In vitro inhibition of human CYP2E1 and CYP3A by quercetin and myricetin in hepatic microsomes is not gender dependent

Quercetin inhibits the metabolism of arachidonic acid by inhibiting the activity of CYP3A4, thereby inhibiting the progression of breast cancer

BACKGROUND

Recent years have witnessed impressive growth in applying natural medicine in tumor treatment. Saffron is reported to elicit an inhibitory property against BC. Herein, we sought to explore the specific components and mechanistic basis of saffron's anti-breast carcinoma (BC) function.

METHODS

Bioinformatics analysis was employed to analyze saffron components' anti-BC activity and screen the corresponding target genes involved in BC. Then, the roles of the main saffron ingredient quercetin in the activity of BC cells were examined using CCK-8, MTS, flow cytometry, colony formation, Transwell, and Gelatin zymogram assays. Additionally, the interactions among Quercetin, EET, and Stat3 were assessed by immunofluorescence and Western blot, and LC-MS/MS determined the levels of AA, EETs, and CYP3A. Finally, BC xenograft mouse models were established to verify the anti-BC function of Quercetin in vivo.

RESULTS

Quercetin, the main active component of saffron, inhibited BC progression. Quercetin suppressed BC cell growth, migration, and invasion and inhibited CYP3A4 expression and activity in BC. Mechanistically, Quercetin down-regulated CYP3A4 to block the nuclear translocation of Stat3 by decreasing the metabolization of AA to EETs, thereby alleviating BC. Moreover, exogenously added EETs counteracted the anti-tumor effect of Quercetin on BC. Quercetin also inhibited the tumor growth of tumor-bearing nude mice.

CONCLUSION

Quercetin could inhibit the activity of CYP3A to down-regulate AA metabolites EETs, consequently hampering p-Stat3 and nuclear translocation, thus impeding BC development.

Biological Activities and Polyphenol Content of Qi Cha Tea®, a Functional Beverage of White Tea Containing Botanicals and Dry Botanical Extracts with European Health Claims

Infusions of Camellia sinensis leaves have been known for their health benefits. The Bio Concentrate Assets® (ABC) method is a method of enriching organic infusion leaves (from Camellia sinensis) with organic dry and concentrated extracts using organic acacia gum, and its application to white tea has provided Qi cha tea®. In the present study, the content of tea polyphenols and caffeine, and the biochemical properties of Qi cha tea® and its botanical constituents (elderberry, tulsi, Echinacea purpurea, orange peel, lemongrass, and acacia gum) were assessed. Antioxidant and cell viability activities were determined by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay and MTT (3-(4, 5-dimethyl thiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay in human Caco-2 and HCT-116 cell lines, and ascorbic acid and tamoxifen, respectively. The caffeine and polyphenol composition of Qi cha tea® was modified with less caffeine and gallic acid and more epigallocatechin gallate (EGCG) than the original white tea. The majority of the tested botanical samples including Qi cha tea® at 50 µg/mL show similar antioxidant activities, with the exception of Echinacea purpurea. The greatest effect was found for white tea. The antioxidant power of the Qi cha tea® (90% at 50 µg/mL for pressurized liquid extraction (PLE) was divided by approximately a factor of two (61% at 50 µg/mL for pressurized liquid extraction products (PLEP)), which corresponds to the 48.3% (mass/mass) white tea original content in the Qi cha tea®. Qi cha tea® shows the lowest cytotoxic activity in the viability of the two cell lines when compared to white tea. The application of the ABC method to Qi cha tea® using various botanicals and dry extract with acacia gum as blinder has allowed the development of a new innovative functional health beverage that complies with European health claims.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Curcumin and quercetin modify warfarin-induced regulation of porcine CYP1A2 and CYP3A expression and activity in vitro

The anticoagulant drug warfarin is used treat atrial fibrillation. Several cases of drug-drug and drug-food interactions has been reported for warfarin.The aim of the current study, were to investigate the interaction between simultaneous administration of warfarin with the two ubiquitous flavonoids quercetin and curcumin.Using porcine primary hepatocytes we demonstrated that warfarin treatment increased the mRNA and protein expression of CYP3A(29), while no changes in CYP1A2 were observed. Co-treatment with quercetin and/or curcumin decreased the warfarin induced CYP3A protein expression. Moreover, when quercetin and curcumin were co-administrated to warfarin-exposed hepatocytes the protein expression of CYP1A2 were decreased. In hepatic microsomes, curcumin inhibited the activity of both CYP1A2 and CYP3A, while warfarin had no effect. Both quercetin and curcumin decreased the CYP1A2 and CYP3A activity when co-administrated with warfarin.The results clearly demonstrated that quercetin and curcumin can cause food-drug interactions with warfarin, and that the cocktail effect of exposure to more compounds than one can further enhance these interactions.

