Structural Characterization of Water-Soluble Polysaccharides from the Fruiting Bodies of Lentinus edodes Mushrooms

Water-soluble polysaccharides have been extracted from the fruiting bodies of Lentinus edodes mushrooms. Three carbohydrate fractions (cold water, hot water and hot aqueous NaOH) from the mushrooms were separated by ethanol precipitation. Size exclusion chromatography revealed the presence of a unique polysaccharide in each fraction. Cold water fraction polysaccharide (PLeC) was composed of glucose and galactose bound by (1→3) and (1→4) linkages with a high degree of branching at O-3 and O-4 of galactose residues. Hot water fraction polysaccharide (PLeH) showed (1→4),(1→6)-linked glucopyranosyl residues with branches at O-4 and O-6. Differently, hot aqueous NaOH fraction (PLeB) consisted of a (1→3),(1→6)-linked glucan branched at O-3 and O-6. NMR studies revealed that the polysaccharides PLeC and PLeH displayed both α and β configurations whereas PLeB presented β anomeric configuration. The analysis of molecular arrangement by complexation with Congo red showed that the three polysaccharides (PLeC, PLeH and PLeB) displayed a triple helix conformation.