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Home > Anti-aging Research > Quercetin


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  • Red onions pack a cancer-fighting punch, study reveals - Science Daily, 6/7/17 - "the study involved placing colon cancer cells in direct contact with quercetin extracted from the five different onion varieties ... We found onions are excellent at killing cancer cells" - See quercetin at Amazon.com.
  • Resveratrol, quercetin could provide new options for cancer therapy - Science Daily, 7/16/15 - "The co-administration of high levels of resveratrol and quercetin, in both in vitro and in vivo studies, shows that it significantly reduces the cardiac toxicity of Adriamycin," Alani said. "And these compounds have a synergistic effect that enhances the efficacy of the cancer drug, by sensitizing the cancer cells to the effects of the drug." - See ReserveAge Resveratrol Vegetarian Capsules, 500 Mg, 60-Count at Amazon.com and quercetin at Amazon.com.
  • New class of drugs dramatically increases healthy lifespan, mouse study suggests - Science Daily, 3/9/15 - "like cancer cells, senescent cells have increased expression of "pro-survival networks" that help them resist apoptosis or programmed cell death. This finding provided key criteria to search for potential drug candidates ... Using these criteria, the team homed in on two available compounds -- the cancer drug dasatinib (sold under the trade name Sprycel®) and quercetin, a natural compound sold as a supplement that acts as an antihistamine and anti-inflammatory ... The two compounds had different strong points. Dasatinib eliminated senescent human fat cell progenitors, while quercetin was more effective against senescent human endothelial cells and mouse bone marrow stem cells. A combination of the two was most effective overall ... In animal models, the compounds improved cardiovascular function and exercise endurance, reduced osteoporosis and frailty, and extended healthspan"
  • Antioxidant may boost exercise endurance - msnbc.com, 6/29/09 - "Compared with days of no supplementation, the quercetin supplement periods were associated with a modest — nearly 4 percent — increase in maximum oxygen uptake. Quercetin was also associated with a 13 percent increase in "ride time" before the volunteers were too fatigued to continue"
  • Quercetin Inhibits Path to Myocardial Ischemia-Reperfusion Injury - Medscape, 3/16/09 - "The naturally occurring flavone quercetin inhibits mRNA and protein expression of several components involved in the pathophysiology of myocardial ischemia-reperfusion injury in rabbits"
  • Cranberry extracts may prevent colon cancer: Lab study - Nutra USA, 2/13/09 - "These findings are important because they demonstrate that the F-κB signalling pathway provides a potential mechanistic link between inflammation and cancer and that the anti-inflammatory properties of crude cranberry extract or quercetin can be used to modulate this pathway" - See cranberry extract at Amazon.com.
  • Flavonoids’ heart health benefits in the blood vessels: Study - Nutra USA, 10/10/08 - "A daily dose of quercetin or (-)-epicatechin led to improvements in endothelial function, a key marker of cardiovascular health" - [Abstract]
  • Substance Found In Fruits And Vegetables Reduces Likelihood Of The Flu - Science Daily, 0/3/08 - "Mice that exercised and took quercetin had nearly the same rate of illness as those that did not exercise. In other words, quercetin canceled out the negative effect of stressful exercise ... Although this study was done with mice, a recent human study found that people who took quercetin suffered fewer illnesses following three days of exhaustive exercise compared to those who did not"
  • Veggies, Exercise May Cut Cancer Risk - WebMD, 4/15/08 - "People who ate quercetin-rich foods at least four times a week, on average, were 51% less likely to have lung cancer than those who ate none"
  • Onion compound linked to lower blood pressure - Nutra USA, 10/23/07 - "receive a daily supplement of quercetin (730 mg, USANA Health Sciences) or placebo for 28 days ... the hypertensives receiving the quercitin supplement experienced reductions in systolic and diastolic BP of seven and five mmHg, respectively, compared to placebo"
  • Chemical in Curry May Cut Colon Cancer - WebMD, 8/2/06 - "Each of the patients then received 480 milligrams of curcumin and 20 milligrams of quercetin three times a day for six months ... The results showed that treatment with the curry and onion compounds reduced the average number of polyps by 60%, and decreased their size by 50%" - See curcumin supplements at Amazon.com and iHerb quercetin products.
