Quercetin:3,3',4',5,7-Pentahydroxyflavone dihydrate:Introduction and Its Benefit Applications.
Contents
Common Benefits of Quercetin.:
Properties: Quercetin has many health promoting effects, including improvement of cardiovascular health, reducing risk for cancer. Quercetin has anti-inflammatory and anti-allergic effects. All these activities are caused by the strong antioxidant action of quercetin. It will help to combat free radicals molecules, which can damage cells.
As many other flavonoids, quercetin prevents the oxidation of LDL (bad) cholesterol.
The anti-inflammatory action of quercetin is caused by the inhibition of enzymes, such as lipoxygenase, and the inhibition of inflammatory mediators. Quercetin also inhibits the release of histamine, which causes congestion, by basophils and mast cells.
Studies have shown that quercetin reduces the cancer risk of prostate, ovary, breast, gastric and colon cells.
Quercetin also seems to reduce the production of uric acid, by inhibiting the xanthine oxidase, thereby easing gout symptoms.
Studies have shown an improved lung function and lower risk of certain respiratory diseases (asthma and bronchitis) for people with high apple (rich in quercetin) intake.
Action: Flavonoid with anticancer activity. Mitochondrial ATPase and phosphodiesterase inhibitor. Inhibits PI3-kinase activity and slightly inhibits PIP Kinase activity. Has antiproliferative effects on cancer cell lines; reduces cancer cell growth via type II estrogen receptors; has been reported to arrest human leukemic T cells in late G1phase of the cell cycle.
Quercetin offers a variety of potential therapeutic uses, primarily in the prevention and treatment of the following conditions:
Allergies, asthma, and hives: Quercetin may inhibit histamine release from basophils (a type of white blood cell) and mast cells (large cells in connective tissue).
Quercetin may also be beneficial in the treatment of dysentery (an intestinal infection causing severe diarrhea), gout (a disease where crystals of uric acid, a component of urine, are deposited in the joints and cause swelling), and psoriasis (a chronic skin disease).
Quercetin is a flavonoid that forms the "backbone" for many other flavonoids, including the citrus flavonoids rutin, hesperidin, naringin and tangeritin. Quercetin is found to be the most active of the flavonoids in studies, and many medicinal plants owe much of their activity to their high quercetin content. Quercetin has demonstrated significant anti-inflammatory activity because of direct inhibition of several initial processes of inflammation. For example, it inhibits both the manufacture and release of histamine and other allergic/inflammatory mediators. In addition, it exerts potent antioxidant activity and vitamin C-sparing action.Together with rhamnose, it forms a glycoside quercitrin.
Canker sores: Quercetin may reduce the frequency of mouth sores and produce mild symptomatic relief.
Heart disease: Individuals with very low intakes of flavonoids are at higher risk for heart disease.
Infection: Quercetin may control the spread of certain viruses within the body.
Rheumatoid arthritis: Quercetin may help reduce tissue destruction.
Anti-tumour:
Quercetin also shows remarkable anti-tumour properties. A recent study in the British Journal of Cancer shows that in combination with ultrasound at 20 KHz for 1 minute duration, skin and prostate cancers show a 90% mortality within 48 hours with no visible mortality of normal cells. Note that ultrasound also promotes topical absorption by up to 1,000 times making the use of topical quercetin and ultrasound wands an interesting proposition.
Quercetin may have positive effects in combating or helping to prevent cancer, prostatitis, heart disease, cataracts, allergies/inflammations, and respiratory diseases such as bronchitis and asthma.
Reductase-inhibiting: Quercetin's aldose reductase-inhibiting properties make it a useful addition to diabetic nutritional supplementation, to prevent cataract and neurovascular complications.
Anti-inflammatory: Quercetin's anti-inflammatory activity appears to be due to its antioxidant and inhibitory effects on inflammation-producing enzymes (cyclooxygenase, lipoxygenase) and the subsequent inhibition of inflammatory mediators, including leukotrienes and prostaglandins. Inhibition of histamine release by mast cells and basophils also contributes to quercetin's anti-inflammatory activity.
