Chemical Composition, Antioxidant Activity, and β-Lactamase Inhibitory Potential of Essential Oil from Micromelum...

Micromelum falcatum (Lour.) Tanaka is a medicinal plant widely utilized in traditional Chinese medicine. In this study, the essential oil (EO) was isolated by hydrodistillation using a Clevenger-type apparatus, and its chemical composition and biological activities were systematically investigated. A total of 63 constituents were identified by GC-MS and GC-FID, with bicyclogermacrene (20.52%), γ-palmitolactone (18.16%), humulene (10.55%), caryophyllene (10.09%), and spathulenol (4.50%) representing the major components. Antioxidant capacity was evaluated using DPPH (IC₅₀ = 15780 ± 1490 μg/mL), ABTS (IC₅₀ = 3440 ± 40 μg/mL), and FRAP assays (Trolox equivalent antioxidant concentration: 734.47 ± 6.82 μmol/g), in which the EO exhibited relatively moderate radical-scavenging and ferric-reducing activities. In addition, the EO demonstrated notable β-lactamase inhibitory activity (IC₅₀ = 25.59 ± 4.99 μg/mL). Molecular docking analysis further suggested that compounds such as isospathulenol, globulol, and spathulenol may interact with the enzyme's active site via hydrogen bonds. These findings indicate that M. falcatum EO represents a promising natural source of bioactive compounds with antioxidant and enzyme-inhibitory potential, warranting further pharmacological investigation.