Structural elucidation and immunostimulating property of a novel polysaccharide extracted from an edible mushroom Lentinus fusipes.

A water soluble heteroglycan (PS-II) with an average molecular weight∼60kDa was isolated from the hot aqueous extract of an edible mushroom Lentinus fusipes. The structural characterization of PS-II was carried out using total acid hydrolysis, methylation analyses, periodate oxidation, Smith degradation and 1D/2D NMR experiments. Total acid hydrolysis indicated the presence of D-galactose and D-glucose in a molar ratio of approximately 1:1. The chemical and NMR analyses revealed that the proposed repeating unit of the PS-II had a backbone chain consisting of three (1→6)-linked α-d-galactopyranosyl residue and two (1→6)-linked β-d-glucopyranosyl residues, one of the β-d-glucopyranosyl residue was branched at O-3 position with a terminal β-d-glucopyranosyl. The PS-II exhibited significant in vitro splenocyte and macrophage activations with optimum dose of 20μg/ml and 80μg/ml respectively. Flow cytometry study revealed the protective role of the PS-II against nicotine stimulated lymphocytes. Moreover, the ROS scavenging property of PS-II was also established using DPPH radical scavenging assay.