Crosstalk between CYP2E1 and PPARα substrates and agonists modulate adipose browning and obesity

Although the functions of metabolic enzymes and nuclear receptors in controlling physiological homeostasis have been established, their crosstalk in modulating metabolic disease has not been explored. Genetic ablation of the xenobiotic-metabolizing cytochrome P450 enzyme CYP2E1 in mice markedly induced adipose browning and increased energy expenditure to improve obesity. CYP2E1 deficiency activated the expression of hepatic peroxisome proliferator-activated receptor alpha (PPARα) target genes, including fibroblast growth factor (FGF) 21, that upon release from the liver, enhanced adipose browning and energy expenditure to decrease obesity. Nineteen metabolites were increased in Cyp2e1-null mice as revealed by global untargeted metabolomics, among which four compounds, lysophosphatidylcholine and three polyunsaturated fatty acids were found to be directly metabolized by CYP2E1 and to serve as PPARα agonists, thus explaining how CYP2E1 deficiency causes hepatic PPARα activation through increasing cellular levels of endogenous PPARα agonists. Translationally, a CYP2E1 inhibitor was found to activate the PPARα–FGF21–beige adipose axis and decrease obesity in wild-type mice, but not in liver-specific Ppara-null mice. The present results establish a metabolic crosstalk between PPARα and CYP2E1 that supports the potential for a novel anti-obesity strategy of activating adipose tissue browning by targeting the CYP2E1 to modulate endogenous metabolites beyond its canonical role in xenobiotic-metabolism.

Effect of Myricetin on CYP2C8 Inhibition to Assess the Likelihood of Drug Interaction Using In Silico, In Vitro, and In Vivo Approaches

Myricetin, a bioflavonoid, is widely used as functional food/complementary medicine and has promising multifaceted pharmacological actions against therapeutically validated anticancer targets. On the other hand, CYP2C8 is not only crucial for alteration in the pharmacokinetics of drugs to cause drug interaction but also unequivocally important for the metabolism of endogenous substances like the formation of epoxyeicosatrienoic acids (EETs), which are considered as signaling molecules against hallmarks of cancer. However, there is hardly any information known to date about the effect of myricetin on CYP2C8 inhibition and, subsequently, the CYP2C8-mediated drug interaction potential of myricetin at the preclinical/clinical level. We aimed here to explore the CYP2C8 inhibitory potential of myricetin using in silico, in vitro, and in vivo investigations. In the in vitro study, myricetin showed a substantial effect on CYP2C8 inhibition in human liver microsomes using CYP2C8-catalyzed amodiaquine-N-deethylation as an index reaction. Considering the Lineweaver-Burk plot, the Dixon plot, and the higher α-value, myricetin is found to be a mixed type of CYP2C8 inhibitor. Moreover, in vitro-in vivo extrapolation data suggest that myricetin is likely to cause drug interaction at the hepatic level. The molecular docking study depicted a strong interaction between myricetin and the active site of the human CYP2C8 enzyme. Moreover, myricetin caused considerable elevation in the oral exposure of amodiaquine as a CYP2C8 substrate via a slowdown of amodiaquine clearance in the rat model. Overall, the potent action of myricetin on CYP2C8 inhibition indicates that there is a need for further exploration to avoid drug interaction-mediated precipitation of obvious adverse effects as well as to optimize anticancer therapy.

