Flavonols Quercetin Research Articles

In Vitro and in Silico Insights on the Biological Activities, Phenolic Compounds Composition of Hypericum perforatum L. Hairy Root Cultures

Three Hypericum perforatum hairy root lines (HR B, HR F and HR H) along with non-transformed roots were analyzed for phenolic compounds composition and in vitro enzyme inhibitory properties. In silico molecular modeling was performed to predict the interactions of the most representative phenolic compounds in HR clones with enzymes related to depression, neurodegeneration and diabetes. Chromatographic analyses revealed that HR clones represent an efficient source of quinic acid and hydroxybenzoic acids, epicatechin and procyanidin derivatives, quercetin and kaempferol glycosides, as well numerous xanthones. In vitro antidepressant activity of HR extracts through monoamine oxidase A (MAO-A) inhibition was attributed to the production of oxygenated and prenylated xanthones. The neuroprotective potential of HR extracts was related to the accumulation of quercetin 6-C-glucoside, epicatechin, procyanidins and γ-mangostin isomers as potential inhibitors of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Vanillic acid and prenylated xanthones in HR clones as promising inhibitors of tyrosinase additionally contributed to the neuroprotective activity. Five preeminent xanthones in HR (γ-mangostin, mangiferin, garcinone C, garcinone E and 1,3,7-trihydroxy-6-metoxy-8-prenyl xanthone) along with the flavonol quercetin 6-C-glucoside effectively inhibited α-amylase and α-glucosidase indicating the antidiabetic properties of HR extracts. Transgenic roots of H. perforatum can be exploited for the preparation of novel phytoproducts with multi-biological activities.

Composição fenólica de Jussara (Euterpe edulisMartius) de Minas Gerais e Espírito Santo, Brasil, determinada por cromatografia líquida de alta eficiência acoplada à detecção de arranjo de diodos e espectrometria de massa contendo sistema de ionização por eletrospray (HPLC-DAD-ESI MS/MS)

ABSTRACT: This research assessed the phenolic composition of Jussara pulp from the Brazilian states of Minas Gerais (MG) and Espírito Santo (ES) using HPLC-DAD-MS/MS. Seventeen anthocyanins were detected in fruits, derived from cyanidin, pelargonidin and peonidin. Among the non-anthocyanic phenolic compounds, flavonols (kaempferol, quercetin and isorhamnetin derivatives), flavan-3-ols (catechin, epicatechin, B-type procyanidins and unknown dimers) and resveratrol in its glycosylated form have been identified. Catechin (32.41-60.56 mg 100g-1) and epicatechin (18.86-40.92 mg 100g-1) were the main flavan-3-ols present in the fruits. The samples showed small concentrations of resveratrol glycosides (0.02-0.91 mg 100g-1). The analytical methodology used (HPLC-DAD-ESI-MS/MS) permitted the identification of newly reported compounds in this fruit.

Scavengome of an antioxidant.

The term "scavengome" refers to the chemical space of all the metabolites that may be formed from an antioxidant upon scavenging reactive oxygen or nitrogen species (ROS/RNS). This chemical space covers a wide variety of free radical metabolites with drug discovery potential. It is very rich in structures representing an increased chemical complexity as compared to the parent antioxidant: a wide range of unusual heterocyclic structures, new CC bonds, etc. may be formed. Further, in a biological environment, this increased chemical complexity is directly translated from the localized conditions of oxidative stress that determines the amounts and types of ROS/RNS present. Biomimetic oxidative chemistry provides an excellent tool to model chemical reactions between antioxidants and ROS/RNS. In this chapter, we provide an overview on the known metabolites obtained by biomimetic oxidation of a few selected natural antioxidants, i.e., a stilbene (resveratrol), a pair of hydroxycinnamates (caffeic acid and methyl caffeate), and a flavonol (quercetin), and discuss the drug discovery perspectives of the related chemical space.

