant toxicity concerns. Molecular dynamics (MD) simulations, including the molecular mechanics Poisson–Boltzmann surface area (MM/PBSA) procedure, also emphasized the binding of the shortlisted compounds. The potential compounds had plausible binding free energies ranging from −81.304 to −1068.26 kJ/mol from the MM/PBSA calculations. ZINC000085511995, a naphthoquinone had more negative binding free energy (−1068.26 kJ/mol) than inositol hexakisphosphate (IHP) [−873.873 kJ/mol], an agonist and a strong binder of ADAR2. The potential displacement of IHP by ZINC000085511995 in the IHP binding site of ADAR2 could be explored for possible deactivation of ADAR2. Bayesian-based biological activity prediction corroborates the neuropharmacological, antineoplastic and antiviral activity of the potential lead compounds. All the potential lead compounds, except ZINC000014612330 and ZINC000013462928, were predicted to be inhibitors of various deaminases. The potential lead compounds also had probability of activity (Pa) > 0.442 and probability of inactivity (Pi) < 0.116 values for treating acute neurologic disorders, except for ZINC000085996580 and ZINC000013462928. Pursuing these compounds for their anti-ADAR2 activities holds a promising future, especially against neurological disorders, some cancers and viral infections caused by RNA viruses. Molecular interaction, hydrogen bond and per-residue decomposition analyses predicted Arg400, Arg401, Lys519, Trp687, Glu689, and Lys690 as hot-spot residues in the ADAR2 IHP binding site. Most of the top compounds were observed to have naphthoquinone, indole, furanocoumarin or benzofuran moieties. Serotonin and tryptophan, which are beneficial in digestive regulation, improving sleep cycle and mood, are indole derivatives. These chemical series may have the potential to treat neurological disorders, prion diseases, some cancers, specific viral infections, metabolic disorders and eating disorders through the disruption of ADAR2 pathways. A total of nine potential lead compounds were shortlisted as plausible modulators of ADAR2.
... 12,[21][22][23][24][25] Medicinal plants, especially those employed in traditional Chinese medicine, have attracted significant attention because they include bioactive compounds that could be used to develop legal drugs against several diseases with no or minimal risks. 26 Two medicinal naturally occurring materials were chosen; Flavonoid quercetin, an antioxidant and signaling molecule and an effective Zinc ionophore, 27 and Curcumin, a medical herb with powerful antioxidant, anti-inflammatory, 28 antimutagenic, antimicrobial, 29,30 and anticancer properties. 31 We utilized two computational drug design methodologies to propose an efficient blocking and viable treatment for COVID-19. ...
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This research theoretically modeled the binding interaction of the Sars-Cov-2 (Spike protein) utilizing molecular docking with some potential repurposed antiviral medications and two botanical products (Curcumin and Quercetin). Molecular docking between the drugs and the Sars-Cov-2 proteins reflecting the pure electrostatic forces and H-bond formation is complemented with the DFT results that shed light on the electronic nature of the interactions. Moreover, DFT computations provide invaluable information about the drug reactivity indices calculated from the energies of the frontier orbitals. The DFT results indicate intermolecular electron donor-acceptor interaction besides the H-bond formation. Most of the considered medication molecules act as electron-sink candidates except EIDD-2801 (molnupiravir), the electron donor. The theoretical results show the high possibility of blocking the human cellular entry against Sare-Cov-2 via strong interaction of the drugs with its peptide sequence (b 6) measured by the high binding energy of docking or weakening its activity due to the electronic donor-acceptor interactions indicated by reactivity indices computed from the frontier molecular orbitals. ARTICLE HISTORY
... IgG is only one of many zinc-binding proteins in the blood, such as other immunoglobulins (IgM and IgA), albumin, α2-macroglobulin, haptoglobulin, fibrinogen, ceruloplasmin, complement C4, prealbumin, and C-reactive protein (Yamanaka et al. 2016). These proteins, together with other zinc-binding nutrients in the blood, such as the bioflavonoid quercetin, will maintain the 'free' zinc levels to facilitate cellular uptake by the ZIP transporters (Singh et al. 2021;Dabbagh-Bazarbachi et al. 2014;Haase and Rink 2014). Free zinc is a potent inhibitor of the SARS-CoV-2 main protease at nanomolar concentrations and is an inhibitor of viral replication (Panchariya et al. 2021). ...
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Multiple nutritional deficiencies (MND) confound studies designed to assess the role of a single nutrient in contributing to the initiation and progression of disease states. Despite the perception of many healthcare practitioners, up to 25% of Americans are deficient in five-or-more essential nutrients. Stress associated with the COVID-19 pandemic further increases the prevalence of deficiency states. Viral infections compete for crucial nutrients with immune cells. Viral replication and proliferation of immunocompetent cells critical to the host response require these essential nutrients, including zinc. Clinical studies have linked levels of more than 22 different dietary components to the likelihood of COVID-19 infection and the severity of the disease. People at higher risk of infection due to MND are also more likely to have long-term sequelae, known as Long COVID.
... High intracellular concentrations of zinc inhibit the replication of SARS-CoV-2 by blocking RNA-dependent RNA polymerase [27]. Some natural ionophores, such as dietary plant polyphenols quercetin (red raspberry, black grapes, broccoli, and red onion) and epigallocatechin-gallate (tea), rapidly increased cell concentrations of zinc [28]. ...
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The COVID-19 pandemic enforced societies to rapidly restructure industrial, social security, and public health care processes. Several countries, where organized anti-epidemic measures were implemented, indicated the efficacy of strict adherence to measures that flexibly balance between self-isolation and social distancing. The population group at the highest risk of mortality and morbidity, most susceptible to infection, and the impaction by stress factors - the elderly - is at the same time strongly endangered by social deprivation, mental health decrease, and suicide. It is thus especially important to establish safe leisure environments and create comfortable conditions for the elderly who live alone. Optimally, a correctly selected set of measures should facilitate efficient use of the free time to enforce physical and mental health, including aspects crucial for the individual quality of life. Here, we propose such a setting of approaches based on the pandemic experience in Russia. We outline general and specific management options that tackle the subpopulation of the elderly, rendering a positive effect on the health status of all citizens, thus at the level of public health.
... Taken together these results suggest that Yak1p promotes Cys4p activity through its kinase activity and that, in the absence of Yak1p, Cys4p activity is reduced. Interestingly, we observed that epigallocatechin-3-gallate (EGCG), an inhibitor of Dyrk1A (De la Torre et al., 2014), which is also a zinc ionophore (Dabbagh-Bazarbachi et al., 2014), increased intracellular pH in both CYS4-OE and WT strains (Supp Fig. 4B), suggesting that common therapeutical leads aiming at decreasing both DYRK1A and CBS activities could be investigated. ...
Thesis
La Cystathionine β-Synthase (CBS) est une enzyme dérégulée dans deux pathologies caractérisées par une déficience intellectuelle : l’homocystinurie, majoritairement causée par des mutations homozygotes de CBS, et le syndrome de Down (trisomie 21), où CBS est tripliqué du fait de sa localisation sur le chromosome 21. Les travaux présentés dans cette thèse rapportent dans un premier temps l’implication de la triplication de CBS dans le phénotype cognitif de souris, ce qui fait de CBS une cible thérapeutique pertinente pour diminuer déficience intellectuelle des patients atteints du syndrome de Down. Nous rapportons par ailleurs le développement d’un modèle levure de la surexpression de ce gène, qui nous a permis d’isoler des molécules pharmacologiques capables de contrecarrer les défauts induits par la surexpression de la CBS de levure (CYS4). L’une des molécules candidates issue de ce criblage en levure s’est révélé efficace pour restaurer le fonctionnement cognitif des souris ayant une triplication de CBS. En outre, nous avons mis en évidence les conséquences cellulaires de la surexpression de CYS4 dans notre modèle, et étudié le mécanisme d’action des molécules isolées lors du criblage pharmacologique. Ces travaux révèlent que la surexpression de CYS4 affecterait l’homéostasie des acides aminés dans la cellule, ce qui conduirait à une inactivation de la voie TORC1, aggravant les défauts d’internalisation des acides aminés. Nous avons également observé que la modulation de CYS4 perturbe le pH cytosolique des levures, phénotype qui n’avait pas été rapporté auparavant. Ainsi, ces travaux ont permis de mieux caractériser les conséquences cellulaires de la modulation de CYS4, et de proposer des molécules candidates pour corriger ces défauts.
... As regards SARS-CoV-2 infections, known zinc ionophores of zinc are quercetin (Annweile et al., 2020) and epigallocatechin-gallate (Armogida et al., 2012) (Figure 3), both natural antioxidants, the former being also an antiviral, and the latter both an antioxidant and a signaling molecule. Those natural compounds play the same role as chloroquine and hydroxychloroquine, favoring the uptake of endogenous zinc by cells and increasing the content of the element in the cell (Dabbagh-Bazarbachi et al., 2014). It could be made assumption that nutritional antioxidants that can behave as zinc chelators could be used in enhancing the uptake of zinc by, and into cells, and might contribute to mitigate the severity of SARS diseases. ...
... Pomegranate is one of the best-known sources of Zinc among common fruits. Quercetin and epigallocatechin-gallate found in the extract of pomegranate fruit function as a zinc ionophore to facilitate the transportation of zinc across the cell membrane [104]. Therefore, it could be suggested that the consumption of pomegranate fruit extract rich in Zinc could help in reducing the viral replication and the viral load which directly correlates with the clinical outcome of the infected individual. ...
