Antifungal Activity of the Essential Oil of Thymus x viciosoi against Candida, Cryptococcus, Aspergillus and Dermatophyte Species

Abstract

The essential oil (EO) of Thymus x viciosoi (Pau) R. Morales was isolated and analysed by GC and GC‐MS. The antifungal activity of the EO and its major components against clinically relevant yeasts and molds was then measured. Their influence on the germ tube formation in Candida albicans and the influence of the EO on the metabolic function and cytoplasmic membrane integrity in the same yeast, analyzed by flow cytometry, were also studied. The EO showed high contents of carvacrol, thymol, and p-cymene. The total EO, as well as its components carvacrol and thymol, displayed very low minimum inhibitory concentrations and minimum fungicidal concentrations against all tested organisms (0.04 to 0.64 µL · mL⁻¹), while p-cymene showed weaker activity (2.5 to > 20.0 µL · mL⁻¹). They also inhibited filamentation at sub-inhibitory concentrations in C. albicans, particularly p-cymene, and the EO led to rapid metabolic arrest, disruption of the plasma membrane and consequently cell death. The EO and its main components were found to display a broad fungicidal activity through the disruption of cytoplasmic membrane integrity leading to leakage of vital intracellular compounds. In conclusion, the phenolic oil of T. x viciosoi may have potential for use in the development of clinically useful antifungal preparations.

Key words

Thymus x viciosoi (Pau) R. Morales - Lamiaceae - phenolic oil - antifungal activity - Candida albicans - flow cytometry - cytoplasmic membrane disruption

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