Atividade antifúngica e antibiofilme de k-aureina e seu efeito sobre os fatores de virulência de isolados de Candida albicans

Abstract

Candida albicans is considered one of the most important opportunistic fungal pathogens, due to its large arsenal of virulence factors that help throughout the progress of the infection. Combined with this scenario, the emergence of fungal resistance demonstrated the need for the development of more effective antifungals. Thus, antimicrobial peptides (AMPs) appear as an alternative, among these, aurein has great antimicrobial action, becoming the basis for the discovery of other bioactive molecules, such as K-aurein (K-au). In this perspective, the study aimed to demonstrate the antifungal activity of K-aurein and the impact of subinhibitory concentrations on the virulence profile of C. albicans isolates. For this, tests were performed to determine the antifungal activity recommended by the Clinical & Laboratory Standards Institute (CLSI) and to analyze the kinetics of death of the isolates against K-au. For the study of virulence factors, the evaluation of the inhibition of hydrolytic enzymes, formation of the germ tube and biofilm was carried out. Tests with preformed biofilm were performed to analyze biomass reduction, cell viability and biofilm breakdown by Scanning Electron Microscopy (SEM). Results demonstrate the antifungal activity of K-au at a concentration of 62.50 µg.mL-1 for all strains tested, with an action time of up to 180 minutes. As for virulence factors, K-au was not able to inhibit the secretion of enzymes, however it significantly interfered in the formation of germ tube and biofilm, suggesting its action on hyphal morphogenesis. Finally, the tests with preformed biofilm using fungicidal concentration of Kau showed a tendency to reduce cell viability, without interference in the biomass of the biofilm. This can be confirmed with the SEM images, which present a disruption of the biofilm with dead cells and the absence of hyphae. The data show the K-au anti-virulence mechanism, enabling the inhibition of polymorphism, which is crucial for the onset of infection and maintenance of C. albicans at the host sites. Therefore, PAM K-au can be considered an alternative against C. albicans, considering that its antivirulent action expands the repertoire of potential targets in these pathogens.