Free Rad Biol Med 2002;32(10):991-1005. Loke WM, Hodgson JM, Proudfoot JM, McKinley AJ, Puddey IB, Croft KD.Pure dietary flavonoids quercetin and (-)-epicatechin augment nitric oxide products and reduce endothelin-1 acutely in healthy men. Most Life Extension members already take either Super Carnosine or Chronoforte to inhibit the glycation process. Neuroprotection by flavonoids. Flavonols have also demonstrated neuroprotective,cardioprotective, chemopreventive, antioxidant, anti-inflammatory, and anti-allergic activity in numerous preclinical studies. As we shall see next, quercetin has been found to inhibit the activity of NF-kB and of the inflammatory cytokines its activity stimulates. Comparative pharmacokinetics in humans demonstrates that the absorption of quercetin, isoquercetin, and rutin in humans involves different mechanisms.
Quercetin is clinically used in the treatment of chronic prostatitis and related inflammatory conditions.
A recent study evaluated the effects of quercetin and catechin on collagen-induced platelet aggregation. SunActive IsoQ is derived from rutin extracted from the flower buds of the Japanese Pagoda tree (Styphnolobium japonicum Schott). Conquer JA, Maiani G, Azzini E, Raguzzini A, Holub BJ. In numerous experimental studies on both animals and humans, quercetin has been found to protect kidney tissues against age-related insult. These men were then followed up for five years. Red wine contains quercetin and other flavonoids that are made bioavailable to the body by the alcohol in the wine. When the blood flowing over a piece of rabbit aorta contained a low concentration of quercetin, platelet thrombi dissolved. Dok-Go and colleagues found quercetin and its 3-methyl ether metabolite prevented xanthine oxidase-induced oxidative neuronal cell injury, scavenged free radicals, and inhibited lipid peroxidation. Brain Res. Murota K, Terao J. Antioxidative flavonoid quercetin: implication of its intestinalabsorption and metabolism. 2003;980(1):156-160. While quercetin is a popular ingredient in the supplements industry, known for benefits ranging from immune and cardiovascular health to cellular health, quercetin in its most common form, free quercetin, is still associated with formulating obstacles related to taste, solubility, and bioavailability. Inhibitory effect of quercetin on carrageenan-induced inflammation in rats. Structure-activity relationships of quercetin in antagonizing hydrogen peroxide-induced calcium dysregulation in cells. Quercetin from shallots(Allium cepa L. var.
Relative bioavailabilityof the antioxidant flavonoid quercetin from various foods in man. Basic biology and clinical application of specific cycloxygenase-2 inhibitors. Genotoxicity of quercetin incultured mammalian cells. Effects of flavonoids on immune and inflammatory cell functions. The brain is particularly susceptible to oxidative damage because of its high utilization of oxygen, its high levels of unsaturated lipids and transition metals like iron, and its relatively inefficient antioxidant defenses. Manach C, Morand C, Demign C, Texier O, Rgrat F, Rmsy C. Bioavailabilityof rutin and quercetin in rats. A limited number of clinical trials have been conducted on isolated flavonols (i.e., quercetin, rutin, hydroxyethylrutosides [a semi-synthetic form of rutin]). Many flavonoids, such as rutin, pass unchanged into the large intestine, where they are hydrolyzed by microbially produced glycosidases, yielding quercetin aglycone and its sugar. Reversal of reserpine-induced orofacial dyskinesia and cognitive dysfunction by quercetin. Hajra L, et al. Rutin has the lowest relative bioavailability and is not significantly absorbed before 2 hours, showing peak plasma concentrations at 6 hours after intake. Its anti-thrombotic action helps prevent the proclotting state that sets the stage for cardiovascular disease and major cardiovascular events. Butterweck V, Hegger M, Winterhoff H . Protein degradation caused by glycation is related to the development of numerous degenerative diseases. Isoquercetin has demonstrated potential protective effects against oxidative neuronal injuries and brain ischemia. Isoquercetin (quercetin-3-glucoside) has been shown to have bioavailability comparable to that of quercetin-4-glucoside. Krasteva I, Nikolova I, Danchev N, Nikolov S. Phytochemical analysis of ethylacetate extract from Astragalus corniculatus Bieb. Induction of sperm abnormalities in mice by quercetin. Day AJ, DuPont MS, Ridley S, et al. Deglycosylation by small intestinalepithelial cell beta-glucosidases is a critical step in the absorption and metabolismof dietary flavonoid glycosides in humans. quercetin reduces besmetting vermindert kans factor inhibitor Researchers tested the effect of quercetin and other flavonoids on calcium regulation in PC12 cells, commonly used in cellular models of the nervous system. When the flow of blood resumes, they are reperfused with blood and oxygen. Morikawa K, Nonaka M, Narahara M, et al. Weldin J, Jack R, Dugaw K, Kapur RP. Men with the lowest flavonoid intake (bottom quartile) were almost four times as likely to suffer a stroke as men with the highest intake (top quartile).6. Secretions