Abstract:

This study investigated antioxidant activities of 1:1:1 (m/m) mixtures of three selected from seven flavonoidcompounds to evaluate their synergism and antagonism in vitro. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavengingactivity, hydroxyl radical scavenging activity, total antioxidant activity and reducing power were used as evaluationindicators under different redox reaction mechanisms. HPLC method was used to analyze the structural change of binaryflavonoid mixtures during DPPH scavenging reaction. The results indicated that the 2,3-double bond and the 4-oxo hadstronger influence on the interactions of mixed flavonoids than the o-dihydroxy structure in the B-ring, and this o-dihydroxystructure had stronger influence than single hydroxy structure in the B-ring. HPLC analysis indicated that the occurrence ofinteraction among flavonoids was related to reaction time and the ratio of reducing agents in the redox reaction, which canhappen only when both conditions reach the required levels. Before that, the component with stronger antioxidant activity inflavonoid mixtures was firstly oxidized.

Key words: mixed flavonoids, antioxidant activity, synergism, antagonism, structural change