Article
COVID-19 is a viral disease caused by Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which has rapidly spread across the world causing a global health crisis. Due to the paucity of therapeutics against SARS-CoV-2, there is an urgent need for the identification of safe and effective treatments for this global pandemic. Thus, existing anti-viral and immunosuppressive drugs, are being evaluated as potential candidates and also an extensive amount of research is being conducted to develop novel therapeutic agents against COVID-19. Since ancient times natural products have been used as a treatment for a variety of diseases and to aid in the synthetic drug development process. The phytochemical constituents of Pomegranate have been extensively investigated in the past decade for their anti-tumor activity. The purpose of this review is to elaborate on how the major phytochemicals of pomegranate such as delphinidin, cyanidin, ellagitannin, and punicalagin could be utilized as pharmacological agents to suppress SARS-CoV-2 cell entry, replication, and immunological sequences that give rise to ARDS, based on current knowledge of interactome between host cells and SARS-CoV-2. The SARS-CoV-2 uses various biological mechanisms to modulate immune reactions, uncontrolled gene expression, and cell invasion to improve their survival inside the human host cells similar to those observed in certain tumors. Existing evidence suggests that certain tumors and SARS-CoV-2 use similar biological pathways for human cell invasion. Therefore, this review utilizes the findings of existing tumor-related research which describe how pomegranate extract interacts with various biological pathways associated with tumor suppression as indirect evidence for its ability to act as a potential therapeutic agent against SARS-CoV-2.
... The homeostasis of intracellular Zn 2+ is strongly regulated and although the major fraction of the metal ion is tightly bound, functioning as a catalytic or structural component of proteins, a loosely bound minor fraction, termed labile or exchangeable zinc, modulates the activity of numerous signaling and metabolic pathways. Specific fluorophores with high affinity for zinc have been employed to detect this metal ion pool to monitor cellular Zn 2+ dynamics in situ (Gee et al. 2002), also unveiling the ionophore ability of different zinc ligands (Dabbagh-Bazarbachi et al. 2014). As above cited, transmembrane zinc transporters control the cellular Zn 2+ uptake and efflux; among the zinc export transporters, the ZnT1 (Shusterman et al. 2014), located at the plasma membrane, is the main regulator of excess zinc cell export. ...
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Spinal cord injury (SCI) leads to long-term and permanent motor dysfunctions, and nervous system abnormalities. Injury to the spinal cord triggers a signaling cascade that results in activation of the inflammatory cascade, apoptosis, and Zn(II) ion homeostasis. Trehalose (Tre), a nonreducing disaccharide, and l-carnosine (Car), (β-alanyl-l-histidine), one of the endogenous histidine dipeptides have been recognized to suppress early inflammatory effects, oxidative stress and to possess neuroprotective effects. We report on the effects of the conjugation of Tre with Car (Tre–car) in reducing inflammation in in vitro and in vivo models. The in vitro study was performed using rat pheochromocytoma cells (PC12 cell line). After 24 h, Tre–car, Car, Tre, and Tre + Car mixture treatments, cells were collected and used to investigate Zn²⁺ homeostasis. The in vivo model of SCI was induced by extradural compression of the spinal cord at the T6–T8 levels. After treatments with Tre, Car and Tre–Car conjugate 1 and 6 h after SCI, spinal cord tissue was collected for analysis. In vitro results demonstrated the ionophore effect and chelating features of l-carnosine and its conjugate. In vivo, the Tre–car conjugate treatment counteracted the activation of the early inflammatory cascade, oxidative stress and apoptosis after SCI. The Tre–car conjugate stimulated neurotrophic factors release, and influenced Zn²⁺ homeostasis. We demonstrated that Tre–car, Tre and Car treatments improved tissue recovery after SCI. Tre–car decreased proinflammatory, oxidative stress mediators release, upregulated neurotrophic factors and restored Zn²⁺ homeostasis, suggesting that Tre–car may represent a promising therapeutic agent for counteracting the consequences of SCI.
... Besides these actions, quercetin supplementation will also help to circumvent the zinc deficiency problem in COVID-19 infected/elderly subjects as it acts as a zinc ionophore (Dabbagh-Bazarbachi et al., 2014), thereby helping in increasing the labile intracellular zinc concentration ( Figure 1). It is noteworthy to mention that zinc has been shown to inhibit RNA-dependent RNA polymerase (RdRp) activity of the SARS virus under in vitro conditions in a dose-dependent manner (reviewed in Read, Obeid, Ahlenstiel, & Ahlenstiel, 2019). ...
Article
The interim results of the large, multinational trials on coronavirus disease 2019 (COVID‐19) using a combination of antiviral drugs appear to have little to no effect on the 28‐day mortality or the in‐hospital course. Therefore, there is a still vivid interest in finding alternate re‐purposed drugs and nutrition supplements, which can halt or slow the disease severity. We review here the multiple preclinical studies, partially supported by clinical evidence showing the quercetin's possible therapeutic/prophylaxis efficacy against severe acute respiratory syndrome coronavirus (SARS‐CoV) as well as comorbidities like chronic obstructive pulmonary disease (COPD), diabetes mellitus, obesity, coagulopathy, and hypertension. Currently, 14 interventional clinical trials are underway assessing the efficacy of quercetin along with other antiviral drugs/nutritional supplements as prophylaxis/treatment option against COVID‐19. The present review is tempting to suggest that, based on circumstantial scientific evidence and preliminary clinical data, the flavonoid quercetin can ameliorate COVID‐19 infection and symptoms acting in concert on two parallel and independent paths: inhibiting key factors responsible for SARS‐CoV‐2 infections and mitigating the clinical manifestations of the disease in patients with comorbid conditions. Despite the broad therapeutic properties of quercetin, further high power randomized clinical trials are needed to firmly establish its clinical efficacy against COVID‐19.
... Since chloroquine treatment has shown adverse side effects in the past, the use of zinc without chloroquine might have an equally positive effect [145]. Theoretically, zinc ionophores like epigallocatechin-gallate and quercetin, with substantially lower toxicity levels, can also be used as an alternative, though clinical trials supported by in vitro studies must be performed to support this theory [146]. In the case of COVID-19, Zn 2+ ions can be specifically targeted in the configuration of the viral proteins. ...
Article
Background On 31st December 2019 in Wuhan, China, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was acknowledged. This virus spread quickly throughout the world causing a global pandemic. The World Health Organization declared COVID-19 a pandemic disease on 11th March 2020. Since then, the whole world has come together and have developed several vaccines against this deadly virus. Similarly, several alternative searches for pandemic disease therapeutics are still ongoing. One of them has been identified as nanotechnology. It has demonstrated significant promise for detecting and inhibiting a variety of viruses, including coronaviruses. Several nanoparticles, including gold nanoparticles, silver nanoparticles, quantum dots, carbon dots, graphene oxide nanoparticles, and zinc oxide nanoparticles, have previously demonstrated remarkable antiviral activity against a diverse array of viruses. Objective This review aims to provide a basic and comprehensive overview of COVID-19's initial global outbreak and its mechanism of infiltration into human host cells, as well as the detailed mechanism and inhibitory effects of various nanoparticles against this virus. In addition to nanoparticles, this review focuses on the role of several antiviral drugs used against COVID-19 to date. Conclusion COVID-19 has severely disrupted the social and economic lives of people all over the world. Due to a lack of adequate medical facilities, countries have struggled to maintain control of the situation. Neither a drug nor a vaccine has a 100% efficacy rate. As a result, nanotechnology may be a better therapeutic alternative for this pandemic disease.
... Te Velthuis and colleagues demonstrated that zinc together with the zinc ionophore pyrithione inhibited the activity of the SARS-CoV RNA-dependent RNA polymerase blocking viral replication in a cell culture [162]. It should be noted that both hydroxychloroquine and the plant phytochemical quercetin are zinc ionophores [163,164]. However, the role of zinc with or without the addition of zinc ionophores in the treatment of COVID-19 remains speculative [165]. ...
Article
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In December 2019, coronavirus disease 2019 (COVID-19), a severe respiratory illness caused by the new coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) 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 non-antiviral 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.
... Quercetin has many beneficial effects on the human body, including antithrombotic, anti-inflammatory, and antitumor properties [1]. It has been regarded as a good antioxidant that removes reactive oxygen species produced naturally in the body, such as O 2 -and ONOO-, and promotes the transfer of zinc into cells as an intracellular antioxidant [2,3], enhancing antioxidation ability of cells. e incidence of cardiovascular disease has increased dramatically year by year, becoming a serious health challenges not only in developed countries but also in developing countries, with the improvement and changes of food. ...