from mast cells play a central role in the development of inflammatory disorders, and recent research implicates them in cardiovascular inflammation, particularly following stress. Methods Find Exp Clin Pharmacol 2001;23(4):175-81. Quercetin, an over-the-counter supplement,causes neuroblastoma-like elevation of plasma homovanillic acid. Quercetin, the predominant flavonoid in the human diet, has been unobtainable as a practical dietary supplement due to poor absorption. Rats given 2 mg/kg of quercetin suffered far less damage to their kidneys when given cyclosporine. Hollman and colleagues in the Netherlands assessed the relative bioavailability and absorption of flavonoids from onions (glucose-conjugated quercetin), apples (both glucose conjugates and non-glucose conjugates), or pure quercetin-3-rutinoside in humans. Ader P, Wessmann A, Wolffram S. Bioavailability and metabolism of theflavonol quercetin in the pig. Rueff J, Laires A, Borba H, Chaveca T, Gomes MI, Halpern M. Genetic toxicologyof flavonoids: the role of metabolic conditions in the induction ofreverse mutation, SOS functions and sister-chromatid exchanges. Researchers tested the effect of quercetin on the activation of NF-kB in cultured rat kidney cells. It was found that the men who took in the most flavonoids were slightly less than half as likely to have suffered a heart attack during the course of the study.5, Moreover, intake of flavonoids, mainly quercetin, was inversely associated with stroke. Difference in absorption of the two structurally similar flavonoid glycosides, hyperoside and isoquercitrin, in rats. Caria H, Chaveca T, Laires A, Rueff J. Genotoxicity of quercetin in the micronucleusassay in mouse bone marrow erythrocytes, human lymphocytes,V79 cell line and identification of kinetochore-containing (CREST staining)micronuclei in human lymphocytes. NutriScience will work with brands to maximize the benefits while minimizing the formulation challenges., AlgaeCal introduces plant-based calcium supplements made from algae, Upcycling: Important opportunities for food development, Gelita opens biotech hub to sustainably develop proteins for nutrition, cosmetics, and more, Bioavailability of dietary isoquercitrin--cyclodextrin molecular inclusion complex in Sprague-Dawley rats and healthy humans. Their urinary output increased and markers of free radical damage dropped.15. Quercetin, a bioflavonoid, protects against oxidative stress-related renal dysfunction by cyclosporine in rats. New research finds that rats given oral low dose quercetin were significantly protected against the injury that normally occurs during ischemia and reperfusion. Now, it can be obtained in a bioavailable form that facilitates absorption. Caloric restriction, which is known to extend life span, has been found to reduce NF-kB activity in the kidneys of rats.13. Taiyos new ingredient is a water-soluble form of isoquercitrin, a quercetin precursor. ermak R, Landgraf S, Wolffram S. The bioavailability of quercetin in pigs depends on the glycoside moiety and on dietary factors. Their urinary output increased and markers of free radical damage dropped. Oxidative processes and antioxidative defense mechanism in theaging brain. Quercetin glycosides with sugar moieties other than glucose (e.g., rutinosides) are absorbed in lower parts of the intestinal tract after deglycosylation. Quercetin glucosides, however, have better bioavailability, resulting in potentially increased efficacy compared to the aglycone form. The next article describes how carnosine inhibits glycation and why it has become a popular supplement for those seeking to stave off the effects of aging. Protective effects of flavonoidscontained in the red vine leaf on venular endothelium against the attack of activated blood components in vitro. Thus it is anticipated that a lower does of isoquercetin would be required for comparable efficacy. Circulation 2002 Oct 29;106(18):2397-403. In one study, men with ileostomies consumed a supplement of fried onions (which is rich in quercetin glucosides), pure rutin, or pure quercetin aglycone. Nees S, Weiss DR, Reichenbach-Klinke E, et al. The researchers concluded that quercetin exerts its anti-thrombotic effect by binding selectively to platelet thrombi on blood vessel walls, and by restoring normal synthesis of endothelium-derived relaxing factor and prostacyclin.1 Prostacyclin inhibits platelet aggregation and is a powerful vasodilator. Quercetin 3-methyl ether, a methanolic extract of quercetin, was a more potent neuroprotectant than any of the other flavonoids tested. Res Commun Chem Pathol Pharmacol 1992 Nov;78(2):211-8. The cells were proximal tubular cells (PTC's), which play a pivotal role in progressive kidney diseases by regulating the accumulation of macrophages. Quercetin glucosides, such as isoquercetin, occur naturally and have the same therapeutic effects, Gulf War Illness: Resveratrol Reduces Symptoms, Luteolin and Fisetin Do Not, Antiangiogenic Phytochemicals Best Poised for Clinical Trial Testing, Turmeric and Frankincense in Inflammation: An Update. Protective effects of quercetin and vitamin C against oxidativestress-induced neurodegeneration.
