Micropartículas de quitosana e óleo essencial de cúrcuma no controle in vitro de cryptococcus spp.: atividade antifúngica em células planctônicas, biofilmes e interação com antifúngicos

Abstract

Species of the Cryptococcus neoformans/Cryptococcus gattii complex are encapsulated yeasts responsible for cryptococcosis, an opportunistic mycosis that affects humans and animals, particularly immunocompromised individuals. Planktonic and biofilm susceptibilities, the interaction with classical antifungal agents already used in the treatment of cryptococcosis, and the cytotoxicity profile of chitosan microparticles associated with turmeric essential oil against species of the Cryptococcus neoformans/Cryptococcus gattii complex were evaluated. Planktonic susceptibility and mature biofilm susceptibility assays were performed following standardized protocols, using crystal violet staining for biomass quantification and the MTT assay to assess metabolic activity. In addition, for chitosan microparticles loaded with turmeric essential oil, the checkerboard method was employed to evaluate interactions with classical antifungal agents, and cytotoxicity was assessed through cell viability assays in cell cultures. Statistical analyses were performed considering p < 0.05. After exposure to different concentrations, the minimum inhibitory concentration (MIC) ranges for chitosan microparticles containing turmeric essential oil were 4–256 μg/mL for 50% inhibition and 256–1024 μg/mL for 100% inhibition. For mature biofilms, the main tested compound was able to inhibit up to 33% of biomass at the highest concentration (256 μg/mL) and to reduce metabolic activity by up to 42% at the same concentration. The test compound showed an indifferent interaction when combined with amphotericin B and fluconazole, with no evidence of synergism or antagonism. Cytotoxicity was observed at a concentration of 400 μg/mL, reducing cell viability by nearly 75%. Finally, chitosan microparticles loaded with turmeric essential oil demonstrated antifungal activity against planktonic cells and mature biofilms of the Cryptococcus neoformans/Cryptococcus gattii species complex in in vitro assays.