龙血树叶降血糖活性多糖的纯化及结构解析

Purification and structural elucidation of hypoglycemic active polysaccharides from leaves of Dracaena cambodiana

龙血树(Dracaena Vandelli ex Linnaeus)是一种热带特有的珍稀药用植物。傣族贝叶经记载龙血树叶具有和血竭相似的医疗功效,且市场反馈显示对糖尿病有一定治疗效果,但其降血糖机制尚未揭示。将柬埔寨龙血树叶在L6大鼠成肌细胞降糖活性模型指导下,经热水浸提、醇沉制备粗多糖,再经Sevag法除蛋白、A-722MP阴离子交换树脂脱色后,上DEAE-52纤维素柱层析和Sephacryl S-100HR凝胶柱分离纯化,得到单一活性组分LZS,利用紫外、红外、核磁共振波谱以及HPAEC-PAD色谱法对LZS的结构进行鉴定。活性组分LZS为7种单糖和柠檬酸组成的一种多糖衍生物,单糖组成为:果糖、葡萄糖、半乳糖、阿拉伯糖、鼠李糖、甘露糖、木糖,摩尔比为54.3∶29.5∶6.9∶6.2∶2.1∶0.7∶0.4,主要由果糖和葡萄糖聚合而成,龙血树叶多糖结构新颖,具有明显的细胞活性。实验结果初步阐明了龙血树叶降糖活性的化学本质,为龙血树叶的利用提供了科学依据。

Dracaena tree is a rare medicinal plant unique to the tropics.The Dai Palm leaf manuscript recorded that Dracaena leaves have similar medical effects to blood resin,and market feedback showed that they have certain therapeutic effects on diabetes,but their hypoglycemic mechanism has not been revealed.Under the guidance of hypoglycemic activity model of myoblast of L6 rat cell strain,a pure active component LZS was prepared by extraction with hot water,alcohol precipitation,decolorization with A-722 MP anion exchange resin,deproteinization with Sevag method,and final purification with DEAE-52 cellulose column chromatography and Sephacryl S-100 HR gel column chromatography.The structure of LZS was solved by UV,IR,NMR and HPAEC-PAD methods,indicating that LZS is a polysaccharide derivative consisting of seven monosaccharides and citric acid.The monosaccharide components of LZS include fructose,glucose,galactose,arabinose,rhamnose,mannose and xylose,which connect with each other viaβ-glucoside bonds with molar ratio of 54.3∶29.5∶6.9∶6.2∶2.1∶0.7∶0.4.The polysaccharides in the leaves of Dracaena cambodiana have novel structure and obvious hypoglycemic activity.Our results clarify the chemical nature of hypoglycemic function of Dracaena leaves,and provide scientific basis for their utilization.