鹿蹄橐吾多糖LW21的分离纯化及其结构分析

目的:确定鹿蹄橐吾多糖LW21的结构,为探讨鹿蹄橐吾多糖的药理活性,合理利用鹿蹄橐吾这种植物资源提供依据。方法:水提取醇沉获得鹿蹄橐吾水溶性粗多糖LW,经酸性乙醇分级和DEAE-SephdexA-25纯化得多糖LW21。纸层析、醋酸纤维薄膜电泳和Sepharose CL-4B柱层析进行纯度鉴定,LW21结构分析采用高碘酸氧化、Smith降解、甲基化分析及IR、NMR、GC和GC-MS等方法。结果表明:LW21为均一多糖,相对分子质量约为1.1×106。其单糖组成为鼠李糖(Rha)、阿拉伯糖(Ara)、甘露糖(Man)、葡萄糖(Glc)、半乳糖(Gal),物质的量比为7.4:11.9:25.7:40.0:14.9。多糖LW21为有分枝结构,主链由Glc和Man构成,其中其中Man主要以β(1→2)和β(1→6)糖苷键连接,β(1→2)糖苷键在3-O处和6-O处有分枝,β(1→6)糖苷键在2-O和4-O处有分枝,Glc也主要以β(1→2)及β(1→6)糖苷键连接,β(1→2)糖苷键在6-O处有分枝,β(1→6)糖苷键连接,在2-O处有分枝。分子支链由Ara、Rha、Gal构成。末端残基为Gal、Ara、Rha、Glc。结论:鹿蹄橐吾多糖LW2 1是一新结构多糖,为首次从鹿蹄橐吾中分离得到。

Isolation,Purification and Structural Analysis of Water-Soluble Polysaccharide LW21 from Ligularia hodgsonii

Objective: to isaolate,purify and structurally characterize a water-soluble polysaccharide from the whole herbs of Ligularia hodgsonii.Methods: crude polysaccharide named as LW was extracted from Ligularia hodgsonii.A ploysaccharide fraction named as LW21 was obtained after acidic ethanol fractionation and DEAE-Sephadex A-25 gel filtration.The purity of LW21 was identified by paper chromatography,Sepharose CL-4B chromatography and cellulous acetate electrophoresis,and its structure was analyzed by HIO4 oxidation,Smith degradation,methylation,IR,NMR,GC and GC-MS.Results: LW21 was a homogenous polysaccharide.LW21 was composed of rhamose(Rha),arabinose(Ara),mannose(Man),glucose(Glc) and galactose(Gal) with a molar ratio of 7.4: 11.9: 25.7: 40.0: 14.9.Its average molecular weight was 110 kD.Its main chain was made up of β-(1→2)-linked or β-(1→6)-linked Man,and β-(1→2)-linked orβ-(1→6)-linked Glc residues.The β-(1→2)-linked Man was substituted at 2-O and 4-O;β-(1→6)-linked Man was substituted at 3-O and 6-O;and β-(1→2)-linked Glc was substituted at 6-O;β-(1→6)-linked Gal was substituted at 2-O.The side chain was composed of Rha,Ara and Gal.The non-reduced end was composed of Gal,Ara,Rha and Glc.Conclusion: LW21 is a new polysaccharide isolated from Ligularia hodgsonii for the first time.