The Immunotoxicity Of The Ionicliquid1-Methyl-3-Octy Limidazolium Bromide On Red Carp (Cypriuns Carpio L.)

Ionic liquids (ILs) are a novel class of technologically advanced solvents. ILs also possess organic or inorganic anions of variable nature. In recent years, ILs have attracted considerable attention due to their unique characteristics and properties, such as negligible vapor pressure, high thermal stability and excellent solvation ability. Thus, ionic liquids are claimed to be environmentally benign and are very good non-volatile solvents for a wide range of inorganic and organic materials. Currently, ILs have been regarded, by both commercial businesses and individual consumers, as promising"green"substitutes for conventional organic solvents in manufacturing, processing, and cleaning technologies.The''green character''of ILs has usually been justified by their negligible vapor pressure, but even if ILs do not evaporate and cause air pollution, most are water-soluble and may enter aquatic environments by accidental leakage of the effluent during usage. Therefore, it can be hypothesized that ILs may pose environmental risks to aquatic ecosystems. Accurate toxicity data and the aquatic environmental fate of ILs are important for hydrophobic ILs. Recently, there has been a considerable number of published studies regarding the biological activity and toxicity of a large number of ILs on algae, bacteria, fungi, daphnia, earthworms, and rodents. However, no data exists on the immunotoxicity of ILs to fish. The aim of the present study is to determine the immunotoxicity of [C₈mim]Br to red carp (Cyprinus carpio L.) by acute toxicity test.According to the primary tests of immunological toxicity, the exposure concentrations were set as 0, 100,and300 mg/L in this study. Each experiment was performed in duplicate with 6 red carps in every group. The fish were treated for 7 days by soaking in the IL-solutions and sampled randonly (2 fish) at 2, 5, 7 day. After sampling, the fish were weighed, andthen the blood were taken by cutting tail. The blood was centrifuged and the supernatant was collected and stored at -20°Cfor lysozyme activity, C3 content, and IgM content determination. The fish were dissected, and their hepatopancreases, kidney and spleen were quickly isolated, washed with ice-cold 0.9% saline solution and then weighed. Two small sections were taken from these organs for histological observations and the remainder was homogenized to a 1/10 (w/v) ratio in cold phosphate buffered saline (PBS, pH 7.2) for lysozyme activity assays. . The results of this study were described as following:(1) The visceral index of fish in low concentration group (100 mg/L) and high concentration group (300 mg/L) were not significantly increased when compared to the control group (p > 0.05).(2) Histopathologic observation results showed that [C₈mim]Br caused damages to hepatopancreases, kidney and spleen, consisting mainly of hepatic cords in a loose connection, hepatic cytoplasmic vacuolation, renal parenchyma vacuolization and intumescence of the renal tubule.(3) In low concentration group (100 mg/L), the lysozyme activity of of fish serum, kidneys, spleen increased significantly in compartion with control. However, in high concentration group (100 mg/L), the lysozyme activity decreased sharply after 5 days of IL-expsoure (p < 0.05).(4) In low concentration group, we found a remarkable changes, first increase and then decrease, in IgM and C3 activities of fish serum, kidneys, spleen IgM after IL-exposure. Meanwhile in high concentration group, they always showed significantly decrease when compared to the control (p < 0.05).(5) These results indicate that [C₈mim]Br has immunetoxicity on red carp.