Resumen:
Due to its analgesic properties, diclofenac (DCF) is one of the most commonly used non-steroidal anti-inflammatory drugs (NSAIDs). While residue from this pharmaceutical agent has been found in diverse water bodies in various countries, there is not enough information of its potential toxicity on aquatic organisms, particularly in species which are economically valuable due to their high consumption by humans, such as the common carp Cyprinus carpio. This study aimed to evaluate potential DCF-induced oxidative stress in brain, liver, gill and blood of C. carpio. The median lethal concentration of DCF at 96 h (96-h LC50) was determined and used to establish the concentration equivalent to the lowest observed adverse effect level (LOAEL). Carp specimens were exposed to this concentration for different exposure times (12, 24, 48, 72 and 96 h) and the following biomarkers were evaluated: lipid peroxidation (LPX) and the activity of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx). Also, the DCF and 4-hydroxy DCF was determined by LC-MS/MS. Results show a statistically significant LPX increase (P<0.05) in liver and gill mainly as well as significant changes in the activity of the antioxidant enzymes evaluated in these organs, with respect to controls (P<0.05). The DCF concentrations decreased in water system and increased in the carp. The DCF biotransformation to 4-hydroxy DCF was observed to 12 h. The pharmaceutical agent DCF is concluded to induce oxidative stress on the common carp C. carpio, with the highest incidence of oxidative damage occurring in liver and gill. Furthermore, the biomarkers employed in this study are useful in the assessment of the environmental impact of this agent on aquatic species.