目的 从虎眼万年青中提取、分离水溶性多糖，初步研究其特征和抗肿瘤活性。方法 采用热水提取，乙醇沉淀，Sevag法脱蛋白，DEAE-Sepharose Fast Flow离子交换柱色谱和Sephadex G-75凝胶过滤柱色谱分离纯化，得到虎眼万年青均一多糖OCAP-2-2。毛细管区带电泳法（CZE）分析单糖组成；采用高效凝胶渗透色谱法(HPGPC)测定多糖纯度和相对分子质量；动物移植性实体瘤的瘤重实验法研究对小鼠S180肉瘤的抑瘤作用，采用细胞体外培养技术，MTT法检测对人白血病细胞株K562细胞的增殖抑制作用。结果 经过分离纯化得到的均一多糖组分OCAP-2-2主要由葡萄糖、木糖、甘露糖、半乳糖等4种单糖组成，其相对分子质量之比为2.16∶1.26：0.88∶1.00，平均相对分子质量9.84×104，总糖含量为92.3%，总糖醛酸含量为6.21%，蛋白质含量为3.68%；在0.1～100 μg·mL-1内与荷瘤对照组相比，OCAP-2-2对小鼠S180肉瘤有显著的抑制活性，其中多糖浓度为100 μg·mL-1时抑瘤率达（53.16±4.23）% (P＜0.001）；OCAP-2-2对K562细胞有明显的增殖抑制作用（P＜0.01），在多糖浓度为0.10 μg·mL-1时，增殖抑制率最高为（39.83±7.31）% (P＜0.01）。结论 OCAP-2-2具有很高的抗肿瘤活性，可以探索作为一种潜在的天然抗肿瘤药物。

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）% (P＜0.001) 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）% (P＜0.01). CONCLUSION OCAP-2-2 has pronounced anti-tumor activity， and has the potential to be used as a natural antitumor drug.