In vitro susceptibility of Microsporum spp. and mammalian cells to Eugenia caryophyllus essential oil, eugenol and semisynthetic derivatives

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 mu g/mL for both of the species of Microsporum evaluated. Also, concentrations of 300 mu g/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 (CC50 > 105 mu g/mL), whereas terbinafine showed CC50 31.00 +/- 0.61 mu g/mL. Conclusions Our study indicates an interesting bioactivity of isoeugenol and methylisoeugenol against M. canis, M. gypseum and mammalian cells.