Purification and Antitumor Activities of Polysaccharide from Ornithogalum caudatum Ait

OBJECTIVE To investigate the extraction,purification,preliminary characterization and antitumor activities of a water-soluble polysaccharide from Ornithogalum caudatum Ait(OCA).METHODS A homogenization polysaccharide(OCAP-2-2) was obtained by hot water extraction,ethanol precipitation and deproteination with Sevag method,then fractionated by DEAE-Sepharose fast-flow column chromatography,and purified by Sephadex G-75 gel-permeation column chromatography.The sugar concentrations in OCAP-2-2 were characterized by capillary zone electrophoresis(CZE).The homogeneity and molecular weight of OCAP-2-2 were determined by high performance size-exclusion chromatography(HPGPC).The antitumor activity of OCAP-2-2 was evaluated in vivo,by the growth of transplantable S180 sarcoma in mice.The effects of OCAP-2-2 on the proliferation of K562 cells were determined by MTT method in vitro.RESULTS The purified fraction OCAP-2-2 was a homogenization polysaccharide containing 92.3% carbohydrate,6.21% uronic acid and 3.68% protein,with a molecular weight of 9.84×104.It contained primarily of xylose(Xyl),glucose(Glc),mannose(Man) and galactose(Gal) in the molar ratio of 1.26∶2.16∶0.88∶1.00.OCAP-2-2 presented significantly higher antitumor activity against solid tumor Sarcoma 180 in vivo than the blank control at the concentrations from 0.1 μg·mL-1 to 100 μg·mL-1.The inhibition rate in S180 mice was(53.16±4.23)%(P0.001) at the concentration of 100 μg·mL-1.OCAP-2-2 could significantly inhibit the proliferation of K562 cells at all tested concentrations.At the concentration of 0.10 μg·mL-1,the inhibition ratio of OCAP-2-2 was the highest with an inhibition ratio beyond(39.83±7.31)%(P0.01).CONCLUSION OCAP-2-2 has pronounced anti-tumor activity,and has the potential to be used as a natural antitumor drug.