Quercetin: potentials in the prevention and therapy of disease

Preventive Effect of Quercetin in a Triple Transgenic Alzheimer's Disease Mice Model

Alzheimer’s disease (AD) is the most common type of dementia and is the leading cause of disability in elderly people worldwide. Current pharmacological therapies do not cure the disease, and for this reason, some pharmacotherapy studies have investigated preventive treatments focused on modifiable nutritional factors such as diet. Quercetin (Qc) is a flavonoid found in fruits and vegetables that has several biological properties. In this study, we evaluated the effect of chronic oral quercetin administration (100 mg/kg) on neurodegeneration markers and cognitive and emotional deficits in a triple transgenic Alzheimer’s disease (3xTg-AD) mouse model using histological and behavioral analyses. Our results suggest that long-term (12 months) oral preventive treatment with quercetin has significant effects on β-amyloidosis reduction and tends to decrease tauopathy in the hippocampus and amygdala. These decreases positively affected the cognitive functional recovery (without modifying the emotional skills) of 3xTg-AD mice. These findings suggest that preventive and chronic administration of Qc might help to delay the development of histopathological hallmarks and cognitive function deficits in AD.

Quercetin: a natural compound for ovarian cancer treatment

Ovarian cancer is the main cause of death among all reproductive cancers in females. In 2018, ovarian cancer was the seventh most common cancer of women entire the world. A wide variety of molecular and genetic alterations as well as different response to therapies in the different types of ovarian cancer lead to problems in design a common therapeutic strategy. Besides, ovarian cancer cells have tendency to acquire resistance to common cancer treatments through multiple mechanisms. Various factors, including cytokines, growth factors, proteases, adhesion molecules, coagulation factors, hormones and apoptotic agents have been examined to find effective cancer treatment. Phytochemicals have been indicated to have great potential anti-cancer properties against various types of cancers. Quercetin is one of the phytochemicals that exists extensively in daily foods. Wide evidences revealed that quercetin is able to inhibit various types of cancers including breast, lung, nasopharyngeal, kidney, colorectal, prostate, pancreatic, and ovarian cancer. Several in vitro and in vivo studied conducted to evaluate cytotoxic effects of quercetin on ovarian cancer. Since quercetin does not harm healthy cells and it is cytotoxic to cancer cells via various mechanisms, researchers suggest that it could be an ideal agent for ovarian cancer treatment or an adjuvant agent in combination with other anti-cancer drugs. Thus, in this review, we focused on chemo-preventive and curative attitude of quercetin for ovarian cancer and summarize some of the most recent findings which regard the possible molecular mechanisms by which this natural compound inhibits this cancer.

Quercetin and Idebenone Ameliorate Oxidative Stress, Inflammation, DNA damage, and Apoptosis Induced by Titanium Dioxide Nanoparticles in Rat Liver

Titanium dioxide nanoparticles (TiO₂-NPs) are extensively used in a wide range of applications; however, many reports have investigated their nanotoxicological effect at the molecular level either in vitro or in vivo systems. The defensive roles of quercetin (Qur) or idebenone (Id) against the hepatotoxicity induced by TiO₂-NPs were evaluated in the current study. The results showed that the coadministration of Qur or Id to rats intoxicated with TiO₂-NPs markedly ameliorated the elevation in hepatic malondialdehyde (MDA), serum alanine amino-transferase (ALT), glucose, tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), immunoglobin G (IgG), and C-reactive protein (CRP) levels compared to their levels in TiO₂-NPs-treated rats. The aforementioned antioxidants also effectively modulated the changes in the levels of serum vascular endothelial growth factor (VEGF), nitric oxide (NO), hepatic DNA breakage, caspase-3, and inhibition of drug metabolizing enzymes (cytochrome P450s; CYP4502E12E1) in rat livers induced by TiO₂-NPs toxicity. The histopathological examination of the liver section showed that TiO₂-NPs caused severe degeneration of most hepatocytes with an increase in collagen in the portal region, while treatment with the antioxidants in question improved liver architecture. These outcomes supported the use of Qur and Id as protective agents against the hepatotoxicity induced by TiO₂-NPs and other hepatotoxic drugs.

Ginsenosides, catechins, quercetin and gut microbiota: Current evidence of challenging interactions

Recent studies have shown the role of gut microbiota in favoring the absorption of herbal products and the transformation of their active principles into metabolites endowed with biological activity. This review focuses on the evidence supporting the changes occurring, after metabolic reactions by specific bacteria that colonize the human gut, to ginseng-derived ginsenosides, green tea-derived catechins, and quercetin, this latter being a flavonoid aglycon bound to sugars and abundant in some vegetables and roots. Furthermore, the results of several studies demonstrating the potential beneficial effects of the active metabolites generated by these biotransformations on ginsenosides, catechins and quercetin will be reported.

CuS@MOF-Based Well-Designed Quercetin Delivery System for Chemo-Photothermal Therapy

Quercetin (QT) is one promising candidate for the treatment of various cancers with virtually no toxic side effects. However, its anticancer effect is severely restricted by its poor bioavailability, low water solubility, and chemical instability in the neutral and alkaline medium. Herein, zeolitic imidazolate framework-8 (ZIF-8) is first reported as the multifunctional nanoplatform to the codelivery of quercetin as an anticancer agent and CuS nanoparticles as a photothermal therapy (PTT) agent for synergistic combination of chemotherapy and PTT as well as overcoming the drawbacks of quercetin. Moreover, folic acid-bovine serum albumin (FA-BSA) conjugates are applied to stabilize the CuS@ZIF-8-QT to promote the bioavailability of quercetin and realize active-targeting drug delivery. Near-infrared (NIR) fluorescent imaging demonstrated the highly increased drug accumulations of FA-BSA/CuS@ZIF-8-QT in tumors, resulting from efficient internalization via FA-receptors-mediated endocytosis. The results of in vivo and in vitro anticancer experiments demonstrate that quercetin and PTT agent can work together efficiently under NIR irradiation, thus remarkably improving the anticancer effect. Therefore, our newly designed FA-BSA/CuS@ZIF-8-QT multifunctional drug delivery system might be a promising nanoplatform for cancer treatment.

