Estimation of the antioxidant activities of flavonoids from their oxidation potentials

A simple electrochemical method for estimating the antioxidant activity (AA ) of flavonoids has been developed. The proposed method is based on a measu rement of the half-wave potential (E-1/2) of the first oxidation wave of fl avonoids by using flow-through column electrolysis. At the same time, the l ipid peroxidation (LPO) inhibiting effects of these flavonoids were determi ned. A quantitative structure-activity relationship was obtained to describ e the AA of flavonoids: IC50(muM) = 30.36 + 151.50E(1/2) (V) - 12.63log P ( r = 0.852), where IC50 represents the concentration for 50% inhibition of L PO, and P represents the octanol/water partition coefficient. This method i s expected to be useful for the quick screening of flavonoid antioxidants, and evaluating the AA of flavonoid-containing foods and medicinal plants.