SOCIALIZATION ABOUT THE RIMBANG FRUIT ACTIVITY TEST (SOLANUM TORVUM SWARTZ) AS AN IMMUNOSTIMULATOR

Decreased immune system function can occur when the invasion of foreign substances cannot be balanced by immune cells. So, we need substances or materials that can improve the immune system and increase its regulation. Rimbang fruit (Solanum torvum Swartz) is a native vegetable that has been consumed by local people for a long time. Previous research stated that rimbang fruit is rich in phenolic compounds, namely flavonoid derivatives, namely flavonols (quercetin, kaempferol, and myricetin) and flavones (apigenin and luteolin). These secondary metabolites indicate that rimbang fruit has the potential to regulate the regulation of the immune system supported by its high antioxidant power. The research method used experimental methods, extraction method with 96% ethanol solvent maceration method. Variations in the dose of rimbang fruit extract used were doses of 50%, 100%, 200%, and 400%. The positive control used was Levamisole. The negative control used was CMC-Na 0.5%. The immunomodulator test method uses the antibody titer method using male rats as test animals. Immunogens used sheep red blood cells. Information provided to pharmacy students. From this it was concluded that the rimbang fruit extract had an immunostimulating effect at an optimal dose of 400 mg/kg body weight. These findings are shared with students and the public through Zoom meetings to help them understand the benefits of rimbang as an immunostimulator.

Acidity constants of hydroxyl groups placed in several flavonoids: Two flavanones, two flavones and five flavonols

Acidity constants (pKa) of nine flavonoids have been spectrophotometrically determined and the obtained values carefully contrasted with those derived from various experimental approaches given in literature, as well as with the ones predicted by Percepta and SPARC programs. To obtain robust pKa values, titrations in both pH ways, from acid to base and vice-versa, have been performed. The well-known instability of most flavonoids in basic media originates some discrepancies between obtained pKa by both titration ways and also with those coming from different experimental approaches previously published. This study tries to overcome the mentioned lack of integrity of several flavonoids avoiding measurements at high pH values or designing titrations at higher speed, which are able to cover the whole pH range with a minimum damage of studied compound. Suitable spectrophotometric titrations in pure water and, for instance, in methanol/water mixtures have been carried out. Achieved results allow the pKa assignation to hydroxyl groups belonging to two flavanones (Hesperetin and Naringenin), two flavones (Apigenin and Crysin) and five flavonols (Fisetin, Galangin, Kaempherol, Morin and Quercetin).

Preliminary Study on the Influence of the Polyphenols of Different Groups on the Digestibility of Wheat Starch, Measured by the Content of Resistant Starch

The scientific goals of this research were to examine the impact of various polyphenols from different groups on resistant starch development. Wheat starch was tested, and the polyphenols were added to starch after its pasting in the amount suggested in the literature as optimal—10 mg, and at twice and half the optimal, i.e., 20 mg and 5 mg. The most frequently consumed and most frequently occurring compounds in food products were selected for the proposed research: (1) phenolic acids—p-coumaric acid, ferulic acid; (2) flavanones—hesperidin, naringenin; (3) flavanols—(+)catechin, epigallocatechin gallate; (4) flavonols—quercetin, kaempferol; (5) anthocyanins—cyanidin-3-O-glucoside, delphinidin-3-O-glucoside. As a result, either the dose or the kind of polyphenolic compound had a statistically significant influence on the wheat starch digestibility (p < 0.05). However the observed impact was dose-dependent, and interestingly, higher amounts of RS were found in the case of the lowest dose applied (5 mg—4.76% of starch gel; mean = 2.94 ± 1.23 g·100 g−1 dm) as compared to the other doses: 10 mg—9.09% of starch gel (mean = 1.58 g·100 g−1 dm) and 20 mg—16.66% of starch gel (mean = 1.51 ± 0.90 g·100 g−1 dm). Among all tested polyphenols added to wheat starch gels in an amount of 10 mg and 20 mg, epigallocatechin gallate was found to be the most effective compound (p < 0.05), while (+)catechin was most efficient in the dose of 5 mg (p < 0.05).

