Assessment of triclosan induced histopathological and biochemical alterations, and molecular docking simulation analysis of acetylcholinesterase enzyme in the gills of fish, Cyprinus carpio.

Triclosan (TCS), an antimicrobial additive in various personal and health care products, has been widely detected in aquatic environment around the world. The present study investigated the impacts of TCS in the gills of the fish, Cyprinus carpio employing histopathological, biochemical, molecular docking and simulation analysis. The 96 h LC50 value of TCS in C. carpio was found to be 0.968 mg/L. Fish were exposed to 1/1000th (1 µg/L), 1/100th (10 µg/L), and 1/10th (100 µg/L) of 96 h LC50 value for a period of 28 days. The histopathological alterations observed in the gills were hypertrophy, hyperplasia, edematous swellings, and fusion of secondary lamellae in TCS exposed groups. The severity of these alterations increased with both the concentration as well as the duration of exposure. The present study revealed that the activity of antioxidant enzymes such as superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione peroxidase, and reduced glutathione content decreased significantly (p < 0.05) in both concentration and duration dependent manner. However, a significant (p < 0.05) increase in the activity of the metabolic enzymes such as acid phosphatase and alkaline phosphatase was observed in all three exposure concentrations of TCS from 7 to 28 days. The activity of acetylcholinesterase declined significantly (p < 0.05) from 7 to 28 days whereas the content of acetylcholine increased significantly at the end of 28 day. The experimental results were further confirmed by molecular docking and simulation analysis that showed strong binding of TCS with acetylcholinesterase enzyme. The study revealed that long-term exposure to sublethal concentrations of TCS can lead to severe physiological and histopathological alterations in the fish.

Ecotoxicological impacts of environmentally relevant concentrations of aspirin in the liver of Labeo rohita: Biochemical and histopathological investigation.

Aspirin is one of the emerging pharmaceutical contaminants in the aquatic environment and thus it could impart toxicity to non-target organisms including fish. The present study aims to investigate the biochemical and histopathological alterations in the liver of the fish, Labeo rohita exposed to environmentally relevant concentrations of aspirin (1, 10, and 100 µg/L) for 7, 14, 21, and 28 days. The biochemical investigation revealed a significant (p < 0.05) decrease in the activity of antioxidant enzymes such as catalase, glutathione peroxidase, glutathione reductase; and reduced glutathione content in a concentration and duration dependent manner. Further, the decrease in the activity of superoxide dismutase was in a dose dependent manner. The activity of glutathione-s-transferase, however, increased significantly (p < 0.05) in a dose dependent manner. The lipid peroxidation and total nitrate content showed a significant (p < 0.05) increase in a dose and duration dependent manner. The metabolic enzymes such as acid phosphatase, alkaline phosphatase, and lactate dehydrogenase showed a significant (p < 0.05) increase in all three exposure concentrations and durations. The histopathological alterations in the liver such as vacuolization, hypertrophy of the hepatocytes, nuclear degenerative changes, and bile stagnosis increased in a dose and duration dependent manner. Hence, the present study concludes aspirin has a toxic impact on fish, which is evidenced by its profound effect on biochemical parameters and histopathological analysis. These can be employed as potential indicators of pharmaceutical toxicity in the field of environmental biomonitoring.