Quercetin metabolites in plasma of rats fed diets containing rutin or quercetin

Exploring the potential of quercetin in Alzheimer's Disease: Pharmacodynamics, Pharmacokinetics, and Nanodelivery systems

Alzheimer's disease (AD) is a primary cause of dementia that affects millions of people worldwide and its prevalence is likely to increase largely in the coming decades. Multiple complex pathways, such as oxidative stress, tau and amyloid-beta (Aβ) pathology, and cholinergic dysfunction, are involved in the pathogenesis of Alzheimer's disease. The conventional treatments provide only symptomatic relief and not a complete cure for the disease. On the other hand, recent studies have looked into the possibility of flavonoids as an effective therapeutic strategy for treating AD. Quercetin, a well-known flavonol, has been extensively studied for AD treatment. Therefore, this review mainly focuses on the pharmacokinetics properties of quercetin and its modes of action, such as antioxidant, anti-inflammatory, anti-amyloidogenic, and neuroprotective properties, which are beneficial in treating AD. It also highlights the nano delivery systems of quercetin, including liposomes, nanostructures lipid carriers, solid lipid nanoparticles, nanoemulsions, microemulsions, self-emulsifying drug delivery systems, and nanoparticles reported for AD treatment. The remarkable potential of quercetin nanocarriers has been reflected in enhancing its bioavailability and therapeutic efficacy. Therefore, clinical studies must be conducted to explore it as a therapeutic strategy for Alzheimer's disease.

Research progress of quercetin in cardiovascular disease

Quercetin is one of the most common flavonoids. More and more studies have found that quercetin has great potential utilization value in cardiovascular diseases (CVD), such as antioxidant, antiplatelet aggregation, antibacterial, cholesterol lowering, endothelial cell protection, etc. However, the medicinal value of quercetin is mostly limited to animal models and preclinical studies. Due to the complexity of the human body and functional structure compared to animals, more research is needed to explore whether quercetin has the same mechanism of action and pharmacological value as animal experiments. In order to systematically understand the clinical application value of quercetin, this article reviews the research progress of quercetin in CVD, including preclinical and clinical studies. We will focus on the relationship between quercetin and common CVD, such as atherosclerosis, myocardial infarction, ischemia reperfusion injury, heart failure, hypertension and arrhythmia, etc. By elaborating on the pathophysiological mechanism and clinical application research progress of quercetin's protective effect on CVD, data support is provided for the transformation of quercetin from laboratory to clinical application.

Avocado (Persea americana Mill) and its phytoconstituents: potential for cancer prevention and intervention

Dietary compounds, including fruits, vegetables, nuts, and spices, have been shown to exhibit anticancer properties due to their high concentrations of vitamins, minerals, fiber, and secondary metabolites, known as phytochemicals. Although emerging studies suggest that avocado (Persea americana Mill) displays antineoplastic properties in addition to numerous other health benefits, current literature lacks an updated comprehensive systematic review dedicated to the anticancer effects of avocado. This review aims to explore the cancer-preventive effects of avocados and the underlying molecular mechanisms. The in vitro studies suggest the various avocado-derived products and phytochemicals induced cytotoxicity, reduced cell viability, and inhibited cell proliferation. The in vivo studies revealed reduction in tumor number, size, and volume as well. The clinical studies demonstrated that avocado leaf extract increased free oxygen radical formation in larynx carcinoma tissue. Various avocado products and phytochemicals from the avocado fruit, including avocatin-B, persin, and PaDef defensin, may serve as viable cancer prevention and treatment options based on current literature. Despite many favorable outcomes, past research has been limited in scope, and more extensive and mechanism-based in vivo and randomized clinical studies should be performed before avocado-derived bioactive phytochemicals can be developed as cancer preventive agents.

Plant Polyphenols and Their Potential Benefits on Cardiovascular Health: A Review

Fruits, vegetables, and other food items contain phytochemicals or secondary metabolites which may be considered non-essential nutrients but have medicinal importance. These dietary phytochemicals exhibit chemopreventive and therapeutic effects against numerous diseases. Polyphenols are secondary metabolites found in vegetables, fruits, and grains. These compounds exhibit several health benefits such as immune modulators, vasodilators, and antioxidants. This review focuses on recent studies on using dietary polyphenols to treat cardiovascular disorders, atherosclerosis, and vascular endothelium deficits. We focus on exploring the safety of highly effective polyphenols to ensure their maximum impact on cardiac abnormalities and discuss recent epidemiological evidence and intervention trials related to these properties. Kaempferol, quercetin, and resveratrol prevent oxidative stress by regulating proteins that induce oxidation in heart tissues. In addition, polyphenols modulate the tone of the endothelium of vessels by releasing nitric oxide (NO) and reducing low-density lipoprotein (LDL) oxidation to prevent atherosclerosis. In cardiomyocytes, polyphenols suppress the expression of inflammatory markers and inhibit the production of inflammation markers to exert an anti-inflammatory response. Consequently, heart diseases such as strokes, hypertension, heart failure, and ischemic heart disease could be prevented by dietary polyphenols.

A Pharmacokinetic Study of Different Quercetin Formulations in Healthy Participants: A Diet-Controlled, Crossover, Single- and Multiple-Dose Pilot Study

This study aimed to evaluate the blood concentrations of quercetin in healthy participants after the administration of different formulations in single- and multiple-dose phases. Ten healthy adults (males, 5; females, 5; age 37 ± 11 years) participated in a diet-controlled, crossover pilot study. Participants received three different doses (250 mg, 500 mg, or 1000 mg) of quercetin aglycone orally. In the single-dose study, blood concentrations (AUC0-24 and Cmax) of standard quercetin were compared with those of LipoMicel®-a food-grade delivery form of quercetin. In the multiple-dose study, blood concentrations of formulated quercetin were observed over 72 h, after repeated doses of LipoMicel (LM) treatments. The AUC0-24 ranged from 77.3 to 1128.9 ng·h/ml: LM significantly increased blood concentrations of quercetin by 7-fold (LM 500) compared to standard quercetin, when tested at the same dose, over 24 h (p < 0.001); LM administered at a higher dose (LM 1000) achieved 15-fold higher absorption (p < 0.001); LM tested at half a dose of standard quercetin increased concentration by approx. 3-fold (LM 250). Quercetin blood concentrations were attained over 72 h. The major metabolites measured in the blood were methylated, sulfate, and glutathione (GSH) conjugates of quercetin. Significant differences in concentrations between quercetin conjugates (sulfate vs. methyl vs. GSH) were observed (p < 0.001). Data obtained from this study suggest that supplementation with LipoMicel® is a promising strategy to increase the absorption of quercetin and its health-promoting effects in humans. However, due to the low sample size in this pilot study, further research is still warranted to confirm the observations in larger populations. This trial is registered with NCT05611827.