Quercetin Inhibits Hsp70 Blocking of Bovine Viral Diarrhea Virus Infection and Replication in the Early Stage of Virus Infection.

Bovine viral diarrhea virus (BVDV), a positive-strand RNA virus of the genus Pestivirus in the Flaviviridae family, is the causative agent of viral diarrheal disease in bovine. BVDV has been used as a surrogate model for the hepatitis C virus (HCV) to evaluate the efficacy of antiviral drugs. The plant flavonol quercetin causes multiple health-promoting effects in humans and animals. It can be made into a variety of additives, and it exerts a variety of immunomodulatory effects with the potential to be used as an antiviral agent. However, quercetin's antiviral effect and mechanism of action on BVDV are still unclear. Therefore, this study was designed to evaluate quercetin's effect on BVDV virus replication in vitro and in vivo and elucidate its mechanism of action. A CCK-8 kit was used to analyze the toxicity of the quercetin to the MDBK cells. Western blot, qRT-PCR, TCID50, and histological analysis were used to determine the mechanism of quercetin's anti-BVDV activity. An oxidative stress kit was used to evaluate the effects of quercetin on ROS, antioxidant enzymes, and MDA indexes. The effect of quercetin on IL-2 and IFN-γ in the serum of mice was determined by using an ELISA kit. The results showed that quercetin inhibits Hsp70, blocks BVDV infection in the early stage of virus infection and inhibits BVDV replication by inhibiting oxidative stress or ERK phosphorylation. In addition, quercetin alleviated the decrease in IFN-γ and IL-2 in the serum of BVDV-infected mice. Quercetin ameliorated BVDV-induced histopathological changes. In summary, this study demonstrated for the first time the role of Hsp70 in BVDV infection and the potential application of quercetin in treating BVDV infection.

Chemical Composition and Polyphenol Compounds of Vaccinium floribundum Kunth (Ericaceae) from the Volcano Chimborazo Paramo (Ecuador)

Mortiño (Vaccinium floribundum Kunth) is considered a “superfruit” due to its antioxidant capacity and possible health benefits. To date, there is no known study that addresses the biochemical characterization of mortiño berries from the paramo of the Chimborazo volcano (Ecuador). So, the aim of this research was to evaluate for the first time the effect of the stage of development of the mortiño berries (two stages) and environment of origin (three sampling areas) on fruit quality. Polyphenol compounds were identified by high-performance liquid chromatography (HPLC) coupled to electrospray ionization mass spectrometric (ESI-MSn) and quantified by high-performance liquid chromatography with a diode array detector (HPLC-DAD). Moreover, antioxidant properties (ABTS•+, and DPPH), sugar and organic acids, and minerals were examined. The main organic acids were quinic and citric acid, while glucose, fructose, sucrose, mannose, and sorbitol were the main sugars determined in the mortiño fruits. The main constituents of the mortiño berries included hydroxycinnamic acids (5-O-caffeoylquinic acid), flavonols (quercetin 3-hexoside, quercetin 5-hexoside, quercetin 3-pentoside, and quercetin-3-O-rhamnoside) and anthocyanins. Seven anthocyanins were identified: glycosides of cyanidin, delphinidin, petunidin, peonidin, and pelargonidin. The research confirms that the mortiño berries produced in the Ecuadorian paramo area are a valuable source of polyphenolics, rich in sugars and organic acids, and can be classified as a good source of microelements.

Conformational Preference of Flavonols and Its Effect on the Chemical Properties Involved in Radical Scavenging Activity

Flavonols are compounds with radical-scavenging activities that can prevent the harmful effects of free radicals. Their radical-scavenging activity has attracted significant attention. Recently, quantum chemistry-based methodologies have significantly improved the understanding of the activity due to dramatic increases in computational power and software improvements. A standardized analysis method for estimating radical scavenging activity, the quantum mechanics-based test for overall free radical scavenging activity (QM-ORSA), has been proposed. An obstacle in applying the QM-ORSA protocol to flavonols is the large number of conformers and hydroxy groups for analysis. In this study, we focused on it and analyzed the conformational dependences of three flavonols (myricetin, quercetin, and kaempferol) on their chemical properties: bond dissociation energy, pKa, and ionization energy. As a result, all chemical properties were insensitive to conformational differences. The conformational search should be performed separately for each in the gas phase and in aqueous solution because of the differences in the major conformer (relative population of each conformer). These results suggest that it is important to perform the conformational search separately in water and in the gas phase and to determine one representative structure for analyzing radical scavenging activity.

