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Home > Anti-aging Research > Quercetin


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  • The good herb: Buckwheat liquor helps cells clean house - Science Daily, 8/16/21 - "When the researchers looked more closely at specific components of tartary buckwheat extract, they found that one component, quercetin, had the same effects as the extract. What's more, both tartary buckwheat extract and quercetin prompted liver cells to clean up protein aggregates through a process known as aggrephagy ... Our findings suggest that tartary buckwheat extract and quercetin induce not only autophagy, but also aggrephagy ... Given that protein aggregates in liver cells are closely linked to alcoholic liver disease, these findings suggest that quercetin could be a useful treatment for patients with this condition. It may also hold promise for treatment of other diseases associated with protein aggregation, such as Alzheimer's" - See quercetin at Amazon.com and iHerb.
  • Molecular 'switch' reverses chronic inflammation and aging - Science Daily, 2/6/20 - "By studying mice and immune cells called macrophages, the team found that a protein called SIRT2 is responsible for deacetylating the NLRP3 inflammasome. Mice that were bred with a genetic mutation that prevented them from producing SIRT2 showed more signs of inflammation at the ripe old age of two than their normal counterparts. These mice also exhibited higher insulin resistance, a condition associated with type 2 diabetes and metabolic syndrome"
  • Tackling Inflammation to Fight Age-Related Ailments - NYT, 12/23/19 - "Specialists in the biology of aging have identified a rarely recognized yet universal condition that is a major contributor to a wide range of common health-robbing ailments, from heart disease, diabetes and cancer to arthritis, depression and Alzheimer’s disease. That condition is chronic inflammation, a kind of low-grade irritant that can undermine the well-being of virtually every bodily system ... recent studies have identified measures potentially available to everyone that can minimize the potency of chronic inflammation and stymie — and possibly even reverse — its progression. The measures will come as no surprise to people familiar with the healthful advice that has been offered in this column for many years: Adopt a wholesome diet (details to follow), get regular exercise, avoid or reduce excess weight, get adequate quality sleep, minimize stress and don’t smoke ... As people age, their immune responses become less well regulated, resulting in elevated blood levels of inflammatory substances like C-reactive protein and chemokines, and allowing inflammatory agents like interleukin-6 (IL-6) and tumor necrosis factor-a (TNF-alpha) to persist in body tissues ... The drug metformin, commonly used to treat Type 2 diabetes, is known to have an anti-inflammatory effect and will be tested for its ability to delay the development of age-related diseases in a forthcoming trial called TAME, the acronym for Targeting Aging with Metformin ... Another consequence of aging is the accumulation of so-called senescent cells, normal cells that stop dividing, contribute to tissue aging and secrete substances like cytokines that induce inflammation. Elimination of senescent cells can counter chronic inflammation, said Steven N. Austad, director of aging studies at the University of Alabama at Birmingham. A combination of two drugs, dasatinib and quercetin, was shown in a Mayo Clinic study in obese mice to remove senescent cells and permit cell growth to resume in the brain ... Dr. Hu recommends frequent consumption of foods known to have an anti-inflammatory effect. They include green leafy vegetables like spinach, kale and collards; fatty fish like salmon, mackerel, tuna and sardines; fruits like strawberries, blueberries, apples, grapes, oranges and cherries; nuts like almonds and walnuts; and olive oil. The recommended plant foods contain natural antioxidants and polyphenols, and the fish are rich in omega-3 fatty acids, all of which counter inflammation ... get regular dental cleanings to control periodontal disease, which can be a source of chronic inflammation ... be judicious in the use of antibiotics, antacids and nonsteroidal anti-inflammatory drugs (NSAIDs) that can disrupt the normally healthy population of microorganisms in the gut and result in “a leaky gut that lets bacteria into circulation and is very pro-inflammatory"
  • 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"
  • 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"


  • The construction of preclinical evidence for the treatment of liver fibrosis with quercetin: A systematic review and meta-analysis - Phytother Res 2022 Aug 2 - "Quercetin (3,3',4',5,7-pentahydroxyflavone), a flavonoid, is widely found in fruits and vegetables and exerts broad-spectrum pharmacological effects in the liver. Many studies have explored the bioactivity of quercetin in the treatment of liver fibrosis ... The results from the analysis showed that the corresponding liver function indexes, such as the levels of HA and LN, were significantly improved in the quercetin group compared with the model group, and liver function, such as the levels of AST and ALT, were also improved in the quercetin group. The species- and model-based subgroup analyses of AST and ALT revealed that quercetin exerts a significant effect. The therapeutic mechanism of quercetin was shown to be related to multiple pathways involving anti-inflammatory and antioxidant activities and lipid accumulation, including regulation of the TGF-β, α-SMA, ROS, and P-AMPK pathways. The results showed that quercetin exerts an obvious effect on liver fibrosis, and more prominent improvement effects on liver function and liver fibrosis indicators were obtained with a dose of 5-200 mg during a treatment course ranging from 4 to 8 weeks. Quercetin might be a promising therapeutic for liver fibrosis" - See quercetin at Amazon.com.
