对古尼虫草多糖进行硫酸酯化修饰（修饰后命名为SPS70），并对修饰后的多糖进行了结构、性质及活性研究。红外光谱分析表明SPS70已具备硫酸酯化多糖的硫酸根基团。研究表明修饰后多糖由中性多糖变为酸性多糖。通过高效液相色谱分析发现，经过DEAE-Sephadex A-25分离纯化后，SPS70纯度达到92.72%，抗氧化活性测定显示，SPS70清除超氧阴离子自由基的能力随样品终质量浓度增大而变强，而对羟基自由基和DPPH自由基的清除能力均在2.5 mg/mL时达到最大抑制率，分别为71.23 %和64.12 %。

In this study, 70% polysaccharides from Cordyceps gunnii (Berk.) Berk. were chemically modified via sulfation and was renamed as SPS70 (Cordyceps gunnii 70% sulfated polysaccharides). The structure, property and bioactivity of SPS70 were subsequently investigated. Infrared spectroscopy analysis demonstrated that SPS70 possessed sulfate groups. After modification, the neutral polysaccharides were turn into acidic polysaccharides. After purification by DEAE-sephadex A-25, the purity of SPS70 reached 92.72% and GPC anlysis showed that its molecular weight was of approximately 8490 Da. Anti-oxidation analysis revealed that the radical scavenging ability of SPS70 towards superoxide anion increased when increasing the final concentration of the polysaccharide. And the maximum hydroxyl and DPPH scavenging properties were abstained when SPS70 concentration was of 2.5 mg/mL, being of 71.23% and 64.12%, respectively.

天津市科技计划项目-应用基础与前沿技术研究计划重点项目(09JCZDJC21800)、天津市高等学校科技发展基金计划项目（20090604）