选择性NMR新技术用于新的3, 28-双糖链三萜皂苷的结构研究

从中药川续断根部的乙醇提取物中分得一个新的三萜皂苷。经过测定,它为:3-O-[α-L-吡喃鼠李糖(1→3)][-β-D-吡喃葡萄糖(1→4)]-β-D-吡喃葡萄糖(1→3)-α-L-吡喃鼠李糖(1→2)-α-L-吡喃阿拉伯糖-常春藤苷元-28-O-β-D-吡喃葡萄糖(1→6)-β-D-吡喃葡萄糖酯苷。研究表明,采用一维SEMDY、旋转坐标NOE差谱和选择性远程DEPT核磁共振新技术相结合的方法测定糖链结构不需要对该化合物1进行化学降解或衍生化,方法简便、快速,测定结果可靠,每个糖基的信号可以分辨和明确归属。

Structural determination of oligosaccharide chains of a new 3, 28- bidesmosidic triterpenoid glycoside by new selective NMR techniques

A new 3, 28-bidesmosidic triterpenoid saponin was isolated from the ethanolic extract of the root of Dipsacus asperoides C. Y. cheng et T. M. Ai and its structure established as 3-O-[α-L-rhammopyranosyl (1→ 3)][-β -D-glycopranosyl (1→4)]-β-D-glycopranosyl (1→3)-α -L- rhammopyranosyl (1→2)-α -L-arabinopyranosyl-hederagenin-28-O-β-D- glycopranosyl (1→ 6)-β-D-glycopranoside. The results obtained showed that the chemical structure of oligosaccharide chains of the saponin could be elucidated by the combination of 1D-SEMDY, NOE difference spectroscopy in rotating frame and selective long-range DEPT techniques, without having recourse to chemical degradation or modification. Complete assignments of severely overlapping proton resonance of the sugar residues were made.