Pregnane glycosides from the leaves of Dregea volubilis and their α-glucosidase and α-amylase inhibitory activities

Three new pregnane glycosides, drevoluosides O-Q (1-3) along with five known volubiloside C (4), dreageoside A11 (5), 17β-marsdenin (6), stavaroside H (7), and hoyacarnoside G (8) were isolated from the methanol extract of the Dregea volubilis leaves. Their structures were elucidated by chemical and spectroscopic methods. Compounds 6-8 showed significant anti α-glucosidase activity with the inhibitory percentages ranging from 32.6 to 47.1% at the concentration of 200 μM. Compound 3 showed significant inhibitory α-amylase activity with IC50 value of 51.3 ± 2.1 μM.