A gel-forming β-glucan isolated from the fruit bodies of the edible mushroom Pleurotus florida

Abstract

Glucans of basidiomycetes are considered to be an important class of polysaccharides, as they can act as biological response modifiers. We now isolate a gel-forming, water-soluble β-glucan, with a molecular mass of 1.2 × 10 6 g/mol (HPSEC), from the fruit bodies of the edible mushroom Pleurotus florida, via alkaline extraction, followed by fractionation by freeze–thawing. Structural assignments were carried out using mono- and bi-dimensional nuclear magnetic resonance spectroscopy, monosaccharide composition, methylation analyses, and a controlled Smith degradation. It was a branched β-glucan, with a main chain of (1→3)-linked-Glc p residues, substituted at O-6 by single-unit Glc p side chains, on average to every fourth residue of the backbone.