Comparison of Structure and Antitumor Activity of Polysaccharides Isolated from Fukurotake, the Fruiting Body of Volvariella volvacea

Abstract

An a-linked D-manno-D-galactan, glycogen, and three kinds of branched (l→3)-β-D-glucans were isolated from Fukurotake, the fruiting body of Volvariella volvacea by successive extractions with cold and hot water, cold and hot alkali, and dimethyl sulfoxide. The mannogalactan, purified from the cold water extract, had a MW of 4x 105, and consisted of an α-(l→ 6) linked D-galactose backbone, one out of every three D-galactose residues being substituted with a single a-D-mannosyl group. The glycogen, isolated from the hot water extract, had a MW of 12 x 105, and 14~15 D-glucose residues as an average chain length, as revealed by methylation analysis. The α-(l→4)-linked unit chains of this glycogen were distributed from DP 6 to 13, approximately in equal numbers. There were three kinds of branched (l→3)-β-D-glucans, isolated from alkali and dimethyl sulfoxide extractions. They contain a backbone of (1→3)-linked D-glucose residues with side chains of single D-glucosyl groups, but having different degrees of branching. In addition, alkali-extracted glucans contain small but significant proportions of (1→6)-linked sugar units. Among these polysaccharides, the cold alkali-extracted glucan (degree of branching, 1:5) showed a potent antitumor activity against Sarcoma 180 solid tumors implanted in mice, and chemical modifications changed its original activity, confirming our previous results. Other polysaccharides, such as the mannogalactan and other (l→3)-β-D-glucans, showed no or lower antitumor activity. © 1986, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.