Chemical profiling, in vitro antifungal properties and molecular docking studies of the leaf and rhizome essential oils of Aframomum atewae (Lock & Hall)

Aframomum species, commonly used as spices, are increasingly being utilized as sources of biodegradable fungicides for controlling various pathogenic fungi. Aframomum atewae, a rare and previously unexamined species, was the focus of this study, which investigated the chemical composition of its leaf (LEO) and rhizome (REO) essential oils and evaluated their antifungal properties and possible mechanism of action. The essential oil yields were 0.1466% for LEO and 0.0985%, (w/w) for REO, with gas chromatography mass spectrometry (GC-MS) analysis revealing corresponding 60 and 64 constituents, respectively. Monoterpene hydrocarbons dominated both LEO (58.40%) and REO (52.53%), with sabinene (25.35%) and β-pinene (22.68%) being the most abundant respective constituents. Additionally, REO contained 16.53% of terpinen-4-ol and demonstrated greater antifungal activity than LEO in the disc diffusion assay, showing inhibition zones of 12.0 ± 0.0, 11.5 ± 0.7 and 10.0 ± 0.0 mm against Candida albicans, C. guilliermondii, and Saccharomyces cerevisiae, respectively, while LEO showed no activity. In the spot test assay, REO maintained its higher antifungal potential, achieving 100% inhibition within the concentration range of 1.49 x 10⁴ to 1.19 x 10⁵ μg/mL. Molecular docking studies of major constituents of LEO and REO against four antifungal protein targets (topoisomerase II, δ-14-sterol reductase, 14-α-demethylase and squalene synthase) showed favourable binding affinities to the target enzymes. Docking configurations of terpinen-4-ol, β-caryophyllene, γ-terpinene and p-cymene provided insights into the molecular interactions that underpin their inhibitory effects. Terpinen-4-ol could enhance the antifungal properties of REO, reinforcing the potential of Aframomum species as sources of natural antifungal agents.