滇黄精多糖的结构及对葡萄糖苷酶的抑制作用

Structure of Polygonatum kingjanttm Polysaccharides and Its Inhibitory Activity against α-Glucosidase

采用UV、FTIR、圆二色谱(CD)技术分析了滇黄精(Polygonatum kingjanttm)多糖的化学结构,运用SEM方法观察了多糖的微观形貌,使用TGA技术探讨了多糖的热稳定性,分析了滇黄精多糖对α-葡萄糖苷酶、α-淀粉酶活力的效应。结果发现:滇黄精多糖中存在吡喃糖苷键,可能是含有糖醛酸的酸性多糖。多糖样品在210 nm波长处有明显的正cotton效应。多糖主要包括多网孔片状结构和多分支链聚集结构两种微观形貌。TGA分析结果表明,在248～350℃内,多糖样品的失重率最大,在30～200℃内次之,在400～700℃内最小。滇黄精多糖不会抑制α-淀粉酶活力,但能明显抑制α-葡萄糖苷酶活力,其半抑制浓度(IC50)为4.5720 g/L。

The chemical structure of Polygonatum kingjanttm polysaccharides was determined by UV, FTIR and circular dichroism(CD) spectroscopy techniques. The micromorphology of polysaccharides was observed by scanning electron microscopy(SEM). The thermal stability of polysaccharides was evaluated by thermogravimetric analysis(TGA). And the effects of Polygonatum kingjanttm polysaccharides onα-glucosidase and α-amylase were investigated. The results suggested that there were pyranosidic linkages in Polygonatum kingjanttm polysaccharides. Polygonatum kingjanttm polysaccharides might be acidic polysaccharides containing uronic acid. Polysaccharides exhibited a positive cotton effect at 210 nm.Microstructures of Polygonatum kingjanttm polysaccharides mainly included porous sheet-like structure and multichain aggregation structure. The loss rate of polysaccharides was the highest at 248~350 ℃,followed by 30~200 ℃ and 400~700 ℃. Polygonatum kingjanttm polysaccharides had no inhibitory effect on α-amylase, but had obvious inhibitory activity on α-glucosidase with an IC50(concentration that inhibits enzyme activity by 50%) value of 4.5720 g/L.