Chemical Profiling and Biological Activity of <i>Alpinia graminifolia</i> Essential Oils: <i>In Vitro</i> and <i>In Silico</i> Studies

This study aimed to characterize, for the first time, the chemical composition and bioactivities of essential oils (EOs) obtained from different parts of Alpinia graminifolia. Materials and Methods: Fresh samples collected in Bac Giang province, Vietnam, were subjected to hydrodistillation using a Clevenger-type apparatus. The chemical profiles of the resulting EOs were determined via gas chromatography-mass spectrometry (GC-MS). Antioxidant activity was assessed using DPPH and ABTS radical scavenging assays and a reducing power test. Additionally, α-amylase and α-glucosidase inhibitory activities were evaluated. Molecular docking simulations were performed to investigate the binding interactions between major EO constituents and the α-amylase active site. Results: GC-MS analysis identified 67 compounds in rhizome EO, 72 in pseudo-stem EO, and 55 in leaf EO. The leaf EO exhibited the strongest α-amylase inhibitory activity (IC₅₀ = 311.58 ± 12.42 µg/mL), while α-glucosidase inhibition was observed only for the rhizome EO (IC₅₀ = 1146.01 ± 17.40 µg/mL). The leaf EO also showed the highest antioxidant activity, although all samples were less active than ascorbic acid. Molecular docking revealed that β-copaen-4α-ol and pogostole displayed stronger binding affinities toward α-amylase than acarbose. The findings demonstrate organ-dependent variations in the chemical composition and bioactivities of A. graminifolia EOs.