Toxic effects of imidazolium-based ionic liquids on Caenorhabditis elegans: The role of reactive oxygen species

By using Caenorhabditis elegans (C. elegans) as a model animal, the present work is aimed to evaluate the acute toxicity of imidazolium-based bromide Ionic Liquids (ILs), and to elucidate the underlying mechanisms involved. Firstly, 24-h median lethal concentration (LC₅₀) for eight ILs with different alkyl chain lengths and one or two methyl groups in the imidazolium ring were determined to be in a range of 0.09–6.64 mg mL⁻¹. Four ILs were selected to investigate the toxic mechanisms. Mortality, levels of reactive oxygen species (ROS), lipofuscin accumulation and expression of superoxide dismutase 3 in C. elegans were determined after exposed to ILs at sub-lethal concentrations for 12 h. A significant increase in the levels of these biomarkers was observed in accordance with the results of 12-h lethality assay. The addition of 0.5% dimethyl sulfoxide, which acts as a radical scavenger, remarkably rescued the lethality of C. elegans and significantly decreased the ROS level in C. elegans. Our results suggest that ROS play an important role in IL-induced toxicity in C. elegans.