Isolation and characterization of the immunostimulating β-glucans of an edible mushroom Termitomyces robustus var.

Two immunostimulating β-glucans, PS-I (water soluble) and PS-II (water insoluble) isolated from hot water extract of the fruiting bodies of an edible mushroom Termitomyces robustus var. showed significant macrophage, splenocyte, and thymocyte activation. On the basis of total hydrolysis, methylation analysis, periodate oxidation, and NMR experiments ((1)H, (13)C, DQF-COSY, TOCSY, DEPT-135, HSQC, and HMBC), the structure of the repeating unit of the polysaccharides is established as: PS-I: ->6)β-D-Glcp-(1→ (Water-soluble glucan) PS-II: →3)-β-D-Glcp-(1→3)-β-D-Glcp-(1→ 6↑1 β-D-Glcp (Water-insoluble glucan, Termitan).