Commercial Essential Oil Combinations against Topical Fungal Pathogens

Abstract

Essential oils are amongst the most popular natural products recommended for the treatment of topical fungal infections. This study investigated the antifungal activity of 128 essential oil combinations against fungal pathogen reference strains using the broth microdilution technique to determine the minimum inhibitory concentration (MIC). The essential oils were investigated at a volume of 100 μL and the combinations comprised of 50:50 μL. Each combination was tested in triplicate and the mean recorded. The fractional inhibitory concentration index was calculated for combinations, and synergistic interactions were investigated further at different ratios and plotted on isobolograms. The fungal pathogens were found to be highly susceptible to the essential oil combinations, with Trichophyton mentagrophytes being inhibited by all but one combination. The essential oil combinations containing Cinnamomum verum or Santalum austrocaledonicum were found to display the strongest inhibition with MIC values as low as 0.06 mg/mL. Potential combinations against fungal pathogens have been presented that could be studied in clinical settings with the goal of decreasing the need for systemic or prolonged antifungal treatments that may result in treatment failure or resistance.