Isolation and anticancer activity of quercetin from Acalypha indica L. against breast cancer cell lines MCF-7 and MDA-MB-231

In this study, the active components of the plant were carefully extracted and identified using three solvent systems. After extraction, we used solvent systems to further purify the main flavonoid chemical constituent. As a result of our analytical strategy, which included HPLC analysis, MS/MS spectroscopic analysis, and NMR data-based constructions, quercetin was determined to be the main chemical constituent. Our study suggests the potential therapeutic advantages of quercetin, a compound found in the leaves of Acalypha indica, for treating breast cancer cell lines MCF-7 and MDA-MB-231. Our comparison of Quercetin to the regularly prescribed medicine Doxorubicin shows that it has the capacity to inhibit MCF-7 and MDA-MB-231 cells. Measurements of apoptosis and cell cycle phase showed this to be the case. Furthermore, a ladder that formed as a result of cellular damage brought on by ROS provided further proof of the drug's impact on DNA integrity. Notably, pro-apoptotic proteins displayed increased apoptosis activity in cells treated with quercetin. Given that it is extracted from plants and has less adverse effects than other compounds, quercetin is a viable option for further clinical study. The objective is to fight breast cancer, one of the most prevalent diseases in the world and a main cause of death for women. Thus, our research makes a significant addition to the ongoing search for potent, plant-based breast cancer treatments.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03705-w.

Rutin Stimulates the Green Alga Chromochloris zofingiensis for Improved Biomass and Astaxanthin Production

Chromochloris zofingiensis represents a potential algal producer of the value-added ketocarotenoid astaxanthin. Here, rutin, a low-cost flavonoid compound, was evaluated regarding its roles in C. zofingiensis production under astaxanthin-inducing conditions via physiological, biochemical, and transcriptomics analyses. The rutin treatment allowed C. zofingiensis to achieve 81.2% more biomass and 20.5% greater astaxanthin content under nitrogen deprivation, leading to more than doubled astaxanthin production. The rutin-treated C. zofingiensis had higher levels of chlorophylls, proteins, and lipids and lower carbohydrate level than the control. Rutin promoted the intracellular abscisic acid (ABA) level, which could be restored by the ABA biosynthesis inhibitor, accompanied by the restoration of biomass concentration and astaxanthin content. The application of exogenous ABA to C. zofingiensis also furthered biomass concentration and astaxanthin accumulation. Together with the comparative transcriptomics analysis, our study provides implications into the involvement of ABA in rutin-mediated stimulation of C. zofingiensis growth and astaxanthin accumulation and highlights a feasible strategy of combining stress and chemical induction for improved microalgal production.

Bioactive Flavonoids: A Comprehensive Review on Pharmacokinetics and Analytical Aspects

Flavonoids are a diversified group of natural substances which were discovered to provide a variety of health benefits in human beings. Vegetables, fruits, wine and tea are the primary flavonoid dietary sources for humans and as the flavonoids are so closely connected to human dietary items and health, it is vital to explore the structural-activity connection. The arrangement, replacement of functional groups, and total number of hydroxyl groups around flavonoid's nucleus structure affect their biological activity, metabolism, and bioavailability. Various flavonoids have been proven to have hepatoprotective properties, that help in the prevention of coronary heart disease. Similarly, these flavonoids also possess anticancer, and anti-inflammatory activities. Flavonoids have been found to have a functional and structural link with their enzyme inhibitory action, that appears to have antiviral effect through acting as antioxidants, damaging cell membranes, blocking enzymes, activating mechanisms of host self-defense, and limiting virus penetration and attaching to cells. Identification, characterization, isolation, and biological role of flavonoids, as well as their uses on health advantages, are all major topics in research and development currently. This review represents a summary of various sources of flavonoids, class, subclass, their chemical structures, biological activities, the pharmacokinetics of flavonoids and various analytical, bioanalytical and electrochemical methods for determination of flavonoids from different matrices.

The potential biological effects of quercetin based on pharmacokinetics and multi-targeted mechanism in vivo

Quercetin is a plant-derived polyphenol flavonoid that has been proven to be effective for many diseases. However, the mechanism and in vivo metabolism of quercetin remains to be clarified. It achieves a wide range of biological effects through various metabolites, gut microbiota and its metabolites, systemic mediators produced by inflammation and oxidation, as well as by multiple mechanisms. The all-round disease treatment of quercetin is achieved through the organic combination of multiple channels. Therefore, this article clarifies the metabolic process of quercetin in the body, and explores the new pattern of action of quercetin in the treatment of diseases.

Site-Specific Binding of Anticancer Drugs to Human Serum Albumin

The interaction of drugs with proteins plays a very important role in the distribution of the drug. Human serum albumin (HSA) is the most abundant protein in the human body and showing great binding characteristics has gained a lot of importance pharmaceutically. It plays an essential role in the pharmacokinetics of a number of drugs and hence several reports are available on the interaction of drugs with HSA. It can bind to cancer drugs and thus it is crucial to look at the binding characteristics of these drugs with HSA. Herein we summarize the binding properties of some anti-cancer drugs by specifically looking into the binding site with HSA. The number of drugs binding at Sudlow's site I situated in subdomain II A is more than the drugs binding at Sudlow's site II.

In Silico Study Approach on a Series of 50 Polyphenolic Compounds in Plants; A Comparison on the Bioavailability and Bioactivity Data

Fifty (50) phytocompounds from several subclasses of polyphenols, chosen based on their abundance in the plant world, were analyzed through density functional methods, using computational tools to evaluate their oral availability and particular bioactivity on several cell modulators; key descriptors and molecular features related to the electron density and electrostatic potential for the lowest energy conformers of the investigated molecules were computed. An analysis of the bioactivity scores towards six cell modulators (GPCR ligand, ion channel modulator, kinase inhibitor, nuclear receptor ligand, protease inhibitor and enzyme inhibitor) was also achieved, in the context of investigating their potential side effects on the human digestive processes. Summarizing, computational results confirmed in vivo and in vitro data regarding the high bioavailability of soy isoflavones and better bioavailability of free aglycones in comparison with their esterified and glycosylated forms. However, by a computational approach analyzing Lipinski’s rule, apigenin and apigenin-7-O-rhamnoside, naringenin, hesperetin, genistein, daidzin, biochanin A and formonetin in the flavonoid series and all hydroxycinnamic acids and all hydroxybenzoic acids excepting ellagic acid were proved to have the best bioavailability data; rhamnoside derivatives, the predominant glycosides in green plants, which were reported to have the lowest bioavailability values by in vivo studies, were revealed to have the best bioavailability data among the studied flavonoids in the computational approach. Results of in silico screening on the phenolic derivatives series also revealed their real inhibitory potency on the six parameters studied, showing a remarkable similitude between the flavonoid series, while flavonoids were more powerful natural cell modulators than the phenyl carboxylic acids tested. Thus, it can be concluded that there is a need for supplementation with digestive enzymes, mainly in the case of individuals with low digestive efficiency, to obtain the best health benefits of polyphenols in humans.

Onco-Preventive and Chemo-Protective Effects of Apple Bioactive Compounds

Cancer is one of the leading causes of death globally. Epidemiological studies have strongly linked a diet high in fruits to a lower incidence of cancer. Furthermore, extensive research shows that secondary plant metabolites known as phytochemicals, which are commonly found in fruits, have onco-preventive and chemo-protective effects. Apple is a commonly consumed fruit worldwide that is available all year round and is a rich source of phytochemicals. In this review, we summarize the association of apple consumption with cancer incidence based on findings from epidemiological and cohort studies. We further provide a comprehensive review of the main phytochemical patterns observed in apples and their bioavailability after consumption. Finally, we report on the latest findings from in vitro and in vivo studies highlighting some of the key molecular mechanisms targeted by apple phytochemicals in relation to inhibiting multiple 'hallmarks of cancer' that are important in the progression of cancer.

