Isolation and chemical characterization of polysaccharides from Iwatake, Gyrophora esculenta Miyoshi.

A heteropolysaccharide and a beta-D-glucan were isolated from a lichen, Gyrophora esculenta Miyoshi (Iwatake), by cold water and alkali extractions, respectively. The chemical properties of purified polysaccharides were examined by acid hydrolysis, methylation, and GC-MS. The heteropolysaccharide is a highly branched galactomannan-type polysaccharide, containing an alpha-(1->6)-linked D-mannan backbone, and the glucan is a linear (1->6)-beta-D-glucan. With regard to the antitumor activity, both the galactomannan and (1->6)-beta-D-glucan had moderate inhibition activities on Sarcoma 180, but lower than those of branched (1->3)-beta-D-glucans.