Pregnane glycosides from Cynanchum menarandrense.

Five new pregnane-type steroidal glycosides, named menarandrosides A-E (1-2, 5-7) were isolated from the aerial parts of $\textit{Cynanchum menarandrense}$, together with three known compounds, carumbelloside I (3), carumbelloside II (4), and pregnenolone-3-O-gentiobioside (8). Their structures were determined on the basis of spectroscopic analyses including NMR and mass spectrometry, reporting C-21 steroids glycosylated only by one or two glucose moieties. Compounds were then investigated for their potential to stimulate glucagon-like peptide-1 (GLP-1) secretion in intestinal cells; although none of the pure compounds had any influence, the fraction enriched in pregnanes exhibited a significant activity, suggesting a possible synergistic effect. Furthermore, none of the purified compounds affected cell viability.This work was supported in Strasbourg by the Region Alsace [n° D11RREG4] and the University of Strasbourg Foundation [n° CONV/ 2011/01/FUDS 18], and in Cambridge by the Wellcome Trust (106262/ Z/14/Z, 106263/Z/14/Z) and the Medical Research Council (MRC_MC_UU_12012/3)