Curcumin exerts antifungal activity via inducing disruption of plasma membrane

The aims of present study are to investigate the antifungal mechanism of curcumin. This polyphenolic compound has been used traditionally in Asia for medicinal, culinary and other purpose. Although antifungal effect of curcumin has been reported, this is first study for its mode of action underlying disruption of plasma membrane in Candida albicans. The leakage of potassium ion from the fungal cytosol and dissipation in membrane potential was detected by bis-(1,3-dibutylbarbituric acid) trimethine oxonol [DiBAC₄(3)] staining. We also investigated an increase in membrane permeability in curcumin-treated C. albicans with influx of propidium iodide assay. Fluorescence analysis with 1,6-diphenyl-1,3,5-hexatriene (DPH) supported the membrane-targeted mechanism of action indicating membrane disruption. Based on these results, we studied the effects of curcumin treatment on model membrane to elucidate its antifungal mechanism. Using calcein leakage assays from curcumin-treated large unilamellar vesicles (LUVs) and giant unilamellar vesicles (GUVs), we found that curcumin has membrane-active mechanism inducing leakage of intracellular component through the flappy membrane. Therefore, this study suggests that curcumin exerts antifungal activity via inducing disruption of fungal plasma membrane.