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Characterisation of anti-Staphylococcus aureus activity of Quercetin
Abstract
Although many antibiotics are available for the treatment of bacterial infections, the emergence and global spread of antibiotic-resistant bacteria is a community-wide problem. To overcome this problem, we must explore alternative antimicrobials. This study investigated the antibacterial properties of quercetin, a flavonoid present in vegetables and fruits. Quercetin was tested against gram-positive and gram-negative bacteria and was found to exert selective antibacterial activity against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), and Staphylococcus epidermidis. Some clinical MRSA strains showed remarkable susceptibility to quercetin. In combination with antibiotics, such as oxacillin, ampicillin, vancomycin, gentamicin, and erythromycin, quercetin showed markedly enhanced antibacterial activity against MRSA. We also report quercetin-induced aggregation of S. aureus cells; the morphological changes in these cells, as assessed by electron microscopy; and the colony-spreading ability of quercetin-sensitive MRSA, all of which revealed the unique antibacterial properties of quercetin against S. aureus.
... Unique antibacterial properties of quercetin in combination with antibiotics (oxacillin, ampicillin, vancomycin, gentamicin and erythromycin) against methicillin-resistant S. aureus were unraveled earlier. Simultaneously, quercetin induced morphological changes and aggregation of S. aureus cells, as assessed by electron microscopy [17][18][19]. In comparison, Wang at al. found that quercetin did not affect S. aureus strain (S. aureus Newman and its CoA mutant) viability but inhibited bacteria-secreted coagulase, which is essential for the virulence of S. aureus. ...
... The pathogenicity of S. aureus is largely due to its ability to secrete enzymes and toxins, primarily α-hemolysin (αHL) [29]. This αHL-secreting bacterial strain is widely used to understand the mechanism(s) of pathogenicity of bacteria and evaluation of the targets of antimicrobial drugs [2,3,15,17,20,29,34,36]. At the same time, due to vast genetic plasticity and strain variability, the specificity of quercetin and other flavonoids should be verified using other pathogens. ...
Search for novel antimicrobial agents, including plant-derived flavonoids, and evaluation of the mechanisms of their antibacterial activities are pivotal objectives. The goal of this study was to compare the antihemolytic activity of flavonoids, quercetin, naringenin and catechin against sheep erythrocyte lysis induced by α-hemolysin (αHL) produced by the Staphylococcus aureus strain NCTC 5655. We also sought to investigate the membrane-modifying action of the flavonoids. Lipophilic quercetin, but not naringenin or catechin, effectively inhibited the hemolytic activity of αHL at concentrations (IC50 = 65 ± 5 µM) below minimal inhibitory concentration values for S. aureus growth. Quercetin increased the registered bacterial cell diameter, enhanced the fluidity of the inner and surface regions of bacterial cell membranes and raised the rigidity of the hydrophobic region and the fluidity of the surface region of erythrocyte membranes. Our findings provide evidence that the antibacterial activities of the flavonoids resulted from a disorder in the structural organization of bacterial cell membranes, and the antihemolytic effect of quercetin was related to the effect of the flavonoid on the organization of the erythrocyte membrane, which, in turn, increases the resistance of the target cells (erythrocytes) to αHL and inhibits αHL-induced osmotic hemolysis due to prevention of toxin incorporation into the target membrane. We confirmed that cell membrane disorder could be one of the direct modes of antibacterial action of the flavonoids.
... Moreover, QR showed synergistic activity against MRSA when combined with other antibiotics, such as erythromycin, vancomycin, ampicillin, oxacillin, and gentamicin. QR also induced the aggregation of S. aureus cells and affected the colony-spreading ability of S. aureus [50]. ...
... The inhibition of the interaction between the glycoprotein spike of SARS-CoV-2 and ACE2 is a potential antiviral therapeutic approach. QR is a potent inhibitor of recombinant hACE2 at physiologically relevant concentrations in vitro, with an IC 50 [68]. It is relevant to note that 3CLpro, also called the main protease (Mpro), is a potential drug target for COVID-19, and Zhang et al. recently crystallized 3CLpro of SARS-CoV-2 with an α-ketoamide inhibitor [69]. ...
The COVID-19 outbreak seems to be the most dangerous challenge of the third millennium due to its highly contagious nature. Amongst natural molecules for COVID-19 treatment, the flavonoid molecule quercetin (QR) is currently considered one of the most promising. QR is an active agent against SARS and MERS due to its antimicrobial, antiviral, anti-inflammatory, antioxidant, and some other beneficial effects. QR may hold therapeutic potential against SARS-CoV-2 due to its inhibitory effects on several stages of the viral life cycle. In fact, QR inhibits viral entry, absorption, and penetration in the SARS-CoV virus, which might be at least partly explained by the ability of QR and its derivatives to inhibit 3-chymotrypsin-like protease (3CLpro) and papain-like protease (PLpro). QR is a potent immunomodulatory molecule due to its direct modulatory effects on several immune cells, cytokines, and other immune molecules. QR-based nanopreparations possess enhanced bioavailability and solubility in water. In this review, we discuss the prospects for the application of QR as a preventive and treatment agent for COVID-19. Given the multifactorial beneficial action of QR, it can be considered a very valid drug as a preventative, mitigating, and therapeutic agent of COVID-19 infection, especially in synergism with zinc, vitamins C, D, and E, and other polyphenols.
... In addition, quercetin was reported to be active against Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA), and also against Staphylococcus epidermidis. [67] Observation under an electron microscope showed that quercetin induced the aggregation of S. aureus cells. Moreover, the combination of quercetin with antibiotics, such as oxacillin, ampicillin, vancomycin, gentamicin, and erythromycin, enhanced the antibacterial action against MRSA. ...
... Moreover, the combination of quercetin with antibiotics, such as oxacillin, ampicillin, vancomycin, gentamicin, and erythromycin, enhanced the antibacterial action against MRSA. [67] Quercetin has been reported to target D -Alanine: D -alanine ligase, the enzyme that catalyses D -Ala-D -Ala ligation, and therefore inhibits peptidoglycan synthesis. [59] Another important mechanism of quercetin on bacteria is the inhibition of β-lactamase. ...
Propolis is a resinous substance from beehive produced by the combination of plants and bee secretions. For a long time, this substance has gotten high attention in traditional and modern medicine. The aim of this review was to discuss the recent advances in the chemical composition and biological activities of propolis. The search for recent publications was based on several databases, such as PubMed, Google Scholar, Science-Direct, and Web of Sciences using relevant keywords. Literature data showed that several new compounds have recently been identified in propolis. The most important biological properties of propolis were discussed in this review, namely antibacterial, antiparasitic, antiviral, antioxidant, antileishmanial, anti-inflammatory, antidiabetic, immunomodulatory, and anticancer. In terms of safety, the data showed low toxicity of propolis even at high doses. Overall, propolis can be considered a promising source of bioactive compounds for drug development.
... Most of the works just mentioned incorporated in the edible coating natural extract or essential oils as active substances to inhibit the microbial growth and oxidation phenomena. Quercetin and quercetin glucoside compounds have been widely studied and applied as active compounds for their antioxidant (Silva-Weiss et al., 2018) and antimicrobial properties against some Gram-positive and Gram-negative bacteria (Hirai et al., 2010). Quercetin and quercetin glucoside compounds have been little studied as active compounds in edible food packaging to date. ...
... Quercetin and quercetin glucoside compounds have been little studied as active compounds in edible food packaging to date. Previous studies on the antibacterial activity of a large number of flavonoids against Staphylococcus aureus have pointed out that quercetin has a considerable inhibition against the selected pathogenic bacteria (Hirai et al., 2010;Manner, Skogman, Goeres, Vyorela & Fallarero, 2013;Yanishlievaa, Marinovaa, & Pokorny, 2006). ...
Alginate edible coatings enriched with quercetin glycosides and hydroxyapatite/quercetin complexes were evaluated as effective active coatings able to slow down the spoilage of fresh chicken fillets during the cold storage. Hydroxyapatite/quercetin complexes were preliminarily analysed by SEM, FTIR and zeta potential. Then alginate coatings were characterized for their ability to release quercetin in an aqueous medium which represents the base condition during the development of active edible food packaging. The microbiological parameters (total viable count, psychotropics bacteria count, Pseudomonas spp. and Enterobacteriaceae), measured during the cold storage period at 6 °C, highlighted the capability of alginate coatings with hydroxyapatite/quercetin glucosides complexes to significantly inhibit the growth of spoilage bacteria, as well as the total volatile basic nitrogen during the cold storage period of 11 days. Likewise, the texture, colour and sensory parameters pointed out a positive effect of quercetin when complexed with hydroxyapatite to maintain the quality of fresh chicken fillet during the storage.
... Another important flavonoid containing in the studied propolis extracts, namely quercetin, was reported as a potent antibacterial molecule. Shu et al. (2011) (Hirai et al., 2010). The electron microscopy observation showed that quercetin induced S. aureus cell aggregation. ...
... The electron microscopy observation showed that quercetin induced S. aureus cell aggregation. Moreover, the combination of quercetin with antibiotics, such as oxacillin, ampicillin, vancomycin, gentamicin, and erythromycin, enhanced the antibacterial action against MRSA (Hirai et al., 2010). It was reported that quercetin target D-Alanine:D-alanine ligase, the enzyme that catalyses the ligation of D-Ala-D-Ala, and as a consequence, quercetin inhibits peptidoglycan synthesis (Wu et al., 2008). ...
Propolis, a resinous substance collected by honeybees from plants, is well-known worldwide by its diversified biological activities. This study was aimed to determine the chemical composition of four ethanol extract propolis (EEP) collected from Morocco and to investigate thier antibacterial and antioxidant activities. The chemical composition was determined by Ultra-High Performance Liquid Chromatography-tandem mass spectrometry (UHPLC/MS). The antibacterial activity was evaluated using the well diffusion and microdilution methods. The antioxidant activity was investigated in vitro using three complementary techniques, namely reduction power, β-carotene bleaching, and DPPH scavenging assays. The identified molecules belong mainly to the flavonoid family, and interestingly, several of them were flavonoid glycosides. The four extracts showed strong antibacterial activity. The inhibitory zones varied from 10.00±00 to 22.5±2.12 mm, and MIC values ranged from 0.15 to > 5mg/ml, while MBC values ranged from 1.25 to > 5mg/ml. The antioxidant activity was relatively strong compared to positive controls, with IC50 varied from 67.61 to 140.04 µg/mL against DPPH free radical, and a relative antioxidant activity varied from 68.40±3.90 to 100.92±4.24, determined by β-carotene bleaching test. The antioxidant property was related to the chemical constituents. These results indicate that Moroccan propolis can be a valuable source of bioactive compounds for further drug discovery.
Keywords: propolis; flavonoids; antibacterial activity; antioxidant activity.
