Chemical Constituents from the Leaves of Ligustrum robustum and Their Bioactivities

The leaves of Ligustrum robustum have been consumed as Ku-Ding-Cha for clearing heat and removing toxins, and they have been used as a folk medicine for curing hypertension, diabetes, and obesity in China. The phytochemical research on the leaves of L. robustum led to the isolation and identification of two new hexenol glycosides, two new butenol glycosides, and five new sugar esters, named ligurobustosides X (1a), X1 (1b), Y (2a), and Y1 (2b) and ligurobustates A (3a), B (3b), C (4b), D (5a), and E (5b), along with seven known compounds (4a and 6-10). Compounds 1-10 were tested for their inhibitory effects on fatty acid synthase (FAS), alpha-glucosidase, and alpha-amylase, as well as their antioxidant activities. Compound 2 showed strong FAS inhibitory activity (IC50 4.10 +/- 0.12 mu M) close to that of the positive control orlistat (IC50 4.46 +/- 0.13 mu M); compounds 7 and 9 revealed moderate alpha glucosidase inhibitory activities; compounds 1-10 showed moderate alpha-amylase inhibitory activities; and compounds 1 and 10 displayed stronger 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) ammonium salt (ABTS) radical scavenging effects (IC50 3.41 +/- 0.08 similar to 5.65 +/- 0.19 mu M) than the positive control L-(+)-ascorbic acid (IC50 10.06 +/- 0.19 mu M). This study provides a theoretical foundation for the leaves of L. robustum as a functional tea to prevent diabetes and its complications.

Automated summary

The leaves of Ligustrum robustum, known as Ku-Ding-Cha, are commonly consumed in China for their heat-clearing and toxin-removing properties. They have also been used as a traditional medicine for hypertension, diabetes, and obesity. Phytochemical research on these leaves resulted in the discovery of several compounds with inhibitory effects on fatty acid synthase, alpha-glucosidase, alpha-amylase, and strong antioxidant activity. This study provides support for the use of Ligustrum robustum leaves as a functional tea for preventing diabetes and its complications.