# Evaluation of Sub-Lethal Toxicity of Benzethonium Chloride in _Cyprimus carpio_ [PERSON]
## 3 Results
### Effect of BEC Exposure on Liver Metabolism  
Within the present study, the levels of lipid peroxidation were measured after 24, 48, and 96 h of fish exposure to BEC. Although the activity of CAT in the hepatic tissue decreased after 24 and 48 h by 20% of the control level, this activity decreased after 96 h by 44% compared to the control (Figure 1a), suggesting the accumulation of hydrogen peroxide and enzyme inhibition. In the case of SOD activity, this slightly decreased after 24 and 48 h and diminished only by 10% of control after 96 h of exposure to BEC (Figure 1b). CAT activity significantly decreased (\(p<0.05\)) after 96 h, indicating a toxic effect of BEC on this antioxidant enzyme. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{2}{c}{**Control Fish**} & \multicolumn{2}{c}{**Exposed Fish**} \\ \cline{2-5}  & **24 h** & **96 h** & **24 h** & **96 h** \\ \hline Body mass (g/fish) & 58.5 \(\pm\) 6.95 & 59 \(\pm\) 11.40 & 64.1 \(\pm\) 14.43 & 65.4 \(\pm\) 10.25 \\ \hline Total length (cm/fish) & 15.87 \(\pm\) 0.7 & 13.38 \(\pm\) 1.98 & 16.04 \(\pm\) 1.18 & 16.2 \(\pm\) 1.63 \\ \hline Liver weight (g/fish) & 1.57 \(\pm\) 0.05 & 1.20 \(\pm\) 0.33 & 1.49 \(\pm\) 0.24 & 1.39 \(\pm\) 0.30 \\ \hline Gonad weight (g/fish) & 0.64 \(\pm\) 0.03 & 0.20 \(\pm\) 0.15 & 0.40 \(\pm\) 0.23 & 0.73 \(\pm\) 0.31 \\ \hline HSI & 2.68 \(\pm\) 0.21 & 2.03 \(\pm\) 0.25 & 2.32 \(\pm\) 0.21 & 2.12 \(\pm\) 0.21 \\ \hline GSI & 1.86 \(\pm\) 0.03 & 0.55 \(\pm\) 0.39 & 0.62 \(\pm\) 0.22 & 1.11 \(\pm\) 0.63 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Hepatosomatic index (HSI) and gonadosomatic index (GSI) of fish groups (n = 5 fish/group) based on the average weight of body mass, liver, and gonads weight measured at 24 h and 96 h of exposure. GSI = (gonad weight/body mass) \(\times\) 100; HSI = (liver weight/body mass) \(\times\) 100. Figure 1: Hepatic activities of catalase (**a**) and superoxide dismutase (**b**) in _Cyprinus carpio_ exposed to 1 mg/L of BEC for 24, 48, and 96 h. Results were expressed relative to control as mean levels of relative specific activities \(\pm\) standard deviation (n = 5 fish for each group). ***\(p\leq\) 0.001 compared to control. Regarding the metabolism of GSH, the most abundant cellular thiol antioxidant, we investigated the variance of GPx, GRed, and GST activities in correlation with GSH level during the fish exposure to BEC (Figure 2). In the hepatic tissue, all of these three enzymes exhibited lower activities compared to control groups. In the presence of BEC, the specific activities of GRed and GPx diminished in a time-dependent manner, with almost 30% (compared to control) after 96 h. Although the GST activity was not significantly decreased after the first intervals of exposure, its activity was reduced by half compared to its control after the 96 h (Figure 2c). A time-dependent decrease was also observed in the case of GSH level, a significant reduction by 44% of control was measured after 96 h, which suggested a depletion of this antioxidant level in hepatic tissues from fish exposed the longest period to BEC. This correlated very well with the decreased activities of GSH-related enzymes (Figure 2). G6 PDH activity decreased only after 48 and 96 h of BEC incubation by 23% and 29% of control, respectively (Figure 3a), revealing the reduction of NADPH formation which affected the GSH level (Figure 2d), as well as GRed activity (Figure 2a). LDH activity slightly increased after 24 and 48 h compared to control, a 20% elevation above the control being assessed after 96 h (Figure 3b). Figure 2: Hepatic activities of glutathione reductase (**a**), glutathione peroxidase (**b**), glutathione S-transferase (**c**) and superoxide dismutase, and levels of reduced glutathione (**d**) in _Cyprinus carpio_ exposed to 1 mg/L of BEC for 24, 48, and 96 h. Results were expressed relative to control as mean levels \(\pm\) standard deviation (n = 5 fish for each group).