DNA Damage And Oxidative Stress Induced By Ionic Liquids [Omim] PF₆and [Omim] Br Exposure In Zebrafish （Danio Rerio）

Ionic liquids, as known as room temperature ionic liquids or low-melting-point salts, aretotally consisting of ions in the room or low temperature. Formally, they were considered asnew green solvents after water and supercritical CO2because of their unique features such asnegligible vapor pressure, broader range of liquid state, and the ability to be recycled. Inrecent decade, the application of these liquids in reaction media for chemical separation,organic synthesis, electrochemistry, and material processing has been well-documented.Nevertheless, the researches on toxic effects of these liquids were backward and only a fewreports focused on their acute toxicity. Zebrafish (Danio rerio) are generally regarded asmodel animals for their advantages including small size, rapid breeding, simple feeding,transparent throughout developmental process in embryo and a clear view of cells withfluorescence dye or other markers in development biology in the word. The present studyexamined the toxic effects on zebrafish (Danio rerio) of exposure to different concentrationsof two ionic liquids1-octyl-3-methylimidazolium hexafluorophosphate and1-octyl-3-methylimidazolium bromide for a28-day period (sampled at7,14,21,28d), withmale and female fish tested separately. The activity of total superoxide dismutase (SOD),catalase (CAT) and;the contents of Reactive Oxygen Species (ROS) and the content ofmalonaldehyde (MDA) were used to estimate oxidative stress and comet assay was applied toevaluate DNA damage in zebrafish (Danio rerio). The present results showed a significanttoxic effects on zebrafish which estimated ecotoxicity and genotoxicity of ionic liquids andalso provide a basis for the comprehensive understanding on their effects to aquatic ecosystem.A marked induction or inhibition was found among these experimental indicators: (1) Overall, the ROS levels were increased in a dose-dependant manner. A similarsituation was also found in DNA damage, especially DNA damage was enhanced with timeincreasing. The activity of antioxidant enzymes were exhibited the tendency of inhibitioneven though there were somewhat differences after exposed to two ionic liquids. MDAcontents were gradually increased with increasing of [Omim]Br concentration. MDA contentsin treatment groups increased and then gradually decreased to control levels with prolongingtime.(2) The activity of antioxidant enzymes was activated and then gradually inhibited afterexposure to [Omim]Br in most sampling time intervals. In contrast, the inhibition was foundat concentrations of [Omim]PF6in all treatment groups. The stimulation of ROS levels wasless in [Omim]Br than in [Omim]PF6in zebrafish liver.(3) The exploration of the correlation among biomarkers namely ROS levels, SOD andCAT activities, DNA damage and lipid peroxidation in zebrafish provide a theoretical basisfor the further estimation on toxicity mechanism of ionic liquids to zebrafish.