中文摘要：

本实验研究金蝉花多糖的抗氧化活性,并对其纯化组分进行结构分析。采用热水浸提、不同浓度乙醇分级沉淀的方法从金蝉花中提取多糖,分别获得_（50）%醇沉金蝉花多糖（_（50）%polysaccharides from Cordyceps cicadas,CP_（50））和_（80）%醇沉金蝉花多糖（CP_（80））,并检测两者的体外抗氧化活性。结果表明：CP_（50）较CP_（80）表现出较强的清除自由基的能力,且具有一定的还原能力和总抗氧化能力。CP_（50）进一步经二乙氨乙基（diethylaminoethyl,DEAE）纤维素-52和Sephadex G-100凝胶柱分离纯化,得到活性多糖CPA-1和CPB-1。经紫外扫描光谱法和高效凝胶过滤色谱法鉴定CPA-1和CPB-1为均一多糖;单糖组成分析显示两个组分中均含有葡萄糖、甘露糖和半乳糖,其物质的量比分别为：1∶0.48∶0.52和1∶0.14∶0.114。红外光谱（infrared spectroscopy,IR）及刚果红实验发现,CPA-1和CPB-1具有典型的多糖红外吸收,且含有三股螺旋分子结构。

英文摘要：

In this study, the antioxidant activities and structural characteristics of polysaccharides from Cordyceps cicadae were determined. Two crude polysaccharide fractions（CP_（50） and CP_（80）） were extracted from Cordyceps cicadae with hot water and isolated by precipitation with different concentrations of ethanol. Their antioxidant activities were also analyzed. The results indicated that both CP_（50） and CP_（80） were effective in antioxidant activity. The radical scavenging activity of CP_（50） was higher than that of CP_（80）. CP_（50） also showed higher reducing capacity and total antioxidant activity. CP_（50） was then further purified by gel filtration on diethylaminoethyl（DEAE）-cellulose-52 and Sephadex G-100 columns, and two purified fractions were obtained, namely CPA-1 and CPB-1. Ultraviolet spectroscopy and high-performance liquid chromatography（HPLC） analysis revealed that CPA-1 and CPB-1 were homogeneous. Monosaccharide analysis revealed that both CPA-1 and CPB-1 were composed of Glc, Gal and Man with a molar ratio of 1：0.48：0.52 and 1：0.14：0.114, respectively. Moreover, both polysaccharide fractions had three helix structures.