... Cadmium-quercetin complex had good inhibition of bacterial growth, but the mercury-quercetin complex was found to exhibit powerful growth inhibitory effect against the four microorganisms (E coli, S aureus, B cereus, K pneumoniae) tested. A study on the antimicrobial activity of quercetin against S. aureus, methicillin resistant S. aureus, and S. epidermidis has indicated that quercetin shows superior and selective antibacterial activity against the abovementioned microorganisms at a concentration of 50 μM [118]. Mn, Hg, Co, and Cd complexes of quercetin have been found to show a better bactericidal effect against all the microorganisms tested [119]. ...
Background Conventional techniques for water disinfection are fraught with issues like personnel exposure to damaging radiation and formation of harmful and carcinogenic disinfection byproducts. There are difficulties related to transportation and handling, and expensive capital and working costs also are involved like costs associated with on-site generation of disinfectants. There is a dire need for newer disinfection technologies that are environment and health friendly. Scope and benefits This article reviews the use of natural disinfectants derived from plants to enhance the quality of water. Researchers have utilized herbal extracts, phytochemicals, and phytochemical-metal complexes for the disinfection of water. Various factors for these chemicals like efficacy, toxicity, cost, and water solubility have been discussed and some useful phytochemical disinfectants are also identified. These disinfection methods particularly when using only pure phytochemicals are generally thought to be free from the deleterious effects associated with chlorination and other conventional technologies. Inherently, chlorinated and other harmful disinfection byproducts are not formed. Key findings and conclusions In various studies eugenol, thymol and extracts of Ocimum sanctum and Azadirachta indica have been utilized with fairly effective disinfection capabilities. The significant antimicrobial effects of allicin, berteroin, sanguinarine, and thymol are reflected from their very low minimum inhibitory concentration values. Even so, presently the efficiency of phytochemicals is not comparable to conventional disinfectants. The use of phytochemical metal complexes is, however, a plausible option that might be investigated further. The metal complexes because of their greater water solubility than pure phytochemicals result in improved disinfection efficiency. Notable among those are flavonoid-metal complexes that should be considered further for use in water disinfection. It is also concluded that phytochemicals may be added to water that has also been disinfected with some other commonly-used
... Tese structural features indicate their antioxidant activity; in particular, favonoid aglycones, such as quercetin, kaempferol, and catechin, have important roles in radical scavenging [33]. Quercetin is one of the most abundant favonols in plants and has several activities such as antibacterial, anti-infammatory, neuroprotective, and anticancer efects [34,35]. In the present study, the range of the total favonoid content was 7.78-23.61 ...
This study evaluated the antioxidant, anticancer, and neuroprotective activities of germinated shoots (cotyledon and true leaves) of wild plants and measured their total phenol, flavonoid, quercetin, and vitamin C contents. The ethanol extract of Geum aleppicum (GA) showed high DPPH and ABTS radical scavenging activities. GA treatment also significantly increased cell viability against hydrogen peroxide-induced oxidative stress in SH-SY5Y neuronal cells, indicating that GA had antioxidant and neuroprotective properties. In AGS gastric cancer cells, the cotyledon of Pinus densiflora (PD1) and the true leaves of Chamaecyparis obtusa (CHA2) significantly inhibited cell proliferation, showing that PD1 and CHA2 elicited anticancer effect. The total phenol content was the highest in the shoots of GA, and the total flavonoid content was the highest in the shoots of true leaves of P. densiflora. The quercetin and vitamin C contents were the highest in the CHA2 and the cotyledon of GA, respectively. In conclusion, this study suggested the antioxidant, anticancer, and neuroprotective activities of the germinated shoots of wild plants and their high total phenol, flavonoid, quercetin, and vitamin C contents. These findings were noteworthy in the case of the germinated shoot of GA and provided a basis for studying functional forestry income resources. Practical Applications. Our results demonstrated that GA exerts strong DPPH and ABTS radical scavenging activities. It also plays a neuroprotective role in oxidative stress-induced cell damage. These effects can be linked to their polyphenol and flavonoid contents in the extract. Moreover, PD1 treatment has inhibitory effect on gastric tumor cells growth and exhibited an effective ∙OH radical scavenging property. These findings indicated that germinated shoot extracts have potential for development of functional food with therapeutic applications.
... Today, three classes, with six different drugs, of FDA-approved SBLis exist based on β-lactams (sulbactam, tazobactam, and clavulanate), 1,6-diazabicyclo octanes (avibactam, relebactam), and boron-based (vaborbactam) scaffolds. Still, and critically, none of antibiotics [32][33][34][35][36][37][38][39][40][41][42]. Of these, only Eumkeb et al. directly mentioned quercetin as a potential MBLi, but without reference to any specific MBL. ...
Among the various mechanisms that bacteria use to develop antibiotic resistance, the multiple expression of β-lactamases is particularly problematic, threatening public health and increasing patient mortality rates. Even if a combination therapy—in which a β-lactamase inhibitor is administered together with a β-lactam antibiotic—has proven effective against serine-β-lactamases, there are no currently approved metallo-β-lactamase inhibitors. Herein, we demonstrate that quercetin and its analogs are promising starting points for the further development of safe and effective metallo-β-lactamase inhibitors. Through a combined computational and in vitro approach, taxifolin was found to inhibit VIM-2 expressing P. aeruginosa cell proliferation at <4 μg/mL as part of a triple combination with amoxicillin and clavulanate. Furthermore, we tested this combination in mice with abrasive skin infections. Together, these results demonstrate that flavonol compounds, such as taxifolin, may be developed into effective metallo-β-lactamase inhibitors.
... Naringenin at a concentration of 0.5 mg/mL did not present significant activity against S. Typhimiurium, corroborating other works that present an MIC of 1 mg/mL [35], although it did exert a significant reduction in OD (600 nm) measurements against S. aureus, adding to earlier work in the field that has found this to be the compounds' MIC [36]. Quercetin, although unsuitable for the OD-based assays devised here due to its natural yellow pigmentation, has previous evidence supporting its antimicrobial capacity [37] and was thus carried forward for further investigation. Kaempferol was also selected on a similar basis [38]. ...
Antimicrobial resistance is now commonly observed in bacterial isolates from multiple settings, compromising the efficacy of current antimicrobial agents. Therefore, there is an urgent requirement for efficacious novel antimicrobials to be used as therapeutics, prophylactically or as preservatives. One promising source of novel antimicrobial chemicals is phytochemicals, which are secondary metabolites produced by plants for numerous purposes, including antimicrobial defence. In this report, we compare the bioactivity of a range of phytochemical compounds, testing their ability to directly inhibit growth or to potentiate other antimicrobials against Salmonella enterica Typhimurium, Pseudomonas aeruginosa, Listeria monocytogenes, and Staphylococcus aureus. We found that nine compounds displayed consistent bioactivity either as direct antimicrobials or as potentiators. Thymol at 0.5 mg/mL showed the greatest antimicrobial effect and significantly reduced the growth of all species, reducing viable cell populations by 66.8%, 43.2%, 29.5%, and 70.2% against S. enterica Typhimurium, S. aureus, P. aeruginosa, and L. monocytogenes, respectively. Selection of mutants with decreased susceptibility to thymol was possible for three of the pathogens, at a calculated rate of 3.77 × 10−8, and characterisation of S. enterica Typhimurium mutants showed a low-level MDR phenotype due to over-expression of the major efflux system AcrAB-TolC. These data show that phytochemicals can have strong antimicrobial activity, but emergence of resistance should be evaluated in any further development.
... The results for HGs enriched with NLC2 + Q or NLC2 + Q + ω 3 are easily explained by the Q activity against S. aureus [92,93], but the effect of Q is diminished in the formulation as there is only a reduction in S. aureus growth. The antibacterial effect is appealing for skincare and protection as it may increase microbiome diversity, which is thought to be a preventive health factor. ...
Chronic skin exposure to external hostile agents (e.g., UV radiation, microorganisms, and oxidizing chemicals) may increase oxidative stress, causing skin damage and aging. Because of their well-known skincare and protective benefits, quercetin (Q) and omega-3 fatty acids (ω3) have attracted the attention of the dermocosmetic and pharmaceutical sectors. However, both bioactives have inherent properties that limit their efficient skin delivery. Therefore, nanostructured lipid carriers (NLCs) and enriched PFC® hydrogels (HGs) have been developed as a dual-approach vehicle for Q and/or ω3 skin topical administration to improve bioactives’ stability and skin permeation. Two NLC formulations were prepared with the same lipid composition but differing in surfactant composition (NLC1—soy lecithin and poloxamer 407; NLC2—Tween® 80 and dioctyl sodium sulfosuccinate (DOSS)), which have an impact on physicochemical properties and pharmaceutical and therapeutic performance. Despite both NLCs presenting high Q loading capacity, NLC2′s physicochemical properties make them more suitable for topical skin administration and ensure longer colloidal stability. Additionally, NLC2 demonstrated a more sustained Q release, indicating higher bioactive storage while improving permeability. The occlusive effect of NLCs-enriched HGs also has a positive impact on skin permeability. Q-loaded NLC2, with or without ω3, -enriched HGs demonstrated efficacy as antioxidant and photoprotective formulations as well as effective reduction in S. aureus growth, indicating that they constitute a promising approach for topical skin administration to prevent skin aging and other damaging cutaneous processes.
... According to one study, quercetin damaged the cell membranes of E. coli [40]. S. aureus cells aggregated in response to quercetin; these cells underwent morphological changes, shows one of the studies [41]. From TEM analysis it was discovered that S. officinarum containing quercetin causes abnormalities in cell morphology and damage to internal structures in E. coli and S. aureus. ...
Antibiotic resistance is a global concern due to the ability of bacteria to continuously develop various mechanisms
of resistance against diverse antimicrobial classes; therefore, there is a critical prerequisite to discover
diverse antibiotics with novel chemical structures and unique mechanisms of action. The research work aimed to
investigate the detailed antibacterial activity and phytochemical characterization of the methanolic extract of
Pistacia integerrima galls. Antibacterial properties were analyzed through the well diffusion method and the
minimum inhibitory concentration (MIC) was determined through the broth dilution method. MIC of Pistacia
integerrima extract (PIE) was found to be 10 mg/mL against both E. coli and S. aureus. Biofilm inhibition was
determined by the crystal violet method where PIE demonstrated significant inhibition of biofilms. In the
presence of PIE, TEM demonstrated morphological changes in both strains. A total of 17 metabolites were
identified through GC-MS analysis with most of the compounds exhibiting antibacterial properties, HPTLC shows
the presence of the important metabolite quercetin. Furthermore, virtual ligand screening revealed quercetin and
phthalic acid as the most medicinally active constituents and potential inhibitors of tyrosyl-tRNA synthetase
(TyrRS) and Dihydrofolate reductase (DHFR). Further research into PIE’s bioactive compounds could lead to the
development of new antibacterial compounds.
