Nine new steroidal glycosides from the roots of Cynanchum stauntonii

Nine new steroidal glycosides, named as stauntosides C-K (2, 5, 7-10, 13, 14, and 16), along with seven known compounds (1, 3, 4, 6, 11, 12, and 15) were isolated from the 95% ethanol extract of the roots of Cynanchum stauntonii. The structures of these new compounds were elucidated on the basis of extensive spectroscopic analyses, mainly 1D and 2D NMR, and HRESI-MS, and qualitative chemical methods. Their significance in terms of the chemotaxonomy of C. stauntonii is discussed.

[Host selection of Oncopeltus fasciatus dall. (Heteroptera: Lygaeidae): Glycosides of asclepiadaceae the chemical basis for host specificity]

The host selection of O. fasciatus is based on typical glycosides sequestered from the Asclepiadaceae. Neither the genins - characterised as 15-oxasteroids - nor the sugars are phagostimulants. After the passage through the insect the glycosides exhibit their biological activity furtheron.