The Emerging Role of Polyphenols in the Management of Type 2 Diabetes

Type 2 diabetes (T2D) is a fast-increasing health problem globally, and it results from insulin resistance and pancreatic β-cell dysfunction. The gastrointestinal (GI) tract is recognized as one of the major regulatory organs of glucose homeostasis that involves multiple gut hormones and microbiota. Notably, the incretin hormone glucagon-like peptide-1 (GLP-1) secreted from enteroendocrine L-cells plays a pivotal role in maintaining glucose homeostasis via eliciting pleiotropic effects, which are largely mediated via its receptor. Thus, targeting the GLP-1 signaling system is a highly attractive therapeutic strategy to treatment T2D. Polyphenols, the secondary metabolites from plants, have drawn considerable attention because of their numerous health benefits, including potential anti-diabetic effects. Although the major targets and locations for the polyphenolic compounds to exert the anti-diabetic action are still unclear, the first organ that is exposed to these compounds is the GI tract in which polyphenols could modulate enzymes and hormones. Indeed, emerging evidence has shown that polyphenols can stimulate GLP-1 secretion, indicating that these natural compounds might exert metabolic action at least partially mediated by GLP-1. This review provides an overview of nutritional regulation of GLP-1 secretion and summarizes recent studies on the roles of polyphenols in GLP-1 secretion and degradation as it relates to metabolic homeostasis. In addition, the effects of polyphenols on microbiota and microbial metabolites that could indirectly modulate GLP-1 secretion are also discussed.

The anticancer potential of the dietary polyphenol rutin: Current status, challenges, and perspectives

Rutin is one of the most common dietary polyphenols found in vegetables, fruits, and other plants. It is metabolized by the mammalian gut microbiota and absorbed from the intestines, and becomes bioavailable in the form of conjugated metabolites. Rutin exhibits a plethora of bioactive properties, making it an extremely promising phytochemical. Numerous studies demonstrate that rutin can act as a chemotherapeutic and chemopreventive agent, and its anticancer effects can be mediated through the suppression of cell proliferation, the induction of apoptosis or autophagy, and the hindering of angiogenesis and metastasis. Rutin has been found to modulate multiple molecular targets involved in carcinogenesis, such as cell cycle mediators, cellular kinases, inflammatory cytokines, transcription factors, drug transporters, and reactive oxygen species. This review summarizes the natural sources of rutin, its bioavailability, and in particular its potential use as an anticancer agent, with highlighting its anticancer mechanisms as well as molecular targets. Additionally, this review updates the anticancer potential of its analogs, nanoformulations, and metabolites, and discusses relevant safety issues. Overall, rutin is a promising natural dietary compound with promising anticancer potential and can be widely used in functional foods, dietary supplements, and pharmaceuticals for the prevention and management of cancer.

Comparative Study of Leaf and Rootstock Aqueous Extracts of Foeniculum vulgare on Chemical Profile and In Vitro Antioxidant and Antihyperglycemic Activities

Foeniculum vulgare is a medicinal plant used in Moroccan folk medicine to treat several diseases such as diabetes. The aim of this study was to determine the phenolic bioactive compounds and to evaluate the antioxidant and antihyperglycemic activities of Foeniculum vulgare leaf and rootstock extracts. Phenolic compounds of F. vulgare rootstock and leaf extracts were determined using HPLC-DAD-QTOFMS analysis. The antioxidant activity was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+) radicals. Moreover, the in vitro antihyperglycemic effects were tested by measuring the inhibition of α-amylase and α-glucosidase activities. HPLC-DAD-QTOFMS analysis identified thirty-two phenolic components in both leaf and rootstock extracts. Caffeic acid, quinic acid, and chlorogenic acid were the major compounds of F. vulgare leaf extract (FVLE), while the main compound of F. vulgare rootstock extracts (FVRE) was quinic acid. In the DPPH assay, F. vulgare leaf extract showed important antioxidant activity (IC50 = 12.16 ± 0.02 μg/mL) than F. vulgare rootstock extract (IC50 = 34.36 ± 0.09 μg/mL). Moreover, fennel leaf extracts revealed also the most powerful antioxidant activity (IC50 = 22.95 ± 0.4 μg/mL) in the ABTS assay. The in vitro antihyperglycemic activity showed that F. vulgare rootstock extract exhibited a remarkable inhibitory capacity (IC50 = 194.30 ± 4.8 μg/mL) of α-amylase compared with F. vulgare leaf extract (IC50 = 1026.50 ± 6.5 μg/mL). Furthermore, the inhibition of α-glucosidase was more importantly with F. vulgare rootstock (IC50 of 165.90 ± 1.2 μg/mL) than F. vulgare leaf extracts (203.80 ± 1.3 μg/mL). The funding of this study showed that F. vulgare rootstock and leaf extracts presented several phenolic compounds and showed important antioxidant and antidiabetic effects. We suggest that the identified molecules are responsible for the obtained activities. However, further studies focusing on the isolation and the determination of antioxidant and antidiabetic effects of F. vulgare rootstock and leaf main compounds are required.

Molecular and Biological Functions of Quercetin as a Natural Solution for Cardiovascular Disease Prevention and Treatment

Cardiovascular disease (CVD) is a worldwide health problem with growing up rates of mortality and morbidity. Many risk factors, including high blood pressure, cigarette smoking, diabetes, obesity, and dyslipidemia are responsible for CVD. CVD can be prevented by some simple and cost-effective steps such as smoking cessation, normalizing body weight, regular physical activity, and dietary changes, including decreasing saturated fats, increasing the intake of vegetables and fruits, and reducing sugar intake. In the last decades, growing up number of studies were performed to explain the possible function of non-nutrient substances from the diet which might prevent CVD. One of these natural compounds is quercetin which is widely present in vegetables, tea, fruits and wine. Many in vitro, in vivo and clinical studies have indicated the cardioprotective functions of quercetin. They can be explained by quercetin's reducing blood pressure, antioxidant potential and some other activities. This review evaluates the experimental and clinical studies that have studied the effect of quercetin in CVD and summarizes the molecular mechanisms of action as well as clinical effects of quercetin in CVD.