... Catechin has also exhibited anti-inflammatory activity (Bae et al. 2020). Quercetin found in PCCR has demonstrated antibacterial, immunostimulatory, and anti-inflammatory properties (Lesjak et al. 2018;Hirai et al. 2010). Moreover, stigmasterol, a noteworthy phytosterol, showed immunomodulating, anti-osteoarthritic, anti-angiogenic, anti-oxidant, anti-inflammatory, and anti-peroxidative characteristics by lowering TNF-α and vascular endothelial growth factor receptor (VEGFR). ...
Populus ciliata (PCCR) is traditionally used to treat muscular swelling, inflammation, pain, and fever. The current study was designed to validate the potential of aqueous ethanolic extract of the plant against inflammation, peripheral neuropathy, and pain in arthritic rats. The PCCR was chemically characterized by gas chromatography-mass spectroscopy and high-performance liquid chromatography. In vitro antioxidant, and in vitro anti-inflammatory assays were carried out on PCCR. For anti-arthritic potential, Wistar rats’ rear paws were injected with 0.1 ml Complete Freund’s Adjuvant using methotrexate (3 mg/kg/week) as standard control. PCCR at 100, 200, and 400 mg/kg was given orally to arthritic rats for 21 days. The PCCR exhibited significant inhibition of bovine serum albumin denaturation (IC-50: 202.1 µg/ml), egg albumin denaturation (IC-50:553.5 mg/ml) and RBC membrane stabilization (IC-50: 122.5 µg/ml) and antioxidant (IC-50 = 49.43 µg/ml) activities. The PCCR notably decreased the paw diameter and increased body weight of treated arthritic animals as equated to diseased control. The treatment notably (p < 0.05–0.0001) decreased malondialdehyde, and increased superoxide dismutase, reduced glutathione, and catalase in the liver and sciatic nerve homogenate in compared to diseased rats. The PCCR treatment remarkably (p < 0.05–0.0001) regulated the levels of nor-adrenaline and serotonin in sciatic nerve in contrast to diseased rats. Treatment with PCCR improved the motor activity, pain, ligament degeneration, and synovial hyperplasia in arthritic rats. Moreover, PCCR significantly (p < 0.01–0.0001) decreased the IL-6 and TNF-α. It is evident from the current study that PCCR had ameliorated polyarthritis and peripheral neuropathy through reduction of inflammatory markers, and improvement of oxidative stress might be due to presence of phenolic acids, flavonoids, phytosterols, and other fatty acids.
Graphical abstract
... Quercetin and its glycoside rutin ( Figure 1) are the most common flavonoids in the diet. Quercetin has pronounced antibacterial properties including activity against MRSA and Staphylococcus epidermidis [21]. Another flavonol, myricetin (Figure 1), has been shown to have a therapeutic effect on many diseases, including tumors of different types, inflammatory diseases, atherosclerosis, thrombosis, cerebral ischemia, diabetes, Alzheimer's disease, and pathogenic microbial infections [22]. ...
This paper discusses the possibility of using plant polyphenols as viral fusion inhibitors with a lipid-mediated mechanism of action. The studied agents are promising candidates for the role of antiviral compounds due to their high lipophilicity, low toxicity, bioavailability, and relative cheapness. Fluorimetry of calcein release at the calcium-mediated fusion of liposomes, composed of a ternary mixture of dioleoyl phosphatidylcholine, dioleoyl phosphatidylglycerol, and cholesterol, in the presence of 4′-hydroxychalcone, cardamonin, isoliquiritigenin, phloretin, resveratrol, piceatannol, daidzein, biochanin A, genistein, genistin, liquiritigenin, naringenin, catechin, taxifolin, and honokiol, was performed. It was found that piceatannol significantly inhibited the calcium-induced fusion of negatively charged vesicles, while taxifolin and catechin showed medium and low antifusogenic activity, respectively. As a rule, polyphenols containing at least two OH-groups in both phenolic rings were able to inhibit the calcium-mediated fusion of liposomes. In addition, there was a correlation between the ability of the tested compounds to inhibit vesicle fusions and to perturb lipid packing. We suggest that the antifusogenic action of polyphenols was determined by the depth of immersion and the orientation of the molecules in the membrane.
... Quercetin in C. alata exhibited promising antibacterial activity. The activity was demonstrated by the multiple hydroxyl groups in the chemical structure [62][63][64][65]. Phosphorylation and sulfation of the hydroxyl groups exhibited antimicrobial activity affecting the functioning of peptides, proteins, and ion channels embedded in the membrane [64,66]. ...
Atopic dermatitis (AD) is an inflamed skin condition with relapsing pruritus and cutaneous physiological dysfunction. This skin disorder is widespread around the world and frequently affects infants, children and adults. Natural products with bioactive lead compounds are the source of natural medicines for complementary and alternative therapy in managing AD. Cassia alata has been used traditionally as a remedy for a variety of health issues. In Asian countries, it is used as an ethnomedicine to treat skin conditions such pityriasis versicolor, ringworm, scabies, shingles, urticaria and itching. According to previously published studies, the phytochemicals in C. alata may have a wide range of significant pharmacological effects. AD management is highlighted here, as this review explores the literature on the pharmacological effects of C. alata and its phytochemical content. Specifically, antibacterial, wound healing, anti-inflammatory and antioxidant effects are reviewed and discussed in relation to AD management.
... In vitro and in vivo studies have revealed that quercetin possesses a wide spectrum of biological effects that include anti-inflammatory [3,4], antilipoperoxidant [5], antitumoral [6,7], antimicrobial [8], anti-diabetic [9,10], anti-atherosclerotic [11], and cardioprotective [12,13] activities. It is well known that the biological activity of flavonoids is mostly related to their antioxidant potential [14]. ...
Flavonols are found in plants as aglycones and as glycosides. Antioxidant activity of flavonols may occur via several mechanisms within the cell, and mitochondria as a target may play an important role. There is a lack of information about the influence of the sugar moiety on biological activity of flavonoid glycosides. The aims of study were to investigate the effects of quercetin and its glycosides on mitochondrial respiration rates at various metabolic states, and to evaluate their antioxidant potential using chemical and biological approaches. Mitochondrial function was measured using an oxygraphic method, cytochrome c reduction spectrophotometrically, H2O2 generation in mitochondria fluorimetrically, and antioxidant activity of flavonoids using an HPLC-post column system. Our data revealed that quercetin and its glycosides isoquercitrin, rutin, and hyperoside uncouple kidney mitochondrial respiration (increasing the State 2 respiration rate) and significantly reduce cytochrome c. Moreover, quercetin, and its glycosides decrease the production of mitochondrial H2O2 and possess radical scavenging and ferric reducing capacities. The highest activity was characteristic for quercetin, showing that the sugar moiety significantly diminishes its activity. In conclusion, our results show the efficient radical scavenging, ferric and cytochrome c reducing capacities, and uncoupling properties of quercetin and its glycosides, as well as the importance of the sugar residue and its structure in the regulation of kidney mitochondrial function.
... Quercetin is known to have antimicrobial effects on some microorganisms [45], while others have the ability to produce or transform quercetin [46,47]. One study reported that its antimicrobial effect targeted the function of mitochondria and nucleic acid synthesis [48]. ...
The fermentation of fruit processing residuals (FPRs) with filamentous fungi can provide protein-rich food products. However, FPRs that contain bioactive compounds with antimicrobial properties present a major challenge. In this work, the resistance of two edible filamentous fungi, Rhizopus oligosporus and Neurospora intermedia, to 10 typically inhibiting bioactive compounds available in FPRs (epicatechin, quercetin, ellagic acid, betanin, octanol, hexanal, D-limonene, myrcene, car-3-ene, and ascorbic acid) was examined. These compounds’ inhibitory and stimulatory effects on fungal growth were examined individually. Three different concentrations (2.4, 24, and 240 mg/L) within the natural concentration range of these compounds in FPRs were tested. These bioactive compounds stimulated the growth yield and glucose consumption rate of R. oligosporus, while there was no increase in the biomass yield of N. intermedia. Ellagic acid caused an up to four-fold increase in the biomass yield of R. oligosporus. In addition, octanol and D-limonene showed antifungal effects against N. intermedia. These results may be helpful in the development of fungus-based novel fermented foods.
... Among all the natural BACs (BioActive Compound) employed by the supplement industry, quercetin is one of the more clinically studied (Katske et al., 2001; National Institute of Diabetes and Digestive and Kidney Diseases,; Vicente-Vicente et al., 2019;). Quercetin is a natural flavonoid known for its multiple pharmacological effect, such as nephronprotector (Aldemir et al., 2014;Vicente-Vicente et al., 2019), anticancer (Vafadar et al., 2020;Zang et al., 2021), anti-inflammation element (Askari et al., 2012) and antibacterial (Hirai et al., 2010). Despite the quercetin therapeutic potential, its actual efficacy is limited by its poor water solubility and consequent low bioavailability. ...
This study unravels a formulation made of food‐based microparticles (MPs) able to control the release of quercetin, a natural anticancer compound, which activity is only limited by its poor aqueous solubility and consequent low bioavailability. To solve this issue, a spray‐dried micro delivery system was developed using a bench mini spray dryer B290 Buchi. The resulting MPs were only manufactured with food‐derived ingredients such as whey proteins and milk, avoiding the use of any other synthetic material. These microparticles were characterised with a testing campaign encompassing either the physical–chemical characterisation with SEM, DSC and DLS, or the technological and biological features with in vitro, ex vivo and in vivo studies, the latter being characterised by a human colon cancer xenograft model. These studies showed as the quercetin solubility and release rate improved when tested in condition mimicking oral administration, resulting in a general improvement of its bioavailability and the consequent anticancer activity. This study shows as the whey proteins may serves as natural adjuvant able to provide valuable technological features when used to manufactures micro carriers by spray drying. Multiple oral administration of quercetin embodied in the microparticles prevents the tumour mass from increasing in volume compared to pure quercetin.
... This is in opposition to other studies, which reported quercetin as an antimicrobial compound. Hirai et al. [55] reported the inhibition of Staphylococcus aureus, a bacteria associated with lipase production [56], in the presence of quercetin at concentration of 50 µM. Rocha et al. [57] mentioned the inhibitory effect that might result in irregularity in nucleic acid synthesis and disorder of mitochondria function. ...
