Antioxidant Flavonoids: Structure, Function and Clinical Usage

Flavonoids occur in most plant species, and account for a significant percentage of the chemical constituents of some; e.g. dried green tea leaves contain approximately 30% flavonoids by weight. Flavonoids have been shown to have antibacterial, anti-inflammatory, antiallergic, antimutagenic, antiviral, antineoplastic, anti-thrombotic, and vasodilatory activity. The potent antioxidant activity of flavonoids—their ability to scavenge hydroxyl radicals, superoxide anions, and lipid peroxy radicals—may be the most important function of flavonoids, and underlies many of the above actions in the body. Oxidative damage is implicated in most disease processes, and epidemiological, clinical, and laboratory research on flavonoids and other antioxidants suggest their use in the prevention and treatment of a number of these. Catechin and its derivatives, oligomeric proanthocyanidins, quercetin and quercetin chalcone, Ginkgo flavone glycosides, silymarin, and others can be utilized in preventative and treatment protocols for cardiovascular disease, cancer, inflammatory conditions, asthma, periodontal disease, liver disease, cataracts and macular degeneration. (Alt Med Rev 1996;1(2):103-111)