Atividade antifúngica de espilantol frente a uma espécie de Candida albicans resistente a multidrogas

Abstract

Candidiasis is an opportunistic fungal infection caused by yeast belonging to the genus Candida. These, in turn, are increasingly resistant to antifungals available today, which drives the search for new antifungal substances of plant origin. Thus, the aim of the present study was to evaluate the in vitro antifungal activity of spilanthol, a compound isolated from several plant species, against the multidrug resistant Candida albicans ATCC® 10231 strain and to determine its physicochemical, pharmacokinetic and pharmacodynamic properties. Thus, serial microdilution assays were performed to determine the minimum inhibitory concentration (MIC) and the effect of this concentration on the growth of this yeast, fungal growth curve analysis, cell density and viability, cell envelope permeability evaluation (uptake crystal, nucleotide extravasation, sorbitol protection and binding to exogenous ergosterol), and the spilantol synergism assay with two azole antifungals (fluconazole and itraconazole) by the checkerboard test. Cell viability was also evaluated in fibroblast (NIH / 3T3) and keratinocyte (HaCaT) strains treated with spilantol. Finally, the analyzes of the physicochemical, pharmacokinetic and pharmacodynamic properties of this compound were determined by in silico tests using computational tools. Spilanthol had a MIC of 200 μg / mL, with fungistatic effect on C. albicans. In addition, it led to greater inhibition of fungal growth and a significant reduction in the number of fungal cells. Spilanthol also caused a significant decrease in yeast metabolic activity, thereby reducing the number of viable cells. After treatment of the fungal cells with this compound, there was an increase in violet crystal uptake, thus demonstrating that spilanthol alters their permeability, leading to an increase in nucleotide release. A MIC value of 800 μg / mL was obtained in the sorbitol and ergosterol assays, which indicates a possible spilanthol activity in the yeast cell envelope. An excellent synergistic effect between spilanthol and fluconazole (ΣCIF = 0.265) and between spilantol and itraconazole (ΣCIF = 0.0019) was also observed. Cell viability results showed that spilanthol at the tested concentrations showed no toxicity to fibroblast and keratinocyte strains. Already in silico studies have shown that it has characteristics that allow its administration orally. Based on the results obtained, it can be noted that spilanthol is possibly acting at the yeast cell envelope level and by in silico analyzes, it can be stated that it presented satisfactory results, with characteristics that allow its classification as a good drug candidate. Given the above, we can highlight the great scientific and therapeutic potential of this substance, opening new perspectives for the treatment of infectious diseases caused by the genus Candida.