Objective: This study investigated the radiation protective effects of Cordyceps sinensis (CS) extract in C57BL/6 mice. Materials and Methods: CS powder was extracted with methanol, concentrated and re-dissolved in de-ionized water as an extract solution. The potential of the extract to eliminate hydroxyl free radicals was measured with an ultra-weak chemiluminescence analyzer. Twelve C57BL/6 mice were used for in vivo and in vitro experiments. After exposure to 0 Gy or 5 Gy whole-body γ-ray irradiation, mice in the experimental groups (3 mice/group) were fed 1 mL of a 1000 μg/mL extract daily for 3 consecutive days while mice in the control groups (3 mice/group) were given saline. After irradiation, monocytes in the peripheral blood of the mice were separated and examined for micronuclei. Tail blood was also used for leukocyte and erythrocyte counts. Bone marrow stem cells from the mice were co-cultured with a 2 μg/mL extract for thein vitro experiment. The expression of the Cbfa (C-Module DNA-Binding Factor) gene in the experimental group was then compared with the controls after 3 days.Results: The inhibition concentration 50% (IC50) value of CS was found to be 16.6 μg/mL, indicating that it had good potential to eliminate hydroxyl free radicals. The in vivo experiment showed that CS was able to reduce the production of micronuclei induced by radiation. The in vitroexperiment indicated that Cbfa gene expression was enhanced by CS.Conclusion: CS was able to reduce depletion in blood cells after irradiation. The radiation protective mechanisms of CS included elimination of hydroxyl free radicals generated at the initial stage of radiolysis and an increase in Cbfa expression which stimulates hematopoietic stem cell differentiation.
