Quercetin CAS# 117-39-5

Quercetin, a natural flavonoid widely found in nature, has gained intensive research and has been found to have multiple biological activities, such as antioxidant, antiviral, and anti-inflammatory effects, and can be used in cellular and animal experiments to treat liver, heart, spleen, lung, kidney, orthopedic diseases, and neurological disorders.

Antioxidant effect

Quercetin is a natural chelator that can chelate iron in the body, reduce iron overload in the body, and reduce oxidative damage caused by iron overload.  Quercetin has various effects such as antioxidant, scavenging free radicals, and inhibiting lipid peroxidation, which can antioxidant and protect cardiovascular health, and has shown better effects in anti-cancer. However, the data from such studies are from cytological experiments or animal experiments, and more validation is still needed to determine whether it works directly in humans.

Tumor-inhibiting activity

In terms of anti-cancer, quercetin has been shown in numerous studies to have inhibitory effects on various cancer cells. In terms of specific mechanisms of action, quercetin has a variety of biological effects, inhibiting a variety of enzymes involved in cell proliferation and signaling pathways in cancer cells.

On the other hand, it has also been shown that quercetin has some synergistic effects when used in combination with commonly used chemotherapeutic agents or radiotherapy, and has some promise for application. For example, quercetin can act in chemosensitization and radiosensitization chemotherapy also as an antiradiation, protecting normal cells from the side effects of chemotherapy and radiotherapy, and these advantages can significantly enhance its anticancer therapeutic effects. Various flavonols such as quercetin, kaempferol, and prunetinone have some preventive and curative effects against pancreatic cancer, especially for smokers, the effects may be more pronounced.

Quercetin may exert antitumor effects by inducing apoptosis in tumor cells. The expression of glucose transporter protein is significantly increased in primary liver cancer, and inhibition of its expression could be a new therapeutic direction for primary liver cancer. In the field of gastric cancer research, quercetin was likewise found to induce apoptosis and exert anti-tumor effects by triggering mitochondrial apoptosis-dependent growth inhibition, which could be a new target for the treatment of gastric cancer.

Mechanism of lipid-lowering and weight loss

Quercetin is a rich source of flavonoids in the diet, and studies have shown its lipid-lowering and weight-loss effects.

Quercetin can inhibit the decomposition of cholesterol esters into free cholesterol and can reduce the solubility of cholesterol in micellar solutions, inhibiting the absorption of cholesterol in the small intestine, which has the purpose of lowering lipids.

Quercetin is a potent regulator of plasma TG (triglyceride) levels.

Quercetin reduces intrahepatic lipid accumulation and decreases insulin resistance and NAFLD activity scores by regulating lipid metabolism gene expression, cytochrome P4502El (CYP2E1)-dependent lipid peroxidation, and associated lipotoxicity.

Quercetin has various effects such as inhibiting the proliferation of preadipocytes, inducing apoptosis of preadipocytes, and promoting lipolysis of mature adipocytes. And it can promote lipolysis metabolism and inhibit lipogenesis.

Quercetin can reduce the expression of IL-18, elevate the expression of IL-10, and alleviate the index abnormalities brought by a high-fat diet. These experiments suggest that quercetin can effectively improve the abnormal expression of inflammatory factors caused by high fat.

Protection of the heart

Quercetin has been shown to lower blood pressure, enhance capillary resistance, reduce capillary fragility, lower blood lipids, dilate coronary arteries, and increase coronary blood flow, and also has adjuvant therapeutic effects in patients with coronary heart disease and hypertension.  

Quercetin effectively attenuates H2O2-mediated oxidative damage in cardiomyocytes, which in turn inhibits cardiomyocyte apoptosis. Treatment with quercetin significantly reduced the number of premature ventricular contractions, suggesting a significant cardioprotective effect of quercetin in coronary artery disease.

Improving cardiac function and reducing myocardial hypertrophy: the dietary polyphenol complex quercetin can effectively regulate plasma cholesterol and non-adaptive myocardial remodeling. In addition, inhibition of myocardial hypertrophy can effectively reduce mortality from cardiovascular disease.

Antiplatelet and prevent thrombosis: quercetin can effectively inhibit the formation of thrombus in diabetes, and can be used as an antiplatelet agent in diabetes treatment. It can also inhibit platelet aggregation and agonist-induced GPIIb/IIIa activation caused by collagen, adenosine diphosphate, and arachidonic acid, and quercetin can also inhibit the extracellular secretion of platelet granules.

Vasodilatation and blood pressure lowering: quercetin can lower blood pressure by reducing the elasticity of blood vessels.

Anti-atherosclerosis: quercetin can significantly reduce atherosclerotic plaque areas in the high-fat group, attenuate oxidative stress in various systems, and block the activation of NADPH oxidase, which suggests that regular consumption of quercetin in the diet plays an important role in inhibiting the formation of atherosclerosis. Quercetin can inhibit oxidant-induced endothelial dysfunction and atherosclerosis.

Lowering blood lipids and lipid peroxidation: quercetin has a certain effect of lowering blood lipids, can promote cell proliferation, and reduce triglycerides. And can inhibit the increase of lipid peroxidation, effectively reduce the accumulation of triglycerides in non-alcoholic fatty liver, insulin resistance, and the secretion of some inflammatory factors, and increase the antioxidant capacity of cells, with the increase of quercetin concentration, cholesterol concentration in red blood cells is getting lower.

Prevent myocardial ischemia-reperfusion injury: quercetin pretreatment can significantly improve myocardial function and reduce myocardial injury and infarct area while improving the improvement of oxidative damage and apoptosis of myocardium.

Hypoglycemia and alleviate insulin resistance: Quercetin can effectively improve hyperglycemia and hyperlipidemia and antioxidant status in type 2 diabetes by alleviating blood glucose uptake and improving insulin resistance status through the AMPK pathway rather than the insulin signaling pathway. In addition, quercetin induces an increase in intracellular calcium ion concentration. And AMPK pathway can play a role in reducing insulin resistance through insulin system bypass.

Effects on exercise

Exercise fatigue is associated with oxidative stress during human exercise, and studies before 2017 showed that exercise fatigue can lead to a reduction in the body’s antioxidant capacity and oxidative stress damage. The powerful antioxidant activity of quercetin may also help to reduce fatigue.

Quercetin supplementation may reduce lipid peroxidation damage by decreasing MDA levels during exercise. In addition, quercetin improves the antioxidant capacity of the body by inhibiting the decrease in SOD and GSH-Px during exercise, thereby delaying fatigue.

Antiviral activity

Quercetin significantly reduced the replication rate of hepatitis C virus, while the infectivity of quercetin-treated virus particles was found to be reduced by 65%, indicating that quercetin affected the integrity of the virus, and it was further confirmed by molecular-level experiments that quercetin could exert antiviral effects by blocking the upregulation of diacylglycerol acyltransferase by hepatitis C virus and the typical localization of hepatitis C virus core protein on the surface of lipid droplets.