Chemical constituents from the stems of Marsdenia tenacissima

Chemical investigation into the EtOH extract of the stems of an ethnological herbal medicine Marsdenia tenacissima led to the isolation of eight sesquiterpenes (1−8) including two unreported eudesmane analogues (1 and 2), one undescribed pyrrole glycoside (9), two phenolic glycosides (10 and 11) and one polyoxygenated cyclohexene (12). Structures of these compounds were elucidated by spectroscopic means and comparison with known analogues, and the absolute configurations of the previously unreported molecules were established on the basis of time-dependent density functional theory (TD-DFT) based electronic circular dichroism (ECD) calculation and specific optical rotation analysis. Our bioassays have established that compound 7 exerted mild activity with an IC50 value of 45.74 ± 0.91 μM, but unfortunately none of them showed obvious inhibition against α-glucosidase.