Flavonols and Flavones as Potential anti-Inflammatory, Antioxidant, and Antibacterial Compounds.

Plant preparations have been used to treat various diseases and discussed for centuries. Research has advanced to discover and identify the plant components with beneficial effects and reveal their underlying mechanisms. Flavonoids are phytoconstituents with anti-inflammatory, antimutagenic, anticarcinogenic, and antimicrobial properties. Herein, we listed and contextualized various aspects of the protective effects of the flavonols quercetin, isoquercetin, kaempferol, and myricetin and the flavones luteolin, apigenin, 3′,4′-dihydroxyflavone, baicalein, scutellarein, lucenin-2, vicenin-2, diosmetin, nobiletin, tangeretin, and 5-O-methyl-scutellarein. We presented their structural characteristics and subclasses, importance, occurrence, and food sources. The bioactive compounds present in our diet, such as fruits and vegetables, may affect the health and disease state. Therefore, we discussed the role of these compounds in inflammation, oxidative mechanisms, and bacterial metabolism; moreover, we discussed their synergism with antibiotics for better disease outcomes. Indiscriminate use of antibiotics allows the emergence of multidrug-resistant bacterial strains; thus, bioactive compounds may be used for adjuvant treatment of infectious diseases caused by resistant and opportunistic bacteria via direct and indirect mechanisms. We also focused on the reported mechanisms and intracellular targets of flavonols and flavones, which support their therapeutic role in inflammatory and infectious diseases.

Flavonoid and Phenolic Acid Profiles of Dehulled and Whole Vigna subterranea (L.) Verdc Seeds Commonly Consumed in South Africa.

Bambara groundnut (BGN) is an underexploited crop with a rich nutrient content and is used in traditional medicine, but limited information is available on the quantitative characterization of its flavonoids and phenolic acids. We investigated the phenolic profile of whole seeds and cotyledons of five BGN varieties consumed in South Africa using UPLC-qTOF-MS and GC-MS. Twenty-six phenolic compounds were detected/quantified in whole seeds and twenty-four in cotyledon, with six unidentified compounds. Flavonoids include flavan-3-ol (catechin, catechin hexoside-A, catechin hexoside-B), flavonol (quercetin, quercetin-3-O-glucoside, rutin, myricetin, kaempherol), hydroxybenzoic acid (4-Hydroxybenzoic, 2,6 Dimethoxybenzoic, protocatechuic, vanillic, syringic, syringaldehyde, gallic acids), hydroxycinnamic acid (trans-cinnamic, p-coumaric, caffeic, ferulic acids) and lignan (medioresinol). The predominant flavonoids were catechin/derivatives, with the highest content (78.56 mg/g) found in brown BGN. Trans-cinnamic and ferulic acids were dominant phenolic acid. Cotyledons of brown and brown-eyed BGN (317.71 and 378.59 µg/g) had the highest trans-cinnamic acid content, while red seeds had the highest ferulic acid (314.76 µg/g) content. Colored BGN had a significantly (p < 0.05) higher content of these components. Whole BGN contained significantly (p < 0.05) higher amount of flavonoids and phenolic acids, except for the trans-cinnamic acid. The rich flavonoid and phenolic acid content of BGN seeds highlights the fact that it is a good source of dietary phenolics with potential health-promoting properties.

The Impact of Heat Treatment of Quercetin and Myricetin on their Activities to Alleviate the Acrylamide-Induced Cytotoxicity and Barrier Loss in IEC-6 Cells.

