Efeito dos óleos essenciais de capim-limão e gerânio encapsulados em nanopartículas de quitosana de baixo peso molecular contra células planctônicas e biofilme das espécies do complexo Cryptococcus neoformans/ Cryptococcus gattii

Abstract

The varieties belonging to the Cryptococcus neoformans/C. gattii are pathogens responsible for the development of cryptococcosis, a condition that, in more severe situations, can lead to cryptococcal meningitis. The application of essential oils and chitosan in controlled environments, against both bacteria and fungi, has proven to be an efficient approach in reducing the proliferation of these microorganisms. For these reasons, this study focused on evaluating the antifungal activity of low molecular weight chitosan, low molecular weight chitosan/lemongrass and low molecular weight chitosan/geranium nanoparticles in planktonic cells and mature Cryptococcus biofilms. spp. After exposure to different concentrations of the test compounds, the minimum inhibitory concentration (MIC) ranges were 128-512 μg/ml for low molecular weight chitosan, 128-256 μg/ml for low molecular weight chitosan/grass lemon and low molecular weight chitosan/geranium, for both. Regarding biofilms, the samples were able to reduce the metabolic activity and biomass of mature biofilms of species from the C. neoformans/C. complex. gattii by 49% and 50% for low molecular weight chitosan nanoparticles, 58% and 53% for low molecular weight chitosan nanoparticles/lemongrass and 65% and 68% for low molecular weight chitosan nanoparticles/geranium, respectively, (P<0.05). In mature biofilms, it was also observed that low molecular weight chitosan/geranium nanoparticles caused greater reductions than chitosan nanoparticles and low molecular weight chitosan/lemongrass. Thus, nanoparticles of low-weight chitosan, low-molecular-weight chitosan/lemongrass and low-molecular-weight chitosan/geranium showed antifungal activity, in vitro, against planktonic species of the C. neoformans/C. complex. gattii, being able to reduce mature biofilms. In view of this, these findings are important to direct future research to better understand the techniques involved in the action of nanoparticles, combined or not, against species of the C. neoformans/C. complex. gattii.