Anticandidal activity of the essential oils of Thymus maroccanus and Thymus broussonetii and their synergism with amphotericin B and fluconazol

The discovery of antifungal drugs had eradicated some infections that ravaged the humankind. But their indiscriminate use has led to the development of multidrug resistant pathogens. One strategy employed to overcome these resistance mechanisms is the use of combination of the essential oils (EOs) of medicinal plants and conventional drugs. In this study, we investigated a possible synergistic effect of the EOs of two Moroccan endemic thymes (Thymus broussonetii and T. maroccanus) with amphotericin B (Amp B) and fluconazol against Candida albicans. The fractional inhibitory concentration indices (FICI) of T. maroccanus and T. broussonetii EOs combined with Amp B and fluconazol, calculated from the checkerboard titer assay, were 0.49, 0.27, 0.37 and 0.3, respectively. Also, our results indicate that the synergistic effect of EOs with fluconazol was stronger than the combination with Amp B. All these data highlight that the EOs tested potentiate the antifungal action of Amp B and fluconazol, suggesting a possible utilization of these EOs in addition to antifungal drugs for the treatment of some candidiasis due to C. albicans. The use of these combinations is likely to reduce the minimum effective dose of the drugs, thus minimizing their toxic side effects and the treatment cost.