Essential Oils of Alpinia vietnamica Rhizomes and Leaves: Chemical Composition, Cytotoxicity, -Glucosidase Inhibition, and Molecular Docking Approach

Objective: Alpinia is a big genus of flowering plants in the family Zingiberaceae. The plants of this genus are generally aromatic due to their essential oils. The current study aims to identify chemical compositions in the rhizome and leaf oils of Alpinia vietnamica H.D. Tran, Luu & Skornick. Methods: Essential oils of A vietnamica rhizomes and leaves obtained by hydrodistillation were investigated by the gas chromatography-flame ionization detection/mass spectrometry (GC-FID/MS) analysis. A vietnamica essential oils have been subjected to cytotoxic and alpha-glucosidase inhibitory assays. The protein interactions of the major compounds were viewed by molecular docking study. Results: In general, monoterpene hydrocarbons (60.4%-62.5%) and their oxygenated derivatives (18.1%-29.0%) were the main chemical classes of the rhizome and leaf oils. In the meantime, 1,8-cineole (25.7%-29.0%), beta-pinene (12.8%-21.3%), geraniol (9.0%-15.2%), and alpha-pinene (6.1%-7.5%) can be seen as the main compounds. A vietnamica essential oils showed cytotoxicity toward four cancer cell lines KB, Hep-G2, Lu-1, and MCF-7 with IC50 values of 82.39 to 254.1 mu g/mL. Significantly, the leaf oil (IC50 115.18 mu g/mL) was better than the standard compound acarbose (IC50 156.68 mu g/mL) in the alpha-glucosidase inhibitory assay. The results of molecular docking simulation suggested that 1,8-cineole, geraniol, alpha-pinene, and beta-pinene could generate a similar inhibition (binding affinities) with acarbose, and the hydrogen and hydrophobic interactions played contributory roles in the binding to alpha-glucosidase enzyme. Conclusion: Further phytochemical investigations on this species, especially chromatographic separations to isolate bioactive metabolites, are needed. As well, pharmacological experiments are welcome since the current study is the first result.