Significant metabolic improvement by a water extract of olives: animal and human evidence

PURPOSE

Dyslipidemia and impaired glucose metabolism are the main health issues of growing prevalence and significant high healthcare cost, requiring novel prevention and/or therapeutic approaches. Epidemiological and animal studies revealed that olive oil is an important dietary constituent, inducing normolipidemia. However, no studies have specifically investigated the polyphenol-rich water extract of olives (OLWPE), generated during olive oil production.

METHODS

In the present work, we initially examined the effect of OLPWE on animals' metabolic parameters. Rats fed with a high-fat diet were treated with three different doses of OLPWE for 4 months. Additionally, bioavailability was explored. Afterwards, OLWPE's metabolic effect was explored in humans. Healthy volunteers consumed microencapsulated OLWPE for 4 weeks, in a food matrix [one portion (30 g) of a meat product].

RESULTS

High-fat-fed rats developed a metabolic dysfunction, with increased LDL and insulin levels and decreased HDL; this syndrome was significantly impaired when treated with OLWPE. Treated rats had increased total plasma antioxidant capacity, while several phenolic compounds were detected in their blood. These findings were also verified in humans that consumed OLWPE, daily, for 4 weeks. Interestingly, in individuals with elements of cardio-metabolic risk, OLWPE consumption resulted in reduced glucose, insulin, total cholesterol, LDL and oxLDL levels.

CONCLUSIONS

Our data clearly show that OLWPE can improve glucose and lipid profile, indicating its possible use in the design of functional food and/or therapeutic interventions.

Suppressive Effect of Quercetin on Nitric Oxide Production from Nasal Epithelial Cells In Vitro

Nitric oxide (NO) is known to play pivotal roles as one of the final effector molecules in the development of allergic diseases, including allergic rhinitis (AR). Although quercetin has been reported to attenuate the clinical conditions of AR, its influence on NO production is not well defined. The present study aimed to examine the influence of quercetin on in vitro NO production from nasal epithelial cells after interleukin- (IL-) 4 stimulation. Human nasal epithelial cells (HNEpCs) at a concentration of 1 x 10⁵ cells/ml were stimulated with 10.0 ng/ml of IL-4 in the presence and absence of quercetin. After 48 hours, the culture supernatants were collected and assayed for NO (NO₂ and NO₃) using the Griess method. The influences of quercetin on the transcription factor, STAT6, activation, and iNOS mRNA expression were also examined using ELISA and real-time quantitative RT-PCR, respectively. Addition of quercetin to cell cultures caused suppression of NO production from HNEpCs after IL-4 stimulation. The minimum concentration of quercetin that caused significant suppression was 1.0 nM. Treatment of cells with quercetin at more than 1.0 nM suppressed STAT6 activation and iNOS mRNA expression induced by IL-4 stimulation. The present results strongly suggested that quercetin favorably modified the clinical condition of AR through the suppression of NO production from nasal epithelial cells after IL-4 stimulation.

Quercetin induces the selective uptake of HDL-cholesterol via promoting SR-BI expression and the activation of the PPARγ/LXRα pathway

Reverse cholesterol transport (RCT) is the process to deliver cholesterol to the liver for further excretion and involves scavenger receptor class B type I (SR-BI)-mediated selective lipid uptake (SLU) from high-density lipoprotein cholesterol (HDL-C). The up-regulation of hepatic SR-BI expression accelerates HDL-C clearance in circulation and impedes the development of atherosclerosis (AS). In the present study, we explored the modulation of hepatic SR-BI expression and SR-BI-mediated SLU by quercetin, a natural flavonoid compound in the diet with a favorable role in cardiovascular disorders. We found that quercetin significantly increased the expression level of SR-BI in HepG2 cells in a concentration- and time-dependent manner. Besides, quercetin had stimulatory effects on the binding of 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (Dil)-labeled HDL to hepatocytes and ¹²⁵I/³H-CE-HDL association. Treatment with small interfering RNA (siRNA) or SR-BI specific inhibitor, BLT-1, inhibited quercetin-induced Dil-HDL binding and selective HDL-C uptake. Treatment with quercetin increased both proliferator-activated receptor γ (PPARγ) and liver X receptor α (LXRα) levels. Additionally, the quercetin-induced expression of SR-BI, Dil-HDL binding and the selective uptake of HDL-C were significantly attenuated by treatment with PPARγ siRNA, LXRα siRNA, and their antagonists, respectively. In C57BL/6 mice, quercetin administration potently increased SR-BI, PPARγ and LXRα levels and lipid accumulation in the liver. Altogether, our results suggest that quercetin-induced up-regulation of SR-BI and subsequent lipid uptake in hepatocytes might contribute to its beneficial effects on cholesterol homeostasis and atherogenesis.

Formulation and evaluation of mixed polymeric micelles of quercetin for treatment of breast, ovarian, and multidrug resistant cancers

Background

Quercetin (QCT), a naturally occurring flavonoid has a wide array of pharmacological properties such as anticancer, antioxidant and anti-inflammatory activities. QCT has low solubility in water and poor bioavailability, which limited its use as a therapeutic molecule. Polymeric micelles (PMs) is a novel drug delivery system having characteristics like smaller particle size, higher drug loading, sustained drug release, high stability, increased cellular uptake and improved therapeutic potential. In the present study, we have formulated and characterized mixed PMs (MPMs) containing QCT for increasing its anticancer potential.

Methods

The MPMs were prepared by thin film hydration method, and their physicochemical properties were characterized. The in vitro anticancer activity of the MPMs were tested in breast (MCF-7 and MDA-MB-231, epithelial and metastatic cancer cell lines, respectively), and ovarian (SKOV-3 and NCI/ADR, epithelial and multi-drug resistant cell lines, respectively) cancer.

