Comprehensive Screening and Characterization of α-glucosidase Inhibitory Components in the Edible Medicinal Plant Pholidota cantonensis Rolfe Using UPLC-Q-TOF-MS/MS Analysis and Molecular Docking.

Abstract

Pholidota cantonensis Rolfe is an edible medicinal plant in the genus Pholidota of the family Orchidaceae. This plant is used to prepare medicated food in China and has been reported to possess anti-α-glucosidase activity. To date, little is known about the active substances responsible for the observed anti-α-glucosidase activity. In the present study, we aimed to screen and characterize the α-glucosidase inhibitory fraction of P. cantonensis using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) analysis and molecular docking. As a result, the 50% ethanol fraction obtained from D101 macroporous adsorption resin column chromatography (D50 fraction) had the highest total phenol content (353.83 ± 6.06mg GAE/g) and the most prominent α-glucosidase inhibitory activity (IC50 = 30.01 ± 7.30µg/mL). Forty-five compounds were identified from the D50 fraction by using UPLC-Q-TOF-MS/MS analysis. Molecular docking results showed that six main constituents, namely, crepidatin, 2,7-dihydroxy-4-methoxyl-9,10-dihydrophenylene, 4,4',5,6-tetrahydroxystilbene, 4,7-dihydroxy-2-methoxyl-9,10-dihydrophenylene, (-)-lariciresinol, and thunalbene, in the D50 fraction occupied the catalytic sites of α-glucosidase through strong hydrophobic interactions, hydrogen bonding, and other patterns. The binding energies were between - 29.95 and - 11.41kJ/mol, indicating good binding between the tested compounds and α-glucosidase. The active ingredients responsible for the α-glucosidase inhibitory activity may include phenanthrenes, stilbenes, dibenzyls, and lignans. The D50 fraction has potential value for developing innovative drugs for the prevention and treatment of diabetes mellitus (DM) and is worthy of in-depth research.