Hirundigenin type C<sub>21</sub> steroidal glycosides from Cynanchum stauntonii and their anti-inflammatory activity
作者:Chang-zhi Lai、Hai-bin Liu、Jian-xin Liu、Qin Ouyang、Shu-wen Pang、Hua Zhou、Hai-yan Tian、Liang Liu、Xin-sheng Yao、Jin-shan Tang
DOI:10.1039/c6ra11957c
日期:——
Six new hirundigenin-type C21 steroidal glycosides, namely hirundigosides E–J (1–6), were obtained from the dried roots of Cynanchum stauntonii. Their chemical structures were elucidated by analyses of HR ESI-TOF MS, 1D, 2D-NMR, and X-ray crystallographic methods together with acidic hydrolysis. Interestingly, they exist in nature as epimers owing to the presence of 14-hemiketal hydroxyl group. Moreover
六种新的Hirundigenin型C 21甾体糖苷,即hirundigosides E–J(1–6),是从Cynanchum stauntonii的干燥根中获得的。通过对HR ESI-TOF MS,1D,2D-NMR和X射线晶体学方法以及酸性水解的分析,阐明了它们的化学结构。有趣的是,由于存在14-半缩水族羟基,它们以差向异构体的形式存在于自然界中。此外,令人惊讶的是,在CDCl 3中测量时,化合物1–6的1 H和13 C NMR光谱中仅出现一组共振信号(14β-OH差向异构体),而两组共振信号(14α-和14β)出现-OH差向异构体)在吡啶-中测量时观察到d 5。这可能是由于在CHCl 3中14β-OH差向异构体中羟基和氧原子的最接近距离(1.86 nm)导致了糖苷配基分子内氢键的有利形成。在CHCl 3中,化合物1的14α-OH差向异构体与14β-OH差向异构体的势能(ΔG)的差约为0