Geraniol encapsulado em micropartículas de quitosana: uma estratégia promissora contra Sporothrix brasiliensis

Abstract

Sporothrix brasiliensis is a dimorphic fungus responsible for causing sporotrichosis, a subcutaneous mycosis of wide distribution and growing relevance in Brazil. This species, associated with zoonotic outbreaks, has high virulence, mainly due to its ability to form biofilms. This structure limits the action of antifungal drugs and contributes to the persistence of the infection. Given this scenario, there is growing interest in new therapeutic strategies, such as using natural compounds with antifungal activity. Geraniol, a monoterpene with recognized antimicrobial action, has its application limited by low solubility, high volatility and chemical instability. To overcome these limitations, encapsulation in chitosan microparticles has emerged as a promising alternative, promoting greater stability and controlled release of the compound. Thus, this study evaluated the effect of chitosan microparticles loaded with geraniol (CMGE) on planktonic cells and biofilms in the formation of S. brasiliensis, as well as their interactions with classical antifungals used in the treatment of sporotrichosis. In this study, nine filamentous strains were used. The antifungal activity of the planktonic form was evaluated using broth microdilution assays, following the CLSI protocol. The effect of the compound on biofilm formation was assessed by quantifying the metabolic activity using the MTT reduction assay. The interaction of the compound with amphotericin B and itraconazole was also evaluated using the checkerboard technique. CMGE showed minimum inhibitory concentrations (MIC) ranging from 2 to 8 μg/mL against S. brasiliensis in the filamentous form. Biofilms were sensitive to the compound, with an 80% reduction in metabolic activity at 32 μg/mL concentration. Furthermore, in the pharmacological interaction tests between CMGE with amphotericin B and itraconazole, no combination showed antagonism, and all were classified as indifferent. These results highlight that the geraniol encapsulated in microparticles of chitosan has antifungal effects on planktonic cells and biofilms of S. brasiliensis in the filamentous form and does not show antagonism with classical antifungals.