Quercetin. a Potential Complementary and Alternative Cancer Therapy

This chapter reviews quercetin as a potential complementary and alternative therapy for cancer. Quercetin is mentioned to be one of the most common flavonoids found in health foods or herbal products and its biological activity is important in understanding the health benefits of these compounds. The beneficial effect of quercetin is believed to be due to its ability to act as a free radical scavenger and its potency to inhibit the proliferation of transformed epithelial cells. This chapter discusses quercetin absorption, blood concentration and its role as an antioxidant and effect on cancer. The molecular action of quercetin is described and its role on cell cycle regulation, DNA damage and induction of apoptosis in tumor cells. Dietary administration of quercetin in a rat model showed reduction in incidence of mammary tumor induction to carcinogens. The anti-tumorogenic activity of quercetin have a dose-dependant effect, with lower concentration resulting in chemoprevention and higher concentrations have pro-oxidant or potential direct therapeutic properties.