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Purpose: Eugenol, the main component of clove bud essential oil (Eugenia caryophyllus), has been linked to antimicrobial, anti-inflammatory, insecticidal and immunomodulatory properties. The purpose of this study was to evaluate the antifungal and cytotoxic activity of eugenol, the essential oil of Eugenia caryophyllus, and some semisynthetic derivatives of eugenol against dermatophytes of the genus Trichophyton., Methodology: We evaluated the antifungal effect of the compounds, determining the minimum inhibitory concentrations (MICs) by the microdilution method and the minimum fungicidal concentrations by cultures from the inhibitions. Additionally, the inhibition of the radial growth of the mycelium of the dermatophyte fungi was tested by poisoned substrate. Cytotoxicity was measured by the colorimetric method on Vero cells., Results: All of the eugenol compounds tested exhibited antifungal properties, showing MICs of 62.5-500 µg ml -1 , determined within three dermatophyte species: Trichophyton rubrum, Trichophyton mentagrophytes and Trichophyton tonsurans. Among these derivatives, methyl isoeugenol, at concentrations of 300 and 100 µg ml -1 , was found to completely inhibit (100 %) radial growth of the mycelium of all three species after 20 days of treatment. Additionally, phenotypic variations related to the decrease in pigment production of T. rubrum were observed after treatment with O-ethyl and O-butyl isoeugenol derivatives. Meanwhile, all of the tested (iso)eugenol molecules exhibited moderate toxicity in Vero cells [50 % cytotoxic concentration (the concentration required for a 50 % reduction in cell viability; CC50): 54.06-265.18 µg ml -1 )., Conclusion: The results suggest that the semisynthetic eugenol derivatives (SEDs) show promising antifungal activity and selectivity against dermatophyte fungi.

Background: Microsporum spp. are keratinophilic dermatophytes that mainly invade the stratum corneum of the skin and hair causing clinical symptoms associated with tinea. Its treatment has several limitations, and the search for new active molecules is necessary., Objective: To evaluate the antifungal and cytotoxic potential of Eugenia caryophyllus essential oil (EO), eugenol, isoeugenol and methylisoeugenol against Microsporum canis, M. gypseum and Vero cells., Methods: The EO was extracted by conventional heating-assisted hydrodistillation, the eugenol obtained commercially and the derivatives through Williamson synthesis. Minimal inhibitory concentration (MICs), minimum fungicidal concentration, inhibition of radial mycelial growth and germination inhibition were used to evaluate the antifungal activity. In addition, a colorimetric test was conducted to evaluate cytotoxic activity., Results: MIC and MFC values for all compounds were 62.5-500 μg/mL for both of the species of Microsporum evaluated. Also, concentrations of 300 μg/mL of the compounds inhibited 100% of M. canis mycelium. The inhibition of germination was observed after 6 hours of treatment (11.86 ± 3.46-85.31 ± 0%). No cytotoxicity was observed in Vero cells (CC 50  > 105 μg/mL), whereas terbinafine showed CC 50 31.00 ± 0.61 μg/mL., Conclusions: Our study indicates an interesting bioactivity of isoeugenol and methylisoeugenol against M. canis, M. gypseum and mammalian cells., (© 2018 Blackwell Verlag GmbH.)