  • Quercetin improves high-fat diet-induced obesity by modulating gut microbiota and metabolites in C57BL/6J mice - Phytother Res 2022 Jul 29 - "High-fat diet-induced obesity is characterized by low-grade inflammation, which has been linked to gut microbiota dysbiosis. We hypothesized that quercetin supplementation would alter gut microbiota and reduce inflammation in obese mice ... Quercetin influenced the production of metabolites that were linked to alterations in obesity-related inflammation and oxidative stress, such as Glycerophospho-N-palmitoyl ethanolamine, sanguisorbic acid dilactone, O-Phospho-L-serine, and P-benzoquinone. Our results demonstrate that the anti-obesity effects of quercetin may be mediated through regulation in gut microbiota and metabolites"
  • Role of Ginseng, Quercetin, and Tea in Enhancing Chemotherapeutic Efficacy of Colorectal Cancer - Front Med (Lausanne) 2022 Jun 20 - "As the most common gastrointestinal malignancy, colorectal cancer (CRC) remains a leading cause of cancer death worldwide. Although multimodal chemotherapy has effectively improved the prognosis of patients with CRC in recent years, severe chemotherapy-associated side effects and chemoresistance still greatly impair efficacy and limit its clinical application. In response to these challenges, an increasing number of traditional Chinese medicines have been used as synergistic agents for CRC administration. In particular, ginseng, quercetin, and tea, three common dietary supplements, have been shown to possess the potent capacity of enhancing the sensitivity of various chemotherapy drugs and reducing their side effects. Ginseng, also named "the king of herbs", contains a great variety of anti-cancer compounds, among which ginsenosides are the most abundant and major research objects of various anti-tumor studies. Quercetin is a flavonoid and has been detected in multiple common foods, which possesses a wide range of pharmacological properties, especially with stronger anti-cancer and anti-inflammatory effects. As one of the most consumed beverages, tea has become particularly prevalent in both West and East in recent years. Tea and its major extracts, such as catechins and various constituents, were capable of significantly improving life quality and exerting anti-cancer effects both in vivo and in vitro" - See ginseng at Amazon.com, quercetin at Amazon.com and green tea extract at Amazon.com.
  • Quercetin ameliorated cardiac injury via reducing inflammatory actions and the glycerophospholipid metabolism dysregulation in a diabetic cardiomyopathy mouse model - Food Funct 2022 Jun 30 - "Quercetin has multiple protective effects against cardiometabolic diseases, but the biological mechanisms underlying the benefits in diabetic cardiomyopathy (DCM) are unclear ... Such findings showed that quercetin may ameliorate cardiac dysfunction and myocardial fibrosis via reducing inflammatory actions and the glycerophospholipid metabolism dysregulation in DCM"
  • Doxorubicin-induced senescence in normal fibroblasts promotes in vitro tumour cell growth and invasiveness: the role of Quercetin in modulating these processes - Mech Ageing Dev 2022 Jun 18 - "Ageing is a complex biological phenomenon representing the major risk factor for developing age-related diseases, such as cardiovascular pathologies, neurodegenerative diseases, and cancer. Geroscience, the new vision of gerontology, identifies cellular senescence as an interconnected biological process that characterises ageing and age-related diseases. Therefore, many strategies have been employed in the last years to reduce the harmful effects of senescence, and among these, the most intriguing ones use nutraceutical compounds. Here we show that a pre-treatment with Quercetin, a bioactive flavonoid present in many fruits and vegetables, increasing cellular antioxidant defence, can alleviate Doxorubicin (Doxo)-induced cellular senescence in human normal WI-38 fibroblasts. Furthermore, our work demonstrates that Quercetin pre-treatment, reducing the number of senescent cells and the production of the senescence-associated secretory phenotype (SASP) factors, can decrease the pro-tumour effects of conditioned medium from Doxo-induced senescent fibroblasts on osteosarcoma cells. Overall, our findings are consistent with the hypothesis that targeting senescent cells can be an emerging strategy for cancer treatment, especially in elderly patients, in which senescent cells are already abundant in several tissues and organs"
  • Quercetin in Tonglong Qibi decoction ameliorates testosterone-induced benign prostatic hyperplasia in rats by regulating Nrf2 signalling pathways and oxidative stress - Andrologia 2022 Jun 20 - "Benign prostatic hyperplasia (BPH) is a common urological disease in older males. Existing pharmacotherapy shows several side effects, and the exploration of new therapeutic strategies is of high significance. Tonglong Qibi (TQ) decoction was proved to ameliorate BPH, while the underlying mechanisms are still unclear. In the current study, we explored the anti-BPH effects of TQ in vivo and identified its main therapeutic component and the underlying mechanisms in vitro. We demonstrated that TQ mitigated BPH in rats and showed no toxicity to the liver and reproductive system. Network pharmacology identified quercetin as the main component in TQ treating BPH. Quercetin reduced proliferation, oxidative stress, and increased Nrf2 expression in hyperplastic prostate epithelial cells. These findings indicate that quercetin in TQ alleviates BPH via inhibiting oxidative stress and activating the Nrf2 signalling pathway"
  • Quercetin attenuates adipogenesis and fibrosis in human skeletal muscle - Biochem Biophys Res Commun 2022 May 14 - "Quercetin suppressed the differentiation of muscle-derived PDGFRα+/CD201+ cells to adipocytes and fibroblasts at concentrations achievable by dietary and dietary supplement intake, which indicated its preventive or therapeutic effect against the loss of muscle quality"
  • Impact of curcumin, quercetin, or resveratrol on the pathophysiology of endometriosis: A systematic review -  Phytother Res 2022 May 18 - "Endometriosis, a gynecological disease that affects reproductive age women is difficultly controlled in the long term by currently available treatments, prompting patients to adopt self-controlled interventions including dietary changes ... By acting on mechanisms of inflammation, oxidative stress, cell proliferation, invasion and adhesion, apoptosis, angiogenesis and glucose and lipid metabolism, curcumin, quercetin, and resveratrol showed to have beneficial effects, evidencing their potential application in the endometriosis treatment" - See curcumin at Amazon.com, quercetin at Amazon.com and resveratrol products at Amazon.com.
  • Curcumin improves the protective effects of quercetin against atrazine-induced testicular injury in adult Wistar rats - Andrologia 2022 Apr 18 - "This study evaluated the beneficial protective effect of cotreatment of curcumin (CUR) and quercetin (QUE) on atrazine (ATZ)-induced testicular toxicity in rats. ATZ challenge diminished luteinizing hormone, follicular stimulating hormone, testosterone and myeloperoxidase enzyme activity, but these effects were attenuated on co-treatment with CUR and QUE. Also, co-treatment of CUR + QUE was better than separate administration of QUE at diminishing malondialdehyde and glutathione and improving tumour necrosis factor-α concentration, germ cell numbers (spermatogonia, spermatocytes and round spermatids) and epididymal sperm quality ... We conclude that CUR can improve the protective effects of QUE against ATZ-induced testicular injury by enhancing the levels of reproductive hormones, recovering testicular biochemical parameters and improving the histological features of the testes" - See curcumin at Amazon.com and quercetin at Amazon.com.
