Quercetin is a flavonol, belonging to the class of flavanoids (antioxidants) that occur ubiquitously in foods of plant origin, such as red wine, onions, green tea, apples, berries, and Brassica vegetables (cabbage, broccoli, cauliflower, turnips).

It is also found in Gingko biloba, St. John’s wart, and American elder.

Quercetin has many activities within the body such as:

   Anti-inflammatory

• Effects produced through the modification of eicosanoid biosynthesis, decreased production of TNF-α, inhibiting respiratory burst activity of polymorphonuclear leukocytes and blocking neutrophil degranulation and superoxide production as well as decreasing the production of IL-8 and IL-10. It interferes with the pro-inflammatory signaling of thrombin resulting in the inhibition of adenosine nucleotide secretion from activated platelets and neutrophil function.

   Antioxidant

• Some explanations for this effect include free radical scavenging activity and decreases H2O2 induced DNA damage.

   Anti-platelet

• Quercetin has potent anti-platelet activity by blocking platelet aggregation, enhancing PGI2, inhibiting platelet cell signaling and thrombus formation, inhibiting platelet adhesion by blocking adhesion molecules P-selectin and ICAM-1, inhibiting thromboxane, hydroxyleptadecatreneate (HHT) and 12-jydroxyeicosatetraenoate (12-HETE)

   Anti-cancer

• Anti-cancer activities occur through cell cycle arrest, inhibiting tyrosine kinase activity, inhibiting protein kinase C activity, antagonistic effects to calmodulin, inhibiting epidermal growth factor, and blocking signal transduction pathways.

It is shown to decrease Coronary Artery Disease, stroke, blood pressure, and atherosclerosis through some of these activities.