Fractionation, Chemical Modification and Antitumor Activity of Water-Insoluble Polysaccharides of the Fruiting Body of Ganoderma lucidum

Abstract

Two groups of water-insoluble polysaccharides from the cultured fruiting body of Ganoderma lucidum, “Reishi,” were successively extracted with 3% NH4-oxalate (100°C) and 5% sodium hydroxide solution (30°C). The two polysaccharide fractions, FII and FIII, were divided into many subfractions by ethanol-precipitation and gel filtration chromatography. We then selected antitumor active polysaccharides from these fractions. Acidic β-d-glucan was extracted with 3% NH4-oxalate (100°C) : [α]D−21° (NaOH), IR 890 cm−1, [formula omitted] 10,000∼30,000, N 1%, contained Glc 77%, GlcUA 10% and a small amount of Fuc, Xyl, Man and Gal. ID50=8.3. Acidic hetero-glucan was precipitated with acetic acid (pH 5∼6) extracted with 5% sodium hydroxide (30°C) : FIII-1, fractionated into FIII-1a, -1b, -1c and -1d by gel filtration. ID50 of these sub-fractions were nearly 7.0. The main fraction was FIII-1b : [α]D + 29° (NaOH), IR 890 cm−1, [formula omitted] 70,000∼100,000, N 0.4%, component sugars——Glc 95%, GlcUA 13% and a small amount of Fuc, Xyl and Man. Glycoproteins not precipitated with acetic acid were precipitated with one volume of ethanol extracted with 5% sodium hydroxide (30°C). FIII-2a and FIII-2b: [α]D−96°, +8° (NaOH); [formula omitted] 2,000,000, 40,000∼70,000; N content : 6.5%, 2.8%; ID50 = 26.3, 6.3. Component sugars of both fractions were Glc, Fuc, Xyl, Man and GlcUA. Hetero-glucan not precipitated with acetic acid were precipitated with two volumes of ethanol extracted with 5% sodium hydroxide (30°C) : FIII-3, [α]D−12° (NaOH), [formula omitted] 30,000∼60,000, N 0.1%. Component sugars were Glc, GlcUA, Fuc, Xyl, Man and Gal, ID50=12.8. The antitumor active polysaccharide showed reduced activity when orally administered to mice intraperitoneally implanted with Sarcoma 180. Polyaldehyde, polyol and controlled Smith degradation products chemically modified from the active polysaccharide did not exhibit increased specific activity. © 1985, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.