Bio-guided isolation of alpha-glucosidase inhibitory compounds from Vietnamese liverwort Marchantia polymorpha: in vitro and in silico studies

Bio-guided isolation was applied to Vietnamese Marchantia polymorpha L. to find alpha-glucosidase inhibition. Fifteen compounds were isolated and structurally determined, including two new compounds, marchatoside (7) and marchanol (8), along with thirteen known compounds: marchantin A (1), isoriccardin C (2), riccardin C (3), marchantin K (4), lunularin (5), 3R-(3,4-dimethoxybenzyl)-5,7-dimethoxyphthalide (6), vitexilactone (9), 12-oleanene-3-one (10), 3,11-dioxoursolic acid (11), ursolic acid (12), artemetin (13), kaempferol (14), and quercetin (15). The structures of these compounds were determined through extensive spectroscopic analyses (1D and 2D NMR, HRESIMS, and ECD) and by comparisons to the existing literature. There are five types of carbon skeleton, including bibenzyl (1–5), 3-benzylphthalide (6 and 7), diterpenoid (8 and 9), triterpenoid (10–12), and flavonoid (13–15). Compounds 6–12 were reported for the first time within the genus Marchantia. Compounds 1–12 were evaluated for their alpha-glucosidase inhibition. Among them, 1–5 and 10–12 displayed potent inhibition, with IC(50) values ranging from 28.9 to 130.6 μM, compared to the positive control acarbose 330.9 μM. A kinetic study and molecular docking were also performed to understand the mechanism.