Chemical characterization and antitumor activity of an exopolysaccharide from Pholiota Squarrosa Quel. AS 5.245

A water-soluble exopolysaccharide (PESP-1) was extracted and purified using DEAE Sephadex A-50 and Sephadex G-100 columns from a submerged culture broth of Pholiota squarrosa Quel. AS 5.245. PEPS-1 was investigated for antitumor activity against Heps tumors implanted in mice. An inhibition rate of 78.46% at a dosage of 100 mg/kg was observed. PEPS-1 significantly (p < 0.05) increased the relative spleen/thymus indices of Heps tumor-bearing mice at a dosage of 100 mg/kg, compared with controls. Antitumor properties were probably related to stimulation of the immune response. Preliminary physicochemical analysis identified PEPS-1 as a heteropolysaccharide mainly containing d-mannose, d-glucose and d-galactose at molar ratios of 50:33:18. Small amounts of d-rhamnose and d-xylose were also detected. The average Mw of PEPS-1 was 3.26x10(4) Da. Structural features probably played an important role in the antitumor activity of PEPS-1.