3种药用石斛多糖的抗氧化活性比较研究

比较了铁皮石斛、大苞鞘石斛和金钗石斛3种石斛茎段粗多糖、精多糖（除蛋白多糖）和多糖组分（过层析柱多糖分离组分）对DPPH、OH和O-2 3种自由基的离体抗氧化活性. 结果表明:随着多糖纯度增强和质量浓度的提高，抗氧化效果均显著增强，在12 g/L时，处理效果最佳，铁皮石斛多糖组分（DOPP-I）、大苞鞘石斛多糖组分（DWPP-I）和金钗石斛多糖组分（DNPP-I）对DPPH自由基的清除率均在75%以上，对OH自由基的清除率在 84%以上，且显著优于Vc (Vitamin c)，但3种多糖组分间差异不显著；3种石斛多糖对O-2自由基的清除能力显著低于Vc，但DWPP-I的清除能力显著高于DOPP-I和DNPP-I. 总之，大苞鞘石斛多糖组分DWPP-I的抗氧化能力略优于铁皮石斛和金钗石斛.

Comparison of Antioxidant Activity of the Polysaccharides from Three Dendrobium Species

The antioxidant activities of polysaccharides from three Dendrobium species (Dendrobium officinale, D. wardianum and D. nobile) were investigated in vitro. The results showed that antioxidant ability of Dendrobium polysaccharides correlated well with the increasing of purities and concentrations, and the scavenging activities were the highest at 12 g/L. At this concentration, the scavenging rates by DOPP-I, DWPP-I and DNPP-I were above 75% for DPPH radicals and above 84% for hydroxyl radicals (OH). It was insignificantly different among the three polysaccharides, but they were significantly higher than the control (Vitamin c). The activity of DWPP-I to scavenge superoxide anion radicals (O-2) was significantly higher than DOPP-I and DNPP-I. Thus, antioxidant activity of polysaccharides DWPP-I (from D. wardianum) was higher than those from the other two Dendrobium polysaccharides.