Chemical constituents of Litsea elliptica and their alpha-glucosidase inhibition with molecular docking

Background: Litsea elliptica (LE) is an edible plant in Thailand, which has been used as vegetables, flavoring materials, and traditional herbal medicine. Some species of Litsea have been reported on anti-diabetic activity. However, LE has not been reported of chemical constituents and their alpha-glucosidase activity. Objectives: The aim was to study on chemical constituents and anti-diabetic activity through in vitro models of LE. Materials and Methods: Chromatographic and colorimetric enzyme methods with computer molecular docking were used in this research. Results: Anew quercetin-diglycoside (1) and six compounds (2-7) were isolated from LE which were elucidated as quercetin-3-O -α-rhamnopyranoside-O -(1→2)-α-apiofuranoside (1), quercetin-3-O -α-rhamnopyranoside (2), quercetin-3-O -β-glucopyranoside (3), uridine (4), isoboldine (5), reticuline (6) and β-sitosterol-D-glucopyranoside (7). Four isolated compounds exhibited anti-alpha glucosidase activity by inhibition concentration at 50% (μg/mL) values as 5 (243.25) <3 (332.19) <1 (335.15) <2 (751.79), respectively. Furthermore, the molecular docking experiment was graphically computed for binding energy between effective compounds and the enzyme. The result suggested that the structure of compound 5 exhibited the lowest binding energy (−7.2 kcal/mol), which interacted at non-catalytic domain at the entrance of the active site. In addition, the mechanism of action of effective compounds could be predicted by the binding sites as non-competitive inhibitor (1 and 5) and competitive inhibitor (3). To sum up, the seven compounds which were isolated of LE are significantly reported for the first time in biological and phytochemical studies, and compound 1 is considerably interpreted as a new compound which presents anti-alpha glucosidase activity.