山药多糖的体外抗氧化活性

为探究山药多糖能否抑制低密度脂蛋白（low density lipoprotein，LDL）氧化，本实验提取了山药（Dioscorea opposita）多糖并除杂，分析了多糖的成分及体外抗氧化活性，对多糖能否抑制LDL氧化进行了初步探讨。结果表明，山药多糖的总糖质量分数为（65.79±1.03）%，蛋白质量分数为（5.89±0.43）%，灰分质量分数为（5.51±0.14）%，糖醛酸质量分数为（10.81±1.14）%；4 个主要多糖组分的分子质量分别为933 742、148 878、39 233、17 318 Da；对1,1-二苯基-2-三硝基苯肼自由基、超氧化物自由基和羟自由基清除率的半抑制质量浓度分别为1.06、1.06 mg/mL和0.98 mg/mL；可有效减缓共轭二烯的形成，1.0 μg/mL山药多糖对硫代巴比妥酸反应物的抑制率为CuSO4组的16.28%（P＞0.05）；但对LDL糖化的抑制作用不大。本研究可为了解山药多糖对LDL氧化的抑制作用提供参考。

In Vitro Antioxidant Activity of Chinese Yam Polysaccharides

The composition and in vitro antioxidant activity of polysaccharides extracted from Chinese yam (Dioscorea opposite Thunb.) were analyzed. Additionally, we tested whether the polysaccharides could inhibit the oxidation of low-density lipoprotein (LDL). The results showed that the purity of the polysaccharides was (65.79 ± 1.03)%, which also contained (5.89 ± 0.43)% protein, (5.51 ± 0.14)% ash and (10.81 ± 1.14)% uronic acid. The molecular masses of the four main polysaccharide components were 933 742, 148 878, 39 233, and 17 318 Da, respectively. The half maximal inhibitory concentration (IC50) values for 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide, and hydroxyl radical scavenging activity were 1.06, 1.06 and 0.98 mg/mL, respectively. The polysaccharides effectively delayed the formation of conjugated diene during LDL oxidation induced by CuSO4. At a concentration of 1.0 μg/mL, the polysaccharides inhibited 16.28% thiobarbituric acid reactive substance (TBARS) production induced by CuSO4 (P > 0.05), but had little inhibitory effect on LDL glycation. The results of the present study may provide useful information for understanding the inhibitory effects of Chinese yam polysaccharides on LDL oxidation.