  • The effect of quercetin on diabetic nephropathy (DN): a systematic review and meta-analysis of animal studies - Food Funct 2022 Apr 13 - "Quercetin, a flavonoid possessing numerous biological activities, is reported to improve renal injury in diabetic animals. Here, the aim of this systematic review and meta-analysis is to assess the effect of quercetin on diabetic nephropathy and summarize its possible mechanisms ... Apart from creatinine clearance and uric acid with no significant difference, quercetin significantly decreased the levels of renal index, serum/plasma creatinine (SCr), blood urea nitrogen (BUN), urine protein, urine albumin, malondialdehyde (MDA), tumor necrosis factor (TNF)-α and interleukin (IL)-1β, and increased superoxide dismutase (SOD) and catalase (CAT) activity. In short, quercetin improves renal function and attenuates the renal oxidative stress level and inflammatory response in DN animal models. Its possible action mechanisms include anti-oxidation, anti-inflammation, anti-fibrosis, and regulation of renal lipid accumulation"
  • Antiosteoporosis Studies of 20 Medicine Food Homology Plants Containing Quercetin, Rutin, and Kaempferol: TCM Characteristics, In Vivo and In Vitro Activities, Potential Mechanisms, and Food Functions - Evid Based Complement Alternat Med 2022 Mar 31 - "Dietary nutraceutical compounds have been evidenced as backbone for bone health in recent years. It is reported that medicine food homology (MFH) plants have multiple nutraceutical compounds. Based on our literature research, 20 MFH plants caught our attention because they contain three popular antiosteoporosis compounds simultaneously: quercetin, rutin, and kaempferol ... Based on the above discussion, these 20 MFH plants could be used as daily food supplements for the prevention and treatment against osteoporosis" - See quercetin at Amazon.com, rutin at Amazon.com and Kaempferia parviflora at Amazon.com.
  • A critical evaluation of risk to reward ratio of quercetin supplementation for COVID-19 and associated comorbid conditions - Phytother Res 2022 Apr 8 - "The interim results of the large, multinational trials on coronavirus disease 2019 (COVID-19) using a combination of antiviral drugs appear to have little to no effect on the 28-day mortality or the in-hospital course. Therefore, there is a still vivid interest in finding alternate re-purposed drugs and nutrition supplements, which can halt or slow the disease severity ... The present review is tempting to suggest that, based on circumstantial scientific evidence and preliminary clinical data, the flavonoid quercetin can ameliorate COVID-19 infection and symptoms acting in concert on two parallel and independent paths: inhibiting key factors responsible for SARS-CoV-2 infections and mitigating the clinical manifestations of the disease in patients with comorbid conditions"
  • Therapeutic and prophylactic effect of flavonoids in post-COVID-19 therapy - Phytother Res 2022 Mar 18 - "Based on articles published from 2003 to 2021, we summarize the flavonoids-based molecular mechanisms associated with the post-COVID-19 syndrome and simultaneously provide a complex view regarding their prophylactic and therapeutic potential. Review clearly sorts out the outcome of post-COVID-19 syndrome according particular body systems. The conclusion is that flavonoids play an important role in prevention of many diseases. We suggest that flavonoids as critical nutritional supplements, are suitable for the alleviation and shortening of the period associated with the post-COVID-19 syndrome. The most promising flavonoid with noteworthy therapeutic and prophylactic effect appears to be quercetin"
  • Quercetin boosts nitric oxide levels and modulates the activities of arginase, acetylcholinesterase and adenosine deaminase in the corpus cavernosum of cyclosporine-treated rats - Andrologia 2022 Feb 25 - "One of the primary causes of erectile dysfunction (ED) in males is cardiovascular disease, such as hypertension (HT). As a result, the goal of this study is to see how quercetin (Q) affects the important biochemical parameters (nitric oxide, endogenous antioxidant enzymes)/specific enzymes (arginase, acetylcholinesterase and adenosine deaminase) linked to be responsible for smooth muscle relaxation in respect to sexual function ... Compared to the control group, Q of both concentrations reduced the activity of these enzymes and improved antioxidant status and NO levels"
  • Protective Effects of Quercetin on Clothianidin-Induced Liver Damage in the Rat Model - Evid Based Complement Alternat Med 2022 Jan 18 - "Clothianidin (CTD) is a member of the neonicotinoid group of insecticides ... Total antioxidant capacity (TAC) ... A significant increase in ALT and AST enzyme activity was observed in the CTD group in comparison with that of the control groups. In the clothianidin + quercetin (10 mg/kg) group, the ALT and AST enzyme levels decreased compared to the clothianidin control group significantly ... Quercetin significantly raised the level of TAC in the liver tissue of the clothianidin + quercetin (10 mg/kg) treated group compared to that of the clothianidin control group ... Nitrate-nitrite level in the liver was decreased in clothianidin + quercetin (10 mg/kg) compared to that of the clothianidin control group significantly"
  • Whole-body senescent cell clearance alleviates age-related brain inflammation and cognitive impairment in mice - Aging Cell 2021 Feb - "Cellular senescence is characterized by an irreversible cell cycle arrest and a pro-inflammatory senescence-associated secretory phenotype (SASP), which is a major contributor to aging and age-related diseases. Clearance of senescent cells has been shown to improve brain function in mouse models of neurodegenerative diseases. However, it is still unknown whether senescent cell clearance alleviates cognitive dysfunction during the aging process. To investigate this, we first conducted single-nuclei and single-cell RNA-seq in the hippocampus from young and aged mice. We observed an age-dependent increase in p16Ink4a senescent cells, which was more pronounced in microglia and oligodendrocyte progenitor cells and characterized by a SASP. We then aged INK-ATTAC mice, in which p16Ink4a -positive senescent cells can be genetically eliminated upon treatment with the drug AP20187 and treated them either with AP20187 or with the senolytic cocktail Dasatinib and Quercetin. We observed that both strategies resulted in a decrease in p16Ink4a exclusively in the microglial population, resulting in reduced microglial activation and reduced expression of SASP factors. Importantly, both approaches significantly improved cognitive function in aged mice. Our data provide proof-of-concept for senolytic interventions' being a potential therapeutic avenue for alleviating age-associated cognitive impairment"
