Abstract: A crude polysaccharide (CP) was obtained by hot-water extraction from the stalk residue of Pleurotus eryngii. The molecular weight distribution of CP was assayed by the combined methods of Gel Permeation Chromatography (GPC), Differential Refraction Detector (RI), and Multi-Angle Light Scattering (MALLS). The monosaccharide composition of CP was assayed by Gas Chromatography (GC). The glycosyl linkages of CP were analyzed by a Gas Chromatography/Mass Spectrometer. The antioxidant activity of CP was assayed by the 2, 2’-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) method. The antitumor activity was assayed by both in vitro 3-(4, 5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) and in vivo method. Results showed that glucose was the predominant monosaccharide (84.4%) of CP; the molecular weight of CP was widely distributed and mainly composed 4 peaks (i.e. 3.816×107, 2.010×106, 4.572×105 and 1.849×105 Dalton). The glycosyl linkages of CP mainly consisted of 1, 3-linked (42.7%) and 1, 6-linked (45.3%) glucose residues. At the concentration of 5 mg/mL, the crude polysaccharides exerted 70.9% scavenging rate of ABTS radical and 45.3% antiproliferative rate of MGC-803 cells. In addition, in vivo experiment showed that CP could significantly inhibit 39.84% growth of transplantable U14 cervical cancer in mice at a dose of 200mg/(Kg ?d) after 12 days’ intragastric administration.

Key words: Pleurotus eryngii, stalk residue, polysaccharide, antioxidant activity, antitumor activity