Abstract: The influence of drugs on chemiluminescence kinetics was observed in CuSO₄ Phen V_C-H₂O₂-DNA chemiluminescent system. Nine natural drugs were studied for their protection against DNA damage and the relationship of drug structure with antioxidant activity was discussed. Three types of antioxidant functions were observed, which indicated that drugs have different functions in different reactions in vivo. In this system, the antioxidant activity of the drugs which depress DNA damage chemiluninescence decreases in the order of ferulic acid、salvianic acid A、rutin、green tea polyphenols、SOD、tans hinone Ⅱ-A、paeonol、γ-schisandrin. The antioxidant activity of the drugs which delay DNA damage chemiluminescence decreases in the order of ferulic acid、rutin、green tea polyphenols、Trolox、salvianic acid A、paeonol. The drugs containing big π conjugated system、hydroxyl group、carboxyl group have relatively great efficiency in depressing DNA damage. This is probably relative to their redox potentials.

Key words: DNA damage, chemiluminescence, antioxidant activity, natural antioxidants