Abstract: Flavonoids were comparatively studied as the scavengers of hydroxyl and superoxide flee radicals by means of spin trapping-electron spin resonance(ESR) method. The relative activity is related to molecular structures, i.e., the number and position of hydroxyl groups. With molecular modeling and quantum chemistry calculation methods, the relationships were also revealed from the structural analysis of the flavonoids and the products of their single electron oxidation. The spin labeling ESR results indicate that some flavonoids Can influence the conformation of membrane protein, which is likely due to oxidative damage. Both antioxidation and prooxidation characteristics of flavdnoids are worth further studying in detail.

Key words: Flavonoids, Reactive oxygen free radical, Antioxidation, Prooxidation, ESR