Abstract: Acanthopanacis Senticosi Polysaccharides (ASPs) were extracted by hot water. ASPs in the filtrate were successively precipitated with alcohol. When the quantity of alcohol was equal to the volume of the ASPs filtrate, the production yield of ASPs was the highest. The yields of the fraction productions were decreasing with the increase of the quantitiy of alcohol and the total yield of ASPs was up to 0.54%. The inhibitions of the fraction productions to O₂^- and ·OH were assayed by the method of pyrogallol in the fenton system. The results show that the antioxidative effect of the fraction productions is improved with the increase of the quantity of alcohol. When the quantity of alcohol was 6 times the volume of ASPs filtrate, the elimination rate of the production to O₂^-could reach to the highest value of 47.7%. When the quantity of alcohol was 4 times the volume of ASPs filtrate, the elimination rate of the production to ·OH could reach to the highest value of 68.2%. The inhibition of ASPs to the lipid peroxidation of the erythrocyte membrane was improved with the increase of the concentration of ASPs. When the concentration of ASPs was above 0.4　g/L, ASPs could not only inhibit the lipid peroxidation but also produce some reductive effect to the erythrocyte membrane.

Key words: acanthopanacis senticosi polysaccaride, extract, biological activity