牛膝多糖降血糖活性成分的分离鉴定

Isolation and Identification of Hypoglycemic Polysaccharide fromAchyranthesbidentata

摘要:

研究牛膝多糖与降血糖活性的关系。牛膝粉碎后先经乙醇提取，再用热水提取，水提液减压浓缩后经醇沉得到牛膝水提醇沉物。采用链脲佐菌素（streptozocin，STZ）诱导方法建立小鼠糖尿病模型，每日给药牛膝各分离组分，连续给药8周，通过测定小鼠血糖、糖化血红蛋白，检测牛膝中具有降血糖活性的组分。采用DEAE、HW-55F、Sephacryl S-400等凝胶色谱柱对具有降血糖活性的牛膝多糖组分进一步分离。运用Sephadex G-100凝胶色谱、飞行时间质谱（time of flight mass spectrometer，TOF-MS）、气相色谱（gas chromatography，GC）、核磁共振（nuclear magnetic resonance，NMR）等手段鉴定多糖纯度、测定相对分子质量、分析结构。结果表明，牛膝的水提醇沉物能显著降低糖尿病小鼠的空腹血糖（fasting plasma glucose，FPG）和糖化血红蛋白（HbA1c）浓度（P＜0.05）。将水提醇沉部分进一步分离得到具有降血糖活性的牛膝多糖，并鉴定其纯度为均一多糖，相对分子质量为1 800.5，该多糖由1分子葡萄糖和10分子果糖组成，以葡萄糖分子为起点，与果糖C₂相连，果糖之间以β-1,2 糖苷键连接形成主链，支链连接在果糖的C₆上，该研究明确了牛膝中具有降血糖活性的多糖分子结构。

Abstract:

The study investigated the relationship between polysaccharides from Achyranthes bidentata and their hypoglycemic activity. The powder of Achyranthes bidentata was first extracted with ethanol, followed by hot water extraction. The resulting water extract was concentrated under reduced pressure, and the Achyranthes bidentata water extract precipitate was obtained by ethanol precipitation. Streptozocin (STZ) induction method was used to establish a diabetic mouse model, mice were given gastric medicine Achyranthes bidentata isolated components daily for eight weeks, and hypoglycemic components in Achyranthes bidentata were detected by measuring blood glucose levels and glycated hemoglobin values in mice. Hypoglycemic polysaccharide components from Achyranthes bidentata were further purified using DEAE, HW-55F and Sephacryl S-400 gel columns. The purity, relative molecular weight, and structure of the polysaccharides were determined using Sephadex G-100 gel chromatography, time of flight mass spectrometer (TOF-MS), gas chromatography (GC), and nuclear magnetic resonance (NMR). Results showed that the Achyranthes bidentata water extract precipitate significantly reduced fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c) levels in diabetic mice （P＜0.05）. The hypoglycemic polysaccharides with a relative molecular weight of 1 800.5 from the water extract precipitate were identified as a homogeneous polysaccharide composed of one glucose molecule and ten fructose molecules, connected to the glucose molecule as the starting point and to C₂ of fructose. The main chain is formed by connecting the fructose molecules with β-1,2 glycosidic bonds linkage, and the branched chains are connected to C₆ of fructose. The molecular structure of the hypoglycemic polysaccharides in Achyranthes bidentata was identified for the first time.