Six New Phenolic Glycosides from the Seeds of Lam. and Their -Glucosidase Inhibitory Activity.

Plant-derived phytochemicals have recently drawn interest in the prevention and treatment of diabetes mellitus (DM). The seeds of Lam. are widely used in food and herbal medicine for their health-promoting properties against various diseases, including DM, but many of their effective constituents are still unknown. In this study, 6 new phenolic glycosides, moringaside B-G (-), together with 10 known phenolic glycosides (-) were isolated from seeds. The structures were elucidated by 1D and 2D NMR spectroscopy and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) data analysis. The absolute configurations of compounds and were determined by electronic circular dichroism (ECD) calculations. Compounds and especially are combined with a 1,3-dioxocyclopentane moiety at the rhamnose group, which are rarely reported in phenolic glycoside backbones. A biosynthetic pathway of and was assumed. Moreover, all the isolated compounds were evaluated for their inhibitory activities against -glucosidase. Compounds and exhibited marked activities with IC values of 382.8 ± 1.42 and 301.4 ± 6.22 μM, and the acarbose was the positive control with an IC value of 324.1 ± 4.99 μM. Compound revealed better activity than acarbose.