Negligible Effect of Quercetin in the Pharmacokinetics of Sulfasalazine in Rats and Beagles: Metabolic Inactivation of the Interaction Potential of Quercetin with BCRP

Breast cancer resistance protein (BCRP) mediates pharmacokinetic drug interactions. This study evaluated the potential of quercetin to inhibit and induce BCRP in vitro and in vivo. The inhibition of BCRP was investigated for quercetin and its metabolites using BCRP/mBcrp1-overexpressing MDCKII cells by flow cytometry. The induction of BCRP was investigated in LS174T cells using quantitative PCR. The expression of rat BCRP in rat small intestine, liver, and kidney was also measured after multiple administrations of quercetin in rats (50, 100, and 250 mg/kg, seven days). The in vivo pharmacokinetic changes of sulfasalazine following single or multiple administration of quercetin in rats and beagles were investigated. Although the induction effect of quercetin on BCRP was observed in vitro, the in vivo expression of rat BCRP was not changed by multiple quercetin administrations. Oral administration of quercetin did not affect the plasma concentration or pharmacokinetic parameters of sulfasalazine, regardless of dose and dosing period in either rats or beagles. In addition, the inhibitory effect of quercetin metabolites on BCRP/mBcrp1 was not observed. These results suggest that the in vivo drug interaction caused by quercetin via BCRP was negligible, and it may be related to the metabolic inactivation of quercetin for the inhibition of BCRP.

Quercetin attenuated the Benzene-induced hemato- and hepatotoxicity in mice

The protective effects of Quercetin (QCN) on Benzene (BNZ)-induced hemato- and hepatotoxicy were investigated. To reach this goal, 36 adult male mice were divided into 6 groups (n = 6). The control group was not exposed to BNZ, while animals in BNZ group were exposed to BNZ (30 ppm) and the animals of QCN group were received QCN (50 mg/kg, orally), the fourth, fifth and sixth groups were exposed to 30 ppm BNZ and received 10, 50 and 100 mg/kg QCN one h before the BNZ exposure, for 28 days. The day after the last exposure following anesthesia and the blood collection, the liver and femur tissues were collected. The bone marrow samples were extracted and subjected to micronucleus assay. The blood samples were processed for hematological and biochemical analyses. Histopathological examinations were performed on the liver samples. QCN reduced significantly (p < 0.05) the BNZ-elevated hepatic enzymes and ameliorated the BNZ-induced WBC and RBC reduction. The BNZ-elevated micronucleus percentage both in the bone marrow and peripheral blood was remarkably declined in the QCN-received groups. QCN improved the BNZ-induced histopathological changes and oxidative status in the liver and serum. Our results suggest that QCN could be a protective supplement to reduce the BNZ-induced hemato- and hepatotoxicities.

Assessment of Metabolic Interaction between Repaglinide and Quercetin via Mixed Inhibition in the Liver: In Vitro and In Vivo

Repaglinide (RPG), a rapid-acting meglitinide analog, is an oral hypoglycemic agent for patients with type 2 diabetes mellitus. Quercetin (QCT) is a well-known antioxidant and antidiabetic flavonoid that has been used as an important ingredient in many functional foods and complementary medicines. This study aimed to comprehensively investigate the effects of QCT on the metabolism of RPG and its underlying mechanisms. The mean (range) IC₅₀ of QCT on the microsomal metabolism of RPG was estimated to be 16.7 (13.0–18.6) μM in the rat liver microsome (RLM) and 3.0 (1.53–5.44) μM in the human liver microsome (HLM). The type of inhibition exhibited by QCT on RPG metabolism was determined to be a mixed inhibition with a K_i of 72.0 μM in RLM and 24.2 μM in HLM as obtained through relevant graphical and enzyme inhibition model-based analyses. Furthermore, the area under the plasma concentration versus time curve (AUC) and peak plasma concentration (C_max) of RPG administered intravenously and orally in rats were significantly increased by 1.83- and 1.88-fold, respectively, after concurrent administration with QCT. As the protein binding and blood distribution of RPG were observed to be unaltered by QCT, it is plausible that the hepatic first-pass and systemic metabolism of RPG could have been inhibited by QCT, resulting in the increased systemic exposure (AUC and C_max) of RPG. These results suggest that there is a possibility that clinically significant pharmacokinetic interactions between QCT and RPG could occur, depending on the extent and duration of QCT intake from foods and dietary supplements.

