Three New Glycosides from the Leaves of Ligustrum robustum and Their Antioxidant Activities and Inhibitory Effects on Fatty Acid Synthase, α ‐Glucosidase, and α ‐Amylase

ABSTRACT In the phytochemical study of the leaves of Ligustrum robustum , two new monoterpenoid glycosides named ligurobustosides V ( 1a ), V 1 ( 1b ), and a new secoiridoid glycoside named ligurobustoside W ( 2 ), together with three known glycosides ( 3 – 5 ), were isolated and identified by spectroscopic and chemical methods. The biological research discovered, compounds 3 and 4 showed powerful fatty acid synthase inhibitory activity (half inhibitory concentration [IC 50 ]: 4.21 ± 0.16–4.51 ± 0.12 µM); compounds 1 , 4 , and 5 displayed some α ‐glucosidase inhibitory activity; compounds 1 ‐ 5 revealed some α ‐amylase inhibitory activity; compounds 1 , 3 , and 4 showed stronger 2,2'‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt radical scavenging effect (IC 50 : 3.98 ± 0.01–6.80 ± 0.07 µM) than L‐(+)‐ascorbic acid (IC 50 : 10.06 ± 0.19 µM). Compounds 1 , 3 , and 4 were considered as some functional constituents of L. robustum to prevent diabetes mellitus and its complications.