Pregnane glycosides from Dregea volubilis and their α-glucosidase inhibitory activity.

• Three new pregnane glycosides, volubilosides D-F were isolated from Dregea volubilis. • The structures were successfully determined by spectroscopic evidence. • Compounds 5 and 6 showed significant α -glucosidase inhibitory activity. Three new pregnane glycosides namely volubilosides D-F (1 – 3) along with three known, dregeoside Da1 (4), volubiloside A (5), and drevoluoside N (6) were isolated from the methanol extract of the leaves of Dregea volubilis using combined chromatographic methods. Their structures were elucidated by 1D-, 2D-NMR, and HR-ESI-MS spectra and comparing with those reported in the literature. Compounds 5 and 6 showed the most significant α -glucosidase inhibitory activity at the concentration of 40 μM with inhibition of 51.3 ± 3.2% and 50.4 ± 3.1%, respectively, compared to acarbose (59.8 ± 1.6%). [ABSTRACT FROM AUTHOR]