Mango (Mangifera indica L.) Polyphenols: Anti-Inflammatory Intestinal Microbial Health Benefits, and Associated Mechanisms of Actions

Mango is rich in polyphenols including gallotannins and gallic acid, among others. The bioavailability of mango polyphenols, especially polymeric gallotannins, is largely dependent on the intestinal microbiota, where the generation of absorbable metabolites depends on microbial enzymes. Mango polyphenols can favorably modulate bacteria associated with the production of bioactive gallotannin metabolites including Lactobacillus plantarum, resulting in intestinal health benefits. In several studies, the prebiotic effects of mango polyphenols and dietary fiber, their potential contribution to lower intestinal inflammation and promotion of intestinal integrity have been demonstrated. Additionally, polyphenols occurring in mango have some potential to interact with intestinal and less likely with hepatic enzymes or transporter systems. This review provides an overview of interactions of mango polyphenols with the intestinal microbiome, associated health benefits and underlying mechanisms.

Insights into oral bioavailability enhancement of therapeutic herbal constituents by cytochrome P450 3A inhibition

Herbal plants typically have complex compositions and diverse mechanisms. Among them, bioactive constituents with relatively high exposure in vivo are likely to exhibit therapeutic efficacy. On the other hand, their bioavailability may be influenced by the synergistic effects of different bioactive components. Cytochrome P450 3A (CYP3A) is one of the most abundant CYP enzymes, responsible for the metabolism of 50% of approved drugs. In recent years, many therapeutic herbal constituents have been identified as CYP3A substrates. It is more evident that CYP3A inhibition derived from the herbal formula plays a critical role in improving the oral bioavailability of therapeutic constituents. CYP3A inhibition may be the mechanism of the synergism of herbal formula. In this review, we explored the multiplicity of CYP3A, summarized herbal monomers with CYP3A inhibitory effects, and evaluated herb-mediated CYP3A inhibition, thereby providing new insights into the mechanisms of CYP3A inhibition-mediated oral herb bioavailability.

Berry-Derived Polyphenols in Cardiovascular Pathologies: Mechanisms of Disease and the Role of Diet and Sex

Cardiovascular disease (CVD) prevalence, pathogenesis, and manifestation is differentially influenced by biological sex. Berry polyphenols target several signaling pathways pertinent to CVD development, including inflammation, oxidative stress, and cardiac and vascular remodeling, and there are innate differences in these pathways that also vary by sex. There is limited research systematically investigating sex differences in berry polyphenol effects on these pathways, but there are fundamental findings at this time that suggest a sex-specific effect. This review will detail mechanisms within these pathological pathways, how they differ by sex, and how they may be individually targeted by berry polyphenols in a sex-specific manner. Because of the substantial polyphenolic profile of berries, berry consumption represents a promising interventional tool in the treatment and prevention of CVD in both sexes, but the mechanisms in which they function within each sex may vary.

Inhibitory Effects of Quercetin and Its Main Methyl, Sulfate, and Glucuronic Acid Conjugates on Cytochrome P450 Enzymes, and on OATP, BCRP and MRP2 Transporters

Quercetin is a flavonoid, its glycosides and aglycone are found in significant amounts in several plants and dietary supplements. Because of the high presystemic biotransformation of quercetin, mainly its conjugates appear in circulation. As has been reported in previous studies, quercetin can interact with several proteins of pharmacokinetic importance. However, the interactions of its metabolites with biotransformation enzymes and drug transporters have barely been examined. In this study, the inhibitory effects of quercetin and its most relevant methyl, sulfate, and glucuronide metabolites were tested on cytochrome P450 (CYP) (2C19, 3A4, and 2D6) enzymes as well as on organic anion-transporting polypeptides (OATPs) (OATP1A2, OATP1B1, OATP1B3, and OATP2B1) and ATP (adenosine triphosphate) Binding Cassette (ABC) (BCRP and MRP2) transporters. Quercetin and its metabolites (quercetin-3'-sulfate, quercetin-3-glucuronide, isorhamnetin, and isorhamnetin-3-glucuronide) showed weak inhibitory effects on CYP2C19 and 3A4, while they did not affect CYP2D6 activity. Some of the flavonoids caused weak inhibition of OATP1A2 and MRP2. However, most of the compounds tested proved to be strong inhibitors of OATP1B1, OATP1B3, OATP2B1, and BCRP. Our data demonstrate that not only quercetin but some of its conjugates, can also interact with CYP enzymes and drug transporters. Therefore, high intake of quercetin may interfere with the pharmacokinetics of drugs.

