Abstract: Objective:Investigating the protective effects of water and ethanol extracts of natural Cordyceps sinensis and Cordyceps militaris and their fermentation preparations against free radical induced oxidative damage in human hepatoma cell line SMMC-7721. Method:The samples were tested through 5 assays:reducing cell growth suppression caused by H2O2;inhibition of free radical induced lipid peroxidation;inhibition of intracellular GSH decrease;inhibition of free radical induced DNA oxidative damage and decreasing intracellular ROS levels. Results:Natural and cultured Cordyceps sp. showed different antioxidant ability, and in most cases, their antioxidant activity was dose dependent. Among all 8 extracts, the aqueous fraction of natural C.militaris indicated the highest activity, the inhibition of cell growth decreased 90.4 %, lipid peroxidation levels decreased 51.3%, intracellular GSH increased 125 %, DNA oxidation damage decreased 54.9%, intracellular ROS levels decreased 54.8% compared with control group at 50μg/ml. Conclusion:Partial Cordyceps sp. and their fermentation preparations could be regarded as potent natural antioxidants, and the fermented process could affect the antioxidant ability of cultured Cordyceps sp much. The work also presumed that the antioxidant activity of samples might mainly derive from reducing intracellular ROS.

Key words: antioxidant, Cordyceps sinensis, Cordyceps militaris, fermentation, free radical, SMMC-7721