枸杞多糖LBP-Ⅱ-b的分离与结构表征

Isolation and structure characterization of polysaccharide LBP-Ⅱ-b from Lycium barbarum L.

目的对宁夏枸杞子中的多糖成分进行研究。方法宁夏枸杞子热水提取、乙醇沉淀,DEAE-Sepharose F.F.和SephacrylS-200柱层析纯化,得到一个酸性果胶多糖LBP-Ⅱ-b,采用IR、NMR、HPLC、GC-MS、部分酸水解及甲基化分析等物理化学方法对其结构进行表征。结果 LBP-Ⅱ-b是一个典型的I型鼠李半乳糖醛酸聚糖(RGI),主链骨架包括:1,4-GalAp构成的无分支的半乳醛酸聚糖(光滑区);1,4-GalAp通过O-4位与1,2-Rhap或1,2,4-Rhap的O-2位交替连接形成的具有较多分支的富含中性糖侧链的鼠李半乳糖醛酸聚糖(毛发区);1,3-Xylp以支链形式连接于1,4-GalAp主链形成的木半乳糖醛酸聚糖(毛发区)。此外,由T-,1,5-Araf和T-,1,4-,1,3,4-Galp聚合形成阿拉伯半乳聚糖或阿拉伯聚糖支链。结论 LBP-Ⅱ-b是首次从枸杞中分离得到的一个新的果胶多糖。

Objective To study the polysaccharides extracted from the plant of Lycium barbarum L. Methods The fruits of L. barbarum, were extracted with hot water, and precipitated with ethanol, and then crude Lycium barbarum polysaccharides was obtained. A new acid pectin polysaccharide LBP-II-b was obtained from the crude polysaccharides successively by column chromatography of DEAE-Sepharose F.F. and Sephacryl S-200. With the methods of IR, NMR, ttPLC, GC-MS, partial acid hydrolysis and methylation reaction, the structure of LBPqI-b was identified. Results LBP-II-b is an acid pectin-type polysaccharide, belong to RGI family, which contained the main part of homogalacturonan fragments as ＂smooth regions＂ with 1,4-GalAp, rhamnogalacturonan ~gments as ＂hairy regions＂ with repeating unit of →4 ） -GalAp- （ 1 →2 ） -Rhap （ 1→, and Xylogalactnronan （ XGA ） segments as ＂hairy regions＂ with a chain of I, 4 -linked galacturonic acid ,which is substituted with Xylose at 0-3 position. Gal and Ara, which were the main constitution of the branch, substituted at O-4 position of Rhap residues of the backbone. And T-, 1,4-, 1,3,4-Galp and T-, 1,5-Araf were linked as arabinogalactan type I and Arabinan at the cite of 0-4 of Rha at the form of the side chain. Conclusion LBP-II-b is an new peptic polysaccharide frum L, barbarum.