Structural characterization and antitumor activity of the extracts from matted mycelium of cultured Grifola frondosa.

Abstract

The fruit body of Grifola frondosa, an edible mushroom, is used as a food in Japan. However, the matted mycelium of the fruit body is not utilized, In this paper, structural characterization and antitumor activity of the extracts from the matted mycelium of this fungus were examined. Hot water, cold alkali, and hot alkali extracts of the mycelium all contained polysaccharides ; that in the cold alkali extract was composed of glucose, but those in the hot water and hot alkali extracts contained glucose, mannose and/or xylose. Each fraction showed potent antitumor activity against murine solid tumor, Sarcoma-180. The antitumor activities of the alkali extracts were more potent than that of the hot water extract. By means of DEAE-Sephadex chromatography, α-amylase treatment, and SP-Sephadex chromatography, a neutral β-1, 3-glucan was purified from the cold alkali extract. From the results of nuclear magnetic resonance spectroscopy, methylation, periodate oxidation, enzymic degradation, and physicochemical characterizations, the purified antitumor glucan was concluded to be a β-1, 3-glucan branched at C-6 of every third main-chain glucosyl unit. The structure is quite similar to that of the antitumor glucan obtained from the fruit body of this fungus. It is concluded that the matted mycelium of G. frondosa may be useful as a source of antitumor β-1, 3-glucan.