Fruit and vegetable processing wastes are global challenges but also suitable sources with a variety of nutrients for different fermentative products using bacteria, yeast or fungi. The interaction of microorganisms with bioactive compounds in fruit waste can have inhibitory or enhancing effect on microbial growth. In this study, the antimicrobial effect of 10 bioactive compounds, including octanol, ellagic acid, (−)-epicatechin, quercetin, betanin, ascorbic acid, limonene, hexanal, car-3-ene, and myrcene in the range of 0–240 mg/L on filamentous fungi Aspergillus oryzae and Aspergillus niger were investigated. These fungi were both found to be resistant to all compounds except octanol, which can be used as a natural antifungal agent, specifically against A. oryzae and A. niger contamination. On the contrary, polyphenols (quercetin and ellagic acid), ascorbic acid, and hexanal enhanced A. niger biomass yield 28%, 7.8%, 16%, and 6%, respectively. Furthermore, 240 mg/L car-3-ene was found to increase A. oryzae biomass yield 8%, while a 9% decrease was observed at lower concentration, 24 mg/L. Similarly, up to 17% decrease of biomass yield was observed from betanin and myrcene. The resistant nature of the fungi against FPW bioactive compounds shows the potential of these fungi for further application in waste valorization.
... Quercetin is a flavonol that is abundant in red onions and kale, as well as in other fruits and vegetables. It inhibits oxidation [24], exerts anxiolytic [25] and anti-bacterial [26] effects, has potential anti-diabetic activity [27], and promotes bone formation [28]. ...
... In fact, this hypothesis was proven in this study, since the chemical analysis showed the presence of several components known by their interesting biological activities. Among these important molecules, there are, as example, caffeic acid, ferulic acid, apigenin, kaempferide, quercetin, sakuranetin which are known to possess multiple biological properties such as antibacterial and antioxidant activities (Guz et al., 2001;Wu et al., 2008;Hirai et al., 2010). ...
The development of multi-drug-resistant bacteria pushed the scientific community to look for new alternatives to solve the problem. Propolis is a beehive substance and one of the richest natural products in bioactive compounds with antibacterial activity. This study was aimed to investigate the possible synergistic interaction between propolis and antibacterial drugs, such as essential oils (EOs) and antibiotics, in order to find increased activity with decreased concentrations. Two ethanol extracts of propolis were used for the test, which were collected from the north of Morocco. The chemical composition was determined by UHPLC-MS. The synergistic effect of propolis extracts with EOs and antibiotics was tested using the checkerboard technique. The chemical analysis showed the presence of more that 100 compounds in propolis extracts, belonging mainly to flavonoids. The combination of propolis with the other antibacterial drugs showed different types of interactions with FIC index values varied from 0.18 to 1, but no antagonist effect was noticed. With FICI<0.5, the synergistic effect was obtained with essential oils as well as with antibiotics. These results indicate that propolis can be a promising source of molecules with medical interest to treat bacterial infection and/or to increase the action of antibiotics.
... In particular, in the last years, several active systems have been developed using the flavonoid quercetin, exploiting principally its antioxidant capacity to prevent oxidation phenomena in food products (Farrag et al., 2018;Silva-Weiss et al., 2018). Besides its established antioxidant activity, some authors report the antimicrobial activity of this flavonoid against Grampositive (Staphylococcus aureus, Listeria spp) and Gram-negative bacteria (E.coli, Salmonella Enteritidis, Salmonella Typhimurium) (Hirai et al. 2010). It must be pointed out that the release time of the preservative from a film or coating has a strong impact on its effectiveness. ...
In this work, active alginate-based coatings were developed using hydroxyapatite nanoparticles as potential carriers for quercetin glycoside compounds. The coatings were produced through the layer-by-layer method and loaded with different concentrations of free quercetin and hydroxyapatite/quercetin complexes. In-vitro release studies of the quercetin glycoside compound through the coatings were performed in an aqueous medium: even if the hydroxyapatite nanocrystals slow down the diffusion process, quercetin released reached the equilibrium in one day for all coatings. Lastly, preliminary antimicrobial tests show that all active coatings display antibacterial activity against Pseudomonas fluorescens. This study highlights the real possibility of applying active edible coating loaded with hydroxyapatite/quercetin complexes to the food shelf life extension
... The exact mechanism of the antimicrobial synergistic interaction occurred by the inhibition of bacterial cell wall synthesis which leads to lyses of the cells, might facilitate the influx of phenolic compounds such as quercetin and xanthotoxin into the bacterial cells, such higher concentrations in the cells will enhance the damage on DNA caused by quercetin which inhibits DNA polymerase-β and xanthotoxin which binds preferentially to the guanine and cytosine moieties of DNA, leading to cross-linking of DNA, thus inhibiting DNA synthesis and function (Bennett and Brown, 2009); (Dewick, 2009); (Schinazi et al., 1997). Quercetin showed markedly enhanced antibacterial activity with antibiotics: oxacillin, ampicillin, vancomycin, gentamicin and erythromycin against Methicillin-Resistant S. aureus (MRSA), (Hirai et al., 2010). Phenolic acids like salicylic acid, p-anisic acid and caffeic acid have been shown to potentiate the activity of β-lactam antibiotics against various strains of Staphylococcus aureus (Kwon et al., 2007); (Muroi et al., 2004). ...
... The results showed its potential for use on sources of infection, in disinfection or antisepsis procedures. Studies on the action of macela flavonoids showed that quercetin is able to induce the aggregation of bacterial cells and cause morphological changes in these cells, being highly effective in controlling MRSA strains (Hirai et al 2010). ...
Methicillin-resistant Staphylococcus aureus (MRSA) causes mastitis in dairy cattle with serious economic and public health significance. This study developed nanoemulsions of Linum usitatissimun oil loaded with Achyrocline satureioides (macela) extract and investigated their in vitro antimicrobial activity against MRSA. Macela-nanoemulsions (NE-ML) were prepared using high-pressure homo-genization (HPH) with different proportions of flaxseed oil, Tween 80 and crude extract. Four majoritarian flavonoids were identified in the macela extract: 3-O methylquercetin, achyrobichalcone, quercetin and luteolin (187.3±0.1, 155.4±11.6, 76.3±0.1 and 30.4±0.0 μg ml −1 , respectively). NE-ML nanoemulsions were successfully obtained by the HPH method and showed a milky aspect with yellowish color. The mean particle size was around 200 nm with monodisperse distribution (PdI<0.2), remaining stable for 160 days at room temperature. When analyzed on a LUMiSizer high-end dispersion analyzer, low values were found (0.5), indicating high stability index, mainly for NE-ML1:5 (0.2). The encapsulation efficiency of macela-nanoemulsions was greater than 94%, considering the four chemical compounds from extract. Minimum inhibitory concentration (MIC) against planktonic bacteria, inhibition of biofilm formation (MBIC), and eradication of MRSA biofilms (MBEC) were determined through in vitro tests on microplates. The MIC of NE-ML against planktonic MRSA showed values ranging from 1.2 to 10% (v/v), while blank-nanoemulsions (NE-B, without macela extract) showed values ranging from 6 to 50% (v/v). MBIC and MBEC of NE-ML were 25 and 80% (v/v), respectively. MBIC showed a mass reduction greater than 64%, and MBEC showed a mass reduction greater than 73%. Macela-nanoemulsions (NE-ML), mainly NE-ML1:5, showed high antimicrobial activity and appeared to represent a new alternative of sustainable antimicrobial product for the control of MRSA. Since this innovative nanoemulsion can impact animal health, future research should include in vitro and in vivo studies to evaluate intramammary therapy and control of MRSA infections in organic and agroecological milk production systems.
... The antimicrobial activity of the L. chinense leaf extract might be due to the phytochemicals present in these plants, which are rich in phenolic acids, such as protocatechuic, gentisic, p-hydroxybenzoic, chlorogenic, p-coumaric, salicylic, and caffeic acid, as well as flavonoids (rutin). Several previous studies observed reductions in microbial populations upon treatment with the phenolic compounds of plant extracts [60][61][62][63]. For instance, p-hydrobenzoic acid effectively inhibited the growth of Staphylococcus aureus [64]. ...
This study aimed at investigating the Lycium chinense Miller leaf extract mineral and phenolic compound profiles as well as antioxidant and antimicrobial potential. We determined the leaf extract mineral composition, identified its major mineral components, and quantified secondary metabolites. We also measured the leaf extract antioxidant potential and found that it varies in a concentration-dependent manner. We observed a significant and higher positive correlation between DPPH and ABTS assays compared with the total phenolic and flavonoid content. Furthermore, our assay results positively correlated with several observed acids, indicating their strong association with the L. chinense antioxidant potential. Our cytotoxic assay revealed weak toxicity at higher tested concentrations. Our MIC assay showed that the 80% methanol extract effectively inhibited the growth of Escherichia coli Castellani and Chalmers (ATCC35150). The 625-ppm leaf extract completely suppressed the growth of Staphylococcus aureus Rosenbach (ATCC13150), Bacillus cereus (ATCC 14579), and Helicobacter pylori (ATCC43504). These results allow us to understand the indigenous medicinal value of L. chinense. Our study suggests that the L. chinense leaf extract phenolic compounds possess a good antioxidant activity against free radicals and are effective antimicrobial agents. Finally, the presence and high level of diverse minerals suggest the potential of L. chinense for nutraceutical and functional food applications.
... In the current study, we found moderate antibacterial activities of hyperoside, quercetin and quercetin 3-glucuronide. Quercetin showed moderate antibacterial activities against S. aureusm, E. coli and P. aeruginosa in previous investigations [62,63]. ...
Acacia saligna and Lawsonia inermis natural populations growing in Northern Saudi Arabia might be a valuable source of polyphenols with potent biological activities. Using high-performance liquid chromatography–diode array detection (HPLC-DAD), several polyphenols were detected tentatively in considerable amounts in the methanolic leaf extracts of A. saligna and L. inermis. A. saligna mainly contained rutoside, hyperoside, quercetin 3-glucuronide, gallic acid and p-coumaric acid, whereas those of L. inermis contained apigenin 5-glucoside, apigetrin and gallic acid. Strong antioxidant activities were found in the leaf extracts of both species due to the presence of hyperoside, quercetin 3-glucuronide, gallic acid, isoquercetin, p-coumaric acid, quercitrin and rutoside. A. saligna and L. inermis leaf extracts as well as hyperoside, apigenin 5-glucoside, and quercetin 3-glucuronide significantly reduced reactive oxygen species accumulation in all investigated cancer cells compared to the control. Methanolic leaf extracts and identified polyphenols showed antiproliferative and cytotoxic activities against cancer cells, which may be attributed to necrotic cell accumulation during apoptotic periods. Antibacterial activities were also found in both species leaf extracts and were twice as high in A. saligna than L. inermis due to the high composition of rutoside and other polyphenols. Finally, strong antifungal activities were detected, which were associated with specific phenols such as rutoside, hyperoside, apigenin 5-glucoside and p-coumaric acid. This is the first study exploring the polyphenolic composition of A. saligna and L. inermis natural populations in northern Saudi Arabia and aiming at the detection of their biological activities.