  • Apples May Ward Off Alzheimer's Disease - WebMD, 11/18/04 - "The results suggest that quercetin "contributes significantly" to the protection of brain cells from free radicals in conditions like Alzheimer's disease"
  • Mediterranean diet 'extends life' - bbc.co.uk. 8/24/03 - "The[y] found that quercetin, which is abundant in olive oil, has a similar effect"
  • Drinking Tea May Help Prevent Heart Attacks - Doctor's Guide, 5/9/02 - "Drinking more tea and increasing flavonoid intake may help primary prevention of ischaemic heart disease ... The intake of the dietary flavonoids quercetin, kaempferol and myricetin was significantly associated inversely with fatal myocardial infarction only in upper tertiles of intake"
  • Quercetin Relieves Prostate Pain - Nutrition Science News, 7/01
  • Quercetin Is Promising for Chronic Prostatitis - Nutrition Science News, 4/01 - "an encouraging 59 percent of the subjects improved"
  • Canceling Cancer: New Cancer Prevention Strategies on the Horizon - WebMD, 3/26/01 - "Xing has shown that quercetin blocks androgen receptors when applied to cancer cells in the laboratory ... We are very excited by our finding that the new approach quercetin [can be used] in the fight against prostate cancer"
  • Eating apples improves lung function - Doctor's Guide, 1/26/00 - "Apples are high in the antioxidant flavoid quercetin. This antioxidant is also found in onions, tea and red wine and it may be important in protecting the lungs from the harmful effects of atmospheric pollution and cigarette smoke"
  • New Study Offers Hope for Chronic Prostatitis Treatment - Medscape, 1/00 - "More than 80% of chronic prostatitis patients who took a proprietary formulation of quercetin, a natural dietary supplement, significantly reduced pain and improved their quality of life, according to a new study published in the December issue of Urology"


  • Sequential Therapy of Breast Cancer Cell Lines with Vitamin C and Quercetin Improves the Efficacy of Chemotherapeutic Drugs - Nutr Cancer. 2017 Jul 25:1-11 - "Prevention by antioxidant agents including vitamin C (VC) and quercetin (QU), which are nontoxic, cost effective, and physiologically bioavailable, is a promising approach in breast cancer handling ... Our results emphasized the importance of VC+QU in combination with the drugs to produce a synergistic antitumor effect in breast cancer cells" - See American Health Products - Ester C W/Citrus Bioflavonoids, 1000 mg, 180 veg tablets at Amazon.com and quercetin at Amazon.com.
  • Effects of supplementation with quercetin on plasma C-reactive protein concentrations: a systematic review and meta-analysis of randomized controlled trials - Eur J Clin Nutr. 2017 May 24 - "The meta-analysis of seven RCTs (10 treatment arms) showed a significant reduction of circulating CRP levels (WMD: -0.33 mg/l; 95% CI: -0.50 to -0.15; P<0.001) following quercetin supplementation" - See quercetin at Amazon.com.  Note:  Remember when CRP was the cover article on Time Magazine.  Now everyone seems to have forgotten about it.
  • The Effect of Quercetin on Inflammatory Factors and Clinical Symptoms in Women with Rheumatoid Arthritis: A Double-Blind, Randomized Controlled Trial - J Am Coll Nutr. 2016 Oct 6:1-7 - "Five hundred milligrams per day quercetin supplementation for 8 weeks resulted in significant improvements in clinical symptoms, disease activity, hs-TNFα, and HAQ in women with RA" - See quercetin at Amazon.com.