Eczema: Once again, natural agents that address excessive histamine release may be beneficial in enhancing the healing response among eczema patients. This is because, as with asthma and other allergic conditions, serum IgE levels are highly elevated in eczema patients, and virtually all eczema patients are positive for allergy testing. Also, many eczema patients either suffer from or go on to develop asthma and/or hay fever. Certainly quercetin is one of the more important of such natural compounds in eczema therapeutics. ,
Hives: Because quercetin inhibits manufacture and release of histamine and other allergic inflammatory mediators by mast cells and basophils, it may be quite useful in treating hives, another condition characterized by increased serum IgE levels. , The drug sodium cromoglycate is quite similar to quercetin in chemical structure. Because sodium cromoglycate offers protection against the development of hives in response to heightened food allergens, it can be speculated that quercetin may prove useful in enhancing the healing response.
Pancreatitis: Limited evidence suggests quercetin may be used in the therapy of pancreatitis. The results of the use of inhibitors of biosynthesis of leukotrienes in the treatment of acute pancreatitis were studied in 68 patients, of whom 29 were operated on. According to the researchers, "A high effectiveness of the method in preventing aggravation or destruction of the pancreatic gland was shown." Again, this may well be due, in part, to quercetin's unique anti-inflammatory activity.
Prostatitis: The National Institutes of Health (NIH) Category III Chronic Prostatitis Syndrome (nonbacterial chronic prostatitis and prostatodynia) is a common disorder with few effective therapies. Bioflavonoids have recently been shown in an open-label study to improve the symptoms of these disorders in a significant proportion of men. The aim of a recent study was to confirm these findings in a prospective randomized, double-blind, placebo-controlled trial. Thirty men with category IIIa and IIIb chronic pelvic pain syndrome were randomized in a double-blind fashion to receive either placebo or the bioflavonoid quercetin (500 mg twice daily) for one month. The NIH Chronic Prostatitis Symptom Score was used to grade symptoms and the quality-of-life impact at the start and at the conclusion of the study. In a follow-up non-blinded, open-label study, 17 additional men received one month of a supplement containing quercetin, as well as bromelain and papain, which enhance bioflavonoid absorption. Two patients in the placebo group refused to complete the study because of worsening symptoms, leaving 13 placebo and 15 bioflavonoid patients for evaluation in the blind study. Both the quercetin and placebo groups were similar in age, symptom duration, and initial symptom score. Patients taking placebo had a mean improvement in NIH symptom score from 20.2 to 18.8 (not significant), while those taking the bioflavonoid had a highly significant mean improvement from 21.0 to 13.1. Twenty percent of patients taking placebo and 67 percent of patients taking the bioflavonoid had an improvement of symptoms of at least 25 percent. Therapy with the bioflavonoid quercetin was shown to be well tolerated and provide significant symptomatic improvement in most men with chronic pelvic pain syndrome.
Canker Sores: Very similar in structure and function to quercetin is the anti-allergy drug disodium cromoglycate that has been shown to be effective in the treatment of recurrent canker sores. Thus, Quercetin may offer similar benefits.
Antioxidant: Quercetin is a strong antioxidant and a major dietary flavonoid. Epidemiological studies suggest that consumption of quercetin protects against cardiovascular disease, but its absorption in man is controversial. We fed nine subjects a single large dose of onions, which contain glucose conjugates of quercetin, apples, which contain both glucose and non-glucose quercetin glycosides, or pure quercetin-3-rutinoside, the major quercetin glycoside in tea. Plasma levels were then measured over 36 h. Bioavailability of quercetin from apples and of pure quercetin rutinoside was both 30% relative to onions. Peak levels were achieved less than 0.7 h after ingestion of onions, 2.5 h after apples and 9 h after the rutinoside. Half-lives of elimination were 28 h for onions and 23 h for apples. We conclude that conjugation with glucose enhances absorption from the small gut. Because of the long half-lives of elimination, repeated consumption of quercetin-containing foods will cause accumulation of quercetin in blood.