Results

The optimal MPM formulations were obtained from Pluronic polymers, P123 and P407 with molar ratio of 7:3 (A16); and P123, P407 and TPGS in the molar ratio of 7:2:1 (A22). The size of the particles before lyophilization (24.83±0.44 nm) and after lyophilisation (37.10±4.23 nm), drug loading (8.75±0.41%), and encapsulation efficiency (87.48±4.15%) for formulation A16 were determined. For formulation A22, the particle size before lyophilization, after lyophilization, drug loading and encapsulation efficiency were 26.37±2.19 nm, 45.88±13.80 nm, 9.01±0.11% and 90.07±1.09%, respectively. The MPMs exhibited sustained release of QCT compared to free QCT as demonstrated from in vitro release experiments. The solubility of QCT was markedly improved compared to pure QCT. The MPMs were highly stable in aqueous media as demonstrated by their low critical micelle concentration. The concentration which inhibited 50% growth (IC₅₀) values of both micellar preparations in all the cancer cell lines were significantly less compared to free QCT.

Conclusion

Both the MPMs containing QCT could be used for effective delivery to different type of cancer and may be considered for further development.

Natural product for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is related to increasing age. It is mainly characterized by progressive neurodegenerative disease, which damages memory and cognitive function. Natural products offer many options to reduce the progress and symptoms of many kinds of diseases, including AD. Meanwhile, natural compound structures, including lignans, flavonoids, tannins, polyphenols, triterpenes, sterols, and alkaloids, have anti-inflammatory, antioxidant, anti-amyloidogenic, and anticholinesterase activities. In this review, we summarize the pathogenesis and targets for treatment of AD. We also present several medicinal plants and isolated compounds that are used for preventing and reducing symptoms of AD.

Natural products: a hope for glioblastoma patients

Glioblastoma (GBM) is one of the most aggressive malignant tumors with an overall dismal survival averaging one year despite multimodality therapeutic interventions including surgery, radiotherapy and concomitant and adjuvant chemotherapy. Few drugs are FDA approved for GBM, and the addition of temozolomide (TMZ) to standard therapy increases the median survival by only 2.5 months. Targeted therapy appeared promising in in vitro monolayer cultures, but disappointed in preclinical and clinical trials, partly due to the poor penetration of drugs through the blood brain barrier (BBB). Cancer stem cells (CSCs) have intrinsic resistance to initial chemoradiation therapy (CRT) and acquire further resistance via deregulation of many signaling pathways. Due to the failure of classical chemotherapies and targeted drugs, research efforts focusing on the use of less toxic agents have increased. Interestingly, multiple natural compounds have shown antitumor and apoptotic effects in TMZ resistant and p53 mutant GBM cell lines and also displayed synergistic effects with TMZ. In this review, we have summarized the current literature on natural products or product analogs used to modulate the BBB permeability, induce cell death, eradicate CSCs and sensitize GBM to CRT.

Quercetin Attenuates Ethanol-Induced Iron Uptake and Myocardial Injury by Regulating the Angiotensin II-L-Type Calcium Channel

SCOPE

Increased iron deposition in the myocardium in alcoholics may lead to increased risk of cardiac dysfunction. Quercetin has been demonstrated to quench production of intracellular free iron-induced -OH, but the effect of quercetin in ethanol-induced cardiac damage remains unclear. This study aims to explore whether quercetin attenuates ethanol-induced iron uptake and myocardial injury by regulating angiotensin II-L-type voltage-dependent Ca2+ channel (Ang II-LTCC).

METHODS AND RESULTS

Adult male C57BL/6J mice are isocalorically pair-fed either a regular or ethanol-containing Lieber De Carli liquid diets supplemented with either quercetin (100 mg kg^-1  bw) or desferrioxamine mesylate (DFO, 100 mg kg^-1 bw) for 15 weeks. Quercetin alleviated ethanol-induced histopathological changes, creatine kinase isoenzyme release, Ang II secretion, ROS generation, total cardiac iron, and labile iron level. Ethanol exposure or quercetin intervention fails to regulate traditional iron transporters except LTCC. LTCC is upregulated by ethanol and inhibited by quercetin. In H9C2 cell, LTCC is increased by ethanol (100 mm) and/or Ang II (1 μm) concomitant with iron disorders and oxidative stress. This effect is partially normalized by quercetin (50 μm), nifedipine (LTCC inhibitor, 15 μm), or losartan (Ang II receptor antagonist, 100 μm).

CONCLUSION

Alcohol-induced cardiac injury is associated with excessive NTBI uptake mediated by Ang II-LTCC activation which may be mediated by quercetin against ethanol cardiotoxicity.

The role of gut microbiota in the modulation of drug action: a focus on some clinically significant issues

INTRODUCTION

A healthy gut microbiota is necessary for the normal operation of several body functions, including gastrointestinal sensitivity and motility, lipid and glucid metabolism, immune surveillance, and host behavior. In addition, intestinal bacteria contribute to determining the pharmacological properties of several drugs by producing different drug metabolizing enzymes. Areas covered: Four enzymatic processes are discussed: prodrug activation; drug inactivation; drug deconjugation; and hydrolysis of natural glycosides with further metabolism of released aglycones. For each of these processes, a literature search has been undertaken on certain paradigmatic examples that have significant clinical implications: aminosalicylates and anthranoid laxatives; digoxin; irinotecan and non-steroidal anti-inflammatory drugs (NSAIDs); rutin, diosmin, and baicalin. Expert commentary: The modulation of certain reactions catalyzed by gut bacterial enzymes may offer new opportunities to improve the clinical efficacy of drugs such as aminosalicylates, and natural glycosides by increasing their metabolic transformation, and of digoxin by reducing its inactivation, or to decrease the lower intestinal toxicity of irinotecan, and NSAIDs by inhibiting the hydrolytic cleavage of their conjugates. Randomized clinical trials are awaited to clarify whether new intervention strategies may modulate these processes and provide clinical benefits such as improved therapeutic outcomes and drug safety profiles.

