白术多糖的分离纯化与结构表征

Isolation and Structure Characterization of Polysaccharide from Atractylodes Macrocephala Koidz

采用UV,IR,NMR,GC-MS,高碘酸氧化和Smith降解等物理化学方法对从白术根茎提取的白术多糖的纯度、理化性质和结构进行了表征.以中药白术的根茎为原料,通过热水(80℃)浸提和乙醇醇沉得到粗多糖,再经DEAE-52阴离子交换柱层析分离和Sephadex G-200凝胶柱层析纯化,得到一种水溶性的白术多糖(WAM).经高效液相色谱(HPLC)分析,多糖WAM是分子量约为3263的均一多糖.GC分析表明,WAM是由葡萄糖和半乳糖以摩尔比3.01∶1构成的杂多糖.甲基化分析、高碘酸氧化、Smith降解、部分酸水解、NMR和IR等分析结果表明,WAM具有多分支结构,主链由β-D-1→3和β-D-1→3,6吡喃葡萄糖构成,每个重复单元具有一个支链,支链由β-D-半乳糖构成,连接在主链葡萄糖的6位碳原子上.

Crude polysaccharides,extracted from the stem of Atractylodes macrocephala Koidz by hot water（80 ℃）,were fractionated by DEAE-52 anion exchange chromatography and purified by Sephadex G-200 gel filtration chromatography to afford a fraction,named WAM.The polysaccharide（WAM） was subjected to structural identification by a combination of chemical and instrumental analysis.The molecular weight of WAM was measured to be 3263 by high performance liquid chromatography.Gas chromatography analysis indicated that WAM composed of glucopyranose and galactopyranose in a molar ratio of 3.01∶1.00.The infrared spectra and nuclear magnetic resonance（NMR） spectra further confirmed that the configuration of D-glucopyranose and D-galactopyranose were of β-form.On the basis of partial acid hydrolysis,periodate oxidation,Smith degradation and methylation analysis,it can be concluded WAM had a backbone consisting of（1→3）-linked-β-D-glucopyranosyl and（1→3,6）-linked-β-D-glucopyranosyl,which was branched with a glycosyl residue,β-D-galactopyanose（1→ linked residue,at the C6 position of glucosyl along the main chain.