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Objective: The patency and quality of transplanted great saphenous vein (GSV) can seriously influence the physical state and life quality of patients who accepted the coronary artery bypass grafting (CABG). Quercetin is known for antioxidant, antithrombotic, anti-inflammatory, and antitumor properties. In this study, we examined the protection of quercetin to the great saphenous vein from oxidative and inflammatory damage. Methods: The GSVs were collected from 15 patients undergoing CABG and cultured. Treated the veins by H2O2 and detected the NO, SOD, and MDA content by the relevant kits to explore the quercetin protection against oxidative damage. Then, for another group of GSVs, sheared them and detected the inflammatory cytokines, such as IL-6, TNFα, CCL20, PCNA, and VEGF. Collect the veins for H&E staining and PCNA and VEGF immunofluorescent staining. Results: Pretreatment by quercetin reduced the production of NO and MDA induced by H2O2, and increased SOD activity. Quercetin also supressed the mRNA expressions of IL-6, TNFα after mechanical damage and had no influence on CCL20 and VEGF. Consistent with the lower expression of PCNA treated by quercetin, the vein intima was thinner. Conclusion: These results demonstrated that quercetin protects GSVs by reducing the oxidative damage and inflammatory response and also suppresses the abnormal thickening of venous endothelium by inhibiting cell proliferation. It reminded that, to some extent, quercetin has the potential to release the great saphenous vein graft damage.
... Some natural ionophores, such as dietary plant polyphenols quercetin (red raspberry, black grapes, broccoli, and red onion) and epigallocatechin-gallate (tea), rapidly increased cell concentrations of zinc [28]. ...
... Among natural compounds, polyphenols like EGCC (Fig. 6), quercetin, and resveratrol can act as Zn ionophores [122,123]. In particular, resveratrol at 5 and 10 μM caused a dramatic increase of cellular total Zn concentration, especially in the presence of a large amount of Zn ions, inhibiting the cell growth of normal human prostate epithelial (NHPrE). ...
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Zinc can play a pathophysiological role in several diseases and can interfere in key processes of microbial growth. This evidence justifies the efforts in applying Zinc ionophores to restore Zinc homeostasis and treat bacterial/viral infections such as coronavirus diseases. Zinc ionophores increase the intracellular concentration of Zinc ions causing significant biological effects. This review provides, for the first time, an overview of the applications of the main Zinc ionophores in Zinc deficiency, infectious diseases, and in cancer, discussing the pharmacological and coordination properties of the Zinc ionophores.
... In addition to antimicrobial properties, studies have demonstrated that zinc ionophores such as EGCG [694] and Quercetin [103] have immunomodulatory effects that are associated with beneficial health outcomes including the prevention of cardiovascular diseases and cancers [695][696][697][698][699][700], anti-angiogenic [701,702], anti-arthritic [703,704], anti-oxidative [705,706], cholesterol lowering [707,708], neuroprotective [709,710] and other anti-inflammatory [271,711] properties. Although many mechanisms of action have been proposed for how these compounds achieve the aforementioned effects [271,712] (Table 7), there is limited information on how, or to what extent, ionophore activity plays a role. ...
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Ionophores are a diverse class of synthetic and naturally occurring ion transporter compounds which demonstrate both direct and in-direct antimicrobial properties against a broad panel of bacterial, fungal, viral and parasitic pathogens. In addition, ionophores can regulate the host-immune response during communicable and non-communicable disease states. Although the clinical use of ionophores such as Amphotericin B, Bedaquiline and Ivermectin highlight the utility of ionophores in modern medicine, for many other ionophore compounds issues surrounding toxicity, bioavailability or lack of in vivo efficacy studies have hindered clinical development. The antimicrobial and immunomodulating properties of a range of compounds with characteristics of ionophores remain largely unexplored. As such, ionophores remain a latent therapeutic avenue to address both the global burden of antimicrobial resistance, and the unmet clinical need for new antimicrobial therapies. This review will provide an overview of the broad-spectrum antimicrobial and immunomodulatory properties of ionophores, and their potential uses in clinical medicine for combatting infection.
... Ионофоры -это жирорастворимые соединения, которые способствуют внутриклеточному транспорту нерастворимого в липидах цинка, независимо от цинксвязывающих белков, присутствующих в плазматической мембране. Такое действие было выявлено у нескольких соединений -лекарственных препаратов (хлорохин, гидроксихлорохин), растительных полифенолов (кверцетин и эпигаллокатехингаллат), ресвератрола и ряда других [85]. Мультицентровое исследование, проведенное в Нью-Йорке, включало 3473 госпитализированных пациента с COVID-19, из которых 1006 получали комбинацию цинка с гидроксихлорохином. ...
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... On the other hand, Refaat et al. showed that liposomes containing the Egyptian propolis extract displayed an effect similar to that of Remdesivir for inhibition of SARS-CoV-2 replication in vitro. Polyphenols from propolis were shown to inhibit viral replication and to have ability to transport Zn ions, which inhibit the viral enzymes necessary for replication in the host cells [49,[54][55][56]. ...
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... It should be stressed that both quercetin and epigallocatechin gallate act as antioxidants and signaling molecules, and the functions of many enzymes activated by polyphenolic compounds depend on zinc. Flavonoids have also been shown to act as zinc ionophores, transporting zinc cations through the plasma membrane [104]. In theory, this could enhance the antiviral effects of zinc. ...
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Propolis, bal arısının bitkilerin filizlerinden, tomurcuklarından ve ağaçların kabuklarından toplanan reçinelerden glikozidik tükürük enzimleri vasıtasıyla balmumu ile karıştırarak kovanda ürettiği, toplandığı kaynağa göre değişmekle beraber, genellikle kahverengi, sarı, yeşil tonlarında olan, suda çözünmeyen, yapışkan, doğal bir arı ürünüdür. Propolis bal arısı tarafından kovan içerisindeki havalandırma alanlarında, giriş-çıkış noktalarında biriktirilerek dış ortamdan gelecek bakteri, virüs ve funguslardan korunmak için kullanır. Oda sıcaklığında yapışkan ve elastik bir yapıya sahip olan propolis, dondurulduğunda kırılgan ve sert bir forma dönüşür (Kumova, 2002). Propolisin kimyasal bileşenlerini flavonoidler, fenolik asitler, glikozitler ve aglikonlar oluşturmaktadır. Propolisin başlıca antimikrobiyal ve antioksidan etkilerini gösteren biyolojik bileşenleri flavonoidler ve fenolik asitlerdir. Trombosit agregasyonunu ve enzimlerin (lökotrienler ve prostaglandin) sentezinin inhibisyonunu ve inflamasyonda rolü olan çeşitli medyatörlerin salınımının engellenmesini sağlayarak antienflamatuar etki gösterirler. Propolisin antikompleman, antikanser, immünomodülatör, antihipertansif, analjezik, antimetastatik, hepatoprotektif vb. çok çeşitli biyolojik aktivitelere sahip olduğu belirtilmiştir (Strehl vd., 1994). Propolisin bileşimi toplandığı coğrafyaya ve elde edildiği kaynağa göre farklılıklara sahip olduğu için medikal amaçlı muamelelerden önce kimyasal içeriğinin belirlenmesi gerekir. Propolis lipofilik karakterde olduğundan önce çözücülerle ekstrakte edilerek saflaştırılmalı ve bu proses esnasında yararlı polifenolik bileşen içeriğinin korunması, inert maddelerin ise uzaklaştırılması sağlanmalıdır (Benkovic vd., 2007).
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Epigallocatechin gallate (EGCG) has attracted increasing attention thanks to its multi-bioactivities, and people are keen on improving the antioxidative and antibacterial performance of EGCG. Based on the favorable biofunctionality of Zn²⁺ and chitosan (CS), an EGCG derivative with a novel formula, i.e., EGCG–Zn–CS, is presented in this study. The structure of EGCG–Zn–CS was characterized by FT-IR, UV-vis, TGA, XPS, and SEM–EDS. The radical elimination results indicate that 0.1 mg mL⁻¹ of EGCG–Zn–CS demonstrates DPPH radical and hydroxyl radical scavenging activities of 94.8% and 92.3%, while 0.1 mg mL⁻¹ of EGCG exhibits only 78.5% and 75.6%, respectively, which means improved antioxidative activity of EGCG–Zn–CS was obtained. Inhibitory experiments against Staphylococcus aureus and Escherichia coli reveal that the minimal inhibitory concentrations (MICs) of EGCG–Zn–CS were 15.625 μg mL⁻¹ and 187.5 μg mL⁻¹, whereas the minimal bactericide concentrations (MBCs) were 46.875 μg mL⁻¹ and 750 μg mL⁻¹, respectively, which indicate that EGCG–Zn–CS exerts much higher antibacterial activity than EGCG. It can be concluded that the complexing of zinc cations and CS could amazingly improve both the antioxidative and antibacterial activity of EGCG, and it is expected that an exploration of EGCG–Zn–CS may inspire the development of simultaneous effective antioxidant and antibacterial agents.
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Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has been identified as the agent responsible for COVID-19 pandemic. Currently, no therapeutic agents have proven effective in combating the virus. Managing the infection is mainly palliative in nature, involving infection prevention strategies and supportive therapy anchored on drugs that practitioners have had previous usage experience. Previously exploited therapeutic agents include antiviral and antimalarial agents (remdesivir, hydroxychloroquine, chloroquine, lopinavir, umifenovir, favipiravir, and oseltamivir). Micronutrients (zinc, selenium) have also been used. There are claims of herbal preparations that are thought to be beneficial. The self-formulated herbal preparation, COVI-MXG contains a unique combination of five plants. In silico methodologies were used to evaluate the phytochemical constituents. This was to determine possible antiviral activity, safety during usage and pharmacokinetic properties. Docking studies of selected phytochemical compounds in COVI-MXG evaluated against the COVID-19 viral protein target showed binding affinity ranging from -8.1 to -4.2 Kcal/mol. Blood brain barrier permeability and gastrointestinal absorption rates varied to different degrees. Toxicity class varied from 3 to 5. LD50 values were relatively high. COVI-MXG contained phytochemical compounds with better binding affinities for SARS-CoV-2 protein (7BV2) than currently employed therapeutic agents (remdesivivr, hydroxychloroquine, chloroquine, lopinavinavir, umifenovir, favipiravir, oseltamivir) which were included in the virtual screening. The phytochemical compounds showed excellent interactions with amino acid residues in the catalytic nsp12 domain. This excellent interaction is likely to result in a better therapeutic outcome in the management of COVID-19. In silico predictions for stability and pharmacokinetic parameters predicted that the formulation can be administered orally. Key words: COVID-19, SAR-CoV-2, COVI-MXG, zinc.
