Antitumor effects of (1->3)-β-D-glucan and (1->6)-β-D-glucan purified from newly cultivated mushroom, Hatakeshimeji (Lyophyllum decastes Sing.).

Abstract Eleven polysaccharides were isolated from a hot-water extract of fruiting bodies of Lyophyllum decastes Sing. by ion-exchange chromatography and gel permeation chromatography. Three polysaccharides (IV-1, IV-2, and IV-3) composed mainly of glucose showed marked antitumor activities against Sarcoma 180 and their average molecular weights were 305 kDa, 130 kDa and 14 kDa, respectively. From methylation analyses and 13 C-NMR spectra, it was suggested that IV-1 was a (1→3)-β- d -glucan-type polysaccharide, IV-3 was a (1→6)-β- d -glucan-type polysaccharide, and IV-2 was a (1→3, 1→6)-β- d -glucan-type polysaccharide or a mixture of both polysaccharides. Increases in the number of peritoneal macrophages and third component of complement (C3)-positive fluorescent cells in mice treated with IV-1 suggested that the inhibitory effect on tumor growth is due to immunological host-mediated mechanisms.