    • Dasatinib - Medline Plus - "Dasatinib is used to treat a certain type of chronic myeloid leukemia (CML; a type of cancer of the white blood cells) as a first treatment and in people who can no longer benefit from other leukemia medications including imatinib (Gleevec) or in those who cannot take these medications because of side effects"
  • Quercetin attenuates the cardiotoxicity of doxorubicin-cyclophosphamide regimen and potentiates its chemotherapeutic effect against triple-negative breast cancer - Phytother Res 2021 Dec 23 - "Doxorubicin combined with cyclophosphamide (AC) is the most commonly used regimen for triple-negative breast cancer (TNBC) chemotherapy; however, its clinical application is severely limited by its serious adverse effect on cardiomyocytes. The cardiotoxicity of AC is mainly the result of oxidative stress caused by the imbalance between reactive oxygen species (ROS) and antioxidants, and it also involves multiple signaling pathways. Quercetin (Que) has been proven to possess strong antioxidant activity, and therefore we investigated whether it had potential protective effect against AC-induced cardiotoxicity ... Que could enhance the antitumor activity of AC by inhibiting ROS accumulation and ERK1/2 pathway in TNBC cells. In addition, our in vivo studies further confirmed that Que could enhance the chemotherapeutic effect of AC against TNBC while it reduced the injury of cardiotoxicity induced by AC. Therefore, Que could be used as a novel agent for the treatment of cardiotoxicity induced by AC regimen in TNBC chemotherapy"
  • Cyclophosphamide-induced testicular oxidative-inflammatory injury is accompanied by altered immunosuppressive indoleamine 2, 3-dioxygenase in Wister rats: Influence of dietary quercetin - Andrologia 2021 Dec 1 - "quercetin protected the testes against cyclophosphamide-induced alterations in immunosuppressive IDO/TDO activities elicited by oxidative-inflammatory mediators" - See quercetin at Amazon.com.
  • Quercetin Reduces Oxidative Stress and Apoptosis by Inhibiting HMGB1 and Its Translocation, Thereby Alleviating Liver Injury in ACLF Rats - Evid Based Complement Alternat Med 2021 Oct 25 - "Acute on chronic liver failure (ACLF) is a syndrome of acute liver failure that occurs on the basis of chronic liver disease, which is characterized by a rapid deterioration in a short period and high mortality. High mobility group box 1 (HMGB1) may be involved in the pathological process of ACLF; its specific role remains to be further elucidated ... Que alleviates liver injury in ACLF rats, and its mechanism may be related to oxidative stress and apoptosis caused by HMGB1 and its translocation" - See quercetin at Amazon.com.
  • Quercetin Improves Mitochondrial Function and Inflammation in H 2 O 2-Induced Oxidative Stress Damage in the Gastric Mucosal Epithelial Cell by Regulating the PI3K/AKT Signaling Pathway - Evid Based Complement Alternat Med 2021 Nov 27 - "Functional dyspepsia (FD) is one of the most common functional gastrointestinal disorders, the therapeutic strategy of which it is limited due to its complex pathogenesis. Oxidative stress-induced damage in gastric mucosal epithelial cells is related to the pathogenesis and development of FD. Quercetin (Que) is one of the active ingredients of Zhishi that showed antioxidant, antiapoptotic, and anti-inflammatory effects ... the current study demonstrates that Que alleviates oxidative stress damage in GES-1 cells by improving mitochondrial function and mucosal barrier and suppressing inflammation through regulating the PI3K/AKT signaling pathway, indicating the potential therapeutic effects of Que on FD"
  • Protective effect of quercetin against the metabolic dysfunction of glucose and lipids and its associated learning and memory impairments in NAFLD rats - Lipids Health Dis 2021 Nov 17 - "Quercetin (QUE) is a flavonol reported with anti-inflammatory and antioxidant activities, and previous results from the group of this study have demonstrated its neuroprotective effect against lipopolysaccharide-induced neuropsychiatric injuries. However, little is known about its potential effect on neuropsychiatric injuries induced or accompanied by metabolic dysfunction of glucose and lipids ... Compared with the control rats, HFD-induced NAFLD model rats presented significant metabolic dysfunction, hepatocyte steatosis, and impaired learning and memory ability, as indicated by the increased plasma concentrations of total cholesterol (TC) and triglyceride (TG), the impaired glucose tolerance, the accumulated fat droplets and balloon-like changes in the liver, and the increased escaping latency but decreased duration in the target quadrant in the Morris water maze. All these changes were reversed in QUE-treated rats. Moreover, apart from improving the morphological injuries in the hippocampus, treatment with QUE could increase the decreased plasma concentration and hippocampal protein expression of TREM1 in NAFLD rats and increase the decreased expression of Syn-1 and Syt-1 in the hippocampus"
  • Quercetin and its derivates as antiviral potentials: A comprehensive review - Phytother Res 2021 Oct 28 - "Quercetin, widely distributed in fruits and vegetables, is a flavonoid known for its antioxidant, antiviral, antimicrobial, and antiinflammatory properties. Several studies highlight the potential use of quercetin as an antiviral, due to its ability to inhibit the initial stages of virus infection, to be able to interact with proteases important for viral replication, and to reduce inflammation caused by infection. Quercetin could also be useful in combination with other drugs to potentially enhance the effects or synergistically interact with them, in order to reduce their side effects and related toxicity"
  • Quercetin inhibiting the PD-1/PD-L1 interaction for immune-enhancing cancer chemopreventive agent - Phytother Res 2021 Sep 24 - "Targeting the PD-1/PD-L1 immune checkpoints has achieved significant positive results in the treatment of multiple cancers. Quercetin is one of the most abundant dietary flavonoids found in various vegetables and fruits, and has a wide range of biological activities including immunomodulation ... Treatment with quercetin dihydrate promoted the killing activity of T cells on MDA-MB-231 and NCI-H460 cancer cells. Experiments using the xenograft mouse model showed that the growth rate of tumor volumes and masses in the quercetin dihydrate-treated mice were decreased. Immunohistochemistry of the tumors showed that CD8, GZMB, and IFN-γ were increased in the quercetin dihydrate-treated mice. These results suggest that quercetin dihydrate attenuates the inhibitory effect of PD-L1 on T cells by inhibiting the PD-1/PD-L1 interaction, which has an exciting potential to be used as a cancer chemopreventive agent" - See quercetin at Amazon.com and iHerb.
