POLYSACCHARIDES OF PLEUROTUS-OSTREATUS - ISOLATION AND STRUCTURE OF PLEURAN, AN ALKALI-INSOLUBLE BETA-D-GLUCAN

An alkali-insoluble skeletal beta-D-glucan has been isolated from the fruit bodies of Pleurotus ostreatus. The polysaccharide has a branched structure consisting of a backbone of (1 --> 3)-linked beta-D-glucopyranosyl residues, every fourth being substituted at 0-6 with single D-glucopyranosyl groups. The polysaccharide contained a small proportion (7%) of (1 --> 6)- and (1 --> 4)-linked interior residues. The beta-D-glucan (pleuran) demonstrated efficacy in promoting the survival of mice susceptible to bacterial infections.