New Method to determine Antioxidant Activity of Polyphenols

Abstract

The capacity of polyphenolic compounds to reduce the â-carotene-linoleic acid cooxidationenzymatically induced by soybean lipoxygenase was assayed to determine their comprehensiveantioxidant ability. The inhibition of the coupled oxidation is a well-known spectrophotometric methodfor the antioxidant activity measurement. A modification of this method is proposed to reduce assaytime and to gain simplicity. The antioxidant abilities of several polyphenols were determined, andquercetin and sinapic acid were most active. These results were compared to those obtained by theDPPH¥ procedure to evaluate the free radical scavenging contribution to the total protective action.The highest values of antiradical activity were found for ellagic and quercetin.