Atividade antifúngica in vitro do óleo essencial de Laurus Nobilis l. (louro) sobre cepas de Cryptococcus neoformans

Abstract

Cryptococcus neoformans is the opportunistic pathogenic yeast with broad geographic capable of infecting all kinds of animal distribution. In humans, cryptococcosis mainly affects the lungs and central nervous system, less frequently the skin, presenting in general with severe and fatal outcomes. People with compromised immune systems are more likely to develop cryptococcosis, especially those affected by human immunodeficiency virus. Conventional treatment of cryptococcosis potentially toxic antifungal use for long periods and that has been the target of resistance of these microorganisms, in addition to the high costs of treatment. Against this background, the searches for natural products with antifungal properties have been a promising alternative, with great attention of scholars as to the analysis of essential oils and their constituents. Thus, the present study aimed to evaluate the in vitro antifungal activity of essential oil of Laurus nobilis L. (Laurel) on strains of Cryptococcus neoformans. The chemical composition of the oil was analyzed by gas chromatography coupled to mass spectrometry (GC / MS) and its antifungal activity, assessed by determining the minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) by microdilution. Its kinetic microbial death and the effects on the morphology were also analyzed. The results of GC / MS revealed the presence of seven phytochemicals, isoeugenol (57%), myrcene (15,9%), chavicol (9,3%), methyleugenol (2,43%), linalool (2,14%), caryophyllenne (2,10%) and limonene (2,02%). The oil showed fungal growth inhibition of 70% of the 10 strains tested, with MIC set at 256 &#956;g/mL and 1024 &#956;g/mL MFC. The curve of microbial death had a fungistatic effect (reduction <3 log10UFC/mL from the initial inoculum) at concentrations of MIC / 2, MIC, MIC x 2 and fungicidal effect (reduction of &#8805; 3 log10UFC/mL from the initial inoculum) in MIC x 4 starting from 2 hours. Not being observed change in micromorphology of LM 2601 strain, selected for the study of kinetics and micromorphology, when subjected to contact with the essential oil in different concentrations. The essential oil of L. nobilis L. showed antifungal activity against all strains of C. neoformans tested and thus may represent a novel antifungal product with potential in the treatment of cryptococcosis.