  • Molecular Targets Underlying the Anticancer Effects of Quercetin: An Update - Nutrients. 2016 Aug 29;8(9). pii: E529 - "Numerous pharmacological effects of quercetin include protection against diseases, such as osteoporosis, certain forms of malignant tumors, and pulmonary and cardiovascular disorders. Quercetin has the special ability of scavenging highly reactive species, such as hydrogen peroxide, superoxide anion, and hydroxyl radicals. These oxygen radicals are called reactive oxygen species, which can cause oxidative damage to cellular components, such as proteins, lipids, and deoxyribonucleic acid. Various oxygen radicals play important roles in pathophysiological and degenerative processes, such as aging"
  • Quercetin, not caffeine, is a major neuroprotective component in coffee - Neurobiol Aging. 2016 Jul 5;46:113-123 - "Epidemiologic studies indicate that coffee consumption reduces the risk of Parkinson's disease and Alzheimer's disease ... quercetin reduced oxidative/nitrative damage to DNA, as well as to the lipids and proteins of SH-SY5Y cells. There was a resultant increase in [GSH]i in SH-SY5Y cells. The data indicate that quercetin is the major neuroprotective component in coffee against Parkinson's disease and Alzheimer's disease"
  • Quercetin lowers plasma uric acid in pre-hyperuricaemic males: a randomised, double-blinded, placebo-controlled, cross-over trial - Br J Nutr. 2016 Jan 20:1-7 - "The intervention included one tablet containing 500 mg quercetin daily for 4 weeks, compared with placebo, with a 4-week washout period between treatments ... After quercetin treatment, plasma uric acid concentrations were significantly lowered by -26·5 µmol/l (95 % CI, -7·6, -45·5; P=0·008), without affecting fasting glucose, urinary excretion of uric acid or blood pressure"
  • Quercetin Attenuates Chronic Ethanol-Induced Hepatic Mitochondrial Damage through Enhanced Mitophagy - Nutrients. 2016 Jan 5;8(1) - "Quercetin alleviated ethanol-elicited mitochondrial damage through enhancing mitophagy, highlighting a promising preventive strategy for alcoholic liver disease"
  • The Combination of Resveratrol and Quercetin Attenuates Metabolic Syndrome in Rats by Modifying the Serum Fatty Acid Composition and by Upregulating SIRT 1 and SIRT 2 Expression in White Adipose Tissue - Evid Based Complement Alternat Med. 2015;2015:474032 - "Resveratrol (RSV) and quercetin (QRC) modify energy metabolism and reduce cardiovascular risk factors included in the metabolic syndrome (MetS). These natural compounds upregulate and activate sirtuins (SIRTs), a family of NAD-dependent histone deacetylases ... In MetS rats body mass, central adiposity, insulin, triglycerides, non-HDL-C, leptin, adiponectin, monounsaturated fatty acids (MUFAs), and nonesterified fatty acids (NEFAs) were increased, while polyunsaturated fatty acids (PUFAs) and HDL-C were decreased. SIRT 1 and SIRT 2 were downregulated, while PPAR-γ was increased. RSV + QRC administration improved the serum health parameters modified by MetS and upregulate SIRT 1 and SIRT 2 expression in white abdominal tissue in MetS animals" - See ReserveAge Resveratrol Vegetarian Capsules, 500 Mg, 60-Count at Amazon.com and quercetin at Amazon.com.
  • Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial - Br J Nutr. 2015 Sep 2 - "randomised to receive 162 mg/d quercetin from onion skin extract powder or placebo in a double-blinded, placebo-controlled cross-over trial with 6-week treatment periods ... In the total group, quercetin did not significantly affect 24 h ABP parameters and office BP. In the subgroup of hypertensives, quercetin decreased 24 h systolic BP by -3.6 mmHg (P=0·022) when compared with placebo (mean treatment difference, -3.9 mmHg; P=0.049). In addition, quercetin significantly decreased day-time and night-time systolic BP in hypertensives, but without a significant effect in inter-group comparison ... In conclusion, supplementation with 162 mg/d quercetin from onion skin extract lowers ABP in patients with hypertension, suggesting a cardioprotective effect of quercetin"
  • Quercetin mitigates fenitrothion-induced testicular toxicity in rats - Andrologia. 2015 Aug 11 - "Fenitrothion (FNT) is a widely used organophosphorus pesticide in agriculture. Quercetin (QR), a plant-derived flavonoid, has a free radical scavenging property ... FNT administration caused significant decreases in sperm count, motility and hormonal levels, a significant increase in abnormal sperm morphology and a significant down-regulation of steroidogenic and antioxidant genes in the testis. However, QR administration ameliorated FNT-induced toxic effects. Our results concluded that QR effectively mitigated testicular damage induced by FNT in rats"
  • Quercetin reduces eIF2α phosphorylation by GADD34 induction - Neurobiol Aging. 2015 May 15 - "After the long-term feeding of quercetin, deterioration in memory assessed by freezing behavior was delayed in APP23 mice. These results indicate that quercetin may reduce eIF2α phosphorylation and ATF4 expression through GADD34 induction in the brain, leading to the improvement of memory in aged mice and the delay of deterioration in memory at the early stage of AD in AD model mice"
  • Quercetin ameliorates polychlorinated biphenyls-induced testicular DNA damage in rats - Andrologia. 2015 Apr 19 - "Polychlorinated biphenyls (PCBs) are a group of environmental contaminants widely reported to cause gonadal toxicity in both humans and animals ... Quercetin cotreatment significantly improved the testicular antioxidant status, decreased DNA fragmentation and restored the testicular histology, thus demonstrating the protective effect of quercetin in PCBs-treated rats"
