Chemical and biological properties of a highly branched β-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 (1 -> 3)-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 10(5) g mol(-1). 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 (1 -> 3), (1 -> 6)-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. (C) 2012 Elsevier Ltd. All rights reserved.