An acidic polysaccharide, H2, was isolated from the alkali-extract CHC of seeds of Cuscuta chinensis Lam. with the molecular weight more than 1.0×106. Chemical and spectroscopic studies led to the structure determination as follows: the backbone chain consists of 1,6-linked-β- D Galp, 1,4-linked-β- D Galp, 1,4-linked-β- D GalA and 1,2- or 1,4-linked-β- L Rhap having branching points at position O-3 of some 1,6-linked-β- D Galp residues (one among eight) and O-4 or O-2 of 1,2- or 1,4-linked-β- L Rhap residues to terminal β-D-galactopyranose. The side chains composed of terminal Galp, 1,6-linked-β- D Galp, 1,4-linked β- D Galp and 1,3,6-linked-β- D Galp also linked at position O-3 of 1,6-linked-β- D Galp residues in the backbone chain. β- L -arabinofuranosyl and terminal β- L -rhamnopyranosyl residues existed in the periphery of this polysaccharide linked to O-3 of 1,6-linked-β- D Galp residues in the backbone chain and the side chains. The polysaccharide H2 increased significantly the survival rate of PC12 cells indicating that it had protective effects against H2O2 insult.
具有抗氧化活性的酸性菟丝子多糖H2的研究
王展 方积年*
（中国科学院上海药物研究所，上海200031）
摘要： 从药用植物菟丝子 (Cuscutachinensis Lam .)的种子中经碱液提取所得的粗多糖CHC ,经进一步分离纯化得一酸性纯多糖H2 ,其分子量大于 1.0× 10 6,利用化学方法和光谱分析方法对其结构进行了研究。多糖H2由 1,6-linked-β-DGalp、1,4-linked-β-DGalp、1,4-linked-β-DGalA和 1,2or 4-linked-β-L-Rhap构成主链 ,并在部分1,6-linked-β-DGalp残基的O-3位和 1,2or 4-linked-β-L-Rhap残基的O-4或O-2形成分枝点 ,以末端半乳糖构成末端。侧链由末端半乳糖 ,1,6-linked-β-DGalp、1,4-linked-β-DGalp和 1,3,6-linked-β-DGalp残基构成 ,连接于主链的1,6-linked-β-DGalp残基的O-3位。阿拉伯糖残基 1,5-linkedAra、1,3,5-linkedAra、末端Ara以及末端鼠李糖残基存在于多糖分子H2的外周 ,连接于侧链和主链的 1,6-linked-β-DGalp残基的O-3位。此外 ,药理研究结果显示 ,H2能减少自由基引起的对大鼠成嗜铬细胞瘤PC12神经细胞系的损伤 ,明显提高细胞的存活率
关键词： 菟丝子；旋花科；多糖PC12细胞
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