Structural characterization of an immunoenhancing heteroglycan of a hybrid mushroom (pfls1h) of Pleurotus florida and Lentinus squarrosulus (Mont.) Singer

Abstract

An immunostimulating water-soluble heteroglycan (PS-II) was isolated from an aqueous extract of the fruit bodies of a hybrid mushroom, pfls1h produced by intergeneric protoplast fusion between Pleurotus florida and Lentinus squarrosulus (Mont.) Singer. Structural characterization of PS-II was carried out using sugar analysis, methylation experiment, periodate oxidation and 1D/2D NMR studies. Sugar analysis indicated the presence of glucose, mannose and galactose in a molar ratio of 1:1:2. Methylation analysis revealed that PS-II was composed of (1→6)- and (1→2,4,6)-α-d-galactopyranosyl, terminal β-d-mannopyranosyl and terminal β-d-glucopyranosyl residues in a relative proportion of approximately 1:1:1:1. On the basis of chemical analysis and NMR studies, the structure of the repeating unit of the heteroglycan was established to consist of a backbone chain of two (1→6)-α-d-galactopyranosyl residues, one of which is branched at O-2 with terminal β-d-Manp and at O-4 with terminal β-d-Glcp. This heteroglycan (PS-II) showed in vitro splenocyte, thymocyte and macrophage activations.