| Antioxidant defense system is an important component of the organism which canprovide effective protection to resist oxidative damage; it was widely used to evaluate the quality of aquatic environments. Antioxidant defense systems is comprised of antioxidant enzymes, for example, superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), glutathione S-transferase (GST), and non-enzymatic scavengers such as reduced glutathione (GSH) vitamin C and Vitamin E. Antioxidase is rapid and sensitive biomarkers of oxidative damage which can effectively provide an early warning for pollutants. The biomarker has an advantage in the conventional ecological toxicology study.Based on the research of the typical organic pollutants, we study the oxidant stress induced by the three typical organic pollutants (PCDPSs, Direct dyes and PAEs) on Carassius auratus (C. auratus). Hereafter, the toxicity of compound series and toxic difference were compared to get more detailed condition aboutvirulence variation. Activities of SOD, CAT and GPx were measured, besides, MDA levels were also studied to measure the impact of the compounds. Furthermore, molecular computing, such as density function theory (DFT) and atom in molecule (AIM) analysis, and integrated biomarker responses (IBR) were employed to speculate the metabolic process and the toxicity differences were constructed. The main contents and the corresponding conclusions are as follows:(1) Increasing concentrations (0.1,1,10,100μg/kg body weight for various PCDPSs and1,10,100mg/kg for diphenylsulfides (DPS)) of test compounds were administrated on fish (C. auratus) for12h, with one group assigned as the control. Meanwhile, time-dependent effects of PCDPSs on the antioxidant defense system using Tris-, Penta-and Hepta-CDPS were carried out. Fish were acutely injected with either10μg/kg of such PCDPSs or corn oil alone (control), and then liver samples were collected at0.5,1,2,3and5d for analysis of antioxidant content. Changes in the activities of SOD, CAT, and in the levels of MDA were detected, suggesting that PCDPSs exhibit potential biotoxicity. In addition, our data indicated that PCDPS toxicity varies with the degree of substitution and the position of substitution attached to two benzene rings, results that were also partly supported by the time-dependent effects elicited by the Tris-, Penta-and Hepta-CDPSs. In particular, our results indicate that Penta-and Hexa-CDPSs may act as highly toxic contaminants that exhibit striking enzymatic inhibitory activity. In short, altered levels of antioxidant enzymes, including SOD and CAT, along with MDA, may serve as potential biomarkers of PCDPS contamination.(2) The toxicity of three direct dyes, Direct Blending Rebine (D-BLL), Direct Blending Scarlet (D-GLN), and Direct Blending Yellow (D-3RNL), were examined by the antioxidase and lipid peroxide index. Fish (C. auratus) were exposed to10mg/L test compounds or injected with200μg/kg corresponding dyes, and then samples of liver were collected at different time (0.5,1,3,5,7,10,13,17and22d) for analysis of SOD, CA), and contents of MDA. There is an obvious difference between two poisoning conditions and results indicated injection pattern have a more sensitive response. Besides, SOD, CAT and MDA levels displayed different variation trend following the prolonged duration, implying that dye metabolism generated less toxic or more active substance. The comparison among their intensity of enzyme inhibition showed that the toxicity order is D-BLL> D-GLN> D-3RNL. Additionally, three direct dye molecules were optimized based on the quantum mechanical charge density of a solute molecule interacting with a continuum description of the solvent (SMD) of Self-consistent Reaction Field Theory (SCRF) on B3LYP/LAN2BM level and the stable configurations were obtained. Wiberg bond orders were analyzed and atom in molecule (AIM)2000program was employed to estimate the interaction between atoms. The possible degradation pathways and toxicities were speculated based on the computations. The calculation is consistent with the experimental results and analysis.(3) Antioxidative responses of9phthalates (PAEs) on fish C. auratus were performed. Fish were injected with10mg/kg body weight of each PAE for1d,4d,8d and14d. The potential biotoxicity of PAEs were examined by the antioxidase and lipid peroxide index. We found that SOD, CAT, GPx, and MDA levels displayed different variation trend following the prolonged duration, implying that metabolism generated less toxic or more active substance. Based on the intensity of enzyme inhibition as well as evaluating MDA content, together with calculated integrated biomarker response (IBR), the toxicity order was tentatively proposed as:DBP> DEP> DIDP> DPP> BBP> DAP> DCHP> DMP> DEHP. In particular, DBP which exhibits striking inhibition in enzymatic activity and the greatest decrease in MDA content may act as a highly toxic contaminant. Furthermore, our results suggested that IBR may serve as a general marker of pollution. |
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