Alkylimidazolium Ionic Liquids as Antifungal Alternatives: Antibiofilm Activity Against and Underlying Mechanism of Action.

is an opportunistic pathogen causes fungal infections that range from common skin infections to persistent infections through biofilm formation on tissues, implants and life threatening systemic infections. New antifungal agents or therapeutic methods are desired due to high incidence of infections and emergence of drug-resistant strains. The present study aimed to evaluate (i) the antifungal and antibiofilm activity of 1-alklyl-3-methyl imidazolium ionic liquids ([CnMIM][X], = 4, 12 and 16) against ATCC 10231 and two clinical strains and (ii) the mechanism of action of promising antifungal ionic liquid on . Two of the tested compounds were identified as more effective in preventing growth and biofilm formation. These ionic liquid compounds with -dodecyl and -hexadecyl alkyl groups effectively prevented biofilm formation by fluconazole resistant 10231 and two other clinical strains. Although both the compounds caused viability loss in mature biofilms, an ionic liquid with -hexadecyl group ([CMIM][Cl]) was more effective in dispersing mature biofilms. This promising ionic liquid compound ([CMIM][Cl]) was chosen for determining the underlying mode of action on cells. Light microscopy showed that ionic liquid treatment led to a significant reduction in cell volume and length. Increased cell membrane permeability in the ionic liquid treated cells was evident in propidium iodide staining. Leakage of intracellular material was evident in terms of increased absorbance of supernatant and release of potassium and calcium ions into extracellular medium. A decrease in ergosterol content was evident when cells were cultured in the presence of antifungal ionic liquid. 2',7'-Dichlorodihydrofluorescein acetate assay revealed reactive oxygen species generation and accumulation in cells upon treatment with antifungal ionic liquid. The effect of antifungal ionic liquid on mitochondria was evident by decreased membrane potential (measured by Rhodamine 123 assay) and loss of metabolic activity (measured by MTT assay). This study demonstrated that imidazolium ionic liquid compound exert antifungal and antibiofilm activity by affecting various cellular processes. Thus, imidazolium ionic liquids represent a promising antifungal treatment strategy in lieu of resistance development to common antifungal drugs.