Antifungal activity of topical microemulsion containing a thiophene derivative

Fungal infections have become a major problem of worldwide concern. Yeasts belonging to the Candida genus and the pathogenic fungus Cryptococcus neoformans are responsible for different clinical manifestations, especially in immunocompromised patients. Antifungal therapies are currently based on a few chemotherapeutic agents that have problems related to effectiveness and resistance profiles. Microemulsions are isotropic, thermodynamically stable transparent systems of oil, water and surfactant that can improve the solubilization of lipophilic drugs. Taking into account the need for more effective and less toxic drugs along with the potential of thiophene derivatives as inhibitors of pathogenic fungi growth, this study aimed to evaluate the antifungal activity of a thiophene derivative (5CN05) embedded in a microemulsion (ME). The minimum inhibitory concentration (MIC) was determined using the microdilution method using amphotericin B as a control. The formulations tested (ME- blank and ME-5CN05) showed physico-chemical properties that would allow their use by the topical route. 5CN05 as such exhibited moderate or weak antifungal activity against Candida species (MIC = 270-540 μg . mL(-1)) and good activity against C. neoformans (MIC = 17 μg . mL(-1)). Candida species were susceptible to ME-5CN05 (70-140 μg . mL(-1)), but C. neoformans was much more, presenting a MIC value of 2.2 μg . mL(-1). The results of this work proved promising for the pharmaceutical industry, because they suggest an alternative therapy against C. neoformans.