DNA damage protecting activity and in vitro antioxidant potential of the methanol extract of Cyclotrichium niveum

Cyclotrichium niveum (Boiss.) Manden. & Scheng., a herb of the Labiate family, has been widely used as a flavoring agent in Turkey; it was examined for its antioxidant potential and DNA damage protecting activity. The antioxidant activity of C niveum aerial parts (stems, leaves, and flowers) was determined from the methanol extract. The antioxidant potency of methanol extract of C niveum was investigated employing various established in vitro systems, such as lipid peroxidation in rat brain homogenate, 1,1-diphenyl-2-picrylhydrazyl (DPPH), hyrdoxyl radical scavenging, reducing power, iron chelation, and inhibitory effect on protein oxidation. The methanol extract of C niveum was able to reduce the stable free radical DPPH with an IC50 of 78.15 mu g/mL. The metal chelating ability was found to be low compare with EDTA. Methanol extract of C. niveum aerial parts showed strong inhibitory activity toward lipid peroxidation of rat brain homogenate induced by the FeCl2-H2O2 system. Furthermore, C. niveum extract exhibited a strong concentration-dependent inhibition of deoxyribose oxidation. The effect on DNA cleavage induced by H2O2 UV-photolysis was also investigated. It showed a concentration-dependent free radical scavenging capacity and protective effect on DNA cleavage. In addition, the oxidative damage of bovine serum albumin (BSA), induced by hydroxyl radical in an acellular system, was inhibited by 10-1000 mu g/mL of methanol extract of C. niveum. The total phenolic content of C niveum was detected in methanol as 200.9 mu g gallic acid/mg extract. These results clearly demonstrated that C niveum extract possesses a marked antioxidant activity and it is a potential source of natural antioxidants.