银杏叶多糖分离纯化、结构鉴定及抗氧化活性研究

Isolation and purification,structure identification and antioxidant activity of polysaccharides of Ginkgo biloba leaf

目的:分离纯化银杏叶多糖(GBLP)并对其结构进行表征及抗氧化活性研究。方法:超声辅助提取制备银杏叶粗多糖,经精制除杂和阴离子交换柱分离获得多糖级分,采用高效凝胶过滤色谱(HPGFC)、气相色谱法(GC)分析相对分子质量和单糖组成;采用体外抗氧化方法评价银杏叶多糖抗氧化活性。结果:GBLP经分离后获得三个级分GBLPⅠ、GBLPⅡ、GBLPⅢ,其相对分子质量(Mw)分别为41861、361352、637533。GBLPⅠ由鼠李糖、阿拉伯糖、甘露糖、葡萄糖、半乳糖组成;GBLPⅡ和GBLPⅢ由鼠李糖、阿拉伯糖、甘露糖、半乳糖组成,但其摩尔比不同。体外抗氧化实验表明GBLPⅢ对羟自由基的清除能力最强,其次为GBLPⅡ、GBLPⅠ、GBLP;而GBLPⅡ和GBLPⅢ对超氧阴离子清除能力相对较好,其次为GBLPⅠ、GBLP。结论:银杏叶多糖各级分的单糖组成比例、相对分子质量有差异;对羟自由基的清除作用强于对超氧阴离子的清除作用,对羟自由基的清除作用差异可能与Mw及结构相关。

Objective：Isolation and purified the polysaccharide from Ginkgo biloba leaf and investigated its structure characterization,antioxidant activity. Method：Extract polysaccharide from G. biloba leaf by ultrasonic assisted,crud polysaccharide was refined and then was isolated by anion exchange column,the relative molecular weight was measured by gel column chromatography,the monosaccharide composition was analyzed by GC,by adopting the method of in vitro antioxidant evaluation of G. biloba leaf polysaccharide antioxidant activity.Result ： G. biloba leaf polysaccharide was purified and got three ingredients named GBLP Ⅰ, GBLP Ⅱ and GBLPⅢ. The relative molecular weight（Mw） was 41861,361352,637533 respectively. GBLPⅠwas consisted of rhamnose, arabia, mannose, glucose, galactose composition. GBLP Ⅱ and GBLP Ⅲ were consisted of rhamnose,arabia,mannose,galactose composition,but and the molar ratio was different. The result of antioxidant experiment in vitro showed that the ability of GBLP Ⅲ scavenging on hydroxyl free radical was strongest,followed by GBLPⅡ,GBLPⅠ,GBLP. While the ability of GBLPⅡand GBLPⅢ scavenging on superoxide anion was relatively good,followed by GBLP,GBLP Ⅰ. Conclusion：The monosaccharide composition and relative molecular mass of the fractions isolated from G. biloba leaf crude polysaccharide was difference. The ability of G. biloba leaf polysaccharide on hydroxyl free radical scavenging was stronger than the scavenging on superoxide anion,the hydroxyl free radical scavenging effect difference might be associated with Mw and structure.