Avaliação in vitro da atividade antifúngica do eugenol sobre cepas de Candida tropicalis e Candida parapsilosis isoladas da cavidade bucal de indivíduos saudáveis

Abstract

The Candida genus usually has a commensal relationship in the oral cavity, modifying factors may alter this relationship directly or indirectly, making it pathogenic, triggering oral candidiasis. The phytotherapeutic products have been constituting a therapeutic alternative, widely used in the treatment of candidiasis. The objective of this study was to isolate and identify strains of Candida tropicalis and Candida parapsilosis from the oral cavity of healthy individuals through macro and micromorphology, physiological and biochemical tests. The in vitro and in silico sensitivity of these strains to eugenol and nystatin was then evaluated by determining the Minimum Inhibitory Concentration (MIC); Minimal Fungicide Concentration (MFC) and analyzing the mechanisms of action through microbial growth kinetics, micromorphology and association study (checkboard), and in silico assay. Eight strains of Candida tropicalis, one from the American Type Culture Collection - ATCC 13803 and seven from clinical origin and seven from Candida parapsilosis to their ATCC standard (22019) and six from clinical isolates were used. An antifungal activity of eugenol on the tested species was observed, a MIC and MFC of 64 μg / mL for Candida tropicalis was determined. The CFM / MIC ratio indicates fungicidal activity compared to 87.5% of the tested strains. In the Candida parapsilosis species the MIC was 256 μg / mL which coincided with the CFM in 100% of the strains tested. Regarding the association assay, strain ATCC 13803 and another clinic - LM-34 of C. tropicalis were used, the results showed antagonism of the substances analyzed for both the ATCC 22019 strain and the LM-34 clinical strain. Micromorphology demonstrated inhibition of virulence structures such as pseudohyphae and blastoconideas at the three concentrations analyzed for C. tropicalis (ATCC 13803 and LM-34) and C. parapsilosis (ATCC 22019 and LM-70) strains. The microbial death curve showed a fungicidal effect after 24 hours of experiment in both species studied. The results of the present study indicate a strong activity of the eugenol molecule on the strains of Candida tropicalis and Candida parapsilosis analyzed and could represent a therapeutic alternative for the treatment of oral candidiasis.