Abstract: Acidic polysaccharide from Prunella vulgaris Linn. after isolation and purification was desulfated by solvent method and sulfated by chlorosulfonic acid-pyridine method, respectively. Then the structures of the acidic polysaccharide and its derivatives were preliminary investigated using IR spectrum. Their antioxidant activities and immunological activities were also determined. The result showed that the sulfate content of acidic polysaccharide (AP) from P.vulgaris was 6.58%. The sulfate content of desulfate prtoduct (APD) was 0.305%. Two sulfated products (sulfated polysaccharide with low sulfate content (APL) and sulfated polysaccharide with high sulfate content (APH)) were obtained from acidic polysaccharide after sulfated, and their sulfate content were 30.95% and 36.35%, respectively. Various polysaccharides showed significant antioxidant activities. The order of their antioxidant ability was APH>APL>AP>APD. The IC₅₀ of various polysaccharides toward ABTS·were APD 4.96 g/L,AP 1.13 g/L,APL 1.01 g/L and APH 0.57 g/L. The IC₅₀ of various polysaccharides toward NO₂^-·were APD 2.11 g/L,AP 1.59 g/L,APL 0.61 g/L and APH 0.34 g/L. Meanwhile, various polysaccharides represent significant immunological activities and their immunological activities were significantly enhanced with the increase of their concentrations and sulfate group content.

Key words: Prunella vulgaris Linn., acidic polysaccharide, antioxidant activity, immunological activity