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The ingredient is currently being offered exclusively through Taiyos U.S. partner NutriScience Innovations (Milford, CT). Rats given 2 mg/kg of quercetin suffered far less damage to their kidneys when given cyclosporine. MacGregor JT, Wehr CM, Manners GD, Jurd L, Minkler JL, Carrano AV. A common trigger of platelet aggregation is collagen exposed when a blood vessel wall is damaged, as for example by an arterial plaque. and brain antihypoxic activity. Prostacyclin-deficient mice develop ischemic renal disorders, including nephrosclerosis and renal infarction. Quercetin works by inhibiting the Mitogen-Activated Protein (MAP) kinase signaling pathway associated with smooth muscle cell migration. Several studies show that quercetin inhibits thromboxane A2, which helps keep prostacyclin and thromboxane A2 in a healthy balance.2 Moreover, new research shows that mice deficient in prostacyclin develop ischemic kidney disorders-one more mechanism through which quercetin protects the kidneys (see "Quercetin and kidney disease" later in the article).3, Clotting begins when blood platelets clump together, a process called platelet aggregation. Glycation is a pathologic mechanism that occurs when a glucose molecule inappropriately binds to a protein molecule. Thermal degradationof onion quercetin glucosides under roasting conditions. Mitochondrial function in response to cardiac ischemia-reperfusion after oral treatment with quercetin. Inhibition of platelet aggregation by some flavonoids. A great many flavonoids have demonstrated health-promoting effects in humans and in animal studies, which will also be addressed. Ischemia and reperfusion, discussed earlier in relation to cardiovascular disease, also damages the kidneys. Morand C, Manach C, Crespy V, Remesy C. Quercetin 3-O-b-glucoside isbetter absorbed than other quercetin forms and is not present in rat plasma. Quercetin glucosides are among the most common flavonoids in the human diet. 
In a study of cyclosporine's effects on rat kidneys, a 20% to 30% reduction in glomerular filtration rate (the rate at which the kidneys filter wastes from the blood) and up to 40% reduction in renal blood flow were found. 2022 Diversified Communications. Quercetin and rutin inhibit the generation of inflammatory mediators (leukotriene LTB4 and prostaglandin E2) in human neutrophils. In the case of quercetin derivatives, onions are a major source of quercetin glucosides. 2022 MJH Life Sciences and Nutritional Outlook. Deglycosylation of flavonoid and isoflavonoidglycosides by human small intestine and liver beta-glucosidase activity. Kim HY, Moon BH, Lee HJ, Choi DH. A traveling clot, called an embolism, can cause ischemia, heart attack, stroke or pulmonary embolism. Inhibition of smooth muscle cell proliferation and migration, During the formation of atherosclerotic lesions, the smooth muscle cells that line the coronary arteries multiply in number and begin to migrate into the interior of those vessels. More than 5,000 flavonoid compounds have been identified. Nakayasu M, Sakamoto H, Terada M, Nagao M, Sugimura T. Mutagenicityof quercetin in Chinese hamster lung cells in culture. Their results support the hypothesis that dietary quercetin actively inhibits oxidative damage in the lens and could play an important role in the prevention of cataract. Regrettably, the poor absorption rate means that people taking conventional quercetin supplements can't translate the impressive roster of research findings into reality. Surgery 2002;131:198-204. Quercetin is a natural antioxidant, producing its antioxidative actions by inhibiting lipid peroxidation through blockade of the enzyme xanthine oxidase, chelating iron, and directly scavenging hydroxyl, peroxy, and superoxide radicals. In the laboratory, hydrogen peroxide causes lens opacification and a pattern of oxidative damage similar to that found in cataracts. Rutin is found in the highest amounts in buckwheat, tomato, apricot, rhubarb, tea, celery, spinach, brussels sprouts and lemon. Free Rad Biol Med 2002;32(11):1220-8. Many of them, including flavonols, have low toxicity in mammals and will be discussed in this profile. It is not, however, the dominant form appearing in nature, and its bioavailability is poor. Quercetin supplementation has been shown to inhibit LDL oxidation in humans, though it does not appear to modify levels of LDL. Not only can a thrombus prevent blood and oxygen from reaching tissues and vital organs, but it can also break off and travel through the blood stream to the heart, brain, lung or a distant blood vessel. These studies are of particular interest because they directly compare the bioavailability of isoquercetin, quercetin aglycone, and rutin. Hsiu SL, Hou YC, Wang YH, et al. Nonalcoholic red wine extract and quercetin inhibit LDL oxidation without affecting plasma antioxidant vitamin and carotenoid concentrations. NF-kB activity in the kidneys increases with age and leads to increased oxidative stress. Researchers demonstrated that a low concentration of quercetin suppressed thrombus deposits on collagen bathed in a stream of blood. MacGregor JT, Jurd L. Mutagenicity of plant flavonoids: structural requirementsfor mutagenic activity in Salmonella typhimurium.
