Comparative Analysis of Chemical Composition and Bioactivities of Essential Oils From Different Parts of Wild-Grown Alpinia siamensis K.Schum. in Vietnam.

This study investigated chemical composition and bioactivities of essential oils (EOs) obtained from the rhizomes (REO), leaves (LEO), and pseudo-stems (SEO) of Alpinia siamensis collected in Vietnam. Gas chromatography-mass spectrometry identified 49 constituents in the EOs, representing 97.9%-98.5% of total compositions. Sesquiterpene hydrocarbons predominated in all the samples (41.3-87.1%), with β-bisabolene as the most abundant compound (23.8-53.7%). Bioactivity evaluation revealed that all the EOs showed dose-dependent inhibition of α-amylase and tyrosinase. REO exhibited the strongest α-amylase inhibitory effect (IC50 = 215.54 ± 3.05 µg/mL), while LEO demonstrated the most potent tyrosinase inhibitory activity (IC50 = 178.85 ± 1.78 µg/mL). Antioxidant assays indicated moderate radical scavenging effects, with LEO and REO showing the highest activity in the DPPH and ABTS assays, respectively, though all were considerably weaker than ascorbic acid. Antibacterial evaluation against five pathogenic bacteria demonstrated that REO possessed the highest activity and inhibited all strains. LEO showed moderate inhibition, whereas SEO displayed the weakest activity and lacked activity against Pseudomonas aeruginosa. The findings provide the first report on A. siamensis EOs and highlight their potential as natural bioactive compounds for pharmaceutical, nutraceutical, and cosmeceutical applications.