Two flavonols quercetin and myricetin were assessed for their in vitro activities to attenuate the acrylamide-induced cytotoxicity and barrier loss in rat intestinal epithelial (IEC-6) cells and to identify whether heat treatment of the flavonols might cause activity changes. The results showed that the flavonols could alleviate the acrylamide-caused cell injury, resulting in higher cell viability, lower lactate dehydrogenase release, and less formation of reactive oxygen species. Meanwhile, the flavonols could antagonize the acrylamide-induced barrier dysfunction via decreasing the paracellular permeability, increasing the transepithelial resistance of cell monolayer, and enhancing the expression of three tight junction proteins namely occludin, claudin-1, and zonula occludens-1. The flavonols also could down-regulate the expression of JNK/Src proteins and thus cause lower relative protein ratios of p-JNK/JNK and p-Src/Src, resulting in a suppressed JNK/Src activation. Totally, quercetin was more potent than myricetin to exert these assessed activities, while the heated flavonols obtained lower activity than the unheated ones. It is thus concluded that the flavonols had beneficial activities towards the intestinal epithelial cells with acrylamide exposure by alleviating the acrylamide-induced cytotoxicity and barrier disruption, while heat treatment of the flavonols was unfavorable because it led to a reduced flavonol activity to the cells.

Aronia Melanocarpa: Identification and Exploitation of Its Phenolic Components.

The phenolic components of Aronia melanocarpa were quantitatively recovered by three successive extractions with methanol. They comprise anthocyanins (mainly cyanidin glycosides) phenolic acids (chlorogenic and neochlorogenic acids) and flavonols (quercetin glycosides). Approximately 30% of the total phenolic compounds are located in the peel and the rest in the flesh and seeds. Peels contain the major part of anthocyanins (73%), while the flesh contains the major part of phenolic acids (78%). Aronia juice, rich in polyphenols, was obtained by mashing and centrifugation, while the pomace residue was dried and subjected to acidified water extraction in a fixed bed column for the recovery of residual phenolics. A yield of 22.5 mg gallic acid equivalents/g dry pomace was obtained; however, drying caused anthocyanins losses. Thus, their recovery could be increased by applying extraction on the wet pomace. The extract was encapsulated in maltodextrin and gum arabic by spray drying, with a high (>88%) encapsulation yield and efficiency for both total phenols and anthocyanins. Overall, fresh aronia fruits are a good source for the production of polyphenol-rich juice, while the residual pomace can be exploited, through water extraction and spray drying encapsulation for the production of a powder containing anthocyanins that can be used as a food or cosmetics additive.

Commercially Available Flavonols Are Better SARS-CoV-2 Inhibitors than Isoflavone and Flavones.

Despite the fast development of vaccines, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still circulating and generating variants of concern (VoC) that escape the humoral immune response. In this context, the search for anti-SARS-CoV-2 compounds is still essential. A class of natural polyphenols known as flavonoids, frequently available in fruits and vegetables, is widely explored in the treatment of different diseases and used as a scaffold for the design of novel drugs. Therefore, herein we evaluate seven flavonoids divided into three subclasses, isoflavone (genistein), flavone (apigenin and luteolin) and flavonol (fisetin, kaempferol, myricetin, and quercetin), for COVID-19 treatment using cell-based assays and in silico calculations validated with experimental enzymatic data. The flavonols were better SARS-CoV-2 inhibitors than isoflavone and flavones. The increasing number of hydroxyl groups in ring B of the flavonols kaempferol, quercetin, and myricetin decreased the 50% effective concentration (EC50) value due to their impact on the orientation of the compounds inside the target. Myricetin and fisetin appear to be preferred candidates; they are both anti-inflammatory (decreasing TNF-α levels) and inhibit SARS-CoV-2 mainly by targeting the processability of the main protease (Mpro) in a non-competitive manner, with a potency comparable to the repurposed drug atazanavir. However, fisetin and myricetin might also be considered hits that are amenable to synthetic modification to improve their anti-SARS-CoV-2 profile by inhibiting not only Mpro, but also the 3′–5′ exonuclease (ExoN).