Efficient synergistic combination effect of Quercetin with Curcumin on breast cancer cell apoptosis through their loading into Apo ferritin cavity

Combination of natural agents has received a great attention in cancer treatment because of synergistically increased apoptotic effect on cancer cell lines by triggering several apoptotic signaling pathways. However, the hydrophobic nature, poor bioavailability and low cellular uptake of most natural agents limit their therapeutic effectiveness. The purpose of this study was to design Apoferritin nanoparticles loaded with Quercetin and Curcumin (Que-Cur-HoS-Apo NPs) and to test their synergistic antitumor properties on a breast cancer cell line (MCF7). The physico-chemical characterization of the Que-Cur-HoS-Apo NPs by Size Exclusion Chromatography (FPLC) and Dynamic Light Scattering (DLS) confirmed the encapsulation of the compounds in the protein cage with narrow size distribution in the range 17.4 ± 1.2 nm. Cell viability study indicated that Que-Cur-HoS-Apo NPs were able to exert a more pronounced effect at lower dose on the MCF7 cell line when compared to the free combination of the drugs. The Que-Cur-HoS-Apo system allowed cellular uptake of natural agents thus triggering enhanced apoptosis. These effects were confirmed by Annexin-V/7-AAD Staining Assay and intracellular Reactive Oxygen Species (ROS) quantitative detection. These results suggest the potential of Que-Cur-HoS-Apo NPs as a promising anti-cancer agent in breast cancer therapy and pave the way to examine Que-Cur-HoS-Apo NPs effect in vivo.

Flavone Hispidulin Stimulates Glucagon-Like Peptide-1 Secretion and Ameliorates Hyperglycemia in Streptozotocin-Induced Diabetic Mice

SCOPE

Loss of functional β-cell mass is central for the deterioration of glycemic control in diabetes. The incretin hormone glucagon-like peptide-1 (GLP-1) plays a critical role in maintaining glycemic homeostasis via potentiating glucose-stimulated insulin secretion and promoting β-cell mass. Agents that can directly promote GLP-1 secretion, thereby increasing insulin secretion and preserving β-cell mass, hold great potential for the treatment of T2D.

METHODS AND RESULTS

GluTag L-cells, INS832/13 cells, and mouse ileum crypts and islets are cultured for examining the effects of flavone hispidulin on GLP-1 and insulin secretion. Mouse livers and isolated hepatocytes are used for gluconeogenesis. Streptozotocin-induced diabetic mice are treated with hispidulin (20 mg kg^-1 day^-1 , oral gavage) for 6 weeks to evaluate its anti-diabetic potential. Hispidulin stimulates GLP-1 secretion from the L-cell line, ileum crypts, and in vivo. This hispidulin action is mediated via activation of cyclic adenosine monophosphate/protein kinase A signaling. Hispidulin significantly improves glycemic control in diabetic mice, concomitant with improved insulin release, and β-cell survival. Additionally, hispidulin decreases hepatic pyruvate carboxylase expression in diabetic mice and suppresses gluconeogenesis in hepatocytes. Furthermore, hispidulin stimulates insulin secretion from β-cells.

CONCLUSION

These findings suggest that Hispidulin may be a novel dual-action anti-diabetic compound via stimulating GLP-1 secretion and suppressing hepatic glucose production.

Beneficial Effects of Citrus Flavonoids on Cardiovascular and Metabolic Health

The prevalence of cardiovascular disease (CVD) is increasing over time. CVD is a comorbidity in diabetes and contributes to premature death. Citrus flavonoids possess several biological activities and have emerged as efficient therapeutics for the treatment of CVD. Citrus flavonoids scavenge free radicals, improve glucose tolerance and insulin sensitivity, modulate lipid metabolism and adipocyte differentiation, suppress inflammation and apoptosis, and improve endothelial dysfunction. The intake of citrus flavonoids has been associated with improved cardiovascular outcomes. Although citrus flavonoids exerted multiple beneficial effects, their mechanisms of action are not completely established. In this review, we summarized recent findings and advances in understanding the mechanisms underlying the protective effects of citrus flavonoids against oxidative stress, inflammation, diabetes, dyslipidemia, endothelial dysfunction, and atherosclerosis. Further studies and clinical trials to assess the efficacy and to explore the underlying mechanism(s) of action of citrus flavonoids are recommended.

In vivo bioavailability of polyphenols from grape by-product extracts, and effect on lipemia of normocholesterolemic Wistar rats

BACKGROUND

The direct use of phenolic extracts from grape by-products can be useful when formulating functional food to improve consumer health. The use of phenolic extracts instead of pure polyphenols as an ingredient is relevant in this context. The present study investigated the bioavailability and absorption of polyphenols from grape by-product extracts and their health effect on cholesterolemia, by adding the extract (GE) to Wistar rats diet (50 g kg^-1 ) in vivo.

RESULTS

GE caused the appearance of (+)-catechin, myricetin and quercetic acid in plasma and liver. (+)-Catechin was the most abundant compound (6 μg mL^-1 in plasma and 0.7 μg mg^-1 protein in liver), whereas no phenolic compounds were detected in plasma or liver in the control group. Similarly, 3,4-hydroxyphenylacetic, a major product of polyphenol digestion, was detected in the plasma, liver and urine of the GE-group only. GE-group had significantly lower cholesterol level and lower total cholesterol/high-density lipoprotein ratio in plasma. Total bile acid content significantly increased in fecal matter after 24 h administration of the GE-enriched diet.

CONCLUSION

Grape extract polyphenols are partially bioavailable and showed improvement in lipid metabolism. Thus, the results suggest that GE is promising as a functional ingredient in the prevention of hypercholesterolemia. © 2018 Society of Chemical Industry.

Therapeutic potential of quercetin as a cardiovascular agent

Flavonoids are integral components of various vegetation and in foods; consequently, they represent an inevitable part of the diet. Historical and epidemiological proof recommend that diet plans consisting of flavonoids such as quercetin have positive health benefits, especially on the heart. Flavonoids have been proven to be active against hypertension, inflammation, diabetes and vascular diseases. Quercetin exhibits significant heart related benefits as inhibition of LDL oxidation, endothelium-independent vasodilator effects, reduction of adhesion molecules and other inflammatory markers, the protective effect on nitric oxide and endothelial function under conditions of oxidative stress, prevention of neuronal oxidative and inflammatory damage and platelet antiaggregant effects. Searching for experimental evidence to validate the cardioprotective effects of quercetin, we review here the recent detailed in vivo studies. Quercetin and its derivatives lead to an enhancement in heart features, indicating the prospective for quercetin to be used therapeutically in the treatment of cardiac diseases. Several evidence-based studies suggest mechanisms to observe cardiovascular diseases such as aging effects, hypertension, angiotensin-converting enzyme activity and endothelial-dependent and independent functions. Different animal models including human are also used to elucidate the in vivo role of quercetin in cardiovascular diseases. The role of quercetin and its derivatives may go beyond their existence in food and has potential as a lead molecule in drug development programs.

Dietary Flavonoids in the Prevention of T2D: An Overview

Type 2 diabetes (T2D) is a progressive metabolic disease that is increasing in prevalence globally. It is well established that insulin resistance (IR) and a progressive decline in functional β-cell mass are hallmarks of developing T2D. Obesity is a leading pathogenic factor for developing IR. Constant IR will progress to T2D when β-cells are unable to secret adequate amounts of insulin to compensate for decreased insulin sensitivity. Recently, a considerable amount of research has been devoted to identifying naturally occurring anti-diabetic compounds that are abundant in certain types of foods. Flavonoids are a group of polyphenols that have drawn great interest for their various health benefits. Results from many clinical and animal studies demonstrate that dietary intake of flavonoids might be helpful in preventing T2D, although cellular and molecular mechanisms underlying these effects are still not completely understood. This review discusses our current understanding of the pathophysiology of T2D and highlights the potential anti-diabetic effects of flavonoids and mechanisms of their actions.