Biochem Pharmacol 1992 Mar 17;43(6):1167-79. Sahu RK, Basu R, Sharma A. Anjaneyulu M, Chopra K. Quercetin, an anti-oxidant bioflavonoid, attenuates diabetic nephropathy in rats. Inhibition of dihydropyridine metabolism in rat and human liver microsomes by flavonoidsfound in grapefruit juice. A clinical studied published late last year1 demonstrated that SunActive IsoQ converts into free quercetin in the body. The researchers found that quercetin and catechin inhibited the hydrogen peroxide burst that signals platelet aggregation.4, Epidemiological studies have shown reduced long-term mortality from coronary heart disease in those who consume diets high in flavonoids- including quercetin, anthocyanins and catechins. Keli SO, et al. The sugar moiety is a majordeterminant of the absorption of dietary flavonoid glucosides in man. This automatically enables members to obtain enhanced benefit without having to take additional pills. Hubbard GP, Wolffram S, Lovegrove JA, Gibbins JM. Am J Clin Nutr 2000;72:1150-5.
Miniscalco A, Lundahl J, Regrdh CG, Edgar B, Eriksson UG. Some bioavailability studies of quercetin have been performed in pigs since the anatomy and physiology of porcine and human digestive gastrointestinal tracts are similar. Isoquercetin, which is less lipophilic than quercetin aglycone, showed better bioavailability regardless of percentage of fat consumed.
Bioavailability of the dietary antioxidant flavonol quercetin in man. Patil CS, Singh VP, Satyanarayan PS, Jain NK, Singh A, Kulkarni SK. The researchers note that quercetin has been found to arrest the cell cycle in cancer cells, and observe that it appears to do the same in vascular smooth muscle cells, locking them into a quiescent state.7, In another study, Japanese researchers found that quercetin inhibited the vascular smooth muscle cell hypertrophy seen during the development of coronary artery disease. Such extensive damage is thought to be due to a combination of factors, including increased free radical production, increases in renal nerve activity that cause constriction of renal arteries, blockade of the release of calcium from the mitochondria and a resultant rise in intracellular calcium. Rohn S, Buchner N, Driemel G, Rauser M, Kroh LW. As the population ages, the prevalence of kidney failure is expected to increase dramatically. Is stress keeping you up at night?
After ingestion of isoquercetin, quercetin, and rutin, quercetin aglycone and intact glycosides of quercetin are not detectable in human plasma and body tissues in significant amounts as these parent compounds. Dietary flavonoid and isoflavone glycosidesare hydrolysed by the lactase site of lactase phlorizin hydrolase. Bioavailability is highest for isoquercetin, lower for quercetin aglycone, and lowest for rutin. Singh A, Naidu PS, Kulkarni SK. As a rule of thumb, isoquercetin could be supplemented in a ratio of 1:5 relative to quercetin aglycone. Quercetin inhibits Shc- and phosphatidylinositol 3-kinase-mediated c-jun N-terminal kinase activation by angiotensin II in cultured rat aortic smooth muscle cells. Lancet 1993;342:1007-11. Genetic effects of the flavonols quercetin,kaempferol, and galangin on Chinese hamster ovary cells in vitro.