Structural Analysis of the Alkali-Soluble β-D-Glucan from the Fruit Body of Grifola frondosa
Kato, K., Inagaki, T., Teranishi, T., Yamauchi, R., Okuda, K., Sano, T., Ueno, Y.
Department of Agricultural Chemistry, Gifu University
The polysaccharide was extracted from the fruit body of Maitake (G. frondosa) with 10% sodium hydroxide. It was further fractionated, to afford F7 (precipated by neutralization of the extract) and F8 (unprecipitated). F7 and F8 were found to be homogeneous β-D-glucans and they had [α]D +10deg and +3.3deg (c0.3, 4% sodium hydroxide), respectively. Their molecular weights were determined by gel filtration to be 980,000 (for F7) and 830,000 (for F8). From methylation study, Smith degradation, and enzymatic hydrolysis, it was concluded that F7 and F8 are polysaccharides composed of a backbone of β-(1->3)-linked D-glucosyl residues and possessed of a single β-D-glucopyranosyl group joined to O-6 of almost every third D-glucopyranosyl residue of the backbone. However, the degree of branching of F7 is slightly smaller than that of F8.