Changes of ultrastructural organization in periodontal complex components in experimental periodontitis and its correction with quercetin

The article presents the results of study the changes of ultrastructural organization in the periodontal complex under conditions of experimental bacterial-immune periodontitis development and treatment effect of flavonol quercetin. Experimental bacterial-immune periodontitis in experimental animals was caused by injection of complex mixture of microorganisms diluted with egg protein into periodontal tissue. The evaluation of the ultrastructural character changes in the gingival area of the periodontal complex was carried out on the basis of electron microscopic examination. In a result study on the 7th day of the experiment were observed changes that manifested disorders of the connective tissue and vessels structure. It were also marked increased diffusive leukocytic infiltration of the connective tissue of the mucosal gingival lamina propria. There was some improvement in respect of the electron microscopic structure of the microcirculatory vessels on the 14th and 30th days of the experiment. The performed studies of hemocapillaries submicroscopic organization of the animal’s gums mucous membrane in conditions of application quercetin for experimental periodontitis has shown that flavonol improved structural organization considerably. The use of quercetin improves the organization of all ultrastructured components of the periodontal complex in experimental periodontitis.

UGT440A1 Is Associated With Motility, Reproduction, and Pathogenicity of the Plant-Parasitic Nematode Bursaphelenchus xylophilus.

Pine wilt disease (PWD) caused by Bursaphelenchus xylophilus is considered a major threat to pine forests worldwide. Uridine diphosphate (UDP)-glycosyltransferases (UGTs) catalyze the conjugation of small lipophilic compounds with sugars and play crucial roles in the detoxification and homeostatic processes in all living organisms. We investigated the molecular characteristics and biological functions of the gene UGT440A1 that encodes UGTs in B. xylophilus. The in situ hybridization results indicated that UGT440A1 is expressed in all developmental stages of B. xylophilus, particularly in the head, intestine, and hypodermis of the second-stage of juveniles (J2), third-stage of juveniles (J3) and fourth-stage of juveniles (J4) females and in almost the whole body of J4 males and adults. Recombinant UGT440A1 was observed mainly in the inclusion bodies, and the enzyme activity assay revealed that UGT440A1 could catalyze the glycosylation reaction of two types of flavonols (kaempferol and quercetin). RNA interference (RNAi) of UGT440A1 suppressed motility, feeding, and reproduction of B. xylophilus. Furthermore, UGT440A1 knockdown caused a delay in the development of PWD symptoms in the pine seedlings inoculated with the nematodes. These results suggest that UGT440A1 is involved in the pathogenic process of B. xylophilus and the information may facilitate a better understanding of the molecular mechanism of PWD.

Genetic and chemical diversity analyses in tale grapes (Vitis vinifera L.)

Vitis vinifera L. is one of the economically important plant crops worldwide which is a valuable food source for humans. This precious plant species has several local varieties and accessions which are continuously under selection and cultivation. Due to these human activities, the grape faces genetic homogeneity and erosion. Therefore, it is important to investigate available genetic diversity in grape plants all over the world. We aimed to study the genetic structure and diversity as well as chemical differences of seven grape cultivars in the country. We used SSR, and SRAP molecular markers for genetic diversity analyses, as well as biochemical traits. Both molecular markers showed a medium to moderate genetic variability in the studied grape cultivars (about 20% genetic polymorphism). Similarly, both molecular markers differentiated the studied cultivars into two genetic groups. AMOVA indicated significant genetic difference in these cultivars. ANOVA analysis of flavonols (quercetin, myricetin, kaempferol, and rutin) contents of seeds extract by HPLC indicated the significant difference (P &lt;0.01) among grape cultivars. PCA biplot of cultivars based on chemical features separated these cultivars into two major groups according to their flavone and flavonoid contents. Pairwise Mantel tests performed between molecular and chemical data showed a significant association between SSR and SRAP data, but no significant association was obtained between either SSR or SRAP data with chemical features in grape cultivars studied. A heat-map constructed based on combined molecular and chemical data revealed that some of the studied grape cultivars are distinct in their genetic and chemical features.

