Zanthoxylum bungeanum Essential Oil: Extraction and Component Analysis for α-Glucosidase Inhibitory Activity and the Underlying Mechanism Based on Molecular Docking

Zanthoxylum bungeanum essential oil was extracted using a low-eutectic solvent (choline chloride and 1,3-butanediol) and steam distillation. The results showed that the yield (9.36 and 10.00%) did not differ significantly between the two methods. The alpha-glucosidase inhibitory activity of essential oils from 20 species was screened by the PNPG (4-p-nitrophenyl-a-d-glucopyranosylase) colorimetric method, and the results showed that the inhibition rate of Zanthoxylum bungeanum essential oil reached 57.1%, far more than those of the other essential oils tested. The main components and contents of Zanthoxylum bungeanum essential oil were terpineol-4-ol (13.13%), (-)-beta-pinene (11.17%), gamma-terpinene (9.45%), terpinyl acetate (9.36%), and alpha-terpineol (5.40%), which were identified by GC-MS (gas chromatography-mass spectrometry). According to the literature, linalool and limonene are also high-content components. These seven components were docked with the alpha-glucosidase molecule. It was found that the binding energies between terpineol-4-ol, (-)-beta-pinene, gamma-terpinene, terpinyl acetate, alpha-terpineol, linalool, limonene, and alpha-glucosidase were -28.88, -25.54, -26.37, -28.46, -27.63, -25.95, and -25.53 (KJ/mol), respectively, similar to those of anthocyanins. From the research results, the following conclusions can be drawn: the extraction rate of Zanthoxylum bungeanum essential oil can be increased with steam distillation. Of the many plant essential oils, Zanthoxylum bungeanum essential oil shows excellent anti-alpha-glucosidase activity, suggesting that it has potential for application in hypoglycemic drugs. The strong binding ability of the monoterpene-based chemical components with the alpha-glucosidase molecule revealed the chemical mechanism of the inhibitory effect of Zanthoxylum bungeanum essential oil on alpha-glucosidase. The above conclusions provide a theoretical basis for the utilization of Zanthoxylum bungeanum essential oil in hypoglycemic drugs and further expand the applications of small-molecule chemical components.