2-Chlorophenol induced ROS generation in fish Carassius auratus based on the EPR method

In the present study, a secondary spin trapping technique was used followed by electron paramagnetic resonance (EPR) analysis, to study the potential of reactive oxygen species (ROS) production after fish (Carassius auratus) were injected i.p. with different doses (50, 100, 200, 250, 500 mg kg−1) of 2-chlorophenol (2-CP). The ROS signal intensity of the EPR spectrum showed a significant increase (p < 0.05, compared with the control) when the 2-CP dose was as low as 50 mg kg−1. There is a good relationship between the 2-CP administered doses and ROS generation. Based on the hyperfine splitting constants and shape of the EPR spectrum, the ROS which was generated in fish liver after intraperitoneal (i.p.) injection of 2-CP was identified as OH. SOD and CAT activities were found to be induced at lower doses of 2-CP. GSH levels fell below the control level following all treatments with 2-CP, and GSSG levels changed along with those of GSH. These observations indicated that the fish experienced oxidative stress. The strong positive correlation (r = 0.966, p < 0.005) between OH radical and lipid peroxidation suggested that lipid peroxidation was possibly induced by OH. The phase II detoxification enzyme glutathione-S-transferase (GST) may play an important role in 2-CP metabolism or excretion and, consequently, reduce ROS production. This study provides strong evidence that level of ROS is significantly increased in 2-CP stressed fish, and ROS may serve as a potential biomarker to indicate 2-CP contamination.