Isolation of a polysaccharide with anticancer activity from Auricularia polytricha using high-speed countercurrent chromatography with an aqueous two-phase system.

Polysaccharides from a crude extract of Auricularia polytricha were separated by high-speed countercurrent chromatography (HSCCC). The separation was performed with an aqueous two-phase system of PEG1000-K2HPO4-KH2PO4-H2O (0.5:1.25:1.25:7.0, w/w). The crude sample (2.0 g) was successfully separated into three polysaccharide components of AAPS-1 (192 mg), AAPS-2 (137 mg), and AAPS-3 (98 mg) with molecular weights of 162, 259, and 483 kDa, respectively. These compounds were tested for growth inhibition of transplanted S180 sarcoma in mice. AAPS-2 had an inhibition rate of 40.4%. The structure of AAPS-2 was elucidated from partial hydrolysis, periodate oxidation, acetylation, methylation analysis, and NMR spectroscopy (1H, 13C). These results showed AAPS-2 is a polysaccharide with a backbone of (1-->3)-linked-beta-d-glucopyranosyl and (1-->3, 6)-linked-beta-D-glucopyranosyl residues in a 2:1 ratio, and has one terminal (1-->)-beta-D-glucopyranosyl at the O-6 position of (1-->3, 6)-linked-beta-D-glucopyranosyl of the main chain.