  • Quercetin Inhibits Proliferation and Drug Resistance in KB/VCR Oral Cancer Cells and Enhances Its Sensitivity to Vincristine - Nutr Cancer. 2014 Dec 16:1-11 - "This study provided evidence that quercetin induced apoptosis and reversed drug resistance in oral tumor cells and may be a potential candidate for other tumors treatment"
  • Renoprotective, anti-oxidative and anti-apoptotic effects of oral low-dose quercetin in the C57BL/6J model of diabetic nephropathy - Lipids Health Dis. 2014 Dec 6 - "Taken together, these data show that quercetin effectively attenuated STZ-induced cytotoxicity in renal tissue. This study provides convincing experimental evidence and perspectives on the renoprotective effects of quercetin in diabetic mice and outlines a novel therapeutic strategy for this flavonoid in the treatment of DN"
  • Quercetin Inhibits Advanced Glycation End Product Formation by Trapping Methylglyoxal and Glyoxal - J Agric Food Chem. 2014 Nov 20 - "We also revealed that in the bovine serum albumin (BSA)-MGO/GO system, quercetin traps MGO and GO directly then significantly inhibit the formation of AGEs"
  • Multi-target effects of Quercetin in Leukemia - Cancer Prev Res (Phila). 2014 Oct 7 - "The antitumor activity of quercetin both in vitro and in vivo revealed in this study, point to quercetin as an attractive antitumor agent for hematological malignancies"
  • Quercetin prevents docetaxel-induced testicular damage in rats - Andrologia. 2014 Mar 6 - "the administration of docetaxel induced the testicular damage (oxidative stress, testes tissue damage and sperm parameters), and quercetin prevented docetaxel-induced testicular damage in rats" - See quercetin at Amazon.com.
  • Site-Specific Anticancer Effects of Dietary Flavonoid Quercetin - Nutr Cancer. 2013 Dec 30 - "Food-derived flavonoid quercetin, widely distributed in onions, apples, and tea, is able to inhibit growth of various cancer cells indicating that this compound can be considered as a good candidate for anticancer therapy. Although the exact mechanism of this action is not thoroughly understood, behaving as antioxidant and/or prooxidant as well as modulating different intracellular signalling cascades may all play a certain role. Such inhibitory activity of quercetin has been shown to depend first of all on cell lines and cancer types; however, no comprehensive site-specific analysis of this effect has been published. In this review article, cytotoxicity constants of quercetin measured in various human malignant cell lines of different origin were compiled from literature and a clear cancer selective action was demonstrated. The most sensitive malignant sites for quercetin revealed to be cancers of blood, brain, lung, uterine, and salivary gland as well as melanoma whereas cytotoxic activity was higher in more aggressive cells compared to the slowly growing cells showing that the most harmful cells for the organism are probably targeted"
  • Chemopreventive Effect of Quercetin in MNU and Testosterone Induced Prostate Cancer of Sprague-Dawley Rats - Nutr Cancer. 2013 Dec 9 - "male Sprague-Dawley rats were induced prostate cancer by hormone (testosterone) and carcinogen (MNU) and simultaneously supplemented with quercetin (200 mg/Kg body weight) thrice a week ... The study concluded that dietary quercetin prevented MNU + T-induced prostate carcinogenesis on both ventral and dorsolateral lobes of Sprague-Dawley rats"
  • Quercetin prevents liver carcinogenesis by inducing cell cycle arrest, decreasing cell proliferation and enhancing apoptosis - Mol Nutr Food Res. 2013 Oct 1 - "Adult male Wistar rats were subjected to a two-phase model of hepatocarcinogenesis (initiated-promoted group). Initiated-promoted animals also received quercetin 10 and 20 mg/kg body weight (IPQ10 and IPQ20 groups, respectively). Antioxidant defenses were modified by quercetin administration at both doses. However, only IPQ20 group showed a reduction in number and volume of preneoplastic lesions. This group showed increased apoptosis and a reduction in the proliferative index"
  • Chemopreventive effect of quercetin, a natural dietary flavonoid on prostate cancer in in vivo model - Clin Nutr. 2013 Sep 3 - "the rats were divided into four groups; Group I: control (propylene glycol-vehicle), Group II: cancer-induced (MNU and Testosterone treated) rats, Group III: cancer-induced + Quercetin (200 mg/kg body wt/orally) and Group IV: Quercetin (200 mg/kg body wt) thrice a week ... Quercetin down regulates the cell survival, proliferative and anti-apoptotic proteins thereby prevents prostate cancer, by acting as a chemopreventive agent in preclinical model"
  • Quercetin Protects Mouse Brain against Lead-induced Neurotoxicity - J Agric Food Chem. 2013 Jul 15 - "Mice were exposed to lead acetate (20 mg/kg body weight/day) intragastrically with or without QE (15 and 30 mg/kg body weight/day) co-administration for three months. Our data showed that QE significantly prevented Pb-induced neurotoxicity in a dose-dependent manner. In exploring the underlying mechanisms of QE action, we found QE administration decreased Pb contents in blood (13.2%, 19.1%) and brain (17.1%, 20.0%). QE markedly increased NO production (39.1%, 61.1%) and PKA activity (51.0%, 57.8%) in brains of Pb-treated mice. Additionally, QE remarkably suppressed Pb-induced oxidative stress in mouse brain. Western blot analysis showed that QE increased the phosphorylations of Akt, CaMKII nNOS, eNOS and CREB in brains of Pb-treated mice" - See quercetin at Amazon.com.
