Purification of an antitumor-active, branched (1→3)-β-d-glucan from Volvariella volvacea, and elucidation of its fine structure

✍ Scribed by Etsu Kishida; Yoshiaki Sone; Akira Misaki

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 864 KB
• Volume: 193
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(89)85121-3

✦ Synopsis

A (l-+3)$-D-glucan branched by O-6 substitution (FCAP), obtained from the cold-alkali extract of the fruiting body of V. volvacea, exhibited potent growthinhibitory activity against implanted tumors in mice. It contained protein and appeared to be heterogeneous.

Fractionation by DEAE-Toyopearl column chromatography yielded an unbound, protein-free glucan fraction ([a],, -30" in M NaOH, mol. wt. 1.5-2 X 106), which showed the highest antitumor activity. The polysaccharide had a moderately branched structure, consisting of a backbone chain of p-(1-+3)-linked-D-glucose residues, one out of five or six being substituted at O-6 with single glucosyl or P-(l+(i)-linked diglucosyl groups. Digestion of the glucan with exo-( l-3)-/3-D-glucanase yielded glucose and gentiobiose (molar ratio, 8.2: l.O), and a highly branched (d.b. l/3), degraded glucan. Digestion with endo-(1-3)~P-D-glucanase gave D-glucose, laminarabiose, a trisaccharide P-D-G@ ( l-+6)-P-D-Glcp-( l-3)-D-Glc, a tetrasaccharide P-D-Glcp-( 1+3)-P-D-Glcp-( 1+3)-[/?-~-Glcp-(l-+6)]-~-Gl c, and a highly branched (d.b. l/2), enzyme-resistant glucan. The results suggest that the Volvariellu glucan is structurally heterogeneous with regard to the distribution of branches, having less branched, moderately branched, and highly branched segments.