  • Quercetin Antagonizes Esophagus Cancer by Modulating miR-1-3p/TAGLN2 Pathway-Dependent Growth and Metastasis - Nutr Cancer 2021 Sep 9 - "The progression of esophagus cancer (EC) is associated with the alterative expressions of multiple microRNAs (miRs). MiR-1-3p is reported to inhibit the development of EC by targeting TAGLN2. Quercetin (Que) is a natural compound capable of antagonizing esophagus carcinoma (EC) ... Collectively, the current study demonstrated that Que exerted inhibitory effects on EC cells by inducing miR-1-3p" - See quercetin at Amazon.com and iHerb.
  • Quercetin and its role in modulating endoplasmic reticulum stress: A review - Phytother Res 2021 Sep 15 - "Quercetin is a plant-derived metabolite belonging to the flavonoids class which presents a range of beneficial effects including anti-inflammatory, cardioprotective, anti-oxidant, anti-obesity, anti-carcinogenic, anti-atherosclerotic, anti-diabetic, anti-hypercholesterolemic, and anti-apoptotic activities. Quercetin also has anti-cancer activity, and can be used as an adjuvant to decrease resistance to cancer chemotherapy. Furthermore, the effect of quercetin can be increased with the help of nanotechnology"
  • Quercetin Protects H9c2 Cardiomyocytes against Oxygen-Glucose Deprivation/Reoxygenation-Induced Oxidative Stress and Mitochondrial Apoptosis by Regulating the ERK1/2/DRP1 Signaling Pathway - Evid Based Complement Alternat Med 2021 Aug 19 - "these results suggested that low concentrations of QCT might alleviate I/R injury by suppressing oxidative stress and improving mitochondrial function through the regulation of ERK1/2-DRP1 signaling, providing a potential candidate for I/R injury prevention"
  • Quercetin and Allicin Can Alleviate the Hepatotoxicity of Lead (Pb) through the PI3K Signaling Pathway - J Agric Food Chem 2021 Aug 9 - "Lead (Pb) is a common toxic heavy metal pollutant in the environment that seriously endangers the health of animals. The liver is a key target organ affected by Pb toxicity. Plant extracts allicin and quercetin have a strong antioxidant capacity that can promote the excretion of heavy metals by improving the body's antioxidant defense and chelating heavy metal ions ... In summary, allicin and quercetin could alleviate oxidative damage and apoptosis in the Pb-poisoned chicken liver through the PI3K signaling pathway, with stronger effects achieved by their combination" - See quercetin at Amazon.com and iHerb and aged garlic at Amazon.com.
  • Quercetin Inhibits the Epithelial to Mesenchymal Transition through Suppressing Akt Mediated Nuclear Translocation of β-Catenin in Lung Cancer Cell Line - Nutr Cancer 2021 Aug 2 - "Lung cancer is a first leading cause of cancer related death worldwide. Quercetin (QUE) has chemo-preventive effect against a variety of cancers .... Our results suggest that QUE can inhibit the metastatic potential in lung cancer by altering the Akt/MAPK/β-catenin signaling pathway and inhibiting the nuclear translocation of β-catenin"
  • ASCs -derived exosomes loaded with vitamin A and quercetin inhibit rapid senescence-like response after acute liver injury - Biochem Biophys Res Commun 2021 Aug 4 - "Acute liver injury is a short-term burst of liver cell damage, which has many causes and complex mechanisms. Despite the unique ability of the liver to heal itself, there is still no effective treatment except liver transplantation for chronic liver injury or even liver failure caused by acute liver injury ... In this study, quercetin and vitamin A loaded adipose mesenchymal stem cells (ASCs)-derived exosomes were constructed and used to treat acute liver injury induced by CCl4 in mice. Quercetin enhances the therapeutic efficacy of exosomes, while vitamin A enhances the liver targeting of exosomes, and it was found that quercetin and vitamin A loaded mesenchymal stem cell exosomes reduce rapid senescence-like response induced by acute liver injury"
  • Quercetin and vitamin E attenuate diabetes-induced testicular anomaly in Wistar rats via the mitochondrial-mediated apoptotic pathway - Andrologia 2021 Jul 18 - "The role of quercetin and vitamin E treatment against streptozotocin (STZ)-induced testicular abnormalities in diabetic rats and the possible mechanism of action they use for protection were investigated ... The study showed a positive correlation in the levels of LH, FSH and testosterone; it was further established that all treatments normalised diabetes-induced alterations. Treatment with quercetin and vitamin E resulted in 34% decrease of apoptogenic cytochrome c release. This protected the testes against excessive apoptosis by decreasing caspase 3 and caspase 9 activation by up to 30 and 28% respectively (p < .05). Histology also showed that treatment prevented testicular cell death. The findings show that quercetin/vitamin E possess free radical scavenging properties that protected against testicular damage in diabetes. This suggests the possibility of pharmaco-therapeutic intervention" - See quercetin at Amazon.com and iHerb and Vitamin E at Amazon.com and iHerb.