  • Quercetin Potentiates Apoptosis by Inhibiting Nuclear Factor-kappaB Signaling in H460 Lung Cancer Cells - Biol Pharm Bull. 2013;36(6):944-951 - "The herbal flavonoid quercetin inhibits the growth of various cancer cells, but how it affects human cancer cells, particularly lung cancer cells, is unclear ... Taken together, these findings suggest that quercetin may be useful in the prevention and therapy of NSCLC"
  • Resveratrol and Quercetin in Combination Have Anticancer Activity in Colon Cancer Cells and Repress Oncogenic microRNA-27a - Nutr Cancer. 2013 Apr;65(3):494-504 - "Resveratrol and quercetin (RQ) in combination (1:1 ratio) previously inhibited growth in human leukemia cells. This study investigated the anticancer activity of the same mixture in HT-29 colon cancer cells. RQ decreased the generation of reactive oxygen species (ROS) by up to 2.25-fold and increased the antioxidant capacity by up to 3-fold in HT-29 cells (3.8-60 μg/mL), whereas IC50 values for viability were 18.13, 18.73, and 11.85 μg/mL, respectively. RQ also induced caspase-3-cleavage (2-fold) and increased PARP cleavage. Specificity protein (Sp) transcription factors are overexpressed in colon and other cancers and regulate genes required for cell proliferation survival and angiogenesis" - See resveratrol products at Amazon.com and quercetin at Amazon.com.
  • Quercetin Induces Apoptosis via Mitochondrial Pathway in KB and KBv200 cells - J Agric Food Chem. 2013 Feb 14 - "In this study, anticancer activities of six compounds of flavonoids were investigated in human epidermoid carcinoma KB and KBv200 cells. Among these compounds, quercetin and acacetin showed strong inhibition of cell growth in KB and KBv200 cells"
  • Dietary fat increases quercetin bioavailability in overweight adults - Mol Nutr Food Res. 2013 Jan 15 - "Epidemiologic evidence supports that dietary quercetin reduces cardiovascular disease (CVD) risk, but its oral bioavailability is paradoxically low. The aim of this study was to determine whether dietary fat would improve quercetin bioavailability in adults at high risk for CVD and to assess lipid-mediated micellarization of quercetin in vitro ... In a randomized, cross-over study, overweight/obese men and postmenopausal women (n = 4 M/5 F; 55.9 +/- 2.1 years; 30.8 +/- 1.4 kg/m(2) ) ingested 1095 mg of quercetin aglycone with a standardized breakfast that was fat-free (<0.5 g), low-fat (4.0 g), or high-fat (15.4 g) ... Compared to the fat-free trial, plasma quercetin maximum concentration (C(max) ), and area under curve (AUC(0-24 h) ) increased (p < 0.05) by 45 and 32%, respectively, during the high-fat trial"
  • Protective Effects of Quercetin on Streptozotocin-induced Diabetic Nephropathy in Rats - Phytother Res. 2012 Dec 27 - "Diabetic nephropathy (DN) is an important microvascular complication and one of the main causes of end-stage renal disease. In this study, we examined the protective effects of quercetin on DN in streptozotocin-induced diabetic rats ... Compared with the levels in the DN group, quercetin decreased the levels of fasting blood glucose, creatinine, blood urea nitrogen, and urine protein, and the intensity of oxidative stress decreased significantly. Quercetin significantly inhibited the expression of advanced glycosylation end products, collagen IV, laminin, connective tissue growth factor, Smad 2/3, and transforming growth factor-β(1) mRNA. Moreover, quercetin was observed to inhibit proliferation of mesangial cells and decrease thickness of glomerular basement membrane. Those results suggest that quercetin has protective effects on several pharmacological targets in the progress of DN and is a potential drug for the prevention of early DN"
