Riboflavin photo-transformation of genistein and changes in radical scavenging activities of photo-transformed genistein derivatives

Genistein was treated with riboflavin photosensitization and the radical scavenging activities of mixtures of genistein and riboflavin were determined using DPPH and ABTS assays. For a period of light irradiation of 100 min, the initial concentration of genistein decreased by 79.1% for riboflavin photosensitization. New peaks were formed and the peak areas increased for a mixture of riboflavin photosensitized genistein. Genistein derivatives were tentatively identified as trihydroxy isoflavones or genisteins with an additional hydroxyl groups. The radical scavenging abilities of photo-sensitized genistein derivatives were significantly (p<0.05) increased, based on DPPH and ABTS results, compared to samples without visible light irradiation for 100 min of photosensitization. Riboflavin photo-transformation can enhance antioxidant activities in isoflavone aglycones.