Fractionation, partial characterization and bioactivity of water-soluble polysaccharides and polysaccharide-protein complexes from Pleurotus geesteranus

Fractionation and purification of mushroom polysaccharides is a critical process for mushroom clinical application. After a hot-water treatment, the crude Pleurotus geesteranus (PG) was further fractionated into four fractions (PG-1, -2, -3, -4) using gradient precipitation with water and ammonia sulphate. By controlling the initial polymer concentration and ratio of solvents, this process produced PG fractions with high chemical uniformity and narrow M-w distribution without free proteins. Structurally, PG-1 and PG-2 are pure homopolysaccharide mainly composed of glucose; and PG-3 and PG-4 are heteropolysaccharide protein complexes. PG-2, a high M-w fraction mainly composed of glucose presented significant cytotoxicity at the concentration of 200 and 100 mu g/ml to human breast cancer cells. Here, we report a new mushroom polysaccharides extraction and fractionation method, with which we produced four fractions of PG with PG-2 appearing effective anti-tumour activity. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.