Gout: Another possible benefit of quercetin is in the treatment of gout. Quercetin has been experimentally shown to inhibit uric acid production in a manner similar to the drug Allopurinol, as well as inhibit the manufacture and release of inflammatory compounds. , ,
Anti-ulcer and Gastro-protective Effects: In an experimental study, the cell-protective properties of quercetin and the involvement of endogenously produced prostaglandins in mucosal injury produced by absolute ethanol were examined. Oral pretreatment with the highest dose of quercetin (200 mg/kg), 120 minutes before absolute ethanol, was most effective in preventing cell death (necrosis). However, subcutaneous administration of indomethacin (10 mg/kg) to the animals treated with quercetin partially inhibited gastric protection. All treated groups showed a marked increase in the amount of gastric mucus, although this increase was less in animals pretreated with indomethacin. Evaluation of gastric damage confirmed a significant increase in mucus production accompanied by a parallel reduction of gastric lesions with the highest dose of quercetin tested. These benefits may be due to inhibition of lipid peroxidation of gastric cells or inhibition of gastric acid secretion. Clinical studies are required to validate whether quercetin may be clinically useful in prevention of ulceration.
Inhibition of Carcinogenicity:
It is in cancer prevention, and possibly therapeutics, wherein many future uses of this natural medicine may be directed. It has been demonstrated that quercetin inhibits the growth of several cancer cell lines and that the anti-proliferative activity of this substance is mediated by a so-called Type II Estrogen-Binding Site (Type II EBS).
In an in vitro study, the effects of Quercetin and cisplatin alone and in combination on the proliferation of the ovarian cancer cell line (OVCA 433) were examined. Both drugs exhibited a dose-related growth inhibition in a range of concentrations between [0.01 - 2.50] mcM and [0.01 - 2.50] mcg/ml for quercetin and cisplatin, respectively. The combination of the two drugs resulted in a synergistic anti-proliferative activity. It should be noted that two other flavonoids tested, i.e., rutin (3-rhamnosylglucoside of Quercetin) and hesperidin (7-b rutinoside of hesperetin [3'-5-3-hydroxy-4-methoxyflavone]) were ineffective both alone and in combination with cisplatin. Since both rutin and hesperidin do not bind to Type II EBS it can be hypothesized that quercetin synergizes cisplatin by acting through an interaction with these binding sites.
Other studies have shown quercetin to possess cisplatin-sensitizing properties in cancer cells. In a recent study, researchers studied the effects of various bioflavonoids on cisplatin toxicity in an in vitro model of cultured tubular epithelial cells. Pretreatment of cells with quercetin for three hours significantly reduced the extent of cell damage. The protective activity of quercetin was concentration dependent. Other bioflavonoids (i.e., catechin, silibinin, rutin) did not diminish cellular injury, even at higher concentrations. Quercetin itself showed some intrinsic cytotoxicity at higher concentrations exceeding 75 mcM.
In another study, the effect of resveratrol and quercetin on growth of human oral cancer cells was studied. Resveratrol and quercetin, in concentrations of [1 - 100] mcM, were incubated in triplicate with human oral squamous carcinoma cells. Resveratrol at 10 and 100 mcM induced significant dose-dependent inhibition in cell growth, as well as in DNA synthesis. Quercetin exhibited a biphasic effect, stimulation at 1 and 10 mcM, and minimal inhibition at 100 mcM in cell growth and DNA synthesis. Combining resveratrol with quercetin resulted in a gradual and significant increase in the inhibitory effect of quercetin on cell growth and DNA synthesis. Thus, it can be shown that resveratrol or a combination of resveratrol and quercetin, in concentrations equivalent to that present in red wines, are effective inhibitors of oral squamous carcinoma cell (SCC-25) growth and proliferation. They certainly warrant further investigation as cancer chemo-preventive agents.
