Abstract: The crude polysaccharide was extracted from D. fordii Prain et Burkill with hot water,and precipitated by ethanol.The refined polysaccharide was prepared after delipid, deprotein and decolor processing with further purification on two timesSephadex G-75 column chromatography. The homogentity was examined with paper chromatography and the determination ofspecific rotatory power identified by ultraviolet spectra. In order to estimate the antioxidation activity of D. fordii Prain et Burkill,three systems of generating superoxide radical, hydroxyl radical and lipid radical respectively in vitro were designed. The resultsshowed that both crude and refined Polysaccharides from D. fordii Prain et Burkill were effective in scavenging superoxide radicaland hydroxyl radical, but only a little effective in scavenging lipid radical, and that the scavenging for capacity superoxide radicaland hydroxyl radical of refined polysaccharide extracted from D. fordii Prain et Burkill were higher than that of crudepolysaccharide alse extracted from D. fordii Prain et Burkill.

Key words: D. fordii Prain et Burkill, polysaccharides, antioxidation, isolation and purification