Quercetin and rutin ameliorates sulphasalazine-induced spermiotoxicity, alterations in reproductive hormones and steroidogenic enzyme imbalance in rats

Certain dietary flavonoids exhibit protective potentials against drug-induced male reproductive toxicities. We investigated the protective effects of quercetin and rutin on sulphasalazine-induced alterations in steroidogenic enzyme activity, hormone profile and spermiotoxicity in rats. Sulphasalazine (SASP, 600 mg/kg bw) was administered alone or in combination with quercetin (20 mg/kg bw) or rutin (10 mg/kg bw) for 14 days. SASP treatment significantly increased relative weights of the epididymis and seminal vesicles. Also, testicular and epididymal sperm numbers (TSN, ESN), motility, daily sperm production (DSP) and acrosome reaction (AR) significantly decreased. SASP altered plasma testosterone, luteinising hormone (LH) and follicle-stimulating hormone (FSH) levels while testicular cholesterol levels, 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase (17β-HSD) activities were decreased. Elevated malondialdehyde levels and concomitant decrease in reduced glutathione, glutathione-S-transferase, peroxidase and superoxide dismutase activities were evident in testis and epididymis of SASP-treated rats. Quercetin or rutin co-treatment with SASP significantly reversed organ weights, preserved sperm integrity, restored plasma hormone levels and increased cholesterol levels, 3β-HSD and 17β-HSD activities in testis. Both flavonoids also prevented oxidative stress in testis and epididymis of SASP-treated rats. Quercetin and rutin protect against the negative effects of SASP treatment on reproductive capacity in male rats.

Metabolomics Reveals that Dietary Ferulic Acid and Quercetin Modulate Metabolic Homeostasis in Rats

Phenolic compounds ingestion has been shown to have potential preventive and therapeutic effects against various metabolic diseases such as obesity and cancer. To provide a better understanding of these potential benefit effects, we investigated the metabolic alterations in urine and feces of rat ingested ferulic acid (FA) and quercetin (Qu) using NMR-based metabolomics approach. Our results suggested that dietary FA and/or Qu significantly decreased short chain fatty acids and elevated oligosaccharides in the feces, implying that dietary FA and Qu may modulate gut microbial community with inhibition of bacterial fermentation of dietary fibers. We also found that dietary FA and/or Qu regulated several host metabolic pathways including TCA cycle and energy metabolism, bile acid, amino acid, and nucleic acid metabolism. These biological effects suggest that FA and Qu display outstanding bioavailability and bioactivity and could be used for treatment of some metabolic syndromes, such as inflammatory bowel diseases and obesity.

Modifications of dietary flavonoids towards improved bioactivity: An update on structure-activity relationship

Over the past two decades, extensive studies have revealed that inflammation represents a major risk factor for various human diseases. Chronic inflammatory responses predispose to pathological progression of chronic illnesses featured with penetration of inflammatory cells, dysregulation of cellular signaling, excessive generation of cytokines, and loss of barrier function. Hence, the suppression of inflammation has the potential to delay, prevent, and to treat chronic diseases. Flavonoids, which are widely distributed in humans daily diet, such as vegetables, fruits, tea and cocoa, among others, are considered as bioactive compounds with anti-inflammatory potential. Modification of flavonoids including hydroxylation, o-methylation, and glycosylation, can alter their metabolic features and affect mechanisms of inflammation. Structure-activity relationships among naturally occurred flavonoids hence provide us with a preliminary insight into their anti-inflammatory potential, not only attributing to the antioxidant capacity, but also to modulate inflammatory mediators. The present review summarizes current knowledge and underlies mechanisms of anti-inflammatory activities of dietary flavonoids and their influences involved in the development of various inflammatory-related chronic diseases. In addition, the established structure-activity relationships of phenolic compounds in this review may give an insight for the screening of new anti-inflammatory agents from dietary materials.

Biophysical exploration of protein-flavonol recognition: effects of molecular properties and conformational flexibility

The current work explores the biomolecular recognition of a series of flavonols by a protein and then uncovers the influences of the structural features of flavonols and the protein's own characteristics, e.g. the dynamics and flexibility, on the bioavailability of flavonols by using the pivotal biomacromolecule hemoglobin as a model. The experimental results revealed that flavonol may lead to a notable decrease in the steady-state fluorescence intensity of the β-37 Trp residue, and in the meantime the R-T transition of the protein transpired. Such noncovalent recognition forms the ground-state adduct, with an association intensity of 3.991 × 10(4) M(-1) in the reaction process, which has already been authenticated by the detailed analysis of time-resolved fluorescence and UV/vis absorption spectra. Furthermore, flavonol can form hydrogen bonds and π-conjugation effects with several amino acid residues on the polypeptide chain, for example, Trp-37, Arg-40, Asp-99 and Asn-102, and this event would induce self-regulation of the compact, regular conformation of the protein to a certain extent, which explicitly corroborates the results of circular dichroism. According to the study of molecular docking and structure-activity relationships, we could see that the recognition capacities of the protein-flavonols are inversely interrelated with the C log P values of the flavonol molecules. Moreover, the properties of the substituents in the structural B-ring unit of flavonols, i.e. polarity, position and number, will also prominently affect the degree of affinity and bioavailability of the protein-flavonol complexes. The analytical results of molecular dynamics (MD) simulation testified that the discussions of the structure-activity relationships are entirely logical, and the conformations of the amino acid residues forming noncovalent interactions tend to be stable in the MD simulation, as further elucidated from the dynamics data. Plainly, molecular recognition of the protein-flavonols might noticeably cause relatively large changes in protein flexibility, and then manifest different recognition strengths and corresponding biological activities. This issue will be carefully validated by the interpretation of root-mean-square fluctuation.

Glucuronidation: driving factors and their impact on glucuronide disposition

Glucuronidation is a well-recognized phase II metabolic pathway for a variety of chemicals including drugs and endogenous substances. Although it is usually the secondary metabolic pathway for a compound preceded by phase I hydroxylation, glucuronidation alone could serve as the dominant metabolic pathway for many compounds, including some with high aqueous solubility. Glucuronidation involves the metabolism of parent compound by UDP-glucuronosyltransferases (UGTs) into hydrophilic and negatively charged glucuronides that cannot exit the cell without the aid of efflux transporters. Therefore, elimination of parent compound via glucuronidation in a metabolic active cell is controlled by two driving forces: the formation of glucuronides by UGT enzymes and the (polarized) excretion of these glucuronides by efflux transporters located on the cell surfaces in various drug disposition organs. Contrary to the common assumption that the glucuronides reaching the systemic circulation were destined for urinary excretion, recent evidences suggest that hepatocytes are capable of highly efficient biliary clearance of the gut-generated glucuronides. Furthermore, the biliary- and enteric-eliminated glucuronides participate into recycling schemes involving intestinal microbes, which often prolong their local and systemic exposure, albeit at low systemic concentrations. Taken together, these recent research advances indicate that although UGT determines the rate and extent of glucuronide generation, the efflux and uptake transporters determine the distribution of these glucuronides into blood and then to various organs for elimination. Recycling schemes impact the apparent plasma half-life of parent compounds and their glucuronides that reach intestinal lumen, in addition to prolonging their gut and colon exposure.

