Acute toxicity, oxidative stress and DNA damage of three task-specific ionic liquids ([C2NH2MIm]BF4, [MOEMIm]BF4, and [HOEMIm]BF4) to zebrafish (Danio rerio)

Abstract

The addition of different functional groups to ionic liquid anions or cations to synthesize task-specific ionic liquids (TSILs) according to specific needs has become a research hotspot. However, there are few studies on the toxicity of TSILs. We selected zebrafish (Danio rerio) to assess the toxicity of three TSILs 1-aminoethyl-3-methylimidazolium tetrafluoroborate ([C2NH2MIm]BF4), 1-methoxyethyl-3-methylimidazolium tetrafluoroborate ([MOEMIm]BF4) and 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate ([HOEMIm]BF4). The 96 h median lethal concentration (96 h LC50) of the three TSILs [C2NH2MIm]BF4, [MOEMIm]BF4 and [HOEMIm]BF4 on zebrafish determined by an acute toxicity test were 143.8 mg/L, 2492.5 mg/L and 3086.7 mg/L, respectively. In the oxidative damage and DNA damage research experiments, zebrafish were exposed to [C2NH2MIm]BF4 (0, 5, 10, 20 and 40 mg/L), [MOEMIm]BF4 and [HOEMIm]BF4 (0, 1, 10, 50 and 100 mg/L) for 28 days, and levels of reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), malondialdehyde (MDA) and olive tail moment (OTM) in zebrafish liver were tested on days 7, 14, 21 and 28 after the exposure test. During the experiment, increased contents of ROS and MDA were detected; enzymatic activities especially SOD were inhibited; and DNA damage occurred in zebrafish. The toxicity of the three TSILs was compared by the integrated biomarker response (IBR). The toxicity order of three TSILs was: [MOEMIm]BF4 > [HOEMIm]BF4 > [C2NH2MIm]BF4. In addition, this study can provide a toxicological basis for application research and the evaluation of functionalized ionic liquids with low toxicity in the future.