  • Quercetin protects against pulmonary oxidant stress via heme oxygenase-1 induction in lung epithelial cells - Biochem Biophys Res Commun. 2011 Nov 25 - "In the present study, we showed that quercetin increased the levels of heme oxygenase (HO)-1 expression and protected against hydroxy peroxide (H(2)O(2))-induced cytotoxicity in lung epithelial cell lines. Quercetin suppressed H(2)O(2)-induced apoptotic events, including hypodiploid cells, activation of caspase 3 enzyme activity and lactate dehydrogenase release. This cytoprotective effect was attenuated by the addition of the HO inhibitor, tin protoporphyrin IX. In addition, the end products of heme metabolites catalyzed by HO-1, carbon monoxide and bilirubin, protect against H(2)O(2)-induced cytotoxicity in LA-4 cells. Quercetin may well be one of the promising substances to attenuate oxidative epithelial cell injury in lung inflammation"
  • Anti-inflammatory, anti-proliferative and anti-atherosclerotic effects of quercetin in human in vitro and in vivo models - Atherosclerosis. 2011 May 5 - "In cultured human endothelial cells, quercetin protected against H(2)O(2)-induced lipid peroxidation and reduced the cytokine-induced cell-surface expression of VCAM-1 and E-selectin. Quercetin also reduced the transcriptional activity of NFκB in human hepatocytes. In human CRP transgenic mice (quercetin plasma concentration: 12.9+/-1.3μM), quercetin quenched IL1β-induced CRP expression, as did sodium salicylate. In ApoE*3Leiden mice, quercetin (plasma concentration: 19.3+/-8.3μM) significantly attenuated atherosclerosis by 40% (sodium salicylate by 86%). Quercetin did not affect atherogenic plasma lipids or lipoproteins but it significantly lowered the circulating inflammatory risk factors SAA and fibrinogen. Combined histological and microarray analysis of aortas revealed that quercetin affected vascular cell proliferation thereby reducing atherosclerotic lesion growth. Quercetin also reduced the gene expression of specific factors implicated in local vascular inflammation including IL-1R, Ccl8, IKK, and STAT3 ...Quercetin reduces the expression of human CRP and cardiovascular risk factors (SAA, fibrinogen) in mice in vivo. These systemic effects together with local anti-proliferative and anti-inflammatory effects in the aorta may contribute to the attenuation of atherosclerosis"
  • Quercetin's Effects on Intestinal Polyp Multiplicity and Macrophage Number in the Apc(Min/+) Mouse - Nutr Cancer. 2011 Mar 1:1 - "Numerous in vitro studies argue for quercetin's chemopreventive potential in colon cancer; however, experimental studies in rodents are limited. Macrophages play a role in tumorigenesis, but the effects of quercetin on macrophage infiltration in colon cancer is unknown. We examined the effects of quercetin on intestinal polyp multiplicity and macrophage number in Apc(Min/+) mice ... These data suggest that quercetin can reduce polyp number and size distribution in the Apc(Min/+) mouse and that these effects may be related to a reduction in macrophage infiltration"
  • The Flavonoid Quercetin Modulates the Hallmark Capabilities of Hamster Buccal Pouch Tumors - Nutr Cancer. 2011 Feb 2:1 - "Epidemiological studies have consistently demonstrated the protective effects of dietary phytochemicals against cancer risk. Quercetin, a ubiquitous dietary flavonoid, has attracted considerable attention owing to its potent antioxidant and antiproliferative activities ... Simultaneous administration of quercetin to DMBA-painted hamsters reduced tumor incidence and tumor burden, while posttreatment of quercetin resulted in a significant tumor growth delay. In addition, quercetin administration induced cell cycle arrest and apoptosis and blocked invasion and angiogenesis. We found a positive correlation between the inhibition of HDAC-1 and DNMT1 by quercetin and its anticancer properties. A dietary phytochemical such as quercetin that modulates a plethora of molecules offers promise as an ideal candidate for multitargeted cancer prevention and therapy"
  • Quercetin is equally or more effective than resveratrol in attenuating tumor necrosis factor-{alpha}-mediated inflammation and insulin resistance in primary human adipocytes - Am J Clin Nutr. 2010 Oct 13 - "These data suggest that quercetin is equally or more effective than trans-RSV in attenuating TNF-α-mediated inflammation and insulin resistance in primary human adipocytes"