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Purpose: To validate the mechanism and inhibitory activity of quercetin against matrix metalloproteinase-9 (MMP-9) using a hybrid in silico and in vitro approach. Methods: The structure of MMP-9 was obtained from the Protein Data Bank, and the active site was identified using previous annotations from the Universal Protein Resource. The structure of quercetin was obtained from ZINC15. Molecular docking was performed to quantify the binding affinity of quercetin to the active site of MMP-9. The inhibitory effect of various concentrations of quercetin (0.0025, 0.025, 0.25, 1.0, and 1.5 mM) on MMP-9 was quantified using a commercially available fluorometric assay. The cytotoxicity of quercetin to immortalized human corneal epithelial cells (HCECs) was quantified by obtaining the metabolic activities of the cells exposed to various concentrations of quercetin for 24 hr. Results: Quercetin interacts with MMP-9 by binding within the active site pocket and interacting with residues LEU 188, ALA 189, GLU 227, and MET 247. The binding affinity predicted by molecular docking was -9.9 kcal/mol. All concentrations of quercetin demonstrated significant inhibition of MMP-9 enzyme activity (all P<0.03). There was little to no reduction of HCEC metabolic activity after a 24-hr exposure to all concentrations of quercetin (P>0.99). Conclusions: Quercetin inhibited MMP-9 in a dose-dependent manner and was well-tolerated by HCECs, suggesting a potential role in therapy for diseases with upregulated MMP-9 as part of its pathogenesis.
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Obesity is associated with an imbalance of micro-and macro-nutrients, dysbiosis, and a “leaky” gut phenomenon. Polyphenols, such as curcumin, resveratrol, and anthocyanin may alleviate the systemic effects of obesity, potentially by improving gut microbiota, intestinal barrier integrity (IBI), and zinc homeostasis. The essential micronutrient zinc plays a crucial role in the regulation of enzymatic processes, including inflammation, maintenance of the microbial ecology, and intestinal barrier integrity. In this review, we focus on IBI– which prevents intestinal lipopolysaccharide (LPS) leakage – as a critical player in polyphenol-mediated protective effects against obesity-associated white adipose tissue (WAT) inflammation. This occurs through mechanisms that block the movement of the bacterial endotoxin LPS across the gut barrier. Available research suggests that polyphenols reduce WAT and systemic inflammation via crosstalk with inflammatory NF-κB, the mammalian target of rapamycin (mTOR) signaling and zinc homeostasis.
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Because of higher adaptability and mutability, there is always a possibility for RNA viral disease outbreaks. There are no approved antivirals for the majority of RNA viruses including SARS-CoV-2, CHIKV, DENV, JEV, ZIKV, and EBOV. To treat these infections and to prepare for future epidemics there is a necessity to identify effective therapeutic strategies with broad-spectrum actions against RNA viruses. Unregulated inflammation is the major cause of the severity associated with these viral diseases. Quercetin is a privileged molecule that is known to interfere at different levels of inflammatory response. Besides, it modulates pathways responsible for viral translation as well as the immune response of the host. It has also been found to inhibit replication by targeting critical targets of some of these viruses. Because of the abilities to inhibit viral targets, modulate host factors, or a combination of both; quercetin has been demonstrated to help recover from some of these viral diseases in preclinical /clinical studies. Thus, it can be a drug candidate for application against a broad range of viral diseases. However, its translational value is limited by the lack of large-scale clinical studies. A major hurdle for oral application is poor solubility. Thus, developing a suitable form of quercetin can enable adequate bioavailability leading to its translational application.
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Metal ion dysregulation has been implicated in a number of diseases from neurodegeneration to cancer. While defective metal ion transport mechanisms are known to cause specific diseases of genetic origin, the role of metal dysregulation in many diseases has yet to be elucidated due to the complicated function (both good and bad!) of metal ions in the body. A breakdown in metal ion speciation can manifest in several ways from increased reactive oxygen species (ROS) generation to an increase in protein misfolding and aggregation. In this review, we will discuss the role of Zn in the proper function of the p53 protein in cancer. The p53 protein plays a critical role in the prevention of genome mutations via initiation of apoptosis, DNA repair, cell cycle arrest, anti-angiogenesis, and senescence pathways to avoid propagation of damaged cells. p53 is the most frequently mutated protein in cancer and almost all cancers exhibit malfunction along the p53 pathway. Thus, there has been considerable effort dedicated to restoring normal p53 expression and activity to mutant p53. This includes understanding the relative populations of the Zn-bound and Zn-free p53 in wild-type and mutant forms, and the development of metallochaperones to re-populate the Zn binding site to restore mutant p53 activity. Parallels will be made to the development of multifunctional metal binding agents for modulating the aggregation of the amyloid-beta peptide in Alzheimer's Disease (AD).
Chapter
Zinc is a trace metal ion that has a role in both physiological and pathological processes, making it one of the most common and necessary components involved in brain function. Besides, zinc is required for cell proliferation control in a variety of mechanisms, including hormonal regulation of cell division. Also, zinc serves as a biochemical signal to immune cells and transcription factors involved in the synthesis of inflammatory cytokines. On the other hand, zinc has a variety of crucial roles in neurogenesis and also acts as a neuromodulator on a wide range of membrane receptors, ion channels, and transporters. Zinc is produced by neurons under several conditions to activate microglia. The link between zinc dysregulation and psychiatric disorder was that zinc acts as an inhibitory modulator at the N-methyl-D aspartic acid (NMDA) glutamate receptor. Ionophores are ion carrier molecules that reversibly bind and transport ions through biological membranes. Ionophores can be natural or synthetic products. Zinc ionophores such as quercetin, epigallocatechin gallate (EGCG), hinokitol, and proanthocyanidins have been shown to protect brain health, particularly in depression clinically significant depression and depressive symptoms in post-COVID-19 syndrome may have severe implications as it relates to life outcomes quality, herein according to previous research studies, we showed zinc deficiency as a possible risk factor for depression symptoms, which were commonly observed following severe infection of COVID-19.
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The study aimed to isolate and characterize zinc ionophores from Terminalia bellirica fruit using a liposome assay and test its utility in H9c2 rat cardiomyoblasts cells subjected to hypoxia/reoxygenation. Ethyl acetate extract that exhibited zinc ionophore activity was resolved to yield three polyphenols that were characterized as epicatechin-3-gallate (ECG), epigallocatechin-3-gallate (EGCG) and epigallocatechin (EGC) by nuclear magnetic resonance and electrospray ionization-mass spectra. The polyphenols enhanced the uptake of zinc into the liposomes and increased FluoZin-3 fluorescence. These polyphenols in the presence of 10 μM ZnCl2 enhanced the zinc import into H9c2 cells, whose intracellular zinc levels were otherwise lowered upon hypoxia/reoxygenation. EGCG proved to be more potent than ECG, which indeed was more effective than EGC in improving cellular zinc levels and in attenuating the apoptosis of H9c2 cells after hypoxia/reoxygenation injury. The polyphenols required zinc for anti-apoptotic effect. The cardioprotective effect is indeed due to enhanced zinc uptake mediated by these polyphenols.
