Structural characterization of an immunoregulatory polysaccharide from the fruiting bodies of Lepista sordida

A water-soluble polysaccharide, named as LSP, was extracted and fractioned from the fruiting bodies of Lepista sordida by DEAE-cellulose anion exchange and Sepharose CL-6B column chromatography. Its molecular weight (Mw) was estimated to be about 4 × 104 Da by using high-performance gel permeation chromatography (HPGPC). According to Fourier transform infrared (FT-IR) spectroscopy, partial acid hydrolysis, periodate oxidation and Smith degradation, methylation and GC–MS analysis, the results indicated LSP had a backbone consisting of (1  →  6)-linked-α-d-glucopyranosyl and (1  →  2,6)-linked-α-d-glucopyranosyl residues, which was terminated with terminal (1  →  )-α-d-galactopyranosyl residue at the O-3 position of (1  →  2,6)-linked-α-d-glucopyranosyl residue along the main chain in the ratio of 2:1.1:0.9. Preliminary tests in vitro showed LSP had potent activation effects on murine macrophages, supported by the fact that the elevated NO production and TNF-α secretion, and its branches played a crucial role for macrophages activation.

► A polysaccharide (LSP) was fractionated from the fruiting bodies of Lepista sordida.
► The structure of LSP was elucidated by chemical and instrumental analysis.
► The effect of LSP and its backbone (LSPA) on macrophages activation were evaluated.
► The branches of LSP played a crucial role for macrophages activation.