  • Quercetin and Luteolin Improve the Anticancer Effects of 5-Fluorouracil in Human Colorectal Adenocarcinoma In Vitro Model: A Mechanistic Insight - Nutr Cancer 2021 Jul 26 - "The aim of this study was to investigate the antitumor effects of quercetin and luteolin combined with 5-Fluorouracil (5-FU) in HT-29 human colorectal cancer cells ... These findings suggested that quercetin and luteolin synergistically enhanced the anticancer effect of 5-FU in HT 29 cells and may therefore minimize the toxic effects of 5-FU in the clinical treatment of colorectal cancer"
  • Quercetin Impairs HuR-Driven Progression and Migration of Triple Negative Breast Cancer (TNBC) Cells - Nutr Cancer 2021 Jul 19 - "the present results demonstrate that elevated HuR levels are associated with TNBC  See quercetin at Amazon.com and iHerb.
  • The effect of Quercetin on the quality of sperm parameters in frozen-thawed semen of patients with Asthenospermia - Andrologia 2021 Jul 5 - "The mean percentage of total motility and progressive motility, normal morphology, viability and antioxidant enzyme activity had significant increase in the Quercetin group than the control group. In the Quercetin group, the MDA level and DNA damage also had significant reduction in comparison with the control group (p ≤ 0.001). Therefore, the Quercetin supplementation improves the quality of cryopreserved human semen"
  • Quercetin as a protective agent for liver diseases: A comprehensive descriptive review of the molecular mechanism - Phytother Res 2021 Jun 22 - "Quercetin is the major representative of the flavonoid subgroup of flavones, with good pharmacological activities for the treatment of liver diseases, including liver steatosis, fatty hepatitis, liver fibrosis, and liver cancer. It can significantly influence the development of liver diseases via multiple targets and multiple pathways via antifat accumulation, anti-inflammatory, and antioxidant activity, as well as the inhibition of cellular apoptosis and proliferation ... quercetin inhibited inflammation of the liver mainly through NF-κB/TLR/NLRP3, reduced PI3K/Nrf2-mediated oxidative stress, mTOR activation in autophagy, and inhibited the expression of apoptotic factors associated with the development of liver diseases. In addition, quercetin showed different mechanisms of action at different stages of liver diseases, including the regulation of PPAR, UCP, and PLIN2-related factors via brown fat activation in liver steatosis. The compound inhibited stromal ECM deposition at the liver fibrosis stage, affecting TGF1β, endoplasmic reticulum stress (ERs), and apoptosis. While at the final liver cancer stage, inhibiting cancer cell proliferation and spread via the hTERT, MEK1/ERK1/2, Notch, and Wnt/β-catenin-related signaling pathways"
  • Dietary Quercetin Reduces Plasma and Tissue Methylglyoxal and Advanced Glycation End Products in Healthy Mice Treated with Methylglyoxal - J Nutr 2021 Jun 5 - "Methylglyoxal (MGO), a precursor of advanced glycation end products (AGEs), has been linked to AGEs-associated diseases ... Quercetin reduced plasma and tissue MGO concentrations and inhibited AGE formation by trapping MGO and regulating the MGO detoxification systems in MGO-administered healthy mice"
  • Quercetin and metabolic syndrome: A review - Phytother Res 2021 Jun 8 - "Metabolic syndrome (MetS) is a complex of diseases that lead to mortality due to the development of cardiovascular problems. Quercetin, as an important flavonoid, has various properties such as decreasing blood pressure, anti-hyperlipidemia, anti-hyperglycemia, anti-oxidant, antiviral, anticancer, anti-inflammatory, anti-microbial, neuroprotective, and cardio-protective effects ... According to these data, quercetin may also have a role in the management of metabolic disorders via different mechanisms such as increasing adiponectin, decreasing leptin, anti-oxidant activity, reduction of insulin resistance, the elevation of insulin level, and blocking of calcium channel"
  • Quercetin Attenuates Atherosclerotic Inflammation by Inhibiting Gal-3-NLRP3 Signaling Pathway - Mol Nutr Food Res 2021 May 3 - "Atherosclerosis is the underlying pathogenesis of cardiovascular events caused by inflammation, and dietary intervention has been recommended as one fundamental prevention strategy ... Gal-3 initiates inflammatory lesions by activating NLRP3 inflammasome which functions as a candidate target of quercetin exerting favorable anti-atherogenic effects. Our findings highlight a promising strategy for atherosclerosis prevention and treatment by naturally-occurring quercetin"
  • Quercetin Relieves D-Amphetamine induced Manic-like Behavior through Activating TREK-1 Potassium Channels in Mice - Br J Pharmacol 2021 Apr 28 - "Quercetin is a prominent neuroprotective compound from flavonoids. Previous studies found it may relieve psychiatric disorders, cognition deficits, and memory dysfunction through anti-oxidation and/or radical scavengingmechanisms ... Our results demonstrated that TREK-1 channel is a novel target on quercetin treatment through PKC-dependent manner, which could contribute to both the neuroprotection and anti-manic-like effects"
  • Effectiveness of supplementation with quercetin-type flavonols for treatment of viral lower respiratory tract infections: Systematic review and meta-analysis of preclinical studies - Phytother Res 2021 Apr 17 - "Viral infections of the lower respiratory tract are considered a public health problem. They affect millions of people worldwide, causing thousands of deaths, and are treated with expensive medicines, such as antivirals or palliative measures. In this study, we conducted a systematic review to describe the use of quercetin-type flavonols against lower respiratory tract viruses and discussed the preclinical impact of this approach on different signs and clinical mechanisms of infection ... The analysis of these studies showed evidence of antiviral activity of quercetin-type flavonols with significantly reduced mortality rate (M-H = 0.19, 95% CI: 0.05 to 0.65, p-value = 0.008) of infected animals and a reduction in the average viral load (IV = -1.93, 95% CI: -3.54 to -0.31, p-value = 0.02). Additionally, quercetin and its derivatives reduced the amount of proinflammatory cytokines, chemokines, reactive oxygen species, mucus production, and airway resistance in animals infected with a respiratory virus. Overall, supplementation with quercetin-type flavonols is a promising strategy for treating viral-induced lower respiratory tract infections"