Impact of covalent grafting of two flavonols (kaemperol and quercetin) to caseinate on in vitro digestibility and emulsifying properties of the caseinate-flavonol grafts

Covalent grafting of one of the two flavonols (kaemperol and quercetin) to caseinate was achieved by a reaction between the heat-oxidized flavonols and caseinate at flavonol-lysine molar ratios of 1:100 and 1:200. Grafted caseinate products (GCPs) showed − NH2 content reduction and respective kaemperol and quercetin contents of 1.08–6.13 and 3.23–6.64 mmol/kg protein. Quercetin was more reactive than kaemperol under the same conditions, while long-time flavonol heat and higher flavonol-lysine molar ratio caused greater flavonol-grafting. GCPs subjected to 180-day storage had further flavonol-grafting, −NH2 content decrease, and weak protein crosslinking. GCPs consistently had higher surface hydrophobicity but lower emulsification and digestibility than caseinate, while greater flavonol-grafting caused a remarkable value change. Meanwhile, the Kjeldahl method was more suitable than the UV-absorption method to evaluate protein digestibility, because the grafted flavonols in this case did not interfere with data results. Collectively, the covalent flavonol-grafting of proteins can impact the assayed protein functionalities.

The Impact of Flavonols on Cardiovascular Risk.

Cardiovascular disease (CVD) is the leading cause of deaths globally. The main target for prevention of cardiovascular (CV) risk are lifestyle changes, including particular dietary recommendations, involving high intake of fruits and vegetables. Flavonols are a subgroup of flavonoids—compounds present in fruits, vegetables, and tea—known for their antioxidative properties. There are many findings about the beneficial impact of flavonols on general CV risk and its factors, but mainly from in vitro and animal model studies. This paper summarizes data from human studies about flavonols’ impact on general CV risk and its factors. A high dietary intake of flavonols could decrease CVD mortality directly or through impact on selected CV factors; however, available data are inconsistent. Nonetheless, specific groups of patients (smoking men, hypertensive and diabetic patients) can potentially benefit from selected dietary modifications or flavonols (quercetin) supplementation. Future investigations about kaempferol and myricetin are needed.

Flavonol Quercetin: Immunomodulatory And Anticancer Properties

Background: Cancer is one of the critical, challenging problems in a clinical setting among non-infectious diseases and poses a considerable burden to the community for its highest fatalities and associated morbidities. Immunotherapy has paid much attention to curbing cancer and protecting against advanced metastasis. Nutritional sources have been well known for their anticancer properties for centuries, although they exhibited multiple intricated mechanisms to deter this notorious disease. Immune-based therapy is getting popular in modern days to fight against various illnesses, including cancer. In recent years, numerous in vitro and clinical trials have been carried out regarding the potential use of flavonoids in cancer therapy; however, the results and achievements were still controversial and obscure. More research on immune-mediated anticancer therapy has to be done to understand more explicit mechanisms of how plant-derived compounds modulate immune cells and subsequent clinical uses. One of the most commonly tested flavonoid compounds that stimulate immune cells and offer significant immune-mediated anticancer activities is flavonol quercetin.&#x0D; Objectives: This present review summarises an updated overview of quercetin, focusing on its anticancer effects. In addition to its chemistry and sources, quercetin’s immunomodulatory properties and the common signalling mechanisms have also been described and proposed the possible research gap for further investigation and future research.&#x0D; Conclusion: This review would provide a new comparative view regarding quercetin’s immunomodulatory and anticancer activities. Moreover, we conclude that quercetin plays a crucial role in eradicating cancer cells and modulating immune cells’ activity based on the literature. It is worthwhile to extensively investigate quercetin’s anticancer and immunomodulatory effects in clinical settings.&#x0D; Key words: Cancer, flavonol, quercetin, anticancer, immunomodulation