Chemical Profiling and Biological Activity of Alpinia graminifolia Essential Oils: In Vitro and In Silico 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.