Reactions of genistein with alkylperoxyl radicals

Antioxidant actions of the soy isoflavone genistein are believed to contrib ute to its overall chemopreventive activity. However, the mechanisms of its antioxidant reactions remain unknown. The objective of this study was to c haracterize the reaction products of genistein (5,7,4'-trihydroxyisoflavone ) with peroxyl radicals generated by thermolysis of 2,2'-azobis(2,4-dimethy lvaleronitrile) (AMVN). Genistein oxidations with AMVN-derived peroxyl radi cals yielded orobol (5,7,3',4'-tetrahydroxyisoflavone), a hydroxylated deri vative of genistein, and several stable adducts of 4'-oxogenistein with AMV N-derived radicals. Some of these adducts include novel structures resultin g from secondary oxidations of the AMVN-derived moiety. For all the observe d oxidation products, the modifications occurred on the B-ring of the molec ule. Genistein oxidation product structures provide potentially useful mark ers of genistein antioxidant chemistry.