DIMINUTION OF SINGLET OXYGEN-INDUCED DNA-DAMAGE BY CURCUMIN AND RELATED ANTIOXIDANTS

Curcumin, the natural antioxidant from turmeric, an Indian spice, and its derivatives have significant abilities to protect plasmid pBR322 D NA against single-strand breaks induced by singlet oxygen (O-1(2)), a reactive oxygen species with potential genotoxic/mutagenic properties. O-1(2) was generated at 37 degrees C in an aqueous buffer system by t he thermal dissociation of the endoperoxide of 3,3'-(1,4-naphthylene)d ipropionate (NDPO2). Among the compounds tested, curcumin was the most effective inhibitor of DNA damage followed by desmethoxycurcumin, bis desmethoxycurcumin and other derivatives. The observed antioxidant act ivity was both time-and concentration-dependent. The protective abilit y of curcumin was higher than that of the well-known biological antiox idants lipoate, alpha-tocopherol and beta-carotene. However, the highe st protective ability with saturating concentrations of curcumin did n ot exceed 50%. The ability of curcumin and its derivatives to protect DNA against O-1(2) seems to be related to their structures and may at least partly explain the therapeutic and other beneficial effects of t hese compounds including anticarcinogenic and antimutagenic properties .