Phenylethanoid and Phenylmethanoid Glycosides from the Leaves of Ligustrum robustum and Their Bioactivities.

The phytochemical study on the leaves of Ligustrum robustum , which have been used as Ku-Ding-Cha, led to the isolation and identification of three new phenylethanoid glycosides and three new phenylmethanoid glycosides, named ligurobustosides R 1 ( 1b ), R 2-3 ( 2 ), R 4 ( 3 ), S 1 ( 4b ), S 2 ( 5 ), and S 3 ( 6 ), and five reported phenylethanoid glycosides ( 7 - 11 ). In the bioactivity test, ( Z )-osmanthuside B 6 ( 11 ) displayed strong fatty acid synthase (FAS) inhibitory activity (IC 50 : 4.55 ± 0.35 μM) as the positive control orlistat (IC 50 : 4.46 ± 0.13 μM), while ligurobustosides R 4 ( 3 ) and S 2 ( 5 ), ligupurpuroside B ( 7 ), cis -ligupurpuroside B ( 8 ), ligurobustoside N ( 9 ), osmanthuside D ( 10 ), and ( Z )-osmanthuside B 6 ( 11 ) showed stronger ABTS radical scavenging activity (IC 50 : 2.68 ± 0.05~4.86 ± 0.06 μM) than the positive control L-(+)-ascorbic acid (IC 50 : 10.06 ± 0.19 μM). This research provided a theoretical basis for the leaves of L. robustum as a tea with function in treating obesity and diabetes.