-Amylase and -Glucosidase Inhibitory Activities of Chemical Constituents from (Osbeck.) Merr. Leaves.

As part of an ongoing search for new natural products from medicinal plants to treat type 2 diabetes, two new compounds, a megastigmane sesquiterpenoid sulfonic acid () and a new cyclohexylethanoid derivative (), and seven related known compounds () were isolated from the leaves of (Osbeck.) Merr. The structures of the compounds were conducted via interpretation of their spectroscopic data (1D and 2D NMR, IR, and MS), and the absolute configurations of compound were determined by the modified Mosher's method. The MeOH extract of was found to inhibit -amylase and -glucosidase inhibitory activities as well as by the compounds isolated from this extract. Furthermore, compound showed the strongest effect with IC values of 112.8 ± 15.1 g/mL (against -amylase) and 785.9 ± 12.7 g/mL (against -glucosidase). Compounds , , and showed moderate -amylase and -glucosidase inhibitory effects. Other compounds showed weak or did not show any effect on both enzymes. The results suggested that the antidiabetic properties from the leaves of are not simply a result of each isolated compound but are due to other components such as the accessibility of polyphenolic groups to -amylase and -glucosidase activities.