Structural analysis of anti-tumor heteropolysaccharide GFPS1b from the cultured mycelia of Grifola frondosa GF9801

A 21-kDa heteropolysaccharide, coded as GFPS1b, was obtained from the cultured mycelia of Grifola frondosa GF9801 by hot-water extraction, ethanol precipitation, and fractioned by DEAE Sepharose Fast-flow, followed by the purification with Sephadex G-100 column chromatography using an AKTA purifier. It exhibited more potent anti-proliferative activity on MCF-7 cells than other polysaccharide fractions. GFPS1b was an acidic polysaccharide with approximately 16.60% protein and 4.3% uronic acid. Gas chromatography of absolute acid hydrolysate of GFPS1b suggested that it was composed of d-glucose, d-galactose, and l-arabinose with a molar ratio of 4:2:1. Periodate oxidation, Smith degradation, partial acid hydrolyzation, methylation analysis, FT-IR, and 1H, 13C NMR spectroscopy analysis revealed that GFPS1b had a backbone consisting of α-(1 → 4)-linked d-galacopyranosyl and α-(1 → 3)-linked d-glucopyranosyl residues substituted at O-6 with glycosyl residues composed of α-l-arabinose–(1 → 4)-α-d-glucose (1→ linked residues.