Abstract
A water-insoluble glucan (N-5P), [α] 23D +2.3° (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 × 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 β-D configuration. From the results of methylation analysis, periodate oxidation, Smith degradation (complete, as well as partial), partial acetolysis, and enzymic hydrolysis, it was concluded that N-5P has a main chain composed of β- (1→3) -linked D-glucopyranosyl residues, with single, β- (1→6) -linked D-glucopyranosyl groups attached as side chains, which account for a quarter of the total sugar residues. In addition, the results of enzymic hydrolysis indicated that the β- (1→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.
