EFFECTS OF THE ESSENTIAL OIL OF Thymus vulgaris L. AGAINST Cryptococcus neoformans

Cryptococcus neoformans is an encapsulated yeast found in the environment, responsible for causing of meningoencephalitis in patients with a compromised immune system. In Brazil, cryptococcosis is the second cause of death among systemic mycoses. The limited efficacy of the available antifungal drugs used in its treatment has encouraged the search for therapeutic alternatives, such as medicinal plants. Thymus vulgaris, popularly known as thyme, is an aromatic plant whose essential oil (EO) possesses antifungal properties. The aim of this study was to assess the action of T. vulgaris EO on C. neoformans clinical isolates. This oil was analyzed by gas chromatography/mass spectrometry (GC/MS), which showed that its main components were thymol, ρ-cymene and linalool. Microdilution broth tests showed that this EO was effective against fungal isolates, with minimum inhibitory concentrations (MICs) ranging from 32 to 128 μg/mL. In vitro interaction tests between this oil and fluconazole (FCZ) showed no potentiation of the antifungal action of this drug. Its effect on mitochondrial metabolism of fungal cells was also evaluated and results demonstrated alterations on the mitochondrial enzyme activity of fungal cells only at concentrations >1,024 μg/mL. The results of the action of this EO on human erythrocytes indicated that it has low cytotoxic activity at MIC values.  This investigation describes the antifungal action of T. vulgaris, showing its potential in the development of alternatives in the treatment of C. neoformans.