The Essential Oils from Cinnamon, Clove and Mint Inhibits Fungal Growth and Impairs the Electron Transport Chain Function Without Increasing ROS Levels

Fungal infections are a growing health concern worldwide due to the increased mortality associated to the development of resistance to triazole antifungal drugs, specially in Candida spp. This has urged the discovering of novel molecules with antifungal properties that may be candidates for the treatment of these infections. Fungi mitochondria may be a target for antifungal drugs as the electron transport chain (ETC) and oxidative phosphorylation constitute virulence factors favoring fungal growth in their hosts. Essential oils from plants may be a source of antifungal molecules as many of its components may target the function of fungal ETC. On this basis, we have tested the ability of the essential oils from cinnamon, clove, and mint to inhibit fungal growth by inhibiting the ETC function and increasing ROS production, using as model the yeast Saccharomyces cerevisiae. The exposure of S. cerevisiae to the above essential oils in liquid YPD medium inhibited the yeast growth by 85%, 83% and 76% at concentrations as low as 0.16%. The mitochondria isolated from yeast grown in the presence of 0.16% essential oils exhibited decreased ROS production using succinate as substrate in contrast with mitochondria from control yeast untreated with the oils. The activity of the complex II from yeast mitochondria exhibited impaired function with the three essential oils. Thus, the unexpected decrease in ROS production elicited by the oils might be the result of impaired entry of electrons into the ETC due to defective succinate oxidation, besides these essential oils contains some molecules with antioxidant activity. Overall, these results suggest that the essential oils from cinnamon, clove, and mint possess a potent antifungal activity against S. cerevisiae by impairing the ETC, but without increasing mitochondrial ROS generation.