Chronic consumption of quercetin reduces erythrocytes oxidative damage: Evaluation at resting and after eccentric exercise in humans

The polyphenolic flavonoid quercetin has been shown to be a powerful antioxidant, in vitro and in murine models. However, its effect on redox status has been poorly examined in humans, particularly in combination with strenuous exercise. We hypothesized that quercetin supplementation would beneficially affect redox homeostasis in healthy individuals undergoing eccentric exercise. To test this hypothesis, the effects of chronic consumption of quercetin on glutathione system (reduced, oxidized, and reduced to oxidized glutathione ratio), oxidative damage [thiobarbituric acid reactive substances (TBARs)], antioxidant enzymatic network (catalase, glutathione peroxidase, superoxide dismutase) and resistance to lysis, were investigated in erythrocytes, a traditional model widely used to study the effects of oxidative stress as well as the protective effects of antioxidants. In a two weeks controlled, randomized, crossover, intervention trial, 14 individuals ingested 2 caps (1 g/d) of quercetin or placebo. Blood samples were collected before, after 2 weeks of supplementation and after a bout of eccentric exercise. Quercetin, reduced significantly erythrocytes lipid peroxidation levels and the susceptibility to hemolysis induced by the free radical generator AAPH, while no differences in antioxidant enzyme activities and glutathione homeostasis were found between the two groups. After a single bout of eccentric exercise, quercetin supplementation improved redox status as assessed by reduced/oxidized glutathione ratio analysis and reduced TBARs levels both in erythrocytes and plasma. In conclusion, our study provides evidences that chronic quercetin supplementation has antioxidant potential prior to and after a strenuous eccentric exercise thus making the erythrocytes capable to better cope with an oxidative insult.

Glutathione homeostasis is significantly altered by quercetin via the Keap1/Nrf2 and MAPK signaling pathways in rats

Previously, we showed that 0.5% quercetin simultaneously decreased serum homocysteine and glutathione (GSH) levels in rats. The aim of the present study was to investigate the effects of 0.5% quercetin on GSH metabolism, related enzymes and signal pathways in rats. Rats were fed the control diet and 0.5% quercetin-supplemented diet for 6 weeks. The results showed that quercetin reduced serum and hepatic content of GSH and the ratio of GSH and oxidized glutathione (GSSG), enhanced hepatic activity and mRNA expression of glutathione S-transferase (GST), inhibited hepatic activity and mRNA expression of glutamate cysteine ligase (GCL), and decreased hepatic glutathione reductase (GR) mRNA expression. Levels of phosphorylated p38 and extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinases (MAPKs) increased, while that of nuclear factor E2-like 2 (Nrf2) protein decreased after quercetin treatment. However, no significant hepatotoxicity was noted. We concluded that quercetin treatment altered hepatic GSH metabolism by modulating GSH metabolic enzyme activities and mRNA expression in rats, and p38, ERK1/2 MAPKs, and Nrf2 were involved in modulating GSH metabolism-related enzymes.

Quercetin reverses the doxorubicin resistance of prostate cancer cells by downregulating the expression of c-met

Chemotherapy is an irreplaceable treatment for prostate cancer. However, the acquisition of chemoresistance is a common and critical problem that requires urgent solutions for the effective treatment of this disease. The aim of the present study was to determine whether the combination of quercetin with doxorubicin reversed the resistance of prostate cancer cells to doxorubicin-based therapy. A prostate cancer (PC)3 cell line (PC3/R) with acquired doxorubicin-resistance was established. A significant drug-resistance to doxorubicin and high activation of the phosphoinositide 3-kinase/protein kinase-B (PI3K/AKT) pathway in PC3/R cells, compared with normal PC3 cells, was demonstrated. Notably, combination treatment of doxorubicin with quercetin significantly promoted the doxorubicin-induced apoptosis in PC3/R cells through the mitochondrial/reaction oxygen species pathway. In PC3/R cells, a significant upregulation of tyrosine-protein kinase-met (c-met) was observed compared with nromal PC3 cells. However, the response to quercetin treatment in PC3/R cells inhibited c-met expression and the downstream PI3K/AKT pathway. In addition, induced expression of c-met rescued quercetin-promoted apoptosis in PC3/R cells treated with doxorubicin. The results of the present study indicated that quercetin is able to reverse prostate cancer cell doxorubicin resistance by downregulating the expression of c-met. It may represent a potential strategy for reversing the chemoresistance of prostate cancer.

Bioactive Components in Moringa Oleifera Leaves Protect against Chronic Disease

Moringa Oleifera (MO), a plant from the family Moringacea is a major crop in Asia and Africa. MO has been studied for its health properties, attributed to the numerous bioactive components, including vitamins, phenolic acids, flavonoids, isothiocyanates, tannins and saponins, which are present in significant amounts in various components of the plant. Moringa Oleifera leaves are the most widely studied and they have shown to be beneficial in several chronic conditions, including hypercholesterolemia, high blood pressure, diabetes, insulin resistance, non-alcoholic liver disease, cancer and overall inflammation. In this review, we present information on the beneficial results that have been reported on the prevention and alleviation of these chronic conditions in various animal models and in cell studies. The existing limited information on human studies and Moringa Oleifera leaves is also presented. Overall, it has been well documented that Moringa Oleifera leaves are a good strategic for various conditions associated with heart disease, diabetes, cancer and fatty liver.

Chitosan/Cyclodextrin/TPP Nanoparticles Loaded with Quercetin as Novel Bacterial Quorum Sensing Inhibitors

The widespread emergence of antibiotic-resistant bacteria has highlighted the urgent need of alternative therapeutic approaches for human and animal health. Targeting virulence factors that are controlled by bacterial quorum sensing (QS), seems a promising approach. The aims of this study were to generate novel nanoparticles (NPs) composed of chitosan (CS), sulfo-butyl-ether-β-cyclodextrin (Captisol®) and/or pentasodium tripolyphosphate using ionotropic gelation technique, and to evaluate their potential capacity to arrest QS in bacteria. The resulting NPs were in the size range of 250-400 nm with CS70/5 and 330-600 nm with CS70/20, had low polydispersity index (<0.25) and highly positive zeta potential ranging from ζ ~+31 to +40 mV. Quercetin, a hydrophobic model flavonoid, could be incorporated proportionally with increasing amounts of Captisol® in the NPs formualtion, without altering significantly its physicochemical properties. Elemental analysis and FTIR studies revealed that Captisol® and quercetin were effectively integrated into the NPs. These NPs were stable in M9 bacterial medium for 7 h at 37 °C. Further, NPs containing Captisol® seem to prolong the release of associated drug. Bioassays against an E. coli Top 10 QS biosensor revealed that CS70/5 NPs could inhibit QS up to 61.12%, while CS70/20 NPs exhibited high antibacterial effects up to 88.32%. These results suggested that the interaction between NPs and the bacterial membrane could enhance either anti-QS or anti-bacterial activities.

