Structure of an alkali-soluble polysaccharide from the fruit body of Ganoderma japonicum Lloyd

Abstract

A water-insoluble glucan (G-A), [α] D 16 + 12.8° ( c 0.4, m sodium hydroxide), was isolated from the alkaline extract of the fruit body of Ganoderma japonicum. G-A was homogeneous as judged by gel filtration, electrophoresis, and ultracentrifugal analysis. The molecular weight and degree of polymerization of G-A were respectively estimated to be 82,000 and 330. The 1H-n.m.r. and i.r. spectra, together with the result of chromium trioxide oxidation, indicated that the glucosidic linkages in G-A have the β- d configuration. From the results of methylation analysis, periodate oxidation, Smith degradation, and partial hydrolysis with acid, it was concluded that G-A is composed of a backbone of β-(1 → 3)-linked d-glucopyranosyl residues, and has side-chains of single, β-(1 → 6)-linked d-glucopyranosyl groups attached, on average, to every 30th residue of the backbone.