Quadratic Concentration–Response Modeling and Molecular Docking of Mespilodaphne quixos (Lam.) Rohwer Essential Oil Against Candida albicans

Candida albicans is an opportunistic fungal pathogen of clinical relevance, and plant-derived antifungal agents have attracted interest because of rising resistance to conventional drugs. This study aimed to characterize the chemical composition of Mespilodaphne quixos (Lam.) Rohwer essential oil (EO) by GC/MS, evaluate its in vitro antifungal activity against C. albicans, model its concentration-dependent response using one-factor quadratic polynomial modeling, and investigate the interactions of its constituents with selected fungal targets using molecular docking. Freshly collected leaves were subjected to steam distillation, then the EO was characterized using GC/MS. Antifungal activity was determined using the Kirby–Bauer disk diffusion method. A one-factor quadratic polynomial model was fitted to describe the inhibition halo diameter as a function of EO concentration. Moreover, 22 identified compounds were docked against 14-α-demethylase, Δ(14)-sterol reductase, and exo-β-(1,3)-glucanase. The EO was mainly composed of (E)-cinnamaldehyde (47.2%), caryophyllene (10.8%), and α-humulene (5.37%). The EO reached an inhibitory capacity of 87.3% relative to ketoconazole. The quadratic model showed good predictive performance. Molecular docking revealed favorable affinities for several sesquiterpenes present in M. quixos essential oil: α-copaene showed the best interaction profile against 14-α-demethylase and Δ(14)-sterol reductase, whereas α-guaiene and spathulenol performed best against exo-β-(1,3)-glucanase. These findings provide preliminary in vitro and in silico evidence supporting the antifungal activity of M. quixos EO.