Studies on the antitumor activity of polysaccharide produced by a strain of Crepidotus sp.

An extracellular polysaccharide isolated from the supernatant of broth culture of a Crepidotus B-145 was soluble in water, giving a highly viscous solution. Estimation of molecular weight with light scattering gave the value of 1.52×166, while the calculation from determination of reducing endogroup gave the value of 1.6-3.6×104, suggesting the formation of molecular aggregates in solution.Analyses of its component sugar with thin layer chromatography and gas-liquid chromatograhy revealed that the polysaccharide was composed largely from glucose. By gas chromatographic analysis of its permethylation-methanolysis products, it was found that the polysaccharide has 1-3 glucosidic linkage in its structure. Infra red spectroscopy indicated that the linkage is of β-configuration.The presence of β 1-3 linkage was further confirmed by the cleavage with β 1-3 glucanase.Interestingly, the treatment with the polysaccharide was found to suppress the growth of Sarcoma 37 in mice as expected from the antitumor activity of yeast glucan, the active structure of which was said to be β 1-3 linkage.