DNA Damage And Oxidative Stress Induced By Imidazolium-based ILs In Zebrafish(Danio Rerio)

Ionic liquids (ILs) are organic salts consisting entirely of ions and exist as liquids at room temperature. As for their superior solubility as well as high stability in water, this is the most possible medium through which ILs will be industrial drained or accidental spilled into the environment. Therefore, relevant information is needed on their fate and transport in the environment, including details of their toxicity. Three imidazolium-based ILs with different lengths of alkyl chain ([C4mim]Br,[C6mim]Br,[C10mim]Br) were chosen to investigate the toxic effects with relatively long-term exposure to low dose of ILs in zebrafish livers. Male and female zebrafish were separated and exposed to five concentrations of ILs (0,5,10,20and40mg/L) and were sampled on days7,14,21and28. The present study comprehensively assessed the effects of ILs on the antioxidant enzyme system including superoxide dismutase (SOD) and catalase (CAT), ROS, MDA and DNA damage in zebra fish. It provides theoretical basics on evaluating the environmental risk in terms of their toxic effects to aquatic ecosystem. As shown in the present results, a marked induction or inhibition was found among these experimental indicators after exposure to different tested concentrations of ILs:1. The activity of SOD was activated and then gradually inhibited after exposure to [C4mim]Br in most sampling time intervals. The inhibition was found at concentrations of [C6mim]Br and [C10mim]Br in all treatment groups. The activity of CAT was activated and then gradually inhibited after exposure to [C4mim]Br and [C6mim]Br in most sampling time intervals. The inhibition was found at all tested concentrations of [C10mim]Br through the experiment period. Although the changes of the activities of antioxidant enzymes were different, the inhibited tendency was found at high concentrations of three ILs. At early stage of [C4mim]Br exposure, the SOD activity was induced significantly for females, but the induction was only found in the concentration of5mg/L for males.2. After exposure to high concentrations of [C4mim]Br. the ROS and MDA levels increased significantly. As for [C6mim]Br and [C10mim]Br, both two indicators increased obviously at most sampling time intervals. All of these ILs can induce the DNA damage in a dose-dependant manner. After exposure to [C4mim]Br, the degree of the increase of MDA content in males was higher than females’on days14and28. According to DNA damage, males were more serious than females.3. In conclusion, the present study investigated the degree of oxidative stree and genotoxicology induced by three imidazolium-based ILs with different lengths of alkyl chain. The order was presented as follows:[C10mim]Br>[C6mim]Br>[C4mim]Br. The exploration of the order of ILs with different lengths of alkyl chain may provide a theorethical basis for the estimation on toxicity of ILs and further application in industry.