  • Quercetin alleviates chronic unpredictable mild stress-induced depressive-like behaviors by promoting adult hippocampal neurogenesis via FoxG1/CREB/ BDNF signaling pathway - Behav Brain Res 2021 Mar 18 - "Quercetin, a naturally occurring flavonoid, has been reported to exert antidepressant effects, however, the underlying mechanisms are still uncertain. Recent studies have demonstrated that Forkhead box transcription factor G1 (FoxG1) regulates the process of adult hippocampal neurogenesis (AHN) and exerts neuroprotective effects. In this study, we explored whether quercetin plays an anti-depressant role via regulation of FoxG1 signaling in mice and revealed the potential mechanisms. To explore the antidepressant effects of quercetin, mice were subjected to behavioral tests after a chronic unpredictable mild stress (CUMS) exposure. We found that chronic quercetin treatment (15 mg/kg, 30 mg/kg) obviously restored the weight loss of mice caused by CUMS and alleviated CUMS-induced depression-like behaviors, such as increased sucrose consumption, improved locomotor activity and shorten immobility time. In addition, to clarify the relationship between quercetin and AHN, we detected neurogenesis markers in the dentate gyrus (DG) of the hippocampus. Furthermore, FoxG1-siRNA was employed and then stimulated with quercetin to further investigate the mechanism by which FoxG1 participates in the antidepressant effects of quercetin. Our results indicate that chronic quercetin treatment dramatically increased the number of doublecortin (DCX)-positive and BrdU/NeuN-double positive cells. Besides, the expression levels of FoxG1, p-CREB and Brain-derived neurotrophic factor (BDNF) were also enhanced by quercetin in the DG. Strikingly, quercetin failed to reverse the levels of p-CREB and BDNF after FoxG1-siRNA was performed in SH-SY5Y cells and Neural Progenitor Cells (NPCs). Our results thus far suggest that quercetin might exert antidepressant effects via promotion of AHN by FoxG1/CREB/ BDNF signaling pathway."
  • The Effects of Quercetin on the Apoptosis of Human Breast Cancer Cell Lines MCF-7 and MDA-MB-231: A Systematic Review - Nutr Cancer 2021 Mar 7 - "This systematic review was performed with a focus on the effects of quercetin (QT) on the human breast cancer cell lines MCF-7 and MDA-MB-231 ... Of 15 studies that examined the effects of QT on MDA-MB-231 cells, 14 reports showed successful apoptosis. It is concluded that QT might be beneficial in the eliminating of breast cancer cells" - See quercetin at Amazon.com.
  • Anti-Inflammatory Effects of Quercetin on High-Glucose and Pro-Inflammatory Cytokine Challenged Vascular Endothelial Cell Metabolism - Mol Nutr Food Res 2021 Jan 22 - "Pro-inflammatory stimuli such as hyperglycemia and cytokines have been shown to negatively affect endothelial cell functions ... human umbilical vein endothelial cell (HUVEC) metabolites ... Treatment of HUVECs with high-glucose concentrations causes significant increases in lactate and glutamate concentrations. Quercetin inhibits glucose-induced increases in lactate and adenosine 5'-triphosphate (ATP) and also increased inosine concentrations. Tumor necrosis factor α-treatment (TNFα) of HUVECs causes increases in asparagine and decreases in aspartate concentrations. Co-treatment with quercetin reduces pyruvate concentrations compared to TNFα-only treated controls. Subsequently, it was shown that quercetin and its HUVEC phase-2 conjugates inhibit adenosine deaminase, xanthine oxidase and 5'nucleotidase (CD73) but not ectonucleoside triphosphate diphosphohydrolase-1 (CD39) or purine nucleoside phosphorylase activities ... Quercetin was shown to alter the balance of HUVEC metabolites towards a less inflamed phenotype, both alone and in the presence of pro-inflammatory stimuli. These changes are consistent with the inhibition of particular enzymes involved in purine metabolism by quercetin and its HUVEC metabolites" - See quercetin at Amazon.com.
  • Dietary quercetin attenuates depressive-like behaviors by inhibiting astrocyte reactivation in response to stress - Biochem Biophys Res Commun 2020 Oct 12 - "The mechanisms underlying the antidepressant activity of quercetin are unknown. We investigated the effect of a quercetin-enriched diet (2 g/kg and 0.5 g/kg doses) on chronic social defeat stress (CSDS)-induced depressive-like behaviors in mice. The 2 g/kg quercetin-enriched diet attenuated depressive-like behaviors when introduced before CSDS (long-term). The long-term 0.5 g/kg quercetin-enriched diet showed a trend toward behavioral improvement ... These findings highlight the key role of astrocyte reactivation in the regulation of quercetin neuroprotective activity and suggest that a diet high in quercetin, whether as a fruit- and vegetable-rich diet or food additive may help cope with stress"
  • Quercetin Supplementation Improves Neuromuscular Function Recovery from Muscle Damage - Nutrients 2020 Sep 17 - "This study was aimed at investigating whether quercetin (Q) may improve the recovery of neuromuscular function and biochemical parameters in the 7 days following an eccentric exercise-induced muscle damage (EEIMD). Sixteen men (25.9 ± 3.3 y) ingested Q (1000 mg/day) or placebo (PLA) for 14 days following a double-blind crossover study design ... The results showed that Q supplementation significantly attenuated the strength loss compared to PLA. During the recovery, force-velocity relationship and mean fibers conduction velocity (MFCV) persisted significantly less when participants consumed PLA rather than Q, especially at the highest angular velocities (p < 0.02). A greater increase in biomarkers of damage was also evident in PLA with respect to Q. Q supplementation for 14 days seems able to ameliorate the recovery of eccentric exercise-induced weakness, neuromuscular function impairment and biochemical parameters increase probably due to its strong anti-inflammatory and antioxidant action" - See quercetin at Amazon.com and iHerb.
