In Vitro Activity of Ebselen and Diphenyl Diselenide Alone and in Combination with Drugs against Trichophyton mentagrophytes Strains

Background: Dermatophytoses are one of the most prevalent infectious diseases in the world for which the pace of developing new drugs has not kept pace with the observed therapeutic problems. Thus, searching for new antifungals with an alternative and novel mechanism of action is necessary. Objective: This study aimed to evaluate the antifungal activity of ebselen and diphenyl diselenide against Trichophyton mentagrophytes clinical isolates. Methods: In vitro antifungal susceptibility was assessed for organoselenium compounds used alone or in combination with allylamines and azoles according to the 3rd edition of the CLSI M38 protocol. Results: Ebselen demonstrated high antifungal activity with MIC(GM) equal to 0.442 μg/mL and 0.518 μg/mL in the case of human and animal origin strains, respectively. The values of MIC(GM) of diphenyl diselenide were higher: 17.36 μg/mL and 13.45 μg/mL for the human and animal isolates, respectively. Synergistic or additive effects between terbinafine and ebselen or diphenyl diselenide were observed in the case of 12% and 20% strains, respectively. In turn, the combination of itraconazole with diphenyl diselenide showed a synergistic effect only in the case of 6% of the tested strains, whereas no synergism was shown in the combination with ebselen. Conclusions: The results highlight the promising activity of organoselenium compounds against Trichophyton mentagrophytes. However, their use in combinational therapy with antifungal drugs seems to be unjustified due to the weak synergistic effect observed.