Flavonoids: antioxidants in diet and potential anticancer agents

Flavonoids possess a wide spectrum of pharmacological properties, the mechanisms of which have been the subject of considerable interest. They are recognized as naturally occurring antioxidants and have been implicated as novel antiviral and antitumour compounds. Studies have established that several of their properties such as binding to DNA and its degradation are similar to those of known anticancer drugs such as bleomycin and duanomycin. For example, it was shown that flavonoids in the presence of transition metals such as Cu(II) and molecular oxygen cause strand cleavage in DNA. In addition, one of the modes of binding to DNA appears to be through intercalation. Several flavonoids such as quercetin stimulate the p-glycoprotein (p-gp) mediated efflux of chemical carcinogens and anticancer drugs and the isoflavone genistein is a specific inhibitor of tyrosine kinase and topoisomerase II and is able to arrest cell cycle progression at G2-Mphase. These properties make flavonoids and their derivatives important in the development of future anticancer agents. Med Sci Res 26:723-728 (C) 1998 Lippincott Williams & Wilkins.