Toxic Effects Of Four Imidazolium Ionic Liquids With Different Hydrocarbon Chain Length On Dugesia Japonica

Ionic liquids (ILs) which completely consist of ions are one category of fluid chemicals at roomtemperature. Due to its unique characteristics, such as negligible vapor pressure, perfect electricconductivity, high thermal stability and excellent solvation ability, it will be the “green” sbustitute oftraditional organic solvent. With the popularization and application in various fields, their biologicaltoxicity and environmental risk assessment have been paid more and more attention. Freshwater planariansinhabiting in clear springs and lakes are very sensitive to the toxic and teratogenic factors in theenvironment. Thus they are one kind of good indication species of water quality. In addition, they arewidespreading, easy to collect, convenient to lab rear and low cost. So the freshwater planarian toxicologyhas been thriving lately. In this study, Dugesia japonica was chosen as the test animal, the acute toxicity,the effects on ingestion and regeneratin, and the effects on antioxidant defense system of of four differentalkyl-chain length imidazole ionic liquids ([C4mim]Br,[C6mim]Br,[C8mim]Br and [C10mim]Br) werestudied via the acute toxicity test, ingestion and regeneration experiment and biochemical analysistechnique. And further the relationship of the alkyl-chain length of imidazole ILs and their toxicity.Themain conclusions are as follows:1. The50%lethal concentration (LC50-72h) of four different alkyl-chain length imidazole ionicliquids ([C4mim]Br,[C6mim]Br,[C8mim]Br and [C10mim]Br) to D. japonica are2079mg/L,919mg/L,312mg/L and32mg/L, respectivety. With the increase of the carbon atoms in the alkyl-chain of ILs, theLC50values decrease, and the toxicity to D. japonica increases.2. Compared with the control group, the number of ingestion planarians declined after the ionic liquidhandling. With the increase of alkyl-chain length of4-10carbon atoms, the number of ingestion planariansreduced at the same timepoint. This indicates ILs exposure will ihibite the ingestion behaviour ofplanarians, and with the increase of alkyl-chain carbon atomes the toxicity of imidazole ionic liquidsincrease, and the inhibition to ingestion behaviour become stronger.3. Compared with the control group, the number of regenerated planarians decreased in the ILsexposure groups. With the increase of alkyl-chain length of4-10carbon atoms, it took the planarians oftreated groups longer time to regenerate completely. This indicates ILs exposure will ihibite the regeneration of planarians, and with the increase of alkyl-chain carbon atomes the inhibition to planarianregeneration become stronger.4. Compared with the control group, the acitivities of the antioxidant enzymes SOD, CAT and GPX,and the levels of antioxidant reagent GSH and the by-product of lipid oxidation MDA increased. And tosome extent the increase tendency was consistent to the increase of alkyl-chain carbon atomes of ILs. Thissuggests ILs caused oxidative stress in D. japonica, and the antioxidant enzymes and GSH were induced asdefense mechanisms. With the increase of alkyl-chain carbon atomes, the stress of ILs exposed toplanarians become stronger and the the degree of lipid oxidation become more seriously.