本研究之目的在評估冬蟲夏草是否可降低小鼠經游離輻射照射後所造成之自由基傷害以及骨髓衰竭的之副作用。爲探討冬蟲夏草對放射治療中產生的OH自由基之清除能力，以90℃熱水萃取後之冬蟲夏草萃取液，藉由超微弱化學發光分析測量其半抑制濃度(inhibitory concentration 50%)；另取C57BL/6小鼠20隻作爲實驗組，經γ射線(5Gy)照射後，連續3天餵食冬蟲夏草萃取液1mg/animal。day，並於照射後於第5天取經骨與腓骨之骨髓細胞，進行培養，比較其與對照組之細胞群落數目變化、分化相關因子骨型態蛋白(BMP)的基因表現，另外取經骨經組織切片，比較實驗組與對照組中骨髓細胞的變化。由動物骨組織切片的結果顯示冬蟲夏草可減緩因輻射照射所引發之骨髓幹細胞數目減少現象。在體外幹細胞培養的結果中，發現冬蟲夏草可增加BMP基因的表現量。在冬蟲夏草的OH自由基清除力試驗中，發現該萃取物之IC50爲116.5μg/mL，顯示此萃取物有良好的自由基清除力。由以上結果推論冬蟲夏草可減低放射治療後骨髓衰竭的副作用，其機轉可能由於其萃取物有良好的OH自由基清除力，可降低輻射對於骨髓細胞的傷害；此外，該萃取物亦能增進細胞分化相關因子BMP的基因表現，故而促進血源性幹細胞的生長。

The aim of this research is to evaluate the effect of cordyceps sinesis against the detriment of free radicals and the side effect of bone marrow failure after irradiation. To investigate the potential of cordyceps sinesis for eliminating OH free radicals generated in radiotherapy, cordyceps sinesis extracted by 90℃ of water was estimated tar the 50% inhibitory concentration (IC50) with an ultra-weak chemiluminescence analyzer. Besides, 20 C57BL/6 mice of the experimental group was red with the extractive (1 mg/animal•day) for continuous 3 days after irradiated with 5 Gy of γ-ray Five days later after irradiation, bone marrow stem cells from tibia and flbu1a of the mice were taken for culture. The variation of the number of cell colonies and the gene expression of bone morphogenetic protein were investigated and compared between the experimental and the control groups. Bone marrow stem cells from tibia issue slice of the mice were also examined compared with the control group. The tissue slice from the mice represented that cordyceps sinesis is capable of reducing the decrease of bone marrow stern cells after irradiation. In vitro culture of the stem cells indicates that the cordyceps sinesis is able to increase the gene expression of BMP, The 50% inhibitory concentration of the cordyceps sinesis is 116.5μ g/ m L indicating that the potential of cordyceps sinesis in eliminating OH free radicals is good. The results described above show that the cordyceps sinesis is able to reduce the bone marrow failure after radiotherapy. This may be ascribed to the potential of cordyceps sinesis in eliminating OH free radicals, which decreases bone; marrow detriment caused by radiation. Besides, the extractive is also capable of promoting the gene expression of BMP which enhances the growth of hematopoietic stem cells.