Structures and Antitumor Activities of the Polysaccharides Isolated from Fruiting Body and the Growing Culture of Mycelium of Ganoderma lucidum.


Sone Y, Okuda R, Wada N, Kishida E




Agric Biol Chem


Several beta-D-glucans, pertaining to the same molecular species but having different degrees of branching, were isolated from water and alkali extracts of the fruiting body of Ganoderma lucidum (Reishi). Chemical structures and antitumor activities of the branched (1----3)- beta-D-glucan fractions were investigated. The purified glucans that are mostly water-insoluble have a backbone of (1----3)-linked D- glucose residues, attached mainly with single D-glucosyl units at O-6 and also with a few short (1----4)-linked glucosyl units at O-2 position. However, their degrees of branching appear to differ in the range of d.b. 1/3 to approx 1/23, depending on the extracted glucan fractions. The fruiting G lucidum body also contained water-soluble heteropolysaccharides, comprising D-glucose, D-galactose, D-mannose, L(or D)-arabinose, D-xylose, and L-fucose. Water and alkali extracted beta-D-glucans having different degrees of branching were tested for antitumor activities by successive ip administration of each polysaccharide as a suspension in phosphate buffered saline (pH 7.0), at a dosage of 10 mg/kg of ICR-JCL mouse/day, starting 24 hr after sc implantation of sarcoma 180 cells (6 x 10(6) cells). After 5 wk, tumor inhibition ratios, and number of treated mice whose tumor had completely regressed, were examined. The hot-water extractable fruiting body glucan of the culture of growing mycelium showed relatively high growth-inhibitory activities against sarcoma 180 when administered by successive ip injections. When the moderately branched glucans were modified to D-glucan-polyols by periodate oxidation and borohydride reduction, they exhibited higher antitumor activities, confirming the previous conclusion that the attachment of polyol groups to the (1----3)-linked backbone significantly enhances its host-mediated antitumor effect. (15 Refs)