A beta-D-glucan from the sclerotia of Pleurotus tuber-regium (Fr.) Sing

An alkali-soluble polysaccharide (Hunai polysaccharide, 1) from the fruit body of Pleurotus tuber-regium (Fr.) Sing was shown to be homogeneous by gel permeation chromatography and its molecular weight was approximately 4.3 x 10(5). Complete acid hydrolysis, periodate oxidation, Smith degradation, methylation, FT-IR and 13C NMR analysis, complex formation with Congo Red, indicated that 1 has a beta-(1 --> 3)-linked D-glucopyranosyl backbone with a single beta-D-glucopyranosyl group at O-6 of every third glucose residue.