A partially methylated mannogalactan from hybrid mushroom pfle 1p: purification, structural characterization, and study of immunoactivation

• A partially methylated mannogalactan was isolated from hybrid mushroom pfle 1p.
• It contained mannose, galactose, and 3-O-Me-galactose.
• Its structure was established by chemical and 1D/2D NMR analyses.
• It showed macrophage, splenocyte, and thymocyte activations.

A new water-soluble heteropolysaccharide (PS-II) with apparent molecular weight ∼1.65 × 105 Da, was isolated from the fruiting bodies of hybrid mushroom pfle 1p by hot aqueous extraction. It is composed of d-mannose, d-galactose, and 3-O-Me-d-galactose in a molar ratio of 1.0:0.99:1.1. The structural investigation of PS-II has been carried out using acid hydrolysis, methylation analysis, periodate oxidation study, and 1D/2D NMR experiments. Based on the results of these experiments, it was established that PS-II contained a main chain of (1 → 6) linked α-d-galactopyranosyl residues, one of which was substituted at C-2 by a terminal mannopyranosyl residue and also methylated at C-3 position. This heteropolysaccharide (PS-II) exhibited macrophage activation by NO production as well as in vitro splenocyte and thymocyte stimulation.

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