A β-glucan from the fruit bodies of edible mushrooms Pleurotus eryngii and Pleurotus ostreatoroseus

The glucans of basidiomycetes are an important class of polysaccharides with potential biological activities. In this work, the β-glucans were isolated from the fruiting bodies of edible mushrooms, Pleurotus eryngii and Pleurotus ostreatoroseus, via extraction with hot water, and then fractionation by freeze-thawing. The insoluble glucans gave similar 13C NMR spectra, monosaccharide composition and methylation analyses, and P. eryngii was selected for further controlled Smith degradation, and DEPT and 1H (obs.), 13C HMQC spectroscopy. It was a branched β-glucan, with a main chain of (1 → 3)-linked-Glcp residues, substituted at O-6 by single-unit β-Glcp side-chains, on average to every third residue of the backbone, as in scleroglucan.