... This antibacterial activity of R. graveolens is attributed to the high contents of specific polyphenols such as chlorogenic acid and p-coumaric acid, but particularly to quercetin. It has been shown that quercetin has strong antibacterial activities against [73], as found in this study, as well as against other bacteria including E. coli and Ps. aeruginosa [74]. ...
Natural populations of Ruta graveolens L. and Artemisia abrotanum L. in northern Saudi Arabia may be a rich source of natural polyphenols with potential biological activities. Therefore, tentative high-performance liquid chromatography–diode array detection was used to analyze the polyphenol contents of leaf extracts. R. graveolens mainly contained the phenolic acids chlorogenic acid and p-coumaric acid and the flavonoids rutoside and quercetin, whereas those of A. abrotanum mainly contained the phenolic acids isochlorogenic acid and rosmarinic acid and the flavonoid quercetin. Leaf extracts of both species showed antioxidant activities due to the presence of quercetin, chlorogenic acid, and p-coumaric acid as well as antiproliferative and cytotoxic activities against cancer cells, which may be attributed to necrotic cell accumulation during the early and late apoptotic periods. Both species also exhibited antibacterial activity, although the activity was higher in R. graveolens due to the high contents of quercetin and other polyphenols. Finally, both species exhibited antifungal activities, which were associated with specific polyphenols. This is the first study to confirm the richness of polyphenols and wide spectrum of biological activities in natural populations of R. graveolens and A. abrotanum in northern Saudi Arabia.
Capsaicin is a phytochemical derived from plants of the genus Capsicum and subject of intensive phytochemical research due to its numerous physiological and therapeutical effects, including its important antimicrobial properties. Depending on the concentration and the strain of the bacterium, capsaicin can exert either bacteriostatic or even bactericidal effects against a wide range of both Gram-positive and Gram-negative bacteria, while in certain cases it can reduce their pathogenicity by a variety of mechanisms such as mitigating the release of toxins or inhibiting biofilm formation. Likewise, capsaicin has been shown to be effective against fungal pathogens, particularly Candida spp., where it once again interferes with biofilm formation. The parasites Toxoplasma gondi and Trypanosoma cruzi have been found to be susceptible to the action of this compound too while there are also viruses whose invasiveness is significantly dampened by it. Among the most encouraging findings are the prospects for future development, especially using new formulations and drug delivery mechanisms. Finally, the influence of capsaicin in somatostatin and substance P secretion and action, offers an interesting array of possibilities given that these physiologically secreted compounds modulate inflammation and immune response to a significant extent.
Infectious diseases have always been a concern for human health, responsible for numerous pandemics throughout history. Even with the advancement of medicine, new infectious diseases have been discovered over the years, requiring constant effort in medical research to avoid future problems. Like the emergence of new diseases, the increase in resistance of certain bacterial strains also becomes a concern, carried out through the misuse of antibiotics, generating the adaptation of certain microorganisms. Worldwide, the resistance developed by several bacterial strains is growing exponentially, creating awareness and developing novel strategies to control their evolution a mandatory research topic. Methicillin-resistant Staphylococcus aureus (MRSA) is an example of a bacterial strain that causes serious and mortal infections. The fact is that this bacterial strain started to develop resistance against commonly used antibiotics, first to penicillin and against methicillin. Thus, the treatment against infections caused by MRSA is limited and difficult due to its capacity to develop defense mechanisms against the antibiotic's action. Given the urgency to find new alternatives, the scientific community has been developing interesting research regarding the exploitation of natural resources to discover bioactive molecules that are able to inhibit/kill MRSA. In this sense, several natural matrices, namely plants, have shown great potential against MRSA, due to the presence of phenolic compounds, molecules with high antimicrobial capacity due to their chemical structure and arrangement.
Ethnopharmacological relevance:
Euphorbia humifusa Willd., known as Di-Jin-Cao in Chinese, has long been utilized as a traditional herb for the treatment of furuncles and carbuncles mainly caused by Staphylococcus aureus infection. Despite extensive chemical and pharmacological studies reported previously for E. humifusa, the antibacterial and antibiofilm activities against S. aureus as well as the related mechanism of action (MoA) remain largely obscure.
Aim of the study:
To investigate the antibacterial and antibiofilm activities of the preferred fractions and compounds from E. humifusa against S. aureus and assess the associated MoA.
Materials and methods:
The bioactive fractions and compounds were obtained from the 75% ethanol extract of E. humifusa (75%-EEEH) with the assistance of the related antibacterial and antibiofilm screening. Their antibacterial activities were determined using the broth microdilution method, whilst the inhibition of biofilm formation and the disruption of preformed biofilm were assessed by crystal violet staining and confocal laser scanning microscopy (CLSM). To achieve more effective therapies, the combinatory effects of different components were also studied. The biofilm metabolic activities of isolated compounds were evaluated by 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction assay. The scanning electron microscopy (SEM) and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to explore the antibiofilm mechanism.
Results:
Fractions DJC06 and DJC07 collected from the ethyl acetate extract of the 75%-EEEH exhibited antibacterial activity (MIC = 256 μg/mL) against S. aureus and further separation of these two fractions led to the isolation and characterization of 22 compounds. Among the isolates, luteolin (LU), quercetin (QU), and kaempferol (KA) are the verified components associated with the antibacterial and antibiofilm activities by displaying individual or combinational MIC values of 8-128 μg/mL and 70.9-99.7% inhibition for biofilm formation. Importantly, QU and KA can work in synergy with LU to significantly enhance the efficacy via destroying cell integrity, increasing membrane permeability, and down-regulating the biofilm-related gene expression.
Conclusions:
The preferred fractions and compounds from E. humifusa exerted desired antibacterial and antibiofilm efficacy against S. aureus via a MoA involving cell morphology disruption and altered genes expression. The findings herein not only support its traditional use in the treatment of furuncles and carbuncles, but reveal E. humifusa is a potential source for producing promising antibiofilm alternatives against S. aureus and highlight the isolated components (LU, QU, KA) that can potentiate the efficacy when used in synergy.
The mycotoxin ochratoxin A (OTA) is produced by the fungi Aspergillus and Penicillium. The flavonoid quercetin (QUE) is distinguished by its antioxidant, anti-inflammatory, and antiapoptotic properties. This study was designed to determine whether QUE can protect broiler chickens against OTA-induced nephrotoxicity. Forty broiler chicks were randomly divided into four equal groups: control, OTA, QUE, and OTA + QUE. For 6 weeks, OTA (0.5mg/kg) and/or QUE (0.5g/kg) were added to the diet of chickens. The results demonstrated that OTA exposure increased serum levels of creatinine, uric acid, and blood urea nitrogen. OTA exposure also increased renal malondialdehyde content but decreased renal antioxidants. OTA-exposed chickens exhibited multiple pathological kidney lesions. Moreover, OTA exposure induced apoptosis in renal tissue, which was manifested by the up-regulation of proapoptotic genes and down-regulation of antiapoptotic genes via the suppression of the PI3K/AKT pathway. In addition, coadministration of QUE and OTA mitigated most of these nephrotoxic effects.
The global emergence of multidrug-resistant (MDR) bacteria has severely compromised the efficacy of current antibacterial drugs and significantly increased the frequency of therapeutic failure. The development of novel and innovative antibacterial drugs with various chemical structures and processes that can combat harmful bacteria is urgently needed. Many studies have recently concentrated on identifying possible answers to these issues. There is a growing interest in medicinal plants for the potential sources of new therapeutic compounds, due to the structural and functional diversity existing in the specialized metabolites found in these plants. So far, many phytochemicals with varied biological activity, such as antibacterial, antifungal, and anti-carcinogenic, have been reported with low toxicity and adverse effects. Anti-quorum sensing (AQS) is a promising strategy for cell–cell communication which plays a vital role in the regulation of various bacterial physiological functions such as pathogenicity, luminescence, mobility, sporulation, etc. A variety of novel plant-based compounds have been discovered with the potential to disrupt bacterial quorum sensing (QS). The present chapter deals with the current developments in the field of plant extracts/phytochemicals, which are being used as the potential antibacterial and antimicrobial agents. Plant-derived molecules, which have antibiofilm or anti-quorum sensing activities, and the various mechanisms involved in their actions are also discussed.KeywordsAlkaloidsAntibacterial
E. coli
Flavonoids
H. pylori
Medicinal plantsMultidrug resistantMultidrug-resistant (MDR) bacteriaMethicillin-resistant S. aureusN-acyl-homoserine lactonesPhenolic compoundsPhytochemicals
S. aureus
Sulfur-containing phytochemicalsSecondary metabolitesTanninsTerpenoidsQuinonesQuorum sensingQuorum sensing inhibition
Quercetin is one of the most bioactive and common dietary flavonoids, with a significant repertoire of biological and pharmacological properties. The biological activity of quercetin, however, is influenced by its limited solubility and bioavailability. Driven by the need to enhance quercetin bioavailability and bioactivity through metal ion complexation, synthetic efforts led to a unique ternary Ce(III)-quercetin-(1,10-phenanthroline) (1) compound. Physicochemical characterization (elemental analysis, FT-IR, Thermogravimetric analysis (TGA), UV–Visible, NMR, Electron Spray Ionization-Mass Spectrometry (ESI-MS), Fluorescence, X-rays) revealed its solid-state and solution properties, with significant information emanating from the coordination sphere composition of Ce(III). The experimental data justified further entry of 1 in biological studies involving toxicity, ROS-suppressing potential, cell metabolism inhibition in Saccharomyces cerevisiae (S. cerevisiae) cultures, and plasmid DNA degradation. DFT calculations revealed its electronic structure profile, with in silico studies showing binding to DNA, DNA gyrase, and glutathione S-transferase, thus providing useful complementary insight into the elucidation of the mechanism of action of 1 at the molecular level and interpretation of its bio-activity. The collective work projects the importance of physicochemically supported bio-activity profile of well-defined Ce(III)-flavonoid compounds, thereby justifying focused pursuit of new hybrid metal-organic materials, effectively enhancing the role of naturally-occurring flavonoids in physiology and disease.
Flavonoid metal ion complexes are one of the classes of biological active molecules with immense pharmacological potential including antioxidant, antidiabetic, antimicrobial, anticancer activity, to name a few. The effectiveness of this complexion depends on the state and nature of the transition metal ions and on the position to which the metal ion coordinates with theircorresponding parent flavonoid. The metal coordination of flavonoids also improves the biological activities to a maximum extent compared to the parent compound. This may be attributed to many factors such as metal ions, coordination sites, structural configuration, and stability of the complexes. On the other hand, some of the metal ion complexes reduce the biological efficiency of the corresponding parent flavonoids which can be due to the shift from antioxidant to pro-oxidant nature as well as the stability of the complexes both in in vitro and in vivo conditions. However, the literature for the stability of flavonoid metal ion complexes in the in vivo conditions is very scanty. Therefore, this review summarizes and critically address all these parameters and puts together in a single slot that favours for the researchers to put forward to understand the mode and detailed molecular mechanism of flavonoid metals complexes compared with their corresponding parent flavonoids.
