Abstract:

Tolypocladium sinense was isolated from the fruiting body of a wild Cordyceps sinensis. After growing for 4 to 10 days at 25 to 28 ℃ by shake culture (150 r/min) in a liquid medium (pH 6 to 7) containing glucose 4%, yeast extract 1%, peptone 0.5%, KH2PO4 0.1% and MgSO4 0.05%, the mycelial biomass of Tolypocladium sinense reaches 8.49 to 9.73 g/L. The mycelia extraction rates with petroleum, ethyl acetate, ethanol and hot water are 3.51%, 1.62%, 4.84% and 23.33%, respectively, and the extraction rate of mycelium polysaccharide is 5.31 %. All these extracts of Tolypocladium sinense have scavenging ability, especially mycelium polysaccharide presents the strongest scavenging rates of 49.13% to DPPH·at 2 mg/ml and 82.5% to·OH at 0.08 mg/ml. Moreover, the cytotoxicity of the ethyl acetate extract against leukemia cells such as K562 and SHI-1 line was observed in a MTT assay. The IC50 values on K562 and SHI-1 cell line are 26.55 and 17.75μg/ml, respectively. However, the ethyl acetate extract has low inhibitory effects against PBMC and mouse bone marrow cells. AO/EB staining and TUNEL test demonstrated that the ethyl acetate extract can induce apoptosis of K562 cells. In conclusion, the extracts of Tolypocladium sinense mycelium are potential anti-oxidant and anti-tumor sources.

Key words: Tolypocladium sinense, anti-oxidant activity, cytotoxicity, apoptosis