Cataract: Cataracts result from oxidative damage to the lens. The mechanism involves disruption of the redox system, membrane damage, proteolysis, protein aggregation, and a loss of lens transparency. Diet has a significant impact on cataract development, but the individual dietary components responsible for this effect are not known. In a study, it was shown that low micromolar concentrations of quercetin inhibit cataractogenesis in a rat lens organ-cultured model exposed to the endogenous oxidant hydrogen peroxide. Other phenolic antioxidants, (+)epicatechin and chlorogenic acid, were much less effective. Quercetin was active both when incubated in the culture medium together with hydrogen peroxide, and was also active when the lenses were pre-treated with quercetin prior to oxidative insult. Quercetin protected the lens from calcium and sodium influx, which are early events leading to lens opacity, and this implies that the non-selective cation channel is protected by this phenolic. It did not, however, protect against formation of oxidized glutathione resulting from H2O2 treatment. The results demonstrate that quercetin helps to maintain lens transparency after an oxidative insult.
Absorption: It is known that oral doses of quercetin are absorbed. In one study, plasma quercetin concentration in subjects with an intact colon, after ingestion of fried onions, apples, and pure quercetin rutinoside, decreased slowly with an elimination half-life of about 25 hours. Thus, repeated dietary intake of quercetin will lead to accumulation in plasma. The relative bioavailability of quercetin from apples and rutinoside was one-third of that from onions. Dietary quercetin would appear to increase the antioxidant capacity of blood plasma. It is also thought that the combination of the proteolytic enzyme bromelain with quercetin enhances absorption and bioavailability of quercetin.
Dosages: Most dosages range from 200 to 500 mg, taken 20 minutes before meals. Asthma and Hay Fever: Take 400 mg 20 minutes before each meal. Canker Sores: Take 400 mg 20 minutes before each meal. Eczema: Take 400 mg 20 minutes before each meal.Gout: Take 200 to 400 mg of quercetin with bromelain between meals three times daily.Hives: Take [200 - 400] mg 20 minutes before each meal. A new water-soluble form of quercetin may be able to reduce dosages to 250- mg three times a day.
Quercetin is a member of a group of naturally occurring compounds, the flavonoids, which have a common flavone nucleus composed of two benzene rings linked through a heterocyclicpyrone ring. Quercetin is found in various plants, food products, and dyes of natural origin. The estimated average daily intake of quercetin by an individual in the United States is 25 mg. The Food and Drug Administration nominated quercetin for toxicity and carcinogenicity studies in the rat because it is a chemical that is widely distributed in foods. Quercetin was administered to rats by dosed feed since human exposure is by dietary consumption.
Information in the literature showed that quercetin administered in the diet to rats at levels up to approximately 4% caused a minor body weight effect, whereas higher dose levels produced greater than 10% reduction in body weight gains relative to controls. Based on this information, the NTP 2-year studies were conducted by administering 0, 1,000, 10,000, or 40,000 ppm quercetin (>95% pure) in feed to groups of 50 male and female rats for 104 weeks. Ten additional animals per dose group were evaluated at 6 and 15 months.Under the conditions of these 2-year feed studies there was some evidence of carcinogenic activity of quercetin in male F344/N rats based on an increased incidence of renal tubule cell adenomas. There was no evidence of carcinogenic activity of quercetin in female F344/N rats receiving 1,000, 10,000 or 40,000 ppm.
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- 1.Quercetin:3,3',4',5,7-Pentahydroxyflavone dihydrate:Introduction and Its Benefit Applications.
This article written and edited via herbalist of MDidea Extracts Professional. They run a range of online descriptions about this herb,including general information related and summarized updating discoveries from findings of professional scientisits this field related.Describe style aimed to form a useful detecting literature space where the intertwined threshold and related questions raise out and visualize themselves.
♣ last edit date:28th,Oct.2010.