Rutin protects against aging-related metabolic dysfunction

Aging is a complex process which is accompanied by multiple related chronic diseases. Among them, metabolic dysfunction is one of the most important aging-related disorders. In the present study, we aimed to investigate the effect of rutin on aging-related metabolic dysfunction. We found that the increase of fasting blood glucose, insulin levels, blood pressure and HOMA-IR in aged rats was significantly inhibited by rutin. In addition, rutin improved glucose and insulin tolerance in aged rats, as reflected by decreased glucose level in IPGTT and IPITT test. Rutin treatment notably increased Akt and IRS-1 phosphorylation in the livers of old rats. The increase of inflammatory markers, such as IL-1β and TNFα, was prevented by the rutin administration. Moreover, in circulation and livers of old rats, rutin treatment significantly decreased the content of TG. Rutin also inhibited the increase of serum AST and ALT levels. Furthermore, rutin treatment markedly inhibited aging-related mitochondrial dysfunction, ER stress, and oxidative stress, as evidenced by increased oxygen consumption rate and activities of Na(+)/K(+)-ATPase and Ca2(+)-ATPase, decreased expression of ATF3 and GRP78, decreased level of MDA, increased content of GSH and enhanced activity of SOD in aged rats. We show that the administration of rutin could effectively improve aging-related metabolic dysfunction. The amelioration of inflammation, lipid accumulation, mitochondrial dysfunction, ER stress, and oxidative stress may be involved in the effect of rutin on aging-related metabolic dysfunction. These findings provide novel insights into the potential use of rutin in the intervention of aging and its related metabolic diseases.

The deleterious effect of cholesterol and protection by quercetin on mitochondrial bioenergetics of pancreatic β-cells, glycemic control and inflammation: In vitro and in vivo studies

Studying rats fed high cholesterol diet and a pancreatic β-cell line (Min6), we aimed to determine the mechanisms by which quercetin protects against cholesterol-induced pancreatic β-cell dysfunction and impairments in glycemic control. Quercetin prevented the increase in total plasma cholesterol, but only partially prevented the high cholesterol diet-induced alterations in lipid profile. Quercetin prevented cholesterol-induced decreases in pancreatic ATP levels and mitochondrial bioenergetic dysfunction in Min6 cells, including decreases in mitochondrial membrane potentials and coupling efficiency in the mitochondrial respiration (basal and maximal oxygen consumption rate (OCR), ATP-linked OCR and reserve capacity). Quercetin protected against cholesterol-induced apoptosis of Min6 cells by inhibiting caspase-3 and -9 activation and cytochrome c release. Quercetin prevented the cholesterol-induced decrease in antioxidant defence enzymes from pancreas (cytosolic and mitochondrial homogenates) and Min6 cells and the cholesterol-induced increase of cellular and mitochondrial oxidative status and lipid peroxidation. Quercetin counteracted the cholesterol-induced activation of the NFκB pathway in the pancreas and Min6 cells, normalizing the expression of pro-inflammatory cytokines. Quercetin inhibited the cholesterol-induced decrease in sirtuin 1 expression in the pancreas and pancreatic β-cells. Taken together, the anti-apoptotic, antioxidant and anti-inflammatory properties of quercetin, and its ability to protect and improve mitochondrial bioenergetic function are likely to contribute to its protective action against cholesterol-induced pancreatic β-cell dysfunction, thereby preserving glucose-stimulated insulin secretion (GSIS) and glycemic control. Specifically, the improvement of ATP-linked OCR and the reserve capacity are important mechanisms for protection of quercetin. In addition, the inhibition of the NFκB pathway is an important mechanism for the protection of quercetin against cytokine mediated cholesterol-induced glycemic control impairment. In summary, our data highlight cellular, molecular and bioenergetic mechanisms underlying quercetin's protective effects on β-cells in vitro and in vivo, and provide a scientifically tested foundation upon which quercetin can be developed as a nutraceutical to preserve β-cell function.

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Quercetin prevents the impairment in glycemic control induced by cholesterol.

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Quercetin prevents cholesterol-impaired insulin secretion in pancreatic β-cells.

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Quercetin improves mitochondrial bioenergetics impaired by cholesterol.

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Quercetin prevents the decrease in SIRT1 expression induced by cholesterol.

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Quercetin prevents NF-kB activation and prevents cholesterol-induced inflammation.

Intravenous rutin in rat exacerbates isoprenaline-induced cardiotoxicity likely due to intracellular oxidative stress

OBJECTIVES

Rutin, quercetin-3-O-rutinoside, a natural flavonol glycoside, has shown various in vitro benefits with potential use treating human diseases, especially cardiovascular system disorders. Antioxidant properties are assumed to underlie the majority of these benefits. Yet rutin pro-oxidant properties have been reported as well. Our research group has recently shown aggravating effects on isoprenaline (ISO)-induced cardiotoxicity in Wistar:Han rats after 24 hours.

METHODS

This study was designed to examine in more detail the reasons for the negative effects of rutin (11.5 and 46 mg/kg, i.v.) after administration of ISO (100 mg/kg, s.c.) in rats within 2 hours of continuous experiment and in the H9c2 cardiomyoblast-derived cell line.

RESULTS

Like our previous findings, rutin did not (11.5 or 46 mg/kg, i.v.) reduce the ISO-induced mortality within 2 hours although the lower dose significantly reduced cardiac troponin T (cTnT) and partly improved the histological findings. In contrast, the higher dose increased the mortality in comparison with solvent (1.26% w/v sodium bicarbonate). This was not caused by any specific haemodynamic disturbances. It appears to be associated with oxidative stress as rutin enhanced intracellular reactive oxygen species formation in vitro and had the tendency to increase it in vivo.

CONCLUSIONS

Rutin, likely due to its pro-oxidative effects, can exacerbate catecholamine cardiotoxicity depending on the dose used.

Estrogen modulation properties of mangiferin and quercetin and the mangiferin metabolite norathyriol

Mango fruit contain many bioactive compounds, some of which are transcription factor regulators. Estrogen receptor alpha (ERα) and beta (ERβ) are two regulators of gene transcription that are important in a variety of physiological processes and also in diseases including breast cancer. We examined the ability of the mango constituents quercetin, mangiferin, and the aglycone form of mangiferin, norathyriol, to activate both isoforms of the estrogen receptor. Quercetin and norathyriol decreased the viability of MCF-7 breast cancer cells whereas mangiferin had no effect on MCF-7 cells. We also determined that quercetin and mangiferin selectively activated ERα whereas norathyriol activated both ERα and ERβ. Despite quercetin, mangiferin and norathyriol having similar polyphenolic structural motifs, only norathyriol activated ERβ, showing that bioactive agents in mangoes have very specific biological effects. Such specificity may be important given the often-opposing roles of ERα and ERβ in breast cancer proliferation and other cellular processes.

