中文摘要：

以霍山石斛苗总多糖（ST）和40％、50％、60％、80％终浓度的乙醇连续沉淀4种多糖组分（S1、S2、S3和S4）为材料，在超氧自由基、H2O2、羟基自由基、还原力、Fe^2＋-VC诱导的脂质过氧化和H2O2诱导的红细胞溶血等不同体系下进行霍山石斛多糖体外抗氧化研究。结果表明：不同相对分子质量霍山石斛多糖均有抗氧化作用，其中相对分子量最大的S1对H2O2、·OH的清除作用强于其他多糖组分，IC50分别为0．15mg／ml和1．81mg／ml，并具有显著的还原力和抑制Fe^2＋-VC诱导脂质过氧化能力，最大效应分别为0．312和45．67％，表明霍山石斛多糖的抗氧化能力与其相对分子质量大小有关。

英文摘要：

Total polysaccharides extracted from seedlings ofDendrobium huoshanense C.Z. Tang et S.J. Cheng were subjected to a sequential precipitation with ethanol at 40%, 50%, 60% and 80% to obtain four fractions of S1, S2, S3 and S4. The antioxidant activities of both the total polysaccharides and four polysaccharide fractions were evaluated in vitro by radical scavenging assay such as O2^-· 1-H2O2 and ·OH, reducing power, anti-lipid peroxidation induced by Fe^2＋-VC and anti-erythrocyte hemolysis induced by H2O2 assays. The four fractions exhibited different antioxidant activities, and among them fraction S 1 with the highest relative molecular mass had the strongest scavenging activities to H2O2 and · OH radicals with ICsovalues of 0.15 mg/ml and 1.81 mg/ml, respectively and the highest reducing power and anti-lipid peroxidation induced by Fe^2＋-VC which reached 0.312 at I mg/ml and 45.67% at 0.5 mg/ml, respectively. The results showed that the antioxidant potential of polysaccharides from Dendrobium huoshanense is presumably related to their relative molecular mass.