Reviewing the mechanisms of natural product-drug interactions involving efflux transporters and metabolic enzymes

The World Health Organization (WHO) and other worldwide health agencies have recently taken initiatives to encourage the use of traditional medicine and/or complementary/alternative medicine in order to promote well-being and public health. In this way, one of the WHO's concerns is the safe use of these therapies. Phytotherapy is a strategy consisting of the use of medicinal plants (MP) and/or herbal medicinal products (HMP) for medicinal purposes. The use of phytotherapy concomitantly with drugs may cause interactions compromising the expected pharmacological action or generating toxic effects. These interactions are complex processes that may occur with multiple medications targeting different metabolic pathways, and involving different compounds present in MP and HMP. Thus, the aim of this review was to summarize the main MP- and HMP-drug interactions that involve specific transporters (P-glycoprotein and BCRP) and CYP450 enzymes (CYP3A4 and CYP2D6), which play relevant roles in the mechanisms of interactions. Firstly, multiple databases were used to search studies describing in vitro or in vivo MP and HMP-drug interactions and, after that, a systematic note-taking and appraisal of the literature was conducted. It was observed that several MP and HMP, metabolic pathways and transcription factors are involved in the transporters and enzymes expression or in the modulation of their activity having the potential to provide such interactions. Thus, the knowledge of MP- and HMP-drug interaction mechanisms could contribute to prevent harmful interactions and can ensure the safe use of these products to help the establishment of the therapeutic planning in order to certify the best treatment strategy to be used.

Anti-tumor Effect of Quercetin Loaded Chitosan Nanoparticles on Induced Colon Cancer in Wistar Rats

Purpose: This study was aimed to evaluate the site-specific drug delivery of 5-FU with chitosan (CS) as a carrier and quercetin (Qu) against induced colon cancer in Wistar rats. Methods: Cross-linked CS-Qu nanoparticles (NPs) were prepared by ionotropic gelation method. Physicochemical characterization of NPs was performed by Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), in vitro drug release, and drug loading efficiency (LE). 1, 2-Dimethylhydrazine (DMH) and dextran sulfate sodium (DSS) were applied to induce adenocarcinoma tumors on inbred male Wistar rats' colon. The treatment group of rats was administered through enema with NPs dispersion. Hematoxylin and eosin staining were performed to the histopathological examination of tumors. Results: Zeta potential and particle size for NPs were +53.5 ± 5 mV and 179 ± 28 nm, respectively. About 96% Qu LE was obtained with a maximum release of 5.63 ±1.59% and 4.62 ± 1.33% after 24 hours in PB solution with pH values of 6 and 7.4, respectively. The numbers of 8 to 21 tumors were observed in all rats administered with DMH and DSS. Significantly decreasing of microvascular density and mitosis count was detected in the treatment group in comparison with cancerous group (P = 0.032 for the former compared to P = 0.016 for the later), respectively. Furthermore, the treatment group showed a high apoptosis rate (P = 0.038). Conclusion: The developed Qu-loaded CS NPs were good candidates for site-specific and sustained drug release in enema treatment. Decreasing of microvascular density and mitosis count, along with increasing the apoptosis percent in the treatment group proved that the NPs could have promising results in site-specific and sustained drug delivery against colorectal cancer.

Fluorescence Spectroscopic Investigation of Competitive Interactions between Quercetin and Aflatoxin B₁ for Binding to Human Serum Albumin

Aflatoxin B₁ (AFB₁) is a highly toxic mycotoxin found worldwide in cereals, food, and animal feeds. AFB₁ binds to human serum albumin (HSA) with high affinity. In previous experiments, it has been revealed that reducing the binding rate of AFB₁ with HSA could speed up the elimination rate of AFB₁. Therefore, we examined the ability of quercetin to compete with AFB₁ for binding HSA by fluorescence spectroscopy, synchronous spectroscopy, ultrafiltration studies, etc. It was shown that AFB₁ and quercetin bind to HSA in the same Sudlow site Ӏ (subdomain IIA), and the binding constant (K_a) of the quercetin-HSA complex is significantly stronger than the complex of AFB₁-HSA. Our data in this experiment showed that quercetin is able to remove the AFB₁ from HSA and reduce its bound fraction. This exploratory work may be of significance for studies in the future regarding decreasing its bound fraction and then increasing its elimination rate for detoxification. This exploratory study may initiate future epidemiological research designs to obtain further in vivo evidence of the long-term (potential protective) effects of competing substances on human patients.