Quercetin, Inflammation and Immunity

In vitro and some animal models have shown that quercetin, a polyphenol derived from plants, has a wide range of biological actions including anti-carcinogenic, anti-inflammatory and antiviral activities; as well as attenuating lipid peroxidation, platelet aggregation and capillary permeability. This review focuses on the physicochemical properties, dietary sources, absorption, bioavailability and metabolism of quercetin, especially main effects of quercetin on inflammation and immune function. According to the results obtained both in vitro and in vivo, good perspectives have been opened for quercetin. Nevertheless, further studies are needed to better characterize the mechanisms of action underlying the beneficial effects of quercetin on inflammation and immunity.

Rutin Increases Muscle Mitochondrial Biogenesis with AMPK Activation in High-Fat Diet-Induced Obese Rats

Decreased mitochondrial number and dysfunction in skeletal muscle are associated with obesity and the progression of obesity-associated metabolic disorders. The specific aim of the current study was to investigate the effects of rutin on mitochondrial biogenesis in skeletal muscle of high-fat diet-induced obese rats. Supplementation with rutin reduced body weight and adipose tissue mass, despite equivalent energy intake (p < 0.05). Rutin significantly increased mitochondrial size and mitochondrial DNA (mtDNA) content as well as gene expression related to mitochondrial biogenesis, such as peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), nuclear respiratory factor-1 (NRF-1), transcription factor A (Tfam), and nicotinamide adenine dinucleotide (NAD)-dependent deacetylase, sirtulin1 (SIRT1) in skeletal muscle (p < 0.05). Moreover, rutin consumption increased muscle adenosine monophosphate-activated protein kinase (AMPK) activity by 40% (p < 0.05). Taken together, these results suggested at least partial involvement of muscle mitochondria and AMPK activation in the rutin-mediated beneficial effect on obesity.

Effect of dietary supplementation of rutin on lactation performance, ruminal fermentation and metabolism in dairy cows

The effect of long-term dietary supplementation with rutin on the lactation performance, ruminal fermentation and metabolism of dairy cows were investigated in this study. Twenty multiparous Chinese Holstein cows were randomly divided into four groups, and each was offered a basal diet supplemented with 0, 1.5, 3.0 or 4.5 mg rutin/kg of diet. The milk yield of the cows receiving 3.0 and 4.5 mg rutin/kg was higher than that of the control group, and the milk yield was increased by 10.06% and 3.37% (p < 0.05). On the basis of that finding, the cows supplemented with 0 or 3.0 mg rutin/kg of diet were used to investigate the effect of rutin supplementation on blood metabolites and hormone levels. Compared with the control group, the serum blood urea nitrogen (BUN) concentration of the 3.0 mg rutin/kg group is significantly decreased (p < 0.05). In another trial, four adult cows with permanent rumen fistula and duodenal cannulae were attributed in a self-control design to investigate the peak occurrence of rutin and quercetin in different parts of the gastrointestinal tract, ruminal fermentation and microbial population in dairy cows. The cows supplemented with 3.0 mg rutin/kg in the diet differed from the control period. Samples of rumen fluid, duodenal fluid and blood were collected at 1, 2, 3, 4, 5, 6, 7 and 8 h after morning feeding. Compared to the control group, the pH, ammonia nitrogen concentration, number and protein content of rumen protozoa and blood urea nitrogen were lower, but the concentration of total volatile fatty acid (TVFA), microbial crude protein (MCP) and serum lysozyme content were higher for the cows fed the rutin diets. The addition of 3.0 mg rutin/kg to diets for a long term tended to increase the milk yield and improve the metabolism and digestibility of the dairy cows.

MK571 inhibits phase-2 conjugation of flavonols by Caco-2/TC7 cells, but does not specifically inhibit their apical efflux

MK571 is a multidrug resistance protein-2 (ABCC2, Mrp2) inhibitor and has been widely used to demonstrate the role of Mrp2 in the cellular efflux of drugs, xenobiotics and their conjugates. Numerous reports have described modulation of Caco-2 cellular efflux and transport of flavonoids in the presence of MK571. Since flavonoids are efficiently conjugated by Caco-2/TC7 cells, we investigated the effects of MK571 on the efflux of flavonoid conjugates. The flavonol aglycones kaempferol, quercetin and galangin were efficiently taken up, conjugated and effluxed by Caco-2/TC7 cells. Apically-applied MK571 caused significant reductions in both the apical and basolateral efflux of flavonol conjugates from Caco-2/TC7 monolayers. MK571 did not significantly alter the apical:basolateral efflux ratio for flavonol conjugates, however, which is not consistent with MK571 specifically inhibiting only apical Mrp2. Since MK571 decreased the total amounts of conjugates formed, and increased cellular flavonol aglycone concentrations, we explored the possibility that MK571 also inhibits phase-2 conjugation of flavonols. MK571 dose-dependently inhibited the intracellular biosynthesis of all flavonol glucuronides and sulphates by Caco-2 cells. MK571 significantly inhibited phase-2 conjugation of kaempferol by cell-free extracts of Caco-2, and production of kaempferol-4′-O-glucuronide was competitively inhibited. These data show that MK571, in addition to inhibiting MRP2, is a potential inhibitor of enterocyte phase-2 conjugation.

Review of the protective effects of rutin on the metabolic function as an important dietary flavonoid

BACKGROUND

In recent years, flavonoids have been revealed to be helpful in the treatment of many diseases. Rutin (3,3',4',5,7-pentahydroxyflavone-3-rhamnoglucoside) is an important flavonoid that is consumed in the daily diet. It is also known as vitamin P and quercetin-3-O-rutinoside. In addition, it is found in many food items, vegetables, and beverages. The cytoprotective effects of rutin, including gastroprotective, hepatoprotective, and anti-diabetic effects, have been shown in several studies. Furthermore, rutin has several pharmacological effects such as anti-inflammatory and anti-glycation activities.

AIM

This work reviewed characteristic, pharmacokinetic, and metabolic effects of rutin in all experimental and human studies.

CONCLUSIONS

Based on the above summarized effects of rutin, this flavonoid appears to be a potent component that could be considered in the treatment of several gastrointestinal diseases and diabetes.

Quantitative analysis of vasodilatory action of quercetin on intramural coronary resistance arteries of the rat in vitro

Background

Dietary quercetin improves cardiovascular health, relaxes some vascular smooth muscle and has been demonstrated to serve as a substrate for the cyclooxygenase enzyme.

Aims

1. To test quantitatively a potential direct vasodilatory effect on intramural coronary resistance artery segments, in different concentrations. 2. To scale vasorelaxation at different intraluminal pressure loads on such vessels of different size. 3. To test the potential role of prostanoids in vasodilatation induced by quercetin.

Methods

Coronary arterioles (70–240 µm) were prepared from 24 rats and pressurized in PSS, using a pressure microangiometer.

Results

The spontaneous tone that developed at 50 mmHg was relaxed by quercetin in the 10⁻⁹ moles/lit concentration (p<0.05), while 10⁻⁵ moles/lit caused full relaxation. Significant relaxation was observed at all pressure levels (10–100 mmHg) at 10⁻⁷ moles/lit concentration of quercetin. The cyclooxygenase blocker indomethacin (10⁻⁵moles/lit) induced no relaxation but contraction when physiological concentrations of quercetin were present in the tissue bath (p<0.02 with Anova), this contraction being more prominent in smaller vessels and in the higher pressure range (p<0.05, Pearson correlation). A further 2–8% contraction could be elicited by the NO blocker L-NAME (10⁻⁴ moles/lit).