Research Proposal
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Research Proposal DOI:10.6084/m9.figshare.15153186 License CC BY 4.0 Authors and Affiliation: Amr Kamel Khalil Ahmed - Director of the tuberculosis program Ghubera, public health department, First health cluster, Ministry of Health, Riyadh, Saudi Arabia ORCiD: https://orcid.org/0000-0003-3477-236X Mahmoud Elkazzaz - Department of chemistry and biochemistry, Faculty of Science, Damietta University, Egypt ORCiD: https://orcid.org/0000-0003-3703-520X Michelle Carole Orzechowski - CEO of Coronavirus Corporation Epidemiology, Research, and Development, - Vaccines/Medications/Lab Testing, Lutz, United States of America ORCiD: https://orcid.org/0000-0002-8541-8726 Project Title: The Combination of Quercetin and Bromelain with Zinc, EGCG, Retinoic Acid, Vitamin C and Vitamin D for the potential Symptom Reducer, Prevention, and Treatment for Coronavirus Disease 2019 (COVID-19) These products are unapproved new drugs not being sold in violation of section 505(a) of the Federal Food, Drug, and Cosmetic Act (FD&C Act), 2pt1 U.S.C. § 355(a). Furthermore, these products are not misbranded drugs under section 502 of the FD&C Act, 21 U.S.C. § 352. The introduction or delivery for introduction of these products into interstate commerce is prohibited under sections 301(a) and (d) of the FD&C Act, 21 U.S.C. § 331(a) and (d). [1] Hypotheses: The Combination of Quercetin and Bromelain with Zinc, EGCG, Retinoic Acid, Vitamin C, and Vitamin D when taken together may Inhibit the Viral Replication of Anti-Cytokine Storm and an Antiviral against RNA Viruses like Coronavirus Disease 2019 (COVID-19) by using the formulations including Zinc; Zinc Ionophores (Quercetin); Bromelain, EGCG, Retinoic Acid, Vitamin C and Vitamin D. Zinc Ionophores possibly enhance transport of Zinc into the Cells to effect Intra-Cellular Zinc levels and potentially impair intracellular replication of Coronavirus Disease 2019 (COVID-19). [12] Zinc regulates Adaptive Immune Cell Functions with High levels of Intracellular pH as RNA-dependent and RNA polymerase decreases the replication of RNA viruses like COVID-19. Quercetin has chelate Zinc Ions and acts as a Zinc Ionophore. Bromelain activates Natural Killer Cells and the production of Granulocyte-Macrophage Colony Stimulating Factor, Interleukin-2, and Interleukin-6 decreases the activation of T-helper cells. EGCG can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Retinoic Acid has a characteristic of antiviral, Immunity induction, ACE2 upregulation or downregulation, and anti-clotting. Vitamin C has Enzymatic Co-Factor for Hormone Production, Collagen Synthesis, and Immune Potentiation. Vitamin D regulates the Inflammatory Cytokine Response. Vitamin D deficiency has been associated with increased COVID-19 mortality and is commonly confounded by increasing age, obesity, diabetes, darker skin tones, and lack of fitness. Introduction: Zinc alone is a potent inhibitor of viral replication. Zinc in the combination with Quercetin potentially synergistic in reducing viral replication since Quercetin is potentially a Zinc Ionophore facilitating intracellular entry and inhibition of intracellular viral replication. Zinc in the combination with Quercetin can access the DNA cellular layer and stop SARS-CoV-2 from replicating RNA cells, potentially resetting replicated cells, Treating the Coronavirus disease 2019 (COVID-19). Quercetin 800 mg, bromelain 165 mg, zinc acetate 50 mg and ascorbic acid 1 g once daily as supplements for 3 to 5 days were safe for patients infected with SARS-CoV-2 and may prevent poor prognosis through restraining from hyper-inflammation and cytokine storm. Randomized clinical trials are needed in the future to ensure the efficacy of quercetin, bromelain, zinc, and ascorbic acid combination. [11.2] In addition to proper PPE and the COVID-19 vaccination, The Combination of Quercetin and Bromelain with Zinc, EGCG, Retinoic Acid, Vitamin C, and Vitamin D may be an effective Symptom Reducer for Coronavirus Disease 2019 (COVID-19) [14] On 09/30/2021 The Center for Biologics Evaluation and Research Vaccines and Related Biological Products Advisory Committee will meet. [15] The pathogen, a novel coronavirus (SARS-CoV-2), was identified by local hospitals using a surveillance mechanism for "pneumonia of unknown etiology" that was established in the wake of the 2003 SARS outbreak to allow timely identification of novel pathogens. The immune system plays a critical role in protecting the human body from infectious diseases. T-cell counts are reduced significantly in COVID-19 patients, and the surviving T-cells appear functionally exhausted. Non-ICU patients with total T cell counts lower than 800/μ L may still require urgent intervention, even in the immediate absence of more severe symptoms due to a high risk for further deterioration in condition. Further research on the severity of comorbidities and all medication received by the patients is mandatory to shed light on these associations. [11] The Role of Zinc Since the discovery of the first reported case with zinc - deficiency in Iran by Prasad et al. in 1961 we have learned a lot about Zinc, and we have much more left to learn. Zinc is the second most abundant common trace mineral in the human body, with vital biological functions from cell growth and development to cell homeostasis and immune response. Mechanical ventilation is a necessary intervention to support patients with lung injury and acute respiratory distress syndrome (ARDS) but can also exacerbate injury through mechanical stress-activated signaling pathways. It is shown that stretch applied to cultured human lung cells, and mouse lungs in vivo induce robust expression of metallothionein, a potent antioxidant and cytoprotective molecule critical for cellular zinc homeostasis. Furthermore, genetic deficiency of murine metallothionein genes exacerbated lung injury caused by injurious mechanical ventilation, identifying an adaptive role for these genes in limiting lung injury. Stretch induction of metallothionein required zinc and the zinc-binding transcription factor MTF- We further show that dietary zinc- deficiency in mice potentiates ventilator-induced lung injury, and that plasma zinc levels were significantly reduced in human patients with ARDS compared to healthy and non-ARDS ICU controls. [11] Zinc sulfate 220 mg (50 mg elemental zinc) can be taken orally per day. [3] Zinc: It May have some anti-viral properties. Doses of 15-30 mg of zinc per day are presumed to be safe, short-term, for one to two weeks. Zinc can interact with other medications (antibiotics and antivirals), and long-term use of high doses of zinc can cause copper deficiency. [13] The Role of Quercetin A natural flavonoid molecule that is distributed broadly in many fruits and vegetables including red onion, cranberry, kale, tomatoes, Hungarian wax, and watercress. It was revealed in previous studies that quercetin has an anti-inflammatory and anti-hypersensitivity effect by preventing pro-inflammatory prostaglandins and leukotrienes through inhibiting cyclooxygenase (COX) and lipoxygenase (LOX) enzymes, therefore; quercetin was used as an extract in various trials to treat different infectious and non-infectious diseases. In addition, quercetin showed to reduce tumor necrosis factor-alpha (TNF-α) production with chronic inflammation. Reduction in the ratio of CD4 + CD8 + T cells and suppression of macrophages, dendritic, mast cells, and interleukin-6 (IL-6) levels were revealed after a specific tissue was treated with quercetin in pre-clinical studies. Besides, quercetin is expected to have antiviral activity by acting as a zinc chelator and as a zinc ionophore as well. However, because most of these studies were done by using quercetin in-vitro with high concentration and in-vivo studies cannot use the same doses; it's showed minimum effect during clinical trials. The available data clarifies that quercetin is a very safe molecule and used as a nutritional supplement with a dose reached 1500 mg divided per day. [11.2] Quercetin (also known as 3,5,7,3',4' pentahydroxyflavone, is a widely distributed plant flavonoid, found in several vegetables, leaves, seeds, and grains, where it is conjugated with residual sugars to form Que glycosides. Studies suggest that Quercetin supplementation may promote antioxidant, anti-inflammatory, antiviral, and immune protective effects. Quercetin has been studied in various types and models of viral infection due to its promising antiviral effects in inhibiting polymerases, proteases, reverse transcriptase, suppressing DNA gyrase, and binding viral capsid proteins. Recently, Quercetin has been shown to inhibit in vitro production of cyclooxygenase (COX) and lipoxygenase (LOX) which are typically induced by inflammation. The anti-inflammatory effect has been supported by in vivo experiments as well. Examples of Quercetins inhibitory qualities include the significant blocking of pro-inflammatory cytokines in cultured fibroblasts. 