Monoterpenoid Glycosides from the Leaves of Ligustrum robustum and Their Bioactivities

The leaves ofLigustrum robustumhave been applied as Ku-Ding-Cha, a functional tea to clear heat, remove toxins, and treat obesity and diabetes, in Southwest China. The phytochemical research on the leaves ofL. robustumled to the isolation and identification of eight new monoterpenoid glycosides (1–8) and three known monoterpenoid glycosides (9–11). Compounds1–11were tested for the inhibitory activities on fatty acid synthase (FAS),α-glucosidase,α-amylase, and the antioxidant effects. Compound2showed stronger FAS inhibitory activity (IC50: 2.36 ± 0.10 μM) than the positive control orlistat (IC50: 4.46 ± 0.13 μM), while compounds1,2,5and11displayed more potent ABTS radical scavenging activity (IC50: 6.91 ± 0.10~9.41 ± 0.22 μM) than the positive control L-(+)-ascorbic acid (IC50: 10.06 ± 0.19 μM). This study provided a theoretical basis for the leaves ofL. robustumas a functional tea to treat obesity.Keywords:Ligustrum robustum;monoterpenoid glycoside;FAS;α-glucosidase;antioxidant;anti-obesity;hypoglycemic