Conclusion

These results demonstrate that circulating levels of quercetin (10⁻⁷ moles/lit) exhibit a substantial coronary vasodilatory effect. The extent of it is commeasurable with that of several other physiological mechanisms of coronary blood flow control. At least part of this relaxation is the result of an altered balance toward the production of endogenous vasodilatory prostanoids in the coronary arteriole wall.

A Soluble Flavonoid-glycoside, αG-Rutin, Is Absorbed as Glycosides in the Isolated Gastric and Intestinal Mucosa

We investigated the absorption and metabolism of the highly soluble quercetin glycoside alphaG-rutin, a glucose adduct of insoluble rutin, using the isolated mucosa of the rat stomach and intestines equipped with the Ussing chamber. alphaG-rutin and rutin appeared in the serosal sides of the gastric body and all the intestinal mucosa after the addition of alphaG-rutin (1 mM) to the mucosal fluid. The degree of alphaG-rutin appearance was much lower in the gastric fundus than in the other parts. Quercetin was not found in the mucosal fluid of any mucosal specimen. The concentrations (microM) of alphaG-rutin and rutin in the serosal fluid as a result of transport from the mucosal side increased time-dependently and linearly with mucosal alphaG-rutin concentration (1, 10 or 100 mM). The highest transport was shown in the ileal mucosa. These results indicate that alphaG-rutin is partly hydrolyzed to rutin through the intestine and absorbed as such.

Salivary α-amylase, serum albumin, and myoglobin protect against DNA-damaging activities of ingested dietary agents in vitro

Potent DNA-damaging activities were seen in vitro from dietary chemicals found in coffee, tea, and liquid smoke. A survey of tea varieties confirmed genotoxic activity to be widespread. Constituent pyrogallol-like polyphenols (PLPs) such as epigallocatechin-3-gallate (EGCG), pyrogallol, and gallic acid were proposed as a major source of DNA-damaging activities, inducing DNA double-strand breaks in the p53R assay, a well characterized assay sensitive to DNA strand breaks, and comet assay. Paradoxically, their consumption does not lead to the kind of widespread cellular toxicity and acute disease that might be expected from genotoxic exposure. Existing physiological mechanisms could limit DNA damage from dietary injurants. Serum albumin and salivary α-amylase are known to bind EGCG. Salivary α-amylase, serum albumin, and myoglobin, but not salivary proline-rich proteins, reduced damage from tea, coffee, and PLPs, but did not inhibit damage from the chemotherapeutics etoposide and camptothecin. This represents a novel function for saliva in addition to its known functions including protection against tannins. Cell populations administered repeated pyrogallol exposures had abatement of measured DNA damage by two weeks, indicating an innate cellular adaptation. We suggest that layers of physiological protections may exist toward natural dietary products to which animals have had high-level exposure over evolution.

Dietary factors affecting polyphenol bioavailability

While many epidemiological studies have associated the consumption of polyphenols within fruits and vegetables with a decreased risk of developing several chronic diseases, intervention studies have generally not confirmed these beneficial effects. The reasons for this discrepancy are not fully understood but include potential differences in dosing, interaction with the food matrix, and differences in polyphenol bioavailability. In addition to endogenous factors such as microbiota and digestive enzymes, the food matrix can also considerably affect bioaccessibility, uptake, and further metabolism of polyphenols. While dietary fiber (such as hemicellulose), divalent minerals, and viscous and protein-rich meals are likely to cause detrimental effects on polyphenol bioaccessibility, digestible carbohydrates, dietary lipids (especially for hydrophobic polyphenols, e.g., curcumin), and additional antioxidants may enhance polyphenol availability. Following epithelial uptake, polyphenols such as flavonoids may reduce phase II metabolism and excretion, enhancing polyphenol bioavailability. Furthermore, polyphenols may act synergistically due to their influence on efflux transporters such as p-glycoprotein. In order to understand polyphenol bioactivity, increased knowledge of the factors affecting polyphenol bioavailability, including dietary factors, is paramount.

Berry antioxidants: small fruits providing large benefits

Small berry fruits are consumed because of their attractive colour and special taste, and are considered one of the richest sources of natural antioxidants. Their consumption has been linked to the prevention of some chronic and degenerative diseases. The term 'berry fruits' encompasses the so-called 'soft fruits', primarily strawberry, currants, gooseberry, blackberry, raspberry, blueberry and cranberry. The objective of this review is to highlight the nutraceutical value of berries and to summarize the factors affecting berry fruit antioxidants. Particular attention is given to postharvest and processing operation factors that may affect fruit phytochemical content. The structure-antioxidant relationships for phenolic compounds - the main group of antioxidants in this fruit group - are presented and major areas for future research are identified.

A review on plant-based rutin extraction methods and its pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Rutin is a common dietary flavonoid that is widely consumed from plant-derived beverages and foods as traditional and folkloric medicine worldwide. Rutin is believed to exhibit significant pharmacological activities, including anti-oxidation, anti-inflammation, anti-diabetic, anti-adipogenic, neuroprotective and hormone therapy. Till date, over 130 registered therapeutic medicinal preparations are containing rutin in their formulations. This article aims to critically review the extraction methods for plant-based rutin and its pharmacological activities. This review provides comprehensive data on the performance of rutin extraction methods and the extent of its pharmacological activities using various in vitro and in vivo experimental models.

MATERIALS AND METHODS

Literatures including journals, patents, books and leaflets reporting on rutin from natural resources are systematically reviewed, particularly in the aspect of its extraction methods and biological activities. Factors affecting the efficiency of rutin extraction such as extraction temperature, duration and solvent to sample ratio are presented based on the findings of previous studies. The observed biological activities followed by clear explanation are also provided accordingly.

RESULTS

The biological activities of rutin varied largely dependent on the geographical and plant origins. The complexity of natural rutin has impeded the development of rutin derived drugs. The detail mechanism of rutin in human body after consumption is still unclear. Therefore, studies are intensively carried out both in vitro and in vivo for the better understanding of the underlying mechanism. The studies are not limited to the pharmacological properties, but also on the extraction methods of rutin. Many studies have focused on the optimization of extraction method to increase the extraction yield of rutin. Currently, the performances of modern extraction approaches have also been compared to the conventional heat reflux method as a benchmark.

CONCLUSION

There are various extraction methods for plant-based rutin ranging from conventional method up to the use of modern techniques such as ultrasound, mechanochemical, microwave, infrared and pressurized assisted methods. However, proper comparison between the methods is very difficult because of the variance in plant origin and extraction conditions. It is important to optimize the extraction method in order to produce high yield and acceptable purity of rutin with a reasonable cost. Even though rutin has been proven to be effective in numerous pharmacological activities, the dosage and toxicity of rutin for such activities are still unknown. Future research should relate the dosage and toxicity of rutin for the ethnobotanical claims based on the underlying mechanisms.