Hispidulin-7-O-Neohesperidoside from Cirsium japonicum var. ussuriense Attenuates the Production of Inflammatory Mediators in LPS-Induced Raw 264.7 Cells and HT-29 Cells

Background:

Inflammatory bowel disease (IBD) is characterized by chronic inflammation of the gastrointestinal tract and involves secretion of inflammatory mediators. The flavone diglycoside hispidulin-7-O-neohesperidoside (HN) isolated from the methanolic extract of aerial parts of Cirsium japonicum var. ussuriense, but its pharmacologic activities, with the exception of alleviation of alcohol toxicity, have not been investigated to date.

Objective:

The aim of the present study was to investigate the anti-inflammatory activities of HN for the treatment of chronic inflammatory illnesses, including IBD.

Materials and Methods:

In lipopolysaccharide (LPS)-induced RAW264.7 cells and HT-29 cells, the effects of HN on cell viability and nitric oxide (NO) production were examined via MTT assay and the Griess reaction, respectively. The expression levels of interleukin (IL)-1α, IL-8, and tumor necrosis factor (TNF)-α and inducible nitric oxide synthase (iNOS) protein levels were measured by enzyme-linked immunosorbent assay and Western blotting, respectively.

Results:

HN concentration-dependently inhibited NO production in LPS-induced RAW 264.7 cells. Treatment with HN considerably downregulated the levels of the pro-inflammatory cytokines, IL-1β and TNF-α and the iNOS protein level in LPS-induced RAW 264.7 cells. Furthermore, HN inhibited the production of the chemotactic cytokine, IL-8, in LPS-induced HT-29 cells.

Conclusion:

HN has potential as an anti-inflammatory agent to prevent and/or treat IBD.

SUMMARY

Hispidulin-7-O-neohesperidoside (HN) is flavone diglycoside isolated from the methanolic extract of aerial parts of Cirsium japonicum var. ussuriense.

HN concentration-dependently inhibited NO production and considerably downregulated the levels of the proinflammatory cytokines, IL-1β and TNF-α, and the iNOS protein level in LPS-induced RAW 264.7 cells.

HN inhibited the production of the chemotactic cytokine, IL-8, in LPS-induced HT-29 cells.

HN has potential as an anti-inflammatory agent to prevent and/or treat IBD.

Abbreviations used: IBD: Inflammatory bowel disease, HN: hispidulin-7-O-neohesperidoside, LPS: lipopolysaccharide, NO: nitric oxide, IL: interleukin, TNF: tumor necrosis factor, iNOS: inducible nitric oxide synthase, CD: Crohn's disease, UC: ulcerative colitis, RT: room temperature, DMEM: Dulbecco's modified Eagle's medium, FBS: fetal bovine serum, PBS: phosphate buffered saline, SDS: sodium dodecyl sulfate, PVDF: polyvinylidene difluoride, SD: standard deviation

Flavonoids from persimmon (Diospyros kaki L.) leaves inhibit proliferation and induce apoptosis in PC-3 cells by activation of oxidative stress and mitochondrial apoptosis

Persimmon (Diospyros kaki L.) leaves are extensively used in Chinese medicine and are also excellent source of dietary polyphenols. Here we investigated the antiproliferative and pro-apoptotic activity of the total flavonoids extracted from persimmon leaves (FPL) in PC-3 cells. After treating cells with different concentration of FPL, Quercetin or Rutin for 24 h, MTT and flow cytometry were used to measure the cytotoxicity, apoptotic rate and cell cycle arrest. Compared with Quercetin and Rutin, FPL showed higher cytotoxicity at 12.5 and 25 μg/ml concentrations and also presented lower IC₅₀ in PC-3 cells. In addition, FPL induced PC-3 cells apoptosis by activation of oxidative stress, as detected by ROS, MDA, nitrite and iNOS activity, and increased mitochondrial membrane permeability. Morphological changes, inactivation of Bcl-2, upregulation of BAX, release of cytochrome c and activation of downstream apoptotic signaling in FPL-treated PC-3 cells also suggested apoptotic death. Meanwhile, FPL significantly inhibited migration of PC-3 cells. Therefore, FPL inhibited proliferation, migration and induced apoptosis of PC-3 cells by activation of oxidative stress and mitochondrial-related apoptosis.

Low concentration of quercetin antagonizes the invasion and angiogenesis of human glioblastoma U251 cells

Glioblastoma is the most aggressive type of brain tumor with a very poor prognosis. Therefore, it is always of great importance to explore and develop new potential treatment for glioblastoma. Quercetin, a flavonoid present in a variety of human foods, has been shown to inhibit various tumor cell proliferation. In this study, we found that treating human glioblastoma U251 cells with 10 μg/mL quercetin for 24 hours, a concentration that was far below the IC₅₀ (113.65 μg/mL) and at which quercetin failed to inhibit cell proliferation, inhibited cell migration (30%) and cell invasion as examined by wound scratch assay and transwell assay, respectively. We further showed that 10 μg/mL quercetin inhibited cell migration and tube formation of human umbilical vein endothelial cells induced by the conditioned medium derived from U251 cell culture. The inhibitory effect of quercetin on migration and angiogenesis is possibly mediated through the downregulation of protein levels of VEGFA, MMP9, and MMP2 as detected by Western blot. Our findings demonstrated that low concentration of quercetin antagonized glioblastoma cell invasion and angiogenesis in vitro.

