Atividade antifúngica do linalol sobre linhagens de Candida albicans e Candida tropicalis

Abstract

Pathogenic yeast such as C. albicans and C. tropicalis are becoming important ethiological agents of invasive fungal infections, specially in imunocompromised patients. Currently known worldwide, the emergence of increasingly resistant microorganisms against conventional antibiotics is induced by the abusive and irrational use of these antimicrobial agents. Due to this reality, the search for new and effective antimicrobial drugs has grown. In this context, the natural products are excellent precursors of a wide diversity of active molecular compounds. Among them, monoterpenes such as linalool which possess tremendous biological potential of human concern. Following these premises, on this study was evaluated the antifungal activity of linalool against clinical-source strains of C. albicans and C. tropicalis of pulmonary origin, through in vitro microbiological assays for the determination of Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) using the microdilution technique. The linalool showed a MIC50% of 32 µg/mL and MFC50% of 128 µg/mL against the Candida spp strains, with this effect being of fungicidal attribute. Next, it was realized the micromorphological analysis, study of the mechanism of action, association and modulation assays. Alterations on the cell's morphology could be observed when exposed to linalool with reduction in the number of fungal microstructures. However, the antifungal effect of linalool was not due to destabilization of the cell wall or by binding with ergosterol in the cell membrane. The association assays did not showed additivity, synergism or antagonism between linalool and amphotericin B through the checkerboard method. Besides, linalool did not modulated the antifungal activity displayed by the amphotericin B. These results suggests that the monoterpene linalool represents a new chance among the products of natural origin with pharmacological activity against infections caused by Candida species.