Effect of hydroxychalcones, flavonoids, and terpenoids on Candida albicans virulence factors

Abstract

Candida albicans is a commensal fungus that becomes an opportunistic pathogen in humans under certain conditions. This species is on the WHO's critical priority list of pathogenic fungi (2022). Therefore, it is necessary to understand its virulence mechanisms and how to control them. The literature shows that some compounds such as hydroxychalcones, flavonoids, and terpenoids have effects on inhibiting the growth of the fungus, but relatively little is known about how they affect the virulence factors of this species. Hydroxychalcones are metabolic intermediates for the synthesis of flavonoids; Both are secondary metabolites that plants defend against. Therefore, this project aims to evaluate the effect of hydroxychalcones, flavonoids, and terpenoids on the virulence factors of Candida albicans. Seven compounds will be evaluated: three flavonoids (dihydromyricetin, quercetin, myricetin), three hydroxychalcones (two 2' hydroxychalcones, one 4' hydroxychalcone), and one terpenoid (tt-farnesol; serve as control that inhibits the morphological transition of yeast to the filamentous form); the vehicle (diluent) will be the other control (growth). Distinct concentrations will be used to verify their effect on the following traits: 1) the morphological transition from yeast cells to filamentous forms (optical and fluorescence microscopy); 2) production of proteinases and phospholipases (degradation of corresponding substrates); 3) susceptibility to oxidative and acid stress (cell viability after exposure to hydrogen peroxide and buffer with different pH values); and 4) biofilm production (crystal violet to determine biomass). The microscopy images will be evaluated descriptively. Quantitative data will be analyzed via descriptive and inferential statistics (±=0.05).