  • Effect of quercetin supplementation on plasma lipid profiles, blood pressure, and glucose levels: a systematic review and meta-analysis - Nutr Rev. 2020 Jan 6 - "Pooled results showed that quercetin significantly lowered both systolic BP (WMD, -3.09 mmHg; 95%CI, -4.59 to -1.59; P = 0.0001) and diastolic BP (WMD, -2.86 mmHg ... Quercetin intake resulted in significantly decreased BP in humans. Moreover, participants who consumed quercetin for 8 weeks or more showed significantly changed levels of high-density lipoprotein cholesterol and triglycerides in trials with a parallel design" - [Nutra USA] - See quercetin at Amazon.com.
  • Enzymatically modified isoquercitrin improves endothelial function in volunteers at risk of cardiovascular disease - Br J Nutr. 2019 Aug 20:1-8 - "A higher intake of food rich in flavonoids such as quercetin can reduce the risk of CVD. Enzymatically modified isoquercitrin (EMIQ®) has a bioavailability 17-fold higher than quercetin aglycone and has shown potential CVD moderating effects in animal studies. The present study aimed to determine whether acute ingestion of EMIQ® improves endothelial function, blood pressure (BP) and cognitive function in human volunteers at risk of CVD ... flow-mediated dilatation (FMD) ... EMIQ® treatment resulted in a significantly higher FMD response compared with the placebo (1·80 (95 % CI 0·23, 3·37) %; P = 0·025). Plasma concentrations of quercetin metabolites were significantly higher (P < 0·001) after EMIQ® treatment compared with the placebo. No changes in BP, arterial stiffness, cognitive function or biochemical parameters were observed. In this human intervention study, the acute administration of EMIQ® significantly increased circulating quercetin metabolites and improved endothelial function" - See EMIQ® at Amazon.com.
  • Effects of enzymatically modified isoquercitrin in supplementary protein powder on athlete body composition: a randomized, placebo-controlled, double-blind trial - J Int Soc Sports Nutr. 2019 Sep 10;16(1):39 - "Enzymatically modified isoquercitrin (EMIQ), a water-soluble quercetin, has been shown to intensify muscle hypertrophy in mice ... Participants received either EMIQ in whey protein (EW, n = 19) or contrast whey protein (W, n = 20) 6 days per week over 4 months ... After 4 months, changes in lower limb fat-free mass and muscle mass were significantly greater in the EW group than in the W group (mean change ±95% CI; W: 324.1 ± 284.3, EW: 950.3 ± 473.2, p = 0.031, W: 255.7 ± 288.6, EW: 930.9 ± 471.5, p = 0.021, respectively). Moreover, the EW group exhibited a significantly higher BAP/d-ROMs ratio, antioxidation index, than the W group after 4 months (mean change ± SD; W: 8.8 ± 1.1, EW: 10.3 ± 2.8; p = 0.028)" - [Nutra USA] - See enzymatically modified isoquercitrin (EMIQ) at Amazon.com.
  • Impact of quercetin on systemic levels of inflammation: a meta-analysis of randomised controlled human trials - Int J Food Sci Nutr. 2019 Jun 18 - "Subgroup analyses revealed a significant reduction in circulating CRP in participants with diagnosed diseases (SMD: -0.24, 95% CI: -0.49, 0.00) and IL-6 in females (SMD: -1.37, 95% CI: -1.93, -0.81), subjects with diagnosed diseases (SMD: -1.37, 95% CI: -1.93, -0.81) and with high-dose interventions (SMD: -0.69, 95% CI: -1.10, -0.38). In conclusion, consumption of quercetin is a promising therapeutic strategy for chronic disease management"
  • Quercetin phytosome® in triathlon athletes: a pilot registry study - Minerva Med. 2018 Aug;109(4):285-289 - "In total, 23 subjects used the supplement and 25 did not. No side effects were reported. The improvement of time to complete the run was greater in subjects on quercetin supplementation compared with the control group (-11.3% vs. -3.9%; P<0.05). Training was considered more valuable in the quercetin group compared with controls (P<0.05). Similarly, post-run muscular pain, cramps, localized pain and the post-exercise recovery time were all considered better with the supplementation (P<0.05). Oxidative stress was also reduced (P<0.05)" - [Nutra USA] - See Quercetin Phytosome® at Amazon.com.
  • Quercetin conjugated with silica nanoparticles inhibits tumor growth in MCF-7 breast cancer cell lines - Biochem Biophys Res Commun. 2018 Apr 23 - "Quercetin is a plant polyphenol from the flavonoid group that plays a fundamental role in controlling homeostasis due to its potent antioxidant properties. However, quercetin has extremely low water solubility, which is a major challenge in drug absorption ... we described a simple method for the synthesis of quercetin nanoparticles. The quercetin nanoparticles had an average diameter of 82 nm and prominent yellow emission under UV irradiation ... Quercetin nanoparticles can inhibit cell growth by blocking the cell cycle and promoting apoptosis in MCF-7 cells more than quercetin. As a result, quercetin nanoparticles may be useful therapy or prevention on breast cancer"
  • Chronic consumption of quercetin reduces erythrocytes oxidative damage: evaluation at resting and after eccentric exercise in humans - Nutr Research, 14 Dec 17 - "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" - [Nutra USA]
  • 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"