Coarse grained molecular dynamics analysis of menthol interactions with ergosterol in a fungal mimetic membrane

Menthol, a monoterpene from peppermint oil, has antifungal activity against Candida species. However, how menthol interacts directly with fungal membrane sterols is still not well understood. In this study, coarse-grained molecular dynamics simulations were used with the Martini force field to investigate menthol in a fungal-mimetic POPC/ergosterol (8:2) membrane. Radial distribution function analysis revealed preferential spatial association between menthol and ergosterol, including a local maxima at approximately 5.0 Å and a broader peak in the 9.5 Å range. Contact analysis further demonstrated persistent transient interactions, with an average of 1.3 ± 0.4 menthol-ergosterol contacts per frame and at least one contact detected in approximately 94% of analyzed frames. Mean square displacement (MSD) analysis indicated laterally mobile menthol behavior within the membrane, with a diffusion coefficient of approximately 13.45 Ų/ps, (R² = 0.94). Density profile analysis revealed a broad membrane distribution of menthol with partial overlap with the ergosterol region. The membrane remained structurally stable throughout the simulation, showing an average sterol-region thickness of approximately 22.95 Å and an area per lipid of approximately 75.03 Ų. Membrane ordering analysis revealed a high orientational order parameter (SCD = 0.7983), indicating a well-organized liquid-ordered phase, with no evidence of pore formation or membrane disruption. Statistical robustness was confirmed via bootstrapping (95% CI: 0.6977-0.9347). The results indicate that menthol preferentially associates with ergosterol-containing regions while retaining considerable lateral mobility, engaging in frequent but transient interactions rather than forming stable complexes. This dynamic behavior provides a plausible molecular basis for the membrane-associated antifungal effects of menthol reported experimentally.