Chemical and biological properties of a highly branched [beta]-glucan from edible mushroom Pleurotus sajor-caju

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 (1a3)-linked [beta]-Glcp main-chain, substituted at O-6 by single-unit [beta]-Glcp side-chains, on the average of two to every third residues of the backbone, with a molar mass of 9.75 X 105 g mola1. In macrophage cell culture, the [beta]-glucan induced production of NO and the cytokines TNF-[alpha], IL-1[beta], 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 (1a3), (1a6)-linked [beta]-glucan from P. sajor-caju may have potential for immunological activities, although additional experiments are necessary for a better understanding of the mechanisms involved.