青天葵多糖的分离纯化、结构表征及其抗氧化活性分析

对水提醇沉获得的青天葵粗多糖进行分离纯化，并对多糖组分进行分析表征和体外抗氧化活性评价。结果表明，用DEAE-52纤维素及葡聚糖凝胶G-100柱色谱分离纯化出的多糖组分NFP-2分子质量为1150 kDa，总糖含量为82.64%，糖醛酸含量为16.65%，蛋白质含量为6.38%。NFP-2由半乳糖、阿拉伯糖、甘露糖、葡萄糖、鼠李糖、半乳糖醛酸组成，摩尔比为21.27:13.21:5.26:3.02:2.82:1，其为不含三螺旋结构的酸性多糖，糖苷键构型为β-构型。体外清除自由基试验结果显示，NFP-2对羟基自由基（IC₅₀ 7.95 mg/mL）和超氧阴离子自由基（当浓度为0.5 μg/mL时，清除率为60%）均有明显清除作用；当NFP-2浓度为10 mg/mL时，ABTS阳离子自由基的清除率为35.44%；当NFP-2浓度为120 μg/mL时，DPPH自由基清除率为17%。

Separation,Purification, Structural Characterization and Antioxidation Effects of a Polysaccharide from Nervilia fordii

The crude polysaccharide from Nervilia fordii obtained by water extraction and ethanol precipitation was separated and purified, and the components of the polysaccharide were analyzed and characterized, and the antioxidant activity in vitro was evaluated. Results showed that: A polysaccharide, NFP-2 was purified by DEAE-52 cellulose and Sephadex G-100 column chromatography from the crude polysaccharides of Nervilia fordii obtained by water extraction and ethanol precipitation. The molecular weight of NFP-2 was determined to be 1150 kDa, and the total sugar content, the uronic acid content and the protein content of NFP-2 were measured to be 82.64%, 16.65% and 6.38%, seperately. It was measured that the NFP-2 was composed of galactose, arabinose, mannose, glucose, rhamnose, and galacturonic acid with their molar ratio of 21.27:13.21:5.26:3.02:2.82:1. And NFP-2 was an acidic polysaccharide without triple helix structure, its glycosidic bond configuration was β-configuration. Its antioxidation effects were tested by several assays in vitro, and it showed that the NFP-2 could scavenge hydroxyl radicals with IC₅₀ 7.95 mg/mL, the scavenging ability of the NFP-2 of 0.5 μg/mL on superoxide anion radicals was 60%, the scavenging ability of the NFP-2 of 10 mg/mL on ABTS cation free radicals was 35.44%, and the scavenging ability of the NFP-2 of 120 μg/mL on DPPH free radicals was 17%.