Polysaccharides in fungi. XX. Structure and antitumor activity of a branched (1.RAR.3)-.BETA.-D-glucan from alkaline extract of Yue er.

Abstract

A water-insoluble glucan-(N-5P), [.alpha.]D23 + 2.3.degree. (c=0.51, 0.5 M sodium hydroxide), was isolated from the alkaline extract of the fruit bodies of Yu er (Chinese name) (Auricularia species). N-5P was homogeneous as judged by gel filtration and electrophoresis. By gel filtration, the molecular weight of N-5P was estimated to be 5.6 .times. 105. The 13C-nuclear magnetic resonance and infrared spectra, together with the result of chromium trioxide oxidation, indicated that glucosidic linkages in N-5P have the .beta.-D configuration. Fromthe results of methylation analysis, periodate oxidation. Smith degradation (complete, aswelll as partial), partial acetolysis, and enzymic hydrolysis, it was concluded that N-5P had a main chanin composed of .beta.-(1.fwdarw.3)-linked D-glucopyranosyl residues, with single, .beta.-(1.fwdarw.6)-linked D-glucopyranosyl groups attached as side chains, which account for a quarter of thetotal sugar residues. In addition, the results of enzymic hydrolysis indicated that the .beta.-(1.fwdarw.6)-linked D-glucosyl side chains are mainly localized in the neighborhood of the nonreducing end of the main chain. Furthermore, N-5P showed potent antitumor activity against the solid form of sarcoma 180 in mice, and exhibited significant carbon clearance-enhancing activity in mice.