  • Dietary flavonoid intake and colorectal cancer: a case-control study - Br J Nutr. 2009 Sep 7:1-8 - "We concluded that flavonols, specifically quercetin, obtained from non-tea components of the diet may be linked with reduced risk of developing colon cancer"
  • Inhibition of UVA and UVB radiation-induced lipid oxidation by quercetin - J Agric Food Chem. 2009 Jun 24;57(12):5301-5 - "Quercetin, which absorbs UV radiation at 255 and 365 nm, was determined to be a stronger inhibitor of lipid oxidation induced by UVB (3.7 radicals scavenged per molecule) than by lipid oxidation induced by UVA (1.9 radicals scavenged per molecule). The values for inhibition of UVB-induced lipid oxidation by quercetin are comparable to those when 2,2'-azobis(2-amidinopropane) was used as an oxidizing system (four radicals scavenged per molecule). The protective effect of quercetin appears to be mainly the result of scavenging of UV-generated radical species, although this may be decreased slightly in the UVA as a result of its absorption at 365 nm"
  • Quercetin inhibits fatty acid and triacylglycerol synthesis in rat-liver cells - Eur J Clin Invest. 2009 Jun 8 - "In hepatocytes from normal rats, the quercetin-induced decrease in both de novo fatty acid and TAG synthesis, with a consequent reduction in VLDL-TAG formation, may represent a potential mechanism contributing to the reported hypotriacylglycerolemic effect of quercetin"
  • Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebo-controlled cross-over study - Br J Nutr. 2009 Apr 30:1-10 - "Subjects were randomised to receive 150 mg quercetin/d in a double-blinded, placebo-controlled cross-over trial with 6-week treatment periods separated by a 5-week washout period. Mean fasting plasma quercetin concentrations increased from 71 to 269 nmol/l (P < 0.001) during quercetin treatment. In contrast to placebo, quercetin decreased systolic blood pressure (SBP) by 2.6 mmHg (P < 0.01) in the entire study group, by 2.9 mmHg (P < 0.01) in the subgroup of hypertensive subjects and by 3.7 mmHg (P < 0.001) in the subgroup of younger adults aged 25-50 years. Quercetin decreased serum HDL-cholesterol concentrations (P < 0.001), while total cholesterol, TAG and the LDL:HDL-cholesterol and TAG:HDL-cholesterol ratios were unaltered. Quercetin significantly decreased plasma concentrations of atherogenic oxidised LDL, but did not affect TNF-alpha and C-reactive protein when compared with placebo ... Blood parameters of liver and kidney function, haematology and serum electrolytes did not reveal any adverse effects of quercetin. In conclusion, quercetin reduced SBP and plasma oxidised LDL concentrations in overweight subjects with a high-CVD risk phenotype. Our findings provide further evidence that quercetin may provide protection against CVD"
  • Quercetin up-regulates paraoxonase 1 gene expression with concomitant protection against LDL oxidation - Biochem Biophys Res Commun. 2009 Jan 10 - "Compared to the pair-fed control group, feeding quercetin (10mg/L) in the liquid diet for 4 weeks increased (a) hepatic expression of PON1 by 35% (p<0.01), (b) serum and liver PON1 activities by 29% (p<0.05) and 57% (p<0.01), respectively, and (c) serum homocysteine thiolactonase (HCTL) activity by 23% (p<0.05). Correspondingly, the lag time of low-density lipoprotein (LDL) oxidation was increased by >3-fold (p<0.001) with plasma HDL from quercetin-fed group compared to the HDL from control group. Our data suggest that quercetin has antiatherogenic effect by up regulating PON1 gene expression and its protective capacity against LDL oxidation"
  • Protective Effect of Quercetin against Gentamicin-Induced Nephrotoxicity in Rats - Pharm Bull. 2009 Jan;32(1):61-7 - "Gentamicin (GM) is an antibiotic widely used in treating severe gram-negative infections. However, its clinical use is limited by its nephrotoxicity ... Histopathological examination of GM-treated rats revealed degenerative changes in glomeruli and tubules. On the other hand, simultaneous administration of quercetin plus gentamicin protected kidney tissues against nephrotoxic effects of gentamicin as evidenced from amelioration of histopathological changes and normalization of kidney biochemical parameters"