The antibacterial properties of methanolic haskap (Lonicera caerulea L.) berry extracts and tannic acid were examined against Cronobacter spp. with a view to determine their potential for the control of this human pathogen in powdered infant formula. The total phenolic content (TPC) and composition of methanolic extracts from three different cultivars were determined. Fruit from cultivar Indigo Gem had the highest TPC (3.67 ± 0.28 g/100 g dw) and was found to contain polyphenolic compounds, including anthocyanins, hydroxycinnamic acids and flavonols, as well as citric, malic, quinic and oxalic acids. Haskap extracts and tannic acid showed bacteriostatic and bactericidal activity against all Cronobacter species tested. Supplementation of powdered infant formula reduced the thermal resistance of C. sakazakii during heating at 55 °C and inactivated the species in reconstituted product during storage. The D-values were reduced from 16.47 ± 0.47 min to 0.94 ± 0.04, 2.03 ± 0.06, and 0.54 ± 0.02 min for haskap extract, tannic acid, and haskap extract + tannic acid, respectively. Haskap berry extracts and tannic acid could improve the safety of powdered infant formula.
The rapid emergence of multidrug resistant bacterial strains clearly highlights the need for the development of new antimicrobial compounds/materials to address associated healthcare challenges. Meanwhile, the adverse side effects of conventional antibiotics on human health urge the development of new natural product-based antimicrobials to minimize the side effects. In this respect, we concisely review the recent scientific contributions to develop natural product-based nano-antibiotics. The focus of the review is on the use of flavonoids, peptides, and cationic biopolymer functionalized metal/metal oxide nanoparticles as efficient tools to hit the MDR bacterial strains. It summarizes the most recent aspects of the functionalized nanoparticles against various pathogenic bacterial strains with respect to their minimal inhibitory concentrations and mechanism of action at the cellular and molecular levels. At the end, the future perspectives to materialize the in vivo applications of nano-antimicrobials are suggested on the basis of the available research.
A total of 320 one-day-old Cobb 500 chicks with an initial weight of 48.3 ± 3.3 g·pen ⁻¹ were assigned to four dietary treatments with eight replicates provided in three phases for 46 d. The treatments were fed as mash diets and included (1) negative control (NC) corn-soybean basal diet, (2) positive control (PC) basal diet with 30 ppm avilamycin, (3) basal diet supplemented with 1000 ppm red-osier dogwood extracts (RDE1), and (4) basal diet with 3000 ppm red-osier dogwood extracts (RDE2). Results showed reduced jejunal crypt depth in RDE1 and increased villus:crypt ratio in groups (either RDE1 or RDE2) (P < 0.05). Cationic amino acid (AA) transporter mRNA abundance was decreased (P < 0.05) in RDE1, RDE2, and PC treatments, but peptide and neutral AA transporter mRNA abundance were higher (P < 0.05) in RDE2 compared with NC. Apparent ileal digestibility of crude fat was increased in RDE2 and PC compared with NC, whereas AA digestibility was greater in RDE1, RDE2, and PC (P < 0.05). In conclusion, red-osier dogwood had no effect on growth performance, improved the intestinal health and function of broiler chickens, and had no detrimental effects on meat quality.
Aim: To develop quercetin-loaded poly(caprolactone) (PCL)/soybean phosphatidylcholine (PC) films coated with silver (Ag) to prevent the formation of postoperative adhesions (POA). Materials & methods: Films were prepared using the solvent casting method, coated with Ag, and underwent in vitro tests. In vivo studies were conducted employing an animal model of sidewall defect and cecum abrasion. Results: Films showed sustained release behavior of quercetin and Ag. Coating films with Ag improved their antimicrobial activity. In vivo studies confirmed superior antiadhesion properties of films compared with the control groups evaluated by gross observation, histochemical staining and immunohistochemistry analyses. Conclusion: Ag-Q-PCL-PC films are a potential candidate to prevent POA by acting as a sustained release delivery system and physical barrier.
Grape marc is an underutilised waste material that poses significant environmental issues. This study offers the first proof-of-concept investigation into the polymerisation of both crude and purified Sauvignon blanc grape marc extracts using the diacyl chlorides terephthaloyl chloride, succinyl chloride, adipoyl chloride, sebacoyl chloride, and the tartaric acid derivative (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-dicarbonyl dichloride to obtain new materials, in what to the best of our knowledge is the first reported example of a direct polymerisation of an agricultural waste extract. A total of 26 novel materials were prepared. It has also shown that quercetin, a phenolic monomer found in grape marc extracts, can be polymerised with (4R,5R)-2,2-dimethyl-1,3-dioxolane-4,5-dicarbonyl dichloride to give a polymer that shows activity towards S. aureus.
Bacterial biofilms often cause medical complications and there has been a great deal of interest in the discovery of small-molecule agents that can inhibit the formation of biofilms. Among these agents, it has been reported that several D-amino acids, such as D-Leu, D-Trp, D-Tyr, and D-Met, exhibit weak inhibitory activity toward bacterial biofilm formation. In this study, we have screened a library of 332 non-proteinogenic amino acids for new biofilm inhibitory agents and discovered several compounds exhibiting biofilm-inhibitory activity against Gram-positive bacteria. In particular, H-DL-β-(3,4-dihydroxyphenyl)-DL-Ser-OH (253) showed potent activity against S. aureus, including methicillin-resistant S. aureus.
Plant-derived medicinal compounds are rich sources of bioactive compounds used for health benefits and have a long history, which formed the basis for the evolution of many modern medicines. These medicinal compounds comprise various groups of secondary metabolites, having antimicrobial activity, exist in healthy plants, and activated in response to pathogen attacks and tissue damages. These compounds displayed a broad range of pharmaceutical and positive health effects on humans by antioxidative, antimicrobial, antiviral, anticancer, and anti-inflammatory activities. Hence, it attracts researchers to identify and isolate these compounds, to understand the mechanism of action, thus providing the molecular mechanism of conquering resistance in microbes. Nowadays, reemerging and new infectious diseases are rising, therefore there is an urgent need to explore a new plants-based antimicrobial compounds having a novel mode of action against microbes. Additionally, the evolution of multiple drug-resistant strains of human pathogens developed higher attention by healthcare and pharmaceutical industries toward plant-derived compounds. Therefore, here we will focus on plant products used as antimicrobial substances and their mode of action against microbes. This chapter aims to provide recent insights into the possibilities of the important plant-derived antimicrobial compounds, useful as an alternative approach to combat infectious.
ABSTRAKMakanan merupakan sumber energi yang berperan penting untuk kelangsungan hidup manusia, salah satunya ikan. Omega 3 dan 6 banyak terdapat pada ikan. Penelitian untuk mengetahui pengaruh konsentrasi bawang merah (Allium cepa) dan temu kunci (Boesenbergia rotunda) sebagai pengawet alami terhadap mutu mutu biologi ikan kembung (Rastrellinger sp.) dan ikan tuna (Thunnus sp.). Rancangan percobaan dari penelitian ini dengan menggunakan model faktorial yaitu konsentrasi bawang merah (Allium Cepa) dan temu kunci (Boesenbergia rotunda). Hasil dari penelitian ini bahwa Konsentrasi bawang merah (Allium cepa) dan temu kunci (Boesenbergia rotunda) sebagai pengawet alami berpengaruh terhadap mutu biologi ikan kembung (Rastrellinger sp.) dan ikan tuna (Thunnus sp.).Kata kunci: Jumlah koloni, Konsentrasi bawang merah, Konsentrasi temu kunci.ABSTRACTFood is an important energy for human life, one of them is fish. Omega 3 and 6 are widely available in fish. The purpose of this Research is to know the content of spanish onion (Allium cepa) and fingerroot (Boesenbergia rotunda) as the preservative of fish and tuna fish (Thunnus sp.). The Design of this research by using factorial mode that is concentration of spanish onion (Allium Cepa) and fingerroot (Boesenbergia rotunda). The results of this research are spanish onion concentration (Allium cepa) and fingerroot (Boesenbergia rotunda) as preservative of fish and tuna fish(Thunnus sp.).Key Words: count of colony, concentration of spanish onion, concentration of fingerroot.
Introduction: Quercetin is a flavonoid compound in most plants that due to its pre-apoptotic and anticancer properties can
increase the toxicity of drugs such as chemotherapy drugs. The study aimed to fabricate and characterize the niosomal system
containing quercetin to increase its therapeutic properties.
Methods: In this in vitro study, with thin-film hydration, niosomal carriers containing quercetin were prepared and after
sonication and size reduction, filtration and free drug separation were performed. Subsequently, the amount of quercetin
was loaded and the process of quercetin release from the niosomal nanosystem was investigated. The nanoparticles were
also evaluated for size, zeta potential, particle morphology, and chemical interactions between the niosomal system and
quercetin.
Results: The encapsulation efficiency of quercetin in the niosomal carriers was 64.49±2.3%, the size and zeta potential of
the nanocarrier before quercetin loading was 153.8 nm and -9.5 mV respectively, and after quercetin loading was 170 nm
and -1.6 mV, respectively. The pattern of drug release indicates that overall quercetin release was slow and 95% of quercetin
was released from the niosome within 72 hours. Electron microscopy images and FT-IR results also show that the niosomal
system was formed and that no chemical interaction was observed between the niosomal system and quercetin.
Conclusion: The results of the present study show that nano-carriers containing quercetin have appropriate physicochemical
properties. Therefore, this niosomal system can be a suitable carrier for quercetin delivery.
To provide insights into phage-host interactions during winemaking, we assessed whether phenolic compounds modulate the phage predation of Oenococcus oeni. Centrifugal partition chromatography was used to fractionate the phenolic compounds of a model red wine. The ability of lytic oenophage OE33PA to kill its host was reduced in the presence of two collected fractions in which we identified five compounds. Three, namely, quercetin, myricetin and p-coumaric acid, significantly reduced the phage predation of O. oeni when provided as individual pure molecules, as also did other structurally related compounds such as cinnamic acid. Their presence was correlated with a reduced adsorption rate of phage OE33PA on its host. Strikingly, none of the identified compounds affected the killing activity of the distantly related lytic phage Vinitor162. OE33PA and Vinitor162 were shown to exhibit different entry mechanisms to penetrate into bacterial cells. We propose that ligand-receptor interactions that mediate phage adsorption to the cell surface are diverse in O. oeni and are subject to differential interference by phenolic compounds. Their presence did not induce any modifications in the cell surface as visualized by TEM. Interestingly, docking analyses suggest that quercetin and cinnamic acid may interact with the tail of OE33PA and compete with host recognition.