Modulations of bovine hepatic microsomal metabolism of benzimidazoles by secondary plant metabolites

The study was aimed to estimate the effect of plant secondary metabolites present in ruminants diet and phytogenic feed additives on liver microsomal metabolism of albendazole and fenbendazole. The selected phytocompounds comprised of flavonoids (apigenin, quercetin) and saponins (hederagenin, medicagenic acid). The experiments were performed on liver microsomal fraction obtained from routinely slaughtered cows. The intensity of albendazole and fenbendazole metabolism in the presence of flavonoids and saponins was analyzed in equimolar concentration (100 μM). The obtained results revealed that both flavonoids and saponins intensify the metabolism of albendazole and fenbendazole in bovine microsomes. In the case of albendazole, apigenin and quercetin doubled the amount of degraded drug and the amount of produced albendazole sulfoxide. Additionally, both flavonoids increased the amount of produced albendazole sulfone. Saponins, hederagenin, and medicagenic acid intensified the degradation of albendazole (1.8-fold) and the production of albendazole sulfoxide (twofold). Medicagenic acid inhibited the production of albendazole sulfone. In the case of fenbendazole, the degradation of the drug and the production of oxfendazole were increased four and five times in the presence of saponins and flavonoids, respectively. The enhancement of benzimidazoles' metabolism caused by the studied plant metabolites could change pharmacokinetics and the efficacy of benzimidazoles' treatment in cattle.

Porcine cytochrome 2A19 and 2E1

Cytochrome P450 (CYP) is a major group of enzymes, which conduct Phase I metabolism. Among commonly used animal models, the pig has been suggested as the most suitable model for investigating drug metabolism in human beings. Moreover, porcine CYP2A19 and CYP2E1 are responsible for the biotransformation of both endogenous and exogenous compounds such as 3‐methylindole (skatole), sex hormones and food compounds. However, little is known about the regulation of porcine CYP2A19 and CYP2E1. In this MiniReview, we summarise the current knowledge about the regulation of porcine CYP2A19 and CYP2E1 by environmental, biological and dietary factors. Finally, we reflect on the need for further research, to clarify the interaction between active feed components and the porcine CYP system.

Joint toxicity on hepatic detoxication enzymes in goldfish (Carassius auratus) exposed to binary mixtures of lead and paraquat

Compared to single exposure, chemical mixtures might induce joint toxicity including additive, synergistic and antagonistic effects on both organisms and environment. Owing to the specific toxicity of oxidative stress and binding to proteins, lead (Pb) is generally recognized a non-essential and threatening heavy metal to animals and human. Paraquat (PQ) is a widely used herbicide in agriculture and can trigger oxidative stress as well as Pb. Little information was available about joint effects of the two chemicals on toxicological responses in organisms, especially in fish. In our present study, goldfish (Carassius auratus) were randomly exposed to single and combined experiments with different concentrations of Pb and PQ for 28 days. Activities of four enzyme biomarkers in liver, ethoxyresorufin-O-deethylase (EROD), 7-benzyloxy-4-trifluoromethyl-coumarin-O-debenzyloxylase (BFCOD), glutathione-S-transferase (GST) and UDP-glucuronosyltransferase (UGT) were evaluated in each experimental group on day 14 and 28. The results showed four enzyme levels were markedly reduced with the increase of concentrations in mixtures and prolonged exposure. The inhibitory EROD and BFCOD activities were not significantly changed in goldfish following PQ-treated groups with or without 0.5 mg/L Pb, which indicated PQ has more inhibitory toxicity on CYP450 enzymes than Pb in co-exposure groups. However, the reduced values of GST were observed only in the combinations containing high doses of Pb or PQ during experimental periods. Although the responses of UGT activity were similar to GST on 14th day, all combinations of Pb and PQ generated stronger inhibitions on UGT activities compared to individual Pb and PQ-treated group. These results suggested that combined exposure of Pb and PQ have more inhibitory toxicity on phase I enzymes than phase II enzymes.