  • Pure dietary flavonoids quercetin and (-)-epicatechin augment nitric oxide products and reduce endothelin-1 acutely in healthy men - Am J Clin Nutr. 2008 Oct;88(4):1018-25 - "Dietary flavonoids, such as quercetin and (-)-epicatechin, can augment nitric oxide status and reduce endothelin-1 concentrations and may thereby improve endothelial function"
  • Serum C-reactive protein concentrations are inversely associated with dietary flavonoid intake in u.s. Adults - J Nutr. 2008 Apr;138(4):753-60 - "Among the flavonoid compounds investigated, quercetin, kaempferol, malvidin, peonidin, daidzein, and genistein had inverse associations with serum CRP concentration"
  • Quercetin inhibits vascular superoxide production induced by endothelin-1: Role of NADPH oxidase, uncoupled eNOS and PKC - Atherosclerosis. 2008 Mar 16 - "Chronic administration of the most abundant dietary flavonoid quercetin exerts antihypertensive effects and improves endothelial function ... endothelin-1 (ET-1, 10nM). ET-1 increased the contractile response induced by phenylephrine and reduced the relaxant responses to acetylcholine in phenylephrine contracted intact aorta, and these effects were prevented by co-incubation with quercetin, isorhamnetin or chelerythrine (protein kinase C (PKC) inhibitor). This endothelial dysfunction was also improved by superoxide dismutase (SOD), apocynin (NADPH oxidase inhibitor) and sepiapterin (tetrahydrobiopterin synthesis substrate). Furthermore, ET-1 increased intracellular O(2)(-) production in all layers of the vessel, protein expression of NADPH oxidase subunit p47(phox) without affecting p22(phox) expression and lucigenin-enhanced chemiluminescence signal stimulated by calcium ionophore A23187. All these changes were prevented by both quercetin and isorhamnetin. Moreover, apocynin, endothelium denudation and N(G)-nitro-l-arginine methylester (l-NAME, nitric oxide synthase inhibitor) suppressed the ET-1-induced increase in A23187-stimulated O(2)(-) generation. Moreover, quercetin but not isorhamnetin, inhibited the increased PKC activity induced by ET-1"
  • The flavonoid luteolin inhibits niacin-induced flush - Br J Pharmacol. 2008 Jan 28 - "Sustained release niacin effectively lowers serum cholesterol, LDL and triglycerides, while raising HDL. However, 75% of patients experience cutaneous warmth and itching known as flush, leading to discontinuation. Acetylsalicylic acid (aspirin) reduces this flush only by about 30% ... Quercetin and luteolin (4.3 mg per rat; 1000 mg per human), administered i.p. 45 min prior to niacin, inhibited the niacin effect by 96 and 88%, respectively. Aspirin (1.22 mg per rat; 325 mg per human) inhibited the niacin effect by only 30%. Niacin almost doubled plasma PGD(2) and 5-HT, but aspirin reduced only PGD(2) by 86%. In contrast, luteolin inhibited both plasma PGD(2) and 5-HT levels by 100 and 67%, respectively"
  • Quercetin selectively inhibits bioreduction and enhances apoptosis in melanoma cells that overexpress tyrosinase - Nutr Cancer. 2007;59(2):258-68 - "quercetin can selectively sensitize Tyr+ expressing melanoma cells to apoptosis and may serve as an adjuvant to chemotherapy by enhancing cell death and interfering with GST-mediated drug resistance"
  • Quercetin reduces blood pressure in hypertensive subjects - J Nutr. 2007 Nov;137(11):2405-11 - "730 mg quercetin/d for 28 d vs. placebo ... reductions in (P < 0.01) systolic (-7 +/- 2 mm Hg), diastolic (-5 +/- 2 mm Hg), and mean arterial pressures (-5 +/- 2 mm Hg) were observed in stage 1 hypertensive patients after quercetin treatment"
  • Comparative effects of quercetin and its predominant human metabolites on adhesion molecule expression in activated human vascular endothelial cells - Atherosclerosis. 2007 Sep 17 - "both quercetin and its metabolites, at physiological concentrations, can inhibit the expression of key molecules involved in monocyte recruitment during the early stages of atherosclerosis"
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