四川九节龙中新四糖三萜皂苷结构和核磁共振研究

从四川九节龙(ArdiseapusillaA.DC)的正丁醇提取物中分得一个三萜皂苷。经过测定,它为:3-O-β-D-吡喃葡萄糖(1→2)]α-L-吡喃鼠李糖(1→3)-β-D-吡喃葡萄糖(1→3)]-α-L-吡喃阿拉伯糖-仙客来亭A,为一新四糖皂苷(1)。糖体间和糖体与苷元间的连接顺序和连接位置采用一维SEMDY和旋转坐标NOE差谱核磁共振新技术相结合的方法进行了研究。结果表明,这一方法用于测定寡糖链结构具有准确、简便、快速等特点,对化合物不需要进行化学降解或衍生化,糖基的重叠^1HNMR信号可以分辨和正确指定。

NMR and chemical structure of a new saponin from Jiu Jiujlong (Ardisea pusilla)

A new triterpenoid saponin has been isolated from Ardisea pusilla A. D C, which possesses improved immunological and antitumor activity. Its structure is deduced as 3-O-α-L-(rhamno-pyranosyl-(1→3)-β -D- lucopyranosyl-(1→3)]β-D-glucopyranosyl(1→2)]-α -L- arabinopyranosyl cyclamiretin A. The results obtained show that the chemical structure of oligosaccharide chains of the saponin could be elucidated by using the techniques of 1D-SEMDY and NOE difference spectroscopy in rotating frame, without recourse to chemical degration or modification. Complete assignments of severely overlapping proton resonances of the sugar residues were achieved. The sites of glycosylation and the sequence of sugars in the glycoside can be determined unambiguously.