Amelioration of oxidative stress by dietary fenugreek (Trigonella foenum-graecum L.) seeds is potentiated by onion (Allium cepa L.) in streptozotocin-induced diabetic rats

Oxidative stress has a crucial role in the progression of diabetes and its complications. Soluble fibre-rich fenugreek seeds (Trigonella foenum-graecum L.) are understood to have a beneficial effect in the management of diabetes. Previously, we have shown that the amelioration of diabetic hyperglycemia and related metabolic abnormalities was potentiated by onion (Allium cepa L.) in experimental rats. The present study evaluated the additive beneficial effect of dietary fenugreek seeds (10%) and onion (3%) on oxidative stress in diabetic rats. These dietary interventions lowered oxidative stress, the combination producing a higher beneficial effect (p < 0.05), although not additive. Dietary fenugreek, onion, or fenugreek+onion countered hypercholesterolemia (p < 0.05), especially from low-density lipoprotein−associated fraction by 43%, 35%, and 54%, respectively. Elevated concentrations of cholesterol and triglycerides in the liver and heart under diabetic conditions were significantly counteracted by these dietary interventions, with the additive combination resulting in greater effect. These findings were also corroborated by restoration of histopathological abnormalities of heart and liver tissues along with lowered heart and liver weights. It is inferred that an alleviation of oxidative stress contributes further to the antidiabetic influence and this nutraceutical potential of fenugreek seeds and onion was higher when consumed together.

Inhibitory effect of quercetin on titanium particle-induced endoplasmic reticulum stress (ERS)-related apoptosis and in vivoosteolysis

Wear particle induced periprosthetic osteolysis is the main cause of aseptic loosening of orthopedic implants. The aim of the present study is to determine the protective effect of quercetin (QUE) against titanium (Ti) particle induced endoplasmic reticulum stress (ERS) related apoptosis and osteolysis. In the present study, RAW264.7 cells were pretreated with different concentrations (40, 80, and 160 μmol/l) of QUE for 30 min and then treated with Ti particle (5 mg/ml) for 24 h. Cell viability and apoptosis were determined using MTT assay and Annexin V-FITC Apoptosis Detection Kit, respectively. Protein and mRNA expressions of ERS-related genes were examined by Western blot and real-time PCR, respectively. The release of inflammatory cytokines was detected by ELISA. Then, a mouse calvarial osteolysis model was established. Histological sections of calvaria were stained with Hematoxylin-Eosin (H&E) or tartrate-resistant acid phosphatase (TRAP). The results showed that Ti particle reduced cell viability and induced apoptosis in RAW264.7 macrophages. The cytotoxic effects of Ti particle were dramatically inhibited by QUE pretreatment. Interestingly, we found that QUE also significantly reduced Ti particle induced up-regulation of the expression levels of protein kinase RNA-like ER kinase (PERK), inositol-requiring enzyme-1 (IRE1), glucose-regulated protein (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12, and caspase-3 and enhanced the down-regulation of Bcl-2. In addition, QUE decreased Ti particle-induced inflammatory cytokines release from RAW264.7 cells. Moreover, treatment with QUE markedly decreased osteoclast number. In a mouse calvarial osteolysis model, QUE inhibited Ti particle induced osteolysis in vivo by inhibiting osteoclast formation and expressions of ERS-related genes. In conclusion, QUE can protect RAW264.7 cells from Ti particle induced ERS-related apoptosis and suppress calvarial osteolysis in vivo.

Anti-arthritic activity of aqueous-methanolic extract and various fractions of Berberis orthobotrys Bien ex Aitch

Background

The roots and stem bark of Berberis orthobotrys (Berberidaceae) have long been used traditionally to treat joint pain. Though, it has not been pharmacologically assessed for rheumatoid arthritis. The current study explores anti-arthritic activity and phytochemical analysis of aqueous-methanolic extract (30:70) and fractions (ethyl acetate, n-butanol, and aqueous) of Berberis orthobotrys roots.

Methods

Anti-arthritic potential was evaluated in vitro using protein denaturation (bovine serum albumin and egg albumin) and membrane stabilization methods at 12.5–800 μg/ml concentration and in vivo via turpentine oil, formaldehyde and Complete Freund Adjuvant (CFA) models at 50, 100 and 150 mg/kg doses. Also, in vitro antioxidant ability was appraised by reducing power assay. Moreover, total flavonoid content, Fourier transform infrared spectroscopy and High performance liquid chromatography of n-butanol fraction were performed.

Results

The results revealed concentration dependent inhibition of albumin denaturation and notable RBC membrane stabilization, with maximum results obtained at 800 μg/ml. Similarly, plant exhibited dose dependent anti-arthritic effect in turpentine oil and formaldehyde models, with maximum activity observed at 150 mg/kg. The results of CFA model depicted better protection against arthritic lesions and body weight alterations. Also, B.orthobotrys remarkably ameliorated altered hematological parameters, rheumatoid factor and positively modified radiographic and histopathological changes. Additionally, plant exhibited remarkable anti-oxidant activity. Moreover, phytochemical analysis revealed polyphenols and flavonoids.

Conclusion

Taken together, these results support traditional use of B.orthobotrys as potent anti-arthritic agent that may be proposed for rheumatoid arthritis treatment.

Effect of quercetin on cadmium chloride-induced impairments in sexual behaviour and steroidogenesis in male Wistar rats

Cadmium chloride (CdCl₂ ) has been reported to cause reproductive toxicity in male rats, mainly through oxidative stress. This study examined its effect on sexual behaviour, as one of the mechanisms of reproductive dysfunction, as well as the possible ameliorative effect of quercetin (QE) on same. Thirty male Wistar rats (10 weeks old), weighing 270-300 g, were used for this study. They were either orally administered 2% DMSO, CdCl₂ (5 mg/kg b.w.), QE (20 mg/kg b.w.) or CdCl₂ +QE, once daily for 4 weeks, before sexual behavioural studies. The 5th group received CdCl₂ for 4 weeks and allowed 4-week recovery period, before sexual behavioural test. Rats were sacrificed after sexual behavioural studies. The blood, testis and penis were collected for biochemical assays. Cadmium increased mount, intromission and ejaculatory latencies, but reduced their frequencies, compared to control. Serum nitric oxide increased, while penile cyclic guanosine monophosphate reduced in the CdCl₂ -exposed rats, compared to control. CdCl₂ increased testicular cholesterol, but reduced 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-HSD activities, and testosterone concentration. QE better attenuated these negative changes compared to withdrawal of CdCl₂ treatment. In conclusion, CdCl₂ suppressed steroidogenesis, penile erection and sexual behaviour, with poor reversal following withdrawal, while QE attenuated these effects.