Eleven fungal endophytes were isolated from the plant parts of Z. nimmonii (J. Graham) Dalzell, an endemic species of the Western Ghats, India, a biodiversity hotspot area. The endophytic isolates were characterized by the sequencing of the Internal Transcribed Spacer (ITS) regions and designated as strains by depositing ITS sequences in the Gen Bank sequence database. All the strains were cultured in Potato Dextrose broth (PDB, 500 mL) contained in Erlenmeyer flasks to obtain the secondary metabolites. The culture filtrate was extracted with ethyl-acetate (EA) three times and concentrated by flash evaporation to obtain EA crude dry extract. The strains were evaluated for the antibacterial potentials against six pathogenic bacterial strains viz., Bacillus subtilis (MTCC 121), Staphylococcus aureus (MTCC 7443) Pseudomonas aeruginosa (MTCC 7093), Escherichia coli (MTCC 729), Enterobacter aerogenes (MTCC 111) and Klebsiella pneumoniae (MTCC 661). Nine endophytic fungal extracts except Alternaria consortiale and Hypocrea lixi showed inhibitory activities against at least two of the six test bacterial strains. Bipolaris specifera (KM114290) exhibited the highest inhibition zones ranging from 15.1 ± 0.3 to 26.7 ± 1.1 mm (diameter), against all six test bacteria in the agar disk diffusion assay, and with Minimum Inhibitory Concentrations (MIC’s) of 0.04–0.14 mg/mL, followed by Aspergillus terreus. B. specifera extract was therefore selected and characterized for the identification of antibacterial compounds by chromatographic techniques. Seven antibacterial compounds viz., (1) Bicyclo[3.2.0]heptan-2-one, 6-hydroxy-5-methyl-6-vinyl; (2) Adipic acid divinyl ester; (3) 1,4-Naphthoquinone, 6-acetyl-2,5-dihydroxy; (4) Decanedioic acid, 3,7-dimethyl ester; (5) (Z)-4-Hexenoic acid 2-acetyl-2-methyl-ethyl ester and (6) Butanoic acid 2-acetyl-3-methyl-methyl ester and (7) Caffeic acid, were identified through liquid and gas chromatography. These compounds are mainly volatile esters of fatty acids, phenolics and adipic acid found rare in nature. This study envisages the possible drug discovery using endophytes from traditional and endemic medicinal species.
The effects of quercetin and cinnamaldehyde, two popular dietary phytochemicals from vegetables and spices on the general nutrient content and whole chemical profile of beef soup during stewing were investigated by routine chemical analysis and an UPLC-MS/MS based untargeted metabolomics analysis. It was found that quercetin decreased the content of total sugar and methionine, and increased solid matters, unsaturated fatty acids and zinc content in beef soup. Cinnamaldehyde decreased total sugar, aspartic acid and zinc content, but increased total fatty acids in beef soup. Metabolomics results showed that a total of 204 metabolites were assigned to putative molecular classes. 12 metabolite species were summarized based on the chemical structure using HMDB. Cinnamaldehyde decreased the content of most of the molecule species in beef soup while quercetin did not have significant effect. In general, cinnamaldehyde decreased the nutritional value of beef soup, thus spices rich in cinnamaldehyde may not be suitable used for preparing meat soup due to its negative effect on nutrient contents in beef soup. This work could help to fully understand the effects of quercetin and cinnamaldehyde on the nutritional value of beef soup.
The present study was aimed at creating a combination between lower dose of sulfamethoxazole (S) as a broad-spectrum synthetic antibiotic and quercetin (Q), a natural polyphenol to decrease the antibiotic side effects and increase its antioxidant activity. Staphylococcus aureus infected animal model was studied both in vitro and in vivo in comparison to doxycycline (Dox) as standard antibiotic. The in vitro test results indicated that Q exhibited activity alone and in combination with S against tested bacterial strains, while S in low concentration was inactive. The in vivo results revealed that the S+Q combination in mice showed significant improvements in the liver and kidney functions as compared to those in the infected group or S- and Dox-treated groups. Moreover, malondialdehyde level was significantly decreased, while superoxide dismutase and catalase activities were significantly increased in the sera of (S+Q)-treated group in comparison to other treated groups. The spleen recovery in the (S+Q)-treated group was observed with the disappearance of S. aureus colonies as compared to the infected mice. In conclusion, the in vivo treatment of S. aureus infection with S+Q combination decreased the sulfamethoxazole side effects while increasing its antibacterial activity, which supported the therapeutic use of this combination in humans.
The prevalence of dengue virus infection (DENV) in Indonesia is still high compared to other tropical countries in the world. Unfortunately, the specific of antiviral drug to DENV is not available yet. The pure compound such as quercetin revealed a good antiviral to DENV candidat. Quercetin is a plant-derived flavonoid that can be found in wide variety of fruits and vegetables. It has been proven that quercetin able to improve body performance and reduce the risk of infection as well as inhibit DENV replication in Vero cell. However, the research on human cell line is not yet conducted. Therefore, this research aims to determine the effectivity of quercetin as antiviral drug towards DENV-2 strain New Guinea C in human cell line Huh 7 it-1. We used Focus Forming Assay and MTT assay To determine the value of IC 50 and CC 50 , respectively. The result of CC 50 value was 217.113 μg/mL and IC 50 value was 18.41 μg/mL, with the SI value of 11.8. From the results imply that quercetin has low toxicity with high effectivity. Thus, quercetin suggested a good candidate of antiviral drug against DENV-2 in future.
Antimicrobial resistance is an imminent threat worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is one of the “superbug” family, manifesting resistance through the production of a penicillin binding protein, PBP2a, an enzyme that provides its transpeptidase activity to allow cell wall biosynthesis. PBP2a's low affinity to most β-lactams, confers resistance to MRSA against numerous members of this class of antibiotics. An Achilles' heel of MRSA, PBP2a represents a substantial target to design novel antibiotics to tackle MRSA threat via inhibition of the bacterial cell wall biosynthesis.
In this review we bring into focus the PBP2a enzyme and examine the various aspects related to its role in conferring resistance to MRSA strains. Moreover, we discuss several antibiotics and antimicrobial agents designed to target PBP2a and their therapeutic potential to meet such a grave threat. In conclusion, we consider future perspectives for targeting MRSA infections.
The incidence of hepatocellular carcinoma is increasing in many countries. The estimated number of new cases annually is over 500,000, and the yearly incidence comprises between 2.5 and 7% of patients with liver cirrhosis. The incidence varies between different geographic areas, being higher in developing areas; males are predominantly affected, with a 2:3 male/female ratio
Experiments were designed to examine the effect of N-Nitrosodiethylamine (NDEA) as cancer-inducer compound and to confirm the preventive effect of the flavonoid quercetin on hepatocellular carcinoma in rats. Briefly, thirty six male albino rats of Wistar strain were divided into 3 groups: the 1st group was administered NDEA alone (NDEA-treated), the 2nd group was treated simultaneously with NDEA and quercetin (NDEA+Q) and the 3rd group was used as control (CON). Randomly amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) as well as p53-specifi PCR assays were employed to determine genomic difference between treated, and control animals. Histological confirmation as well as oxidant/antioxidant status of the liver tissue was done.
RAPD analysis of liver samples generated 8 monomorphic bands and 22 polymorphic bands in a total of 30-banded RAPD patterns. Cluster analysis and statistical analyses of RAPD data resulted in grouping control and NDEA+Q samples in the same group with 80% similarity cut-off value. NDEA-treated samples were clustered in a separate group. Specific PCR assay for polymorphism of P53 gene revealed a uniform pattern of allele separation in both control and NDEA+Q samples. Quercetin anticancer effect was exhibited in significant decrease of oxidative stress and significant decrease of antioxidant activity. Histopathological studies showed normal liver histology of the NDEA+Q samples. Meanwhile, several cancer-induced features were clearly observable in NDEA-treated samples.
This paper demonstrated that preventive effect of quercetin on hepatocarcinoma in rats by RAPD-PCR, tracing the effect on p53 gene and by histopathological evidence. Hereby, it was proved that quercetin exerted its preventive effect via decreased oxidative stress and decreased antioxidant activity.
The antibacterial effects of tea polyphenols (TPP) extracted from Korean green tea (Camellia sinensis) against clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) were evaluated. Characterization of the minimal inhibitory concentration (MIC) of oxacillin for 30 S. aureus strains isolated from patients treated with oxacillin identified 13 strains with an oxacillin MIC >or= 4 microg/mL as methicillin-resistant Staphylococcus aureus (MRSA) (range: 8 to 512 microg/mL), while 17 strains were methicillin-susceptible Staphylococcus aureus (MSSA) (range: 0.25-0.5 microg/mL). The MICs of TPP ranged from 50 to 180 microg/mL for both the MSSA and the MRSA strains. The MICs of oxacillin for each of the 13 MRSA strains were reduced between 8- and 128-fold when these strains were coincubated with sub-MIC (<or= 0.5x MIC) levels of TPP, demonstrating that the combination of TPP plus oxacillin was synergistic for all of the clinical MRSA isolates. Two-dimensional polyacrylamide gel electrophoresis identified 14 extracellular proteins of MRSA-13 down-regulated and 3 proteins up-regulated by exposure to TPP. These studies demonstrate that TPP can differentially stimulate the expression of various proteins in these bacteria and synergize the bactericidal activity of oxacillin for MRSA.
Wild-type Staphylococcus aureus rapidly expands on the surface of soft agar plates. The rates of expansion and the shapes of the resultant giant colonies
were distinct for different strains of laboratory stocks and clinical isolates. The colony spreading abilities did not correlate
with the biofilm-forming abilities in these strains. Insertional disruption of the dltABCD operon, which functions at the step of d-alanine addition to teichoic acids, and of the tagO gene, which is responsible for the synthesis of wall teichoic acids, decreased the colony spreading ability. The results
indicate that wall teichoic acids and d-alanylation of teichoic acids are required for colony spreading.
The aim of this review, a summary of the putative biological actions of flavonoids, was to obtain a further understanding of the reported beneficial health effects of these substances. Flavonoids occur naturally in fruit, vegetables, and beverages such as tea and wine. Research in the field of flavonoids has increased since the discovery of the French paradox,ie, the low cardiovascular mortality rate observed in Mediterranean populations in association with red wine consumption and a high saturated fat intake. Several other potential beneficial properties of flavonoids have since been ascertained. We review the different groups of known flavonoids, the probable mechanisms by which they act, and the potential clinical applications of these fascinating natural substances.
This paper proposes a review of some alternative approaches for food stabilisation and shelf life prolonging (based on the use of natural compounds and/or non-thermal techniques). After a brief description of food structure implication on the way of using the alternative approaches, two paragraphs summarise the topics of natural molecules (essential oils, lysozyme, lactoferrin and lactoperoxidase system, fatty acids, chitosan) and non-thermal approaches (high hydrostatic and homogenisation pressures, pulsed electric fields, high power ultrasound and irradiation). Finally, the last sections deal with the use of combined hurdles (along with the proposal of three possible modes of action of a multi-target preservation), the mathematical approaches for shelf life evaluating and some critical issues to be addressed in the future for a real scaling up of the proposed techniques.
