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Abstract
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Dermatophytosis is a common fungal infection caused by dermatophytes, often resistant to conventional antifungal drugs
like terbinafine and triazoles. Menthol, a plant-derived antifungal agent, offers potential when combined with standard
drugs. Nanoencapsulation enhances menthol's stability, bioavailability, and antifungal efficacy. This study investigates the
antifungal effects of pure and nanoencapsulated menthol in combination with voriconazole against human and animal
Trichophyton mentagrophytes isolates. It aims to evaluate the synergistic potential and address resistance challenges in
dermatophyte infections. Menthol-loaded nanocapsules were prepared via a nanoprecipitation method and characterized
using Zeta Potential Analysis, Dynamic Light Scattering (DLS), and Scanning Electron Microscopy (SEM). Antifungal
activity against 15 clinical T. mentagrophytes isolates was evaluated using Clinical and Laboratory Standards Institute
(CLSI) -compliant microdilution and checkerboard assays, determining minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and fractional inhibitory concentration index (FICI) values for menthol, nanoencapsulated menthol, and voriconazole. Statistical analysis assessed differences in antifungal efficacy. Menthol-loaded
nanocapsules were predominantly rod-shaped with an average size of 300 nm, stable zeta potential (-0.5 mV), and low
polydispersity (PDI: 0.549) confirming their suitability for antifungal applications. Nanoencapsulated menthol exhibited
higher MIC (1979.26 μg/mL) and MFC (4145.74 μg/mL) than pure menthol, indicating reduced fungicidal potency. All
T. mentagrophytes isolates demonstrated resistance to voriconazole, with human-derived isolates showing exceptionally
high resistance levels. Synergistic effects were observed in 100% of isolates with nanoencapsulated menthol and voriconazole (FICI: 0.34±0.11), outperforming non-encapsulated menthol (FICI: 0.47±0.1). Nanoencapsulation significantly
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