Differential effect of quercetin on cisplatin-induced toxicity in kidney and tumor tissues

Strategies to minimize the nephrotoxicity of platinated antineoplastics without affecting its antitumour efficacy are strongly necessary to improve the pharmacotoxicological profile of these drugs. The natural flavonoid quercetin has been shown to afford nephroprotection without affecting cisplatin antitumour effect. The purpose of the present study has been to assess the differential mechanisms of action of cisplatin and quercetin on kidney and tumour tissues that could explain these effects. Wistar rats bearing subcutaneous tumours were treated with cisplatin and quercetin (and the appropriate controls). Tumour size and renal function evolution was monitored during 6 days. Platinum and quercetin content were also determined in both tissues. All the parameters studied, including blood supply, inflammation, apoptosis, critical MAPK signaling and oxidative stress in the cisplatin-treated animals are almost normalized by quercetin in the kidneys, but unaffected in the tumours. Our results suggest that in a cancer model in vivo, the protection exerted by quercetin on cisplatin nephrotoxicity is related to its antioxidant, vascular, anti-inflammatory and antiapoptotic effects, but these properties do not affect the mechanisms responsible for the antitumour effect of cisplatin.

Isolation and characterization of a novel chalcone synthase gene family from mulberry

Chalcone synthase (CHS) is the pivotal enzyme that catalyzes the first committed step of the phenylpropanoid pathway leading to flavonoids. Here, five CHS genes were determined in mulberry (Morus atropurpurea Roxb.). Interestingly, phylogenetic analysis tended to group three MaCHSs in the stilbene synthase (STS) family and initially annotated these as MaSTSs. A co-expression system that harbored a 4-coumarate:CoA ligase gene and one of the candidate genes was established to determine the functions of this novel gene family. The fermentation result demonstrated that MaSTS in fact encoded a CHS enzyme, and was consequently retermed MaCHS. Tissue-specific expression analysis indicated that MaCHS1/MaCHS2 was highly abundant in fruit, and MaCHS4 had significant expression in root bark, stem bark and old leaves, while MaCHS3 and MaCHS5 were more expressed in old leaves. Subcellular localization experiments showed that MaCHS was localized to the cytoplasm. Transcription levels suggested MaCHS genes were involved in a series of defense responses. Over-expression of MaCHS in transgenic tobacco modified the metabolite profile, and resulted in elevated tolerance to a series of environmental stresses. This study comprehensively evaluated the function of MaCHS genes and laid the foundation for future research on MaCHS in mulberry.

Effectiveness of quercetin in an experimental rat model of allergic rhinitis

We aimed to investigate whether quercetin had a therapeutic effect in an experimental rat model of allergic rhinitis. The study was conducted with 35 rats, which were randomly assigned into 4 groups: group 1 (n = 5), sham group; group 2 (quercetin group, n = 10) received 80 mg/kg day quercetin; group 3 (steroid group, n = 10) received steroid (mometasone furoate); and group 4 (control group, n = 10), received ovalbumin alone. Rats were sensitized by administration of ovalbumin on alternate days over 14 days via an intraperitoneal route. On day 15, in addition to ovalbumin via an intranasal route, quercetin and steroid were given over 7 days to the corresponding groups. All rats were then sacrificed and nasal turbinates were evaluated histopathologically, and serum total IgE and ovalbumin (OVA)-specific IgE values were measured before and after treatment. A significant increase in OVA-specific IgE values was detected in all groups except sham group. A significant increase was detected in post-treatment total IgE levels in the control group, while no significant change was detected in the sham, quercetin, and intranasal steroid groups. On histopathological evaluation, it was observed that findings of allergic rhinitis were suppressed in the quercetin group when compared to the control group. In immunohistochemical evaluation, it was detected that COX-2 and VIP expressions were weaker in the quercetin group compared to the control group. Based on these findings, we conclude that quercetin was effective in allergic rhinitis induced by ovalbumin in rats both histopathologically and serologically.

STAT3 targeting by polyphenols: Novel therapeutic strategy for melanoma

Melanoma or malignant melanocytes appear with the low incidence rate, but very high mortality rate worldwide. Epidemiological studies suggest that polyphenolic compounds contribute for prevention or treatment of several cancers particularly melanoma. Such findings motivate to dig out novel therapeutic strategies against melanoma, including research toward the development of new chemotherapeutic and biologic agents that can target the tumor cells by different mechanisms. Recently, it has been found that signal transducer and activator of transcription 3 (STAT3) is activated in many cancer cases surprisingly. Different evidences supply the aspect that STAT3 activation plays a vital role in the metastasis, including proliferation of cells, survival, invasion, migration, and angiogenesis. This significant feature plays a vital role in various cellular processes, such as cell proliferation and survival. Here, we reviewed the mechanisms of the STAT3 pathway regulation and their role in promoting melanoma. Also, we have evaluated the emerging data on polyphenols (PPs) specifically their contribution in melanoma therapies with an emphasis on their regulatory/inhibitory actions in relation to STAT3 pathway and current progress in the development of phytochemical therapeutic techniques. An understanding of targeting STAT3 by PPs brings an opportunity to melanoma therapy. © 2016 BioFactors, 43(3):347-370, 2017.