10 𝜇M Quercetin downregulated the production of COX-2, the Nuclear Factor kappa B (NF-𝜅B), and NO. 10–25 𝜇M Quercetin inhibited the level of NO and TNF-𝛼. Other properties of 50 and 100 𝜇M Quercetin include reducing the secretion of IL6 and TNF-𝛼 in LPS-stimulated RAW 264.7 microphages, while at 25 and 50 𝜇M it proved to be the most efficient blocker of TNF-𝛼 secretion in macrophages. Finally, at low concentrations, Quercetin (less than 50 𝜇M) also stimulated anti-inflammatory cytokine IL-10. Similarly, 25𝜇M Quercetin blocked IL-1𝛽, IL-6, IFN-𝛾, and TNF-𝛼 secretion in human whole blood induced by LPS. Quercetin can also inhibit pro-inflammatory cytokines. A six-week regiment of 150 milligrams of Quercetin taken daily by human subjects significantly lowered cytokine TNF-𝛼 serum concentrations. Quercetin effectively inhibited LPS-induced DC activation by reducing the production of pro-inflammatory cytokines/chemokines and the expression levels of MHC class II and costimulatory molecules. In addition, Quercetin uniquely blocked endocytosis by Dendritic Cells DCs, and the LPS-induced DC migration was diminished by Quercetin treatment. Quercetin has been shown clinically to block human mast cell cytokine release, possibly inhibiting the clinical manifestation of a cytokine storm. Severe COVID-19 disease progression is associated with increased levels of C-Reactive protein, D-Dimer, Ferritin, IL-2, and IL-6. Quercetin has been shown in studies to reduce all these markers. Balancing systemic iron levels within narrow limits is critical for maintaining human health. There are no known pathways to eliminate the excess iron from the body and therefore iron homeostasis is maintained by modifying dietary absorption so that it matches daily obligatory losses. Several dietary factors can modify iron absorption. Polyphenols are plentiful in the human diet and many compounds, including Quercetin's most abundant dietary polyphenol, are potent iron chelates. Quercetin is a zinc ionophore and could have a similar antiviral activity to chloroquine but is described as a safe choice in the treatment of viral infections. [11.3] 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. 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. The suggested dose of quercetin is 500 mg BID. [10] Quercetin: A naturally occurring antioxidant/flavonoid that may have benefits for allergic rhinitis and possibly in exercise-induced respiratory infections. Quercetin may interact with some antibiotics known as fluoroquinolones (ciprofloxacin, levofloxacin) and could also interact with other medications that are metabolized through your liver system known as the cytochrome p450 enzyme system (3A4 and 2C9). These drugs may include warfarin, midazolam, cyclosporine, drugs known as the "statins" (atorvastatin, pravastatin, rosuvastatin, simvastatin), medications known as non-steroidal anti-inflammatory drugs (ibuprofen, diclofenac, naproxen), tamoxifen, and possibly losartan. There is also a possibility it may interact in those individuals with hypothyroidism. Use caution in these patients. Doses of 500 mg twice daily have been studied and shown to be possibly safe for up to twelve weeks. [13] The Role of Bromelain Protein enzyme is found mainly in the stem of the pineapple plant. The bioavailability of bromelain was high through the oral route and was safe even when consumed more than 11 grams per day. In vitro studies showed that bromelain exerts anti-inflammatory effects through reducing bradykinin serum and modulating the expression of some genes related to inflammation. Three genes related to inflammation including TLR4, TNF-α, and IL-8 were found to be less expressed after bromelain treatment. On the other hand, PPARγ gene expression was elevated after treatment with bromelain. Therefore, bromelain may have a role in reducing inflammations during various disorders and may be used in combination with other analgesics and anti-inflammatory drugs. Since the inflammatory status of patients during COVID-19 may lead to severe consequences and even death if not prevented or treated adequately; it is important to ensure high-quality care to patients and provide evidence-based prophylaxis and treatment. [11.2] Bromelain activates the inflammatory mediators, including interleukin (IL)-1β, IL-6, interferon (INF)-γ, and tumor necrosis factor (TNF)-α in mouse macrophage and human peripheral blood mononuclear cells (PBMC) (Barth). These results indicated that bromelain potentially activates the healthy immune system in association with the rapid response to cellular stress. Conversely, bromelain reduces IL-1β, IL-6, and TNF-α secretion when immune cells are already stimulated in the condition of inflammation-induced overproduction of cytokines. It was also found that bromelain upregulated p53 and Bax with consequent activation of Caspase 3 and Caspase 9 with a concomitant decrease in BCL2. Marked inhibition of cyclooxygenase 2 (COX2) expression with inactivation of NF Kappa B by blocking phosphorylation and degradation of IK B α were blocked by bromelain. Furthermore, bromelain ameliorated extracellular signal of regulated protein kinase ERK1/2, P38 mitogen-activated protein kinase MAPK and Akt activity. So, it modulated defective cellular signaling cascades. Bromelain prevents or minimizes the severity of angina pectoris and transient ischemic attack (TIA). It is useful in the prevention and treatment of thrombophlebitis. It may also break down cholesterol plaques and exert a potent fibrinolytic activity. A combination of bromelain and other nutrients protects against ischemia/reperfusion injury in skeletal muscle. Bromelain influences blood coagulation by increasing the serum fibrinolytic ability and by inhibiting the synthesis of fibrin, a protein involved in blood clotting. [11.3] Bromelain: An enzyme that comes from the stalk of the pineapple. It has been shown to have some activity in reducing symptoms for acute sinusitis2. It can, however, interact with blood thinners such as warfarin, and also certain antibiotics such as tetracyclines. Use with caution for these agents [13] The Role of EGCG Via activating Nrf2, can suppress ACE2 (a cellular receptor for SARS-CoV-2) and TMPRSS2, which mediate cell entry of the virus. Through inhibition of SARS-CoV-2 main protease, EGCG may inhibit viral reproduction. EGCG via its broad antioxidant activity may protect against SARS-CoV-2 evoked mitochondrial ROS (which promote SARS-CoV-2 replication) and against ROS burst inflicted by neutrophil extracellular traps. By suppressing ER-resident GRP78 activity and expression, EGCG can potentially inhibit the SARS-CoV-2 life cycle. EGCG also shows protective effects against 1) cytokine storm-associated acute lung injury/acute respiratory distress syndrome, 2) thrombosis via suppressing tissue factors and activating platelets, 3) sepsis by inactivating redox-sensitive HMGB1, and 4) lung fibrosis through augmenting Nrf2 and suppressing NF-κB. These activities remain to be further substantiated in animals and humans. The possible concerted actions of EGCG suggest the importance of further studies on the prevention and treatment of COVID-19 in humans. These results also call for epidemiological studies on the potential preventive effects of green tea drinking on COVID-19. [12] The Role of Retinoic Acid Angiotensin-converting enzyme (ACE2) protein found on the cell membranes is the target of SARS-CoV-2 for entering into the host cells. Viral spike protein-binding with ACE2 down-regulates it. As ACE2 is known to protect the lung from injuries, SARS-CoV-2-induced ACE2 deficiency may expose patients to lung damage. In this Review, we use established and emerging evidence based on the findings of previous studies and researches to propose a testable hypothesis that a Combination of chemopreventive agents (All-Trans Retinoic acid and Tamoxifen) can be tested to prevent inflammatory complications in severe acute respiratory syndrome coronavirus 2 infections via two mechanisms by inhibiting bradykinin B1, B2 receptors expression and upregulating the depleted ACE2 in COVID-19. Bradykinin B1 receptors are not expressed under physiological conditions but are induced under inflammatory conditions. Here we hypothesize that permanent attack and invasion of COVID-19 to lung epithelial cells via binding to ACE2 leads to tissue injury and inflammation and that increases BK levels and BK-B2-receptor (B2R) stimulation A study reported that tissue injury and inflammation increases BK levels and BK-B2-receptor (B2R) stimulation. We suggest that Bradykinin mediates and induces lung injury, pro-inflammatory cytokines, and inflammation likely precipitates life-threatening respiratory complications in COVID-19. Further experiments showed that BK treatment stimulated IL-6 production On the other hand a study reported that cells treated with Retinoic acid and Tamoxifen for 48 h significantly decreased the BK-B2 receptor protein levels (70.3 ± 0.6% vs. 100% of control, P < 0.05). Retinoids inhibit bradykinin B1 receptor-sensitized responses and this action could participate in their anti-inflammatory and immunomodulatory effects. In addition, retinoic acid is known to possess in vivo anti-inflammatory, antiplatelet and fibrinolytic activities. A study investigated the in vitro thrombin and platelet aggregation inhibitory activities of retinoic acid and retinaldehyde. Retinoic acid, retinaldehyde, and retinol exhibited potent inhibition of thrombin, with IC50 values of 67μg/ml, 74μg/ml and 152μg/ml, respectively for the inhibition of thrombin (Sigma); and 49μg/ml, 74μg/ml and 178μg/ml, respectively for the inhibition of thrombin (plasma). Amongst vitamin A and its derivatives, retinoic acid showed the highest inhibition of both forms of thrombin. Besides the effectiveness of TAM on cancer cells, it also has other effects on numerous microbes including parasites, fungi, bacteria, and some viruses such as the Ebola virus and human immunodeficiency virus (HIV). Furthermore, Tamoxifen can block the action of interleukin 6 and inhibit neutrophils. A study demonstrated that tamoxifen has side effects associated with neutropenia. Since tamoxifen can cause neutropenia and subsequently influence the neutrophil-to-lymphocyte ratio (NLR) value In addition it has an anti-malarial effect similar to chloroquine In conclusion. [16] The Role of Vitamin C Exerts its antiviral properties by supporting lymphocyte activity, increasing interferon-α production, modulating cytokines, reducing inflammation, improving endothelial dysfunction, and restoring mitochondrial function. There are also suggestions that Vitamin C may be directly viricidal. The in vitro effects constitute a reflection of both the supra-physiological concentrations of ascorbate and the interaction between Vitamin C and