Chemical and biological properties of a highly branched β-glucan from edible mushroom Pleurotus sajor-caju.

Abstract Hot aqueous extraction of the basidiocarps of the mushroom Pleurotus sajor-caju provided a cold water-soluble, gel-like glucan, which was characterized chemically, and its effects on RAW 264.7 cell line (mouse leukaemic monocyte macrophage) activation were determined. NMR spectroscopy, HPSEC, methylation analysis, and a controlled Smith degradation showed it to have a branched structure with a (1→3)-linked β-Glc p main-chain, substituted at O-6 by single-unit β-Glc p side-chains, on the average of two to every third residues of the backbone, with a molar mass of 9.75 × 10 5  g mol −1 . In macrophage cell culture, the β-glucan induced production of NO and the cytokines TNF-α, IL-1β, these effects being very similar as those of Escherichia coli serotype 0111:B4 Sigma–Aldrich lipopolysaccharide (LPS), although not modifying the response of LPS-activated macrophages. The results suggest that the (1→3), (1→6)-linked β-glucan from P. sajor-caju may have potential for immunological activities, although additional experiments are necessary for a better understanding of the mechanisms involved.