Abstract:

Crude polysaccharide was extracted from the fruit bodies of Leucopaxillus giganteus by water extraction and
alcohol precipitation and was purified through sequential steps: acidic ethanol fractionation, Sepharose CL-4B and Sephadex
G-100 gel filtration chromatography to homogeneity as confirmed by high performance liquid chromatography (HPLC).
The purified polysaccharide was designated as DBZG4-b and its molecular weight was measured by HPLC. Moreover, the
structure of DBZG4-b was elucidated by means of gas chromatography, paper chromatography, infrared (IR) spectroscopy,
gas chromatography-mass spectrometry after methylation, and nuclear magnetic resonance (NMR). Results showed that the
average relative molecular weight of the homogeneous polysaccharide, DBZG4-b, was 6 864. Its main chains were composed
of Glc and Gal, and both of them were conjugated to 1→6 glycoside bond; Glc was substituted at 3-O while Gal was
substituted at 4-O. The side chain was composed of (1→3)-Ara, (1→3)-Glc, and (1→4)-Gal. The terminal residue was made
up of Ara, Xyl, Rha, Man, Glc and Gal. Furthermore, DBZG4-b had significant scavenging potential against hydrolxyl and
DPPH free radicals.

Key words: Leucopaxillus giganteus, polysaccharide, isolation and purification, structure, free radicals