metal-containing culture media - both of which are pro-oxidant, generating reactive oxygen species. [11] Vitamin C has been used in a variety of viral infections and could be useful in combination with other supplements in COVID19 [10] Vitamin C: may help reduce the severity and duration of a cold, especially if you start taking Vitamin C before feeling ill. 500 mg- 1000 mg of Vitamin C twice a day is a typical starting dose to try to help boost immunity. People with kidney issues should use it with caution as Vitamin C is eliminated by the kidneys. [13] The Role of Vitamin D Coronavirus disease 2019 (COVID-19) has caused global disruption and a significant loss of life. Existing treatments that can be repurposed as prophylactic and therapeutic agents could reduce the pandemic's devastation. Emerging evidence of potential applications in other therapeutic contexts has led to the investigation of dietary supplements and nutraceuticals for COVID-19. Such products include Quercetin, Bromelain, Zinc, EGCG, Vitamin C, and Vitamin D; all of which are currently under clinical investigation. In this review, we critically appraise the evidence surrounding dietary supplements and nutraceuticals for the prophylaxis and treatment of COVID-19. Overall, further study is required before evidence-based recommendations can be formulated, but nutritional status plays a significant role in patient outcomes, and these products could help alleviate deficiencies. For example, evidence indicates that vitamin D deficiency may be associated with a greater incidence of infection and severity of COVID-19, suggesting that vitamin D supplementation may hold prophylactic or therapeutic value. A growing number of scientific organizations are now considering recommending vitamin D supplementation to those at high risk of COVID-19. Because research in vitamin D and other nutraceuticals and supplements is preliminary, here we evaluate the extent to which these nutraceutical and dietary supplements hold potential in the COVID-19 crisis. [12.23] Vitamin D: May help reduces the number of respiratory illnesses, especially for those who are deficient. Supplementing with 1,000-2,000 international units per day may be beneficial. Vitamin D levels can be monitored, it is recommended to not exceed blood levels of 50 nanograms/ milliliter of Vitamin D. [13] Background: Milan, Italy had the first specimen detect SARS-CoV-2 from the specimen source: Oropharyngeal Swab, collected on 2019-12-05 but was submission received was reported on 2020-11-30. Wuhan, China, however, had the first specimen identified SARS-CoV-2 from the specimen source: Bronchoalveolar lavage, collected on 2019-12-24 and submission received was reported first on 2020-01-11. Reported submissions of SARS-CoV-2 globally in Humans, Animals, and the Environment. Currently, 9 different Variants are emerging from SARS-CoV-2 including Alpha, Beta, Gamma, Delta, Eta, Iota, Kappa, Lambda, and Mu that have been reported as of 01-Sep-2021. There have been over 1,200 reported cases of SARS-CoV-2 in the following submitted specimens for 14 different Animals including Dog, Cat, Hamster, Mouse, Otter, Monkey, Gorilla, Anteater, Mink, Lion, Tiger, Leopard, Snow Leopard, and Bat. There have been over 1,200 reported cases of SARS-CoV-2 in the Environment from the following samples: Sewer and Wastewater. [0] There is currently a global outbreak of respiratory disease caused by a novel coronavirus that has been named "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2). The disease caused by the virus has been named "Coronavirus Disease 2019" (COVID-19). On January 31, 2020, the Department of Health and Human Services (HHS) issued a declaration of a public health emergency related to COVID-19 and mobilized the Operating Divisions of HHS. In addition, on March 13, 2020, there was a Presidential declaration of a national emergency in response to COVID-19. Therefore, FDA is taking urgent measures to protect consumers from certain products that, without approval or authorization by FDA, claim to mitigate, prevent, treat, diagnose, or cure COVID-19 in people. [1] At the Pharmacy Compounding Advisory Committee on September 12, 2018, the FDA was proposing that quercetin dihydrate NOT be included on the 503A Bulks List. The Vote Result proposing if quercetin dihydrate should be placed on the list was: YES: 0 NO: 11 ABSTAIN: 0. The Meeting Committee Discussion for the Vote was that: The committee unanimously agreed that quercetin dihydrate NOT be included on the 503A Bulks List. Many committee members expressed concerns with the lack of reasonable data supporting the use of quercetin dehydrate in its proposed indications, the number of known drug interactions with this product, and the number of products that are currently available for these conditions are already proven to be safe and efficacious. Several committee members also noted that the product is widely available over-the-counter as an oral dietary supplement, and in the future, more substantial data would be needed to consider an IV formulation. Please note that one committee member was not present for the vote. Please see the transcript for details of the committee discussion. [2] Discussion: There are an overwhelming amount of Abstracts currently for Coronavirus Disease 2019 (COVID-19) using either Quercetin, Bromelain, Zinc, EGCG, Vitamin C, or Vitamin D as a Symptom Reducer, Prevention and/or treatment. [12] There is only ONE study currently on https://clinicaltrials.gov for Quercetin and Bromelain with Zinc and Vitamin C for Coronavirus Disease 2019 (COVID-19) [11] There are ZERO studies on https://clinicaltrials.gov for Quercetin and Bromelain with Zinc, EGCG, Vitamin C, and Vitamin D for Coronavirus Disease 2019 (COVID-19) [12] Limitations: There is a lack of research conducted for Quercetin and the FDA voted not to during Evaluation and Research on 09/2018 [2], The FDA decreased the daily dose of Zinc, Vitamin C, and Vitamin D on 03/2020 [3], A 02/2021 FDA warning letter issued regarding Zinc, Vitamin C and Vitamin D stating without approval or authorization by FDA to claim to mitigate, prevent, treat, diagnose, or cure COVID-19 in people. [1] On 11-FEB-2021 the COVID-19 Treatment Guidelines Panel Voted as followed and was published for the 25-AUG-2021 COVID-19 Treatment Guidelines: [15] Vitamin C - There is insufficient evidence for the COVID-19 Treatment Guidelines Panel (the Panel) to recommend either for or against the use of vitamin C for the treatment of COVID-19. Vitamin D - There is insufficient evidence for the Panel to recommend either for or against the use of vitamin D for the treatment of COVID-19. Zinc - There is insufficient evidence for the Panel to recommend either for or against the use of zinc for the treatment of COVID-19. • The Panel recommends against using zinc supplementation above the recommended dietary allowance for the prevention of COVID-19, except in a clinical trial (BIII). In addition to the antiviral medications and the immune-based therapies that are discussed elsewhere in the COVID-19 Treatment Guidelines, adjunctive therapies are frequently used in the prevention and/or treatment of COVID-19 or its complications. Some of these agents are being studied in clinical trials. Some clinicians advocate for the use of vitamin and mineral supplements to treat respiratory viral infections. Ongoing studies are evaluating the use of vitamin and mineral supplements for both the treatment and prevention of SARS-CoV-2 infection. [15] The Food and Drug Administration, Center for Drug Evaluation and Research on 12-Sep-2018 unanimously voted not to research quercetin dihydrate for the indications: Asthma, allergy, cancer prevention and treatment, and hypertension. Many committee members expressed concerns with the lack of reasonable data supporting the use of quercetin dehydrate in its proposed indications, the number of known drug interactions with this product, and the number of products that are currently available for these conditions Also, that are already proven to be safe and efficacious. the product is widely available over-the-counter as an oral dietary supplement [2] On 18-Feb-2021 the FDA took urgent measures to protect consumers from certain products that, without approval or authorization by FDA, claim to mitigate, prevent, treat, diagnose, or cure COVID-19 in people. [1] With changes on March 2020 for the Daily Value and Percent Daily Value: Changes on the New Nutrition and Supplement Facts Labels. FDA suggested doses as of 03/2020 are as followed: [3] Zinc - 11 mg QD - FDA suggested dose Before 03/2020 Zinc 15 mg QD [1] Vitamin A – 900 mcg QD - FDA suggested dose Before 03/2020 5,000 IU QD [1] Vitamin C - 90 mg QD - FDA suggested dose Before 03/2020 60 mg QD [1] Vitamin D - 20 mcg QD - FDA suggested dose Before 03/2020 400 IU QD [1] Significance: The Counter use of Quercetin and Bromelain is available for ages Two Years Old and older at a Maximum Suggested Dose of Quercetin 800 mg, and Bromelain 200 mg. [6.3] [7.5] Conclusion: Over the Counter Quercetin 800 mg QD, Bromelain 200 mg QD, Zinc 11mg QD, Vitamin A 900 mcg QD, Vitamin C 90 mg QD, and Vitamin D 20 mcg QD taken in combination together with Green Tea is potentially safe together for reducing the severity of symptoms in COVID-19 infection from ages Two Years Old and Older. The Combination of Quercetin and Bromelain with Zinc, EGCG, Retinoic Acid, Vitamin C, and Vitamin D might help reduce the COVID-19 vaccine symptoms and would potentially be a promising addition to proper PPE with COVID-19 Vaccinations to help combat the fight on Coronavirus Disease 2019 (COVID-19). This combination is available online and in stores around the world. [17] Conflict of Interest: The Authors have no Conflict of Interest. Funding: N/A Authors: Dr. Amr Ahmed - Ministry of Health - Saudi Arabia Dr. Abdullah Al.Kattan - King Faisal University - Saudi Arabia Mahmoud Elkazzaz - Biochemistry Master Degree – Kafr Elksheikh University, Egypt Michelle C. Orzechowski - Certified Clinical Research Coordinator – United States of America Correspondence to: Author/Abstract Writer: Michelle C. Orzechowski, CCRC Email: Morzechowski4122014@Gmail.com Keywords: Quercetin Intake, Bromelain Treatment, Zinc Chelating Strategies, EGCG, Retinoic Acid, Vitamin C Effect, Vitamin D Acts References: [0] Evidence of SARS-CoV-2 RNA in an Oropharyngeal Swab Specimen, Milan, Italy, Early December 2019 https://wwwnc.cdc.gov/eid/article/27/2/20-4632_article GISAID [1] Secretary of Health and Human Services, Determination that a Public Health Emergency Exists (originally issued Jan. 31, 2020, and subsequently renewed), available at https://www.phe.gov/emergency/news/healthactions/phe/Pages/default.aspx. Proclamation on Declaring a National Emergency Concerning the Novel Coronavirus Disease (COVID-19) Outbreak (Mar. 13, 2020), available at https://trumpwhitehouse.archives.gov/presidential-actions/proclamationdeclaring-national-emergency-concerning-novel-coronavirus-disease-covid-19-outbreak/. As explained in the next paragraph, there is currently an outbreak of a respiratory disease named "Coronavirus Disease 2019" (COVID-19) https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/mercolacom-llc-607133-02182021 [2] Food and Drug Administration Center for Drug Evaluation and Research Summary Minutes of the Pharmacy Compounding Advisory Committee Meeting September 12, 2018, https://www.fda.gov/media/121380/download https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act [3] Daily Value and Percent Daily Value: Changes on the New Nutrition and Supplement Facts Labels https://www.fda.gov/media/135301/download [4] Zinc https://www.drugs.com/npp/zinc.html https://www.drbvitamins.com/shop/zinc-90-veggiecap Zinc and SARS‑CoV‑2: A molecular modeling study of Zn interactions with RNA‑dependent RNA‑polymerase and 3C‑like proteinase enzymes Link: https://www.spandidos-publications.com/10.3892/ijmm.2020.4790 [5] EGCG https://www.drugs.com/npp/green-tea.html https://www.nowfoods.com/supplements/egcg-green-tea-extract-400-mg-veg-capsules [6] Quercetin https://www.drugs.com/npp/quercetin.html https://www.drbvitamins.com/shop/quercetin-bromelain-veggiecap https://reddremedies.com/products/childrens-sinus-support https://www.nowfoods.com/supplements/quercetin-bromelain-veg-capsules [7] Bromelain https://www.drugs.com/npp/pineapple.html https://www.drbvitamins.com/shop/quercetin-bromelain-veggiecap https://www.fda.gov/food/generally-recognized-safe-gras/enzyme-preparations-used-food-partial-list https://rd.springer.com/content/pdf/10.1007/PL00000936.pdf https://creeksidenaturals.com/product/snifflex/ https://www.nowfoods.com/supplements/quercetin-bromelain-veg-capsules [8] Vitamin C https://www.drugs.com/mtm/vitamin-c.html https://www.drbvitamins.com/shop/vitamin-c-1000mg-360-veggiecaps https://www.nowfoods.com/supplements/c-1000-zinc-immune-veg-capsules [9] Vitamin D https://www.drugs.com/pro/vitamin-d-ergocalciferol.html https://www.drbvitamins.com/shop/vitamin-d-5000iu-360-softgel https://www.nowfoods.com/supplements/vitamin-d-3-5000-iu-softgels [10] Sabine Hazan, M.D A Study of Hydroxychloroquine, Vitamin C, Vitamin D, and Zinc for the Prevention of COVID-19 Infection (HELPCOVID-19) https://clinicaltrials.gov/ct2/show/NCT04335084 Multifaceted highly targeted sequential multidrug treatment of early ambulatory high-risk SARS-CoV-2 infection (COVID-19) Link: https://dx.doi.org/10.31083/j.rcm.2020.04.264 Detection of SARS‑CoV‑2 from patient fecal samples by whole genome sequencing Link: https://dx.doi.org/10.1186/s13099-021-00398-5 [11] Dr. Abdullah Al.Kattan & Dr. Amr Ahmed The Study of Quadruple Therapy Zinc, Quercetin, Bromelain and Vitamin C on the Clinical Outcomes of Patients Infected With COVID-19 Link: https://clinicaltrials.gov/ct2/show/NCT04468139 Ahmed, Amr & Abdelseed, Heba & Albalawi, Yousef & Aslsalameen, Eman & Almutairi, Yousef & Alkattan, Abdullah & Arabia, Saudi. (2020). Evaluation of the Effect of Zinc, Quercetin, Bromelain, and Vitamin C on COVID-19 Patients. 10.1101/2020.12.22.20245993. 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 using 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. This study aims 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 are needed in the future to ensure the efficacy of quercetin, bromelain, zinc, and vitamin c combination. Research References: Evaluation of the Effect of Zinc, Quercetin, Bromelain and Vitamin C on COVID-19 Patients December 2020 https://dx.doi.org/10.1101/2020.12.22.20245993 Sadeghi Dousari, Amin et al. "COVID-19 (Coronavirus Disease 2019): A New Coronavirus Disease." Infection and drug resistance vol. 13 2819-2828. 12 Aug. 2020, Link: https://dx.doi.org/10.2147/IDR.S259279 Kaur, Supreet et al. "The looming storm: Blood and cytokines in COVID-19." 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Clinical and vaccine immunology: CVI vol. 13,3 (2006): 319-28. Link: https://dx.doi.org/10.1128/CVI.13.3.319-328.2006 Kobori, Masuko et al. "Quercetin suppresses immune cell accumulation and improves mitochondrial gene expression in adipose tissue of diet-induced obese mice." Molecular nutrition & food research vol. 60,2 (2016): 300-12. Link: https://doi:10.1002/mnfr.201500595 Gang Xiong, Wansheng Ji, Fei Wang, Fengxiang Zhang, Peng Xue, Min Cheng, Yanshun Sun, Xia Wang, Tianliang Zhang, "Quercetin Inhibits Inflammatory Response Induced by LPS from Porphyromonas gingivalis in Human Gingival Fibroblasts via Suppressing NF-κB Signaling Pathway", BioMed Research International, vol. 2019, Article ID 6282635, 10 pages, 2019 Link: https://dx.doi.org/10.1155/2019/6282635 Dabbagh-Bazarbachi H, Clergeaud G, Quesada IM, Ortiz M, O'Sullivan CK, Fernández-Larrea JB. Zinc ionophore activity of quercetin and epigallocatechin-gallate: from Hepa 1-6 cells to a liposome model. J Agric Food Chem. 2014 Aug 13;62(32):8085-93..Epub 2014 Jul 31. Link: https://dx.doi.org/10.1021/jf5014633 Larson, Abigail J et al. "Quercetin: A Treatment for Hypertension?-A Review of Efficacy and Mechanisms." Pharmaceuticals (Basel, Switzerland) vol. 3,1 237-250. 19 Jan. 2010, Link: https://dx.doi.org/10.3390/ph3010237 Pavan, Rajendra et al. "Properties and therapeutic application of bromelain: a review." Biotechnology research international vol. 2012 (2012): 976203. Link: https://dx.doi.org/10.1155/2012/976203 Lotz-Winter H. On the pharmacology of bromelain: an update with special regard to animal studies on dose-dependent effects. Planta Med. 1990 Jun;56(3):249-53. PMID: 2203073 Link: https://dx.doi.org/10.1055/s-2006-960949 Rathnavelu, Vidhya et al. "Potential role of bromelain in clinical and therapeutic applications." Biomedical reports vol. 5,3 (2016): 283-288. 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Link: https://dx.doi.org/10.1016/j.apjtm.2015.12.002 Jasso-Miranda, Carolina, et al. "Antiviral and immunomodulatory effects of polyphenols on macrophages infected with dengue virus serotypes 2 and 3 enhanced or not with antibodies." Infection and drug resistance vol. 12 1833-1852. 1 Jul. 2019, Link: https://dx.doi.org/10.2147/IDR.S210890 Aucoin, Monique et al. "The effect of quercetin on the prevention or treatment of COVID-19 and other respiratory tract infections in humans: A rapid review." Advances in integrative medicine, 10.1016/j.aimed.2020.07.007. 30 Jul. 2020, Link: https://dx.doi.org/10.1016/j.aimed.2020.07.007 Wu, Wenjiao et al. "Quercetin as an Antiviral Agent Inhibits Influenza A Virus (IAV) Entry." Viruses vol. 8,1 6. 25 Dec. 2015, Link: https://dx.doi.org/10.3390/v8010006 Ahmed, Amr & Albalawi, Yousef & Shora, Hassan & Abdelseed, Hiba & Al-Kattan, Abdulla. (2020). Effects of Quadruple Therapy: Zinc, Quercetin, Bromelain, and Vitamin C on the Clinical Outcomes of Patients Infected with COVID-19. 10.37179/rijed.000005. 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 specific treatment is available and supportive care is all that could be done to rescue patients. Quadruple therapy consisting of Zinc, Quercetin, Bromelain, and Vitamin C showed promising results in improving clinical outcomes among COVID-19 patients. Keywords: COVID-19, Cytokines, zinc, Quercetin, Bromelain, Vitamin C. 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Link: https://bit.ly/3gCeGRh [12] Abstract References: The combination of Quercetin and Bromelain with Zinc, Vitamin C, and Vitamin D, when taken together, may inhibit the viral replication of antiviral and Anti-Cytokine Storm by restraining Hyper-Inflammation and Cytokine Storm An Antiviral against RNA viruses like COVID-19 using the combination of Zinc with a Zinc Ionophore Acidifies parts of Cellular Milieu and increase Metallothioneins. Link: https://dx.doi.org/10.6084/m9.figshare.15153186 Dietary Supplements for COVID-19 Chapter May 2021Advances in Experimental Medicine and Biology Gerard E. MullinBerkeley LimektkaiLin Wang[...]Edward Giovannucci 1 Citation Link: https://dx.doi.org/10.1007/978-3-030-63761-3_29 Zinc supplementation and COVID-19 pandemic Preprint Full-text availableJul 2021 Mohammad Sarwar MirAbas Khan Link: https://dx.doi.org/10.13140/RG.2.2.24657.45922 Zinc supplementation and COVID-19 Article Full-text available 2020 Abas KhanMohammad Sarwar Mir Link: http://jmcrr.info/index.php/jmcrr Dietary Supplements and Nutrcaceutical Remedies for COVID-19ArticleFull-text availableMay 2021Poshadri AchinnaH.W. Deshpande Link: https://www.agricosemagazine.com Is nutraceutical supplementation appropriate for COVID-19 management? Article Apr 2021Allergy and Asthma Proceedings Michele PiazzaAttilio L BonerSandro Girotto[...]Joseph A. 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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.
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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.
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