Effects of Quercetin and Mannitol on Erythropoietin Levels in Rats Following Acute Severe Traumatic Brain Injury

Objective

The aim of this study to investigate the normal values of erythropoietin (EPO) and neuroprotective effects of quercetin and mannitol on EPO and hematocrit levels after acute severe traumatic brain injury (TBI) in rat model.

Methods

A weight-drop impact acceleration model of TBI was used on 40 male Wistar rats. The animals were divided into sham (group I), TBI (group II), TBI+quercetin (50 mg/kg intravenously) (group III), and TBI+mannitol (1 mg/kg intravenously) (group IV) groups. The malondialdehyde, glutathione peroxidase, catalase, EPO, and hematocrit levels were measured 1 and 4 hour after injury. Two-way repeated measures analysis of variance and Tukey’s test were used for statistical analysis.

Results

The malondialdehyde levels decreased significantly after administration of quercetin and mannitol compared with those in group II. Catalase and glutathione peroxidase levels increased significantly in groups III and IV. Serum EPO levels decreased significantly after mannitol but not after quercetin administration. Serum hematocrit levels did not change significantly after quercetin and mannitol administration 1 hour after trauma. However, mannitol administration decreased serum hematocrit levels significantly after 4 hour.

Conclusion

This study suggests that quercetin may be a good alternative treatment for TBI, as it did not decrease the EPO levels.

Biotransformation of Rutin Using Crude Enzyme from Rhodopseudomonas palustris

Rhodopseudomonas palustris was selected for the ability to grow in diglycosylated flavonoids-based media, exhibited deglycosylation activity. The present study aimed to investigate the ability of a crude enzyme from Rhodopseudomonas palustris to transform rutin. Our results showed the crude enzyme was found to transform rutin to quercetin via isoquercitrin. The maximum enzyme activities were observed at pH 7.0, 25 °C, and rutin concentration of 1.0 mg mL^- 1. Under optimal conditions, 13.11 μM rutin was biotransformed into 6.86 μM isoquercitrin and 11.64 μM quercetin after 11 and 21 h, respectively. The study demonstrates an eco-friendly and potential economically viable 'green' conversion route to convert rutin to isoquercitrin and quercetin, which is of great interest, considering the therapeutic applications of isoquercitrin and quercetin. The specific biotransformation of rutin to isoquercitrin and quercetin, using the crude enzyme from Rhodopseudomonas palustris, may potentially serve as a new method for industrial production of isoquercitrin and quercetin.

Actions of Quercetin, a Polyphenol, on Blood Pressure

Disorder of blood pressure control causes serious diseases in the cardiovascular system. This review focuses on the anti-hypertensive action of quercetin, a flavonoid, which is one of the polyphenols characterized as the compounds containing large multiples of phenol structural units, by varying the values of various blood pressure regulatory factors, such as vascular compliance, peripheral vascular resistance, and total blood volume via anti-inflammatory and anti-oxidant actions. In addition to the anti-inflammatory and anti-oxidant actions of quercetin, we especially describe a novel mechanism of quercetin’s action on the cytosolic Cl⁻ concentration ([Cl⁻]_c) and novel roles of the cytosolic Cl⁻ i.e., (1) quercetin elevates [Cl⁻]_c by activating Na⁺-K⁺-2Cl⁻ cotransporter 1 (NKCC1) in renal epithelial cells contributing to Na⁺ reabsorption via the epithelial Na⁺ channel (ENaC); (2) the quercetin-induced elevation of [Cl⁻]_c in renal epithelial cells diminishes expression of ENaC leading to a decrease in renal Na⁺ reabsorption; and (3) this reduction of ENaC-mediated Na⁺ reabsorption in renal epithelial cells drops volume-dependent elevated blood pressure. In this review, we introduce novel, unique mechanisms of quercetin’s anti-hypertensive action via activation of NKCC1 in detail.

Wine lees modulate lipid metabolism and induce fatty acid remodelling in zebrafish

This study investigates the ability of a polyphenolic extract obtained from a wine lees by-product to modulate zebrafish lipid metabolism.

Quercetin and derivatives: useful tools in inflammation and pain management

Inflammation represents a very frequent condition in humans; it is often underestimated, making the problem an increasingly alarming phenomenon. For these reasons, conventional therapies are losing their effectiveness, leaving room for innovative therapies. In this field, natural products showed their efficacy in various diseases; and flavonoids, in particular quercetin, is known for its broad range of activities. In this review, we have highlighted its efficacy in various models of inflammation, focusing also on the activity of its semisynthetic derivatives, and those naturally present in plant extracts. Finally, the analgesic property of quercetin, intrinsically linked to its anti-inflammatory action, has been also evaluated, to investigate about an innovative approach to this interesting natural compound, such as analgesic remedial.

Chitosan nanoparticles plus quercetin suppress the oxidative stress, modulate DNA fragmentation and gene expression in the kidney of rats fed ochratoxin A-contaminated diet

This study aimed to evaluate the protective role of chitosan nanoparticles (COS-NPs) singly or plus quercetin (Q) against OTA-induced oxidative stress and renal genotoxicity. Twelve groups of male Sprague-Dawley rats were treated orally for 3 weeks included the control group, animals fed OTA-contaminated diet (3 mg/kg diet); COS-NPs-treated groups at low (140 mg/kg b.w.) or high (280 mg/kg b.w.) dose, Q-treated group (50 mg/kg b.w.), Q plus low or high dose of COS-NPs-treated groups and OTA plus Q and/or COS-NPs at the two tested doses-treated groups. The results indicated that COS-NPs were roughly rod in shape with average particle size of 200 nm and zeta potential 31.4 ± 2.8 mV. Animals fed OTA-contaminated diet showed significant changes in serum biochemical parameters, increase kidney MDA and DNA fragmentation and decreased GPx and SOD gene expression accompanied with severe histological changes. Q and/or COS-NPs at the two tested doses induced significant improvements in all tested parameters and succeeded to overcome these effects especially in the animals treated with Q plus the high dose of COS-NPs. It could be concluded that COS-NPs are promise candidate to enhance the antioxidant effect of Q and protect against the nephrotoxicity of OTA in high endemic areas.