Plant phenolics, especially dietary flavonoids, are currently of growing interest owing to their supposed functional properties in promoting human health. Antimicrobial screening of 13 phenolic substances and 29 extracts prepared from Finnish plant materials against selected microbes was conducted in this study. The tests were carried out using diffusion methods with four to nine microbial species (Aspergillus niger, Bacillus subtilis, Candida albicans, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa, Saccharomyces cerevisiae, Staphylococcus aureus and Staphylococcus epidermidis). Flavone, quercetin and naringenin were effective in inhibiting the growth of the organisms. The most active plant extracts were purple loosestrife (Lythrum salicaria L.) against Candida albicans, meadowsweet (Filipendula ulmaria (L.) Maxim.), willow herb (Epilobium angustifolium L.), cloudberry (Rubus chamaemorus L.) and raspberry (Rubus idaeus L.) against bacteria, and white birch (Betula pubescens Ehrh.), pine (Pinus sylvestris L.) and potato (Solanum tuberosum. L.) against gram-positive Staphylococcus aureus.
Oral treatment with quercetin protected ABD2F1/Jena mice significantly against intraperitoneal encephalomyocarditis, Col, SK, MM, Mengo M,L and MengoM virus infections, but not against intracerebral challenge with MengoM virus. Enhanced resistance to MengoM virus were induced in the genetically different DBA 2/Jena, C57BL/Jena, C57BL/Lati and ABC2F1/Jena mice, C57BL6/Jena nu/nu mice were also protected, indicating that the thymus was non-essential to the protective effects of quercetin. In AB/Jena and Lati:CFLP mice the drug failed to be effective. Quercetin was not virucidal and did not interfere with Mengo virus replication in L cells. Interferon was not detected (less than 1 : 8) in sera of ABD2F1/Jena mice 1-48 h after oral administration of the drug. The virus spread from the site of injection to the lymph nodes and other target organs were impaired. Silica treatment, to suppress macrophage function, did not evidently increase the susceptibility of ABC2F1/Jena mice to Mengo virus. However, this treatment abolished the antiviral activity of quercetin, indicating the requirement for macrophages for quercetin to be effective. Virus replication could not be demonstrated in cultures of adherent peritoneal macrophages from either untreated or quercetin-treated ABD2F1/Jena mice.
Quercetin is a flavonoid present in many vegetables, fruits, and beverages. Due to its anti-oxidant, anti-tumor, and anti-inflammatory activity, quercetin has been studied extensively as a chemoprevention agent in several cancer models. Since most of these studies used higher doses of quercetin than clinically achievable, we focused on the effectiveness of physiologically relevant doses of quercetin. A low dose of quercetin exerted cancer cell-specific inhibition of proliferation and this inhibition resulted from cell cycle arrest at the G(1) phase. Quercetin induced p21 CDK inhibitor with a concomitant decrease of phosphorylation of pRb, which inhibits the G(1)/S cell cycle progression by trapping E2F1. A low dose of quercetin induced mild DNA damage and Chk2 activation, which is the main regulator of p21 expression by quercetin. In addition, quercetin down-regulated the cyclin B1 and CDK1, essential components of G(2)/M cell cycle progression. Inhibition of the recruitment of key transcription factor NF-Y to cyclin B1 gene promoter by quercetin led to transcriptional inhibition. This study proved that the chemo-preventive efficacy of a physiologically relevant dose of quercetin can be achievable through the inhibition of cell cycle progression.
The French paradox is a dietary anomaly which has focused attention on the Mediterranean diet. Epidemiological studies revealed that this diet, replete in flavonoid-rich foods (Allium and Brassica vegetables, and red wine), correlated with the increased longevity and decreased incidence of cardiovascular disease seen in these populations. The most frequently studied flavonoid, quercetin, has been shown to have biological properties consistent with its sparing effect on the cardiovascular system. Quercetin and other flavonoids have been shown to modify eicosanoid biosynthesis (antiprostanoid and anti-inflammatory responses), protect low-density lipoprotein from oxidation (prevent atherosclerotic plaque formation), prevent platelet aggregation (antithrombic effects), and promote relaxation of cardiovascular smooth muscle (antihypertensive, antiarrhythmic effects). In addition, flavonoids have been shown to have antiviral and carcinostatic properties. However, flavonoids are poorly absorbed from the gut and are subject to degradation by intestinal micro-organisms. The amount of quercetin that remains biologically available may not be of sufficient concentration, theoretically, to explain the beneficial effects seen with the Mediterranean diet. The role of flavonoids may transcend their presence in food. The activity of flavonoids as inhibitors of reverse transcriptase suggests a place for these compounds in the control of retrovirus infections, such as acquired immunodeficiency syndrome (AIDS). In addition to specific effects, the broad-modulating effects of flavonoids as antioxidants, inhibitors of ubiquitous enzymes (ornithine carboxylase, protein kinase, calmodulin), and promoters of vasodilatation and platelet disaggregation can serve as starting material for drug development programmes.
The antimicrobial potential of eight phenolic compounds isolated from olive cake was tested against the growth of Escherichia coli, Klebsiella pneumoniae, Bacillus cereus, Aspergillus flavus and Aspergillus parasiticus. The phenolic compounds included p-hydroxy benzoic, vanillic, caffeic, protocatechuic, syringic, and p-coumaric acids, oleuropein and quercetin. Caffeic and protocatechuic acids (0.3 mg/ml) inhibited the growth of E. coli and K. pneumoniae. The same compounds apart from syringic acid (0.5 mg/ml) completely inhibited the growth of B. cereus. Oleuropein, and p-hydroxy benzoic, vanillic and p-coumaric acids (0.4 mg/ml) completely inhibited the growth of E. coli, K. pneumoniae and B. cereus. Vanillic and caffeic acids (0.2 mg/ml) completely inhibited the growth and aflatoxin production by both A. flavus and A. parasiticus, whereas the complete inhibition of the moulds was attained with 0.3 mg/ml p-hydroxy benzoic, protocatechuic, syringic, and p-coumaric acids and quercetin.
Methicillin resistance in staphylococci is due to an acquired penicillin-binding protein, PBP2' (PBP2a). This additional PBP, encoded by mecA, confers an intrinsic resistance to all beta-lactams and their derivatives. Resistance levels in methicillin-resistant Staphylococcus aureus (MRSA) depend on efficient PBP2' production and are modulated by chromosomal factors. Depending on the genetic background of the strain that acquired mecA, resistance levels range from phenotypically susceptible to highly resistant. Characteristic for most MRSA is the heterogeneous expression of resistance, which is due to the segregation of a more highly resistant subpopulation upon challenge with methicillin. Maximal expression of resistance by PBP2' requires the efficient and correct synthesis of the peptidoglycan precursor. Genes involved in cell-wall precursor formation and turnover, regulation, transport, and signal transduction may determine the level of resistance that is expressed. At this stage, however, there is no information available on the functionality or efficacy of such factors in clinical isolates in relation to methicillin resistance levels.
In our previous studies, bacteriostatic action of flavonoids against Staphylococcus aureus ATCC 25 923 and Escherichia coli ATCC 25 922 was demostrated. In the present work synergism of their combinations in order to improve the bacteriostatic action against the same microorganisms was determined. The experiences were made in nutritive broth, maintaining constant one drug concentration (20 microg/ml) and increasing the other one. A turbidimetric kinetic method was used and by means of a mechanism previously proposed, the minimal inhibitory concentrations (MIC's) of each flavonoid combination were determined. The MIC's for assayed combinations against S. aureus were: variable morin - constant rutin: 157.44 microg/ml and variable quercetin - constant morin: 29.9 microg/ml. The values obtained against E. coli were: variable morin - constant rutin: 78.5 microg/ml; variable quercetin - constant rutin: 47.4 microg/ml; variable quercetin - constant morin: 25 microg/ml; variable morin - constant quercetin: 27.4 microg/ml.
An investigated flavonoid, quercetin, is reviewed in this article. Quercetin is a bioflavonoid found in red wine, grapefruit, onions, apples, black tea, and, in lesser amounts, in leafy green vegetables and beans. Quercetin has an antioxidant and anti-inflammatory activity and prevents cancer. Quercitin inhibits the growth of certain malignant cells in vitro, and histamine and most cyclin-dependent kinases and also displays unique anticancer properties. Quercetin is a natural compound that blocks substances involved in allergies and is able to act as an inhibitor of mast cell secretion, causes a decrease in the release of tryptase, MCP-1 and IL-6 and the down-regulation of histidine decarboxylase (HDC) mRNA from few mast cell lines. Quercetin is a safe, natural therapy that may be used as primary therapy or in conjunction with conventional methods.
Quercetin is an anti-oxidative flavonoid widely distributed in the plant kingdom. Phenolic hydroxyl groups at the B-ring and the 3-position are responsible for its free radical-scavenging activity. Quercetin is commonly present as a glycoside and is converted to glucuronide/sulfate conjugates during intestinal absorption and only conjugated metabolites are therefore found in circulating blood. Although metabolic conversion attenuates its biological effects, active aglycone may be generated from the glucuronide conjugates by enhanced beta-glucuronidase activity during inflammation. With respect to its relationship with molecular targets relevant to cancer prevention, quercetin aglycone has been shown to interact with some receptors, particularly an aryl hydrocarbon receptor, which is involved in the development of cancers induced by certain chemicals. Quercetin aglycone has also been shown to modulate several signal transduction pathways involving MEK/ERK and Nrf2/keap1, which are associated with the processes of inflammation and carcinogenesis. Rodent studies have demonstrated that dietary administration of this flavonol prevents chemically induced carcinogenesis, especially in the colon, whilst epidemiological studies have indicated that an intake of quercetin may be associated with the prevention of lung cancer. Dietary quercetin is, therefore, a promising agent for cancer prevention and further research is warranted.
Antibiotics have been effective in treating infectious diseases, but resistance to these drugs has led to the emergence of new and the reemergence of old infectious diseases. One strategy employed to overcome these resistance mechanisms is the use of combination of drugs, such as beta-lactams together with beta-lactamase inhibitors. Several plant extracts have exhibited synergistic activity against microorganisms. This review describes in detail, the observed synergy and mechanism of action between natural products including flavonoids and essential oils and synthetic drugs in effectively combating bacterial, fungal and mycobacterial infections. The mode of action of combination differs significantly than that of the same drugs acting individually; hence isolating a single component may lose its importance thereby simplifying the task of pharma industries.
Prolonging microbial shelf life of foods through the use of natural compounds and non-thermal approaches
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