Structural studies on a polysaccharide from an edible mushroom, Termitomyces eurhizus

A polysaccharide (PS), isolated from the hot aqueous extract of the mushroom, Temlitomyces eurhiZlIs, is found to contain, D-glucose, D-galactose, D-mannose and D-galacturonic acid in a mole ratio of about 0.9:0.9: 1.0:0.9. From the peiiodate oxidation and methylation analysis of the PS, the linkages among the constituent sugar residues are identified as, D-Galp (1,6 linked), DManp (1 ,2,3 linked), D-G1cp (1,3 linked) and D-galacturonic acid. The anomeric configuration of the constituent sugar residues are detennined by the chromium trioxide oxidation studies of the acetylated polysaccharide. It is concluded that galactose and mannose have the f)-configuration while glucose and galacturonic acid have the a-configuration. Based on the above observations, the structure of the repeating unit of the polysaccharide was assigned as,