Put "gender glasses" on the effects of phenolic compounds on cardiovascular function and diseases

INTRODUCTION

The influence of sex and gender is particularly relevant in cardiovascular diseases (CVD) as well as in several aspects of drug pharmacodynamics and pharmacokinetics. Anatomical and physiological differences between the sexes may influence the activity of many drugs, including the possibility of their interaction with other drugs, bioactive compounds, foods and beverages. Phenolic compounds could interact with our organism at organ, cellular, and molecular levels triggering a preventive action against chronic diseases, including CVD.

RESULTS

This article will review the role of sex on the activity of these bioactive molecules, considering the existence of sex differences in oxidative stress. It describes the pharmacokinetics of phenolic compounds, their effects on vessels, on cardiovascular system, and during development, including the role of nuclear receptors and microbiota.

CONCLUSIONS

Although there is a large gap between the knowledge of the sex differences in the phenolic compounds' activity and safety, and the urgent need for more research, available data underlie the possibility that plant-derived phenolic compounds could differently influence the health of male and female subjects.

A high-throughput screening campaign to identify inhibitors of DXP reductoisomerase (IspC) and MEP cytidylyltransferase (IspD)

The rise of antibacterial resistance among human pathogens represents a problem that could change the landscape of healthcare unless new antibiotics are developed. The methyl erythritol phosphate (MEP) pathway represents an attractive series of targets for novel antibiotic design, considering each enzyme of the pathway is both essential and has no human homologs. Here we describe a pilot scale high-throughput screening (HTS) campaign against the first and second committed steps in the pathway, catalyzed by DXP reductoisomerase (IspC) and MEP cytidylyltransferase (IspD), using compounds present in the commercially available LOPAC1280 library as well as in an in-house natural product extract library. Hit compounds were characterized to deduce their mechanism of inhibition; most function through aggregation. The HTS workflow outlined here is useful for quickly screening a chemical library, while effectively identifying false positive compounds associated with assay constraints and aggregation.

The effect of quercetin on the pharmacokinetics of chlorzoxazone, a CYP2E1 substrate, in healthy subjects

PURPOSE

Previous in vitro studies have demonstrated that quercetin inhibits CYP2E1 enzyme, but there are no available data to indicate that quercetin inhibits CYP2E1 enzyme in humans. The purpose of the present study was to assess the effect of quercetin on CYP2E1 enzyme activity in healthy subjects using chlorzoxazone (CHZ) as a CYP2E1 substrate.

METHODS

An open-label, two-period, sequential study was conducted in 12 healthy subjects. A single dose of CHZ 250 mg was given to subjects during control phase and after treatment phases. Quercetin at a dose of 500 mg was given to subjects twice daily for a period of 10 days. The blood samples were collected at predetermined time intervals after CHZ dosing and analyzed to determine the concentrations of CHZ and 6-hydroxychlorzoxazone (6-OHCHZ).

RESULTS

Treatment with quercetin significantly enhanced the maximum plasma concentration (C _max), area under the curve (AUC), and half-life (t _1/2) by 47.8, 69.3, and 36.4%, respectively, while significantly decreased the elimination rate constant (k _el) and apparent oral clearance (CL/F) of CHZ by 25.1 and 41.6%, respectively, in comparison with the control. On the other hand, C _max and AUC of 6-OHCHZ were decreased by 30.1 and 32.6%, respectively, after quercetin treatment when compared to control. In addition, geometric mean ratios and 90% confidence intervals for C _max and AUC of CHZ and 6-OHCHZ were both out of the no-effect boundaries of 0.80-1.25, which indicates a significant pharmacokinetic interaction present between CHZ and quercetin. Furthermore, treatment with quercetin significantly decreased the metabolic ratios of C _max and AUC by 57.1 and 60.1%, respectively, as compared to control suggesting that reduced formation of CHZ to 6-OHCHZ.

CONCLUSIONS

The results suggest that altered pharmacokinetics of CHZ might be attributed to quercetin-mediated inhibition of CYP2E1 enzyme. Further, the inhibition of CYP2E1 by quercetin may represent a novel therapeutic approach for minimizing the ethanol-induced CYP2E1 enzyme activity and results in reduced hepatotoxicity of ethanol.