Background: Paraquat is nonselective bipyridyl herbicide that induces hepatotoxicity through oxidative stress. Vitamin C and chitosan have antioxidant as well as radical scavenger properties and show protective effects against reactive oxygen species (ROS). In the present study, hepatoprotective effects of chitosan and vitamin C were evaluated in common carp exposed to paraquat.

Methods: While exposed to 0.02 mg. L^-1paraquat for 21 days, common carp were fed chitosan (1000 mg. kg^‑1 feed), vitamin C (1000 mg. kg^-1 feed), and vitamin C combined with chitosan. At the end of the experiment, activities of hepatic enzymes and oxidative stress biomarkers were evaluated.

Results: Paraquat induces changes in the activity of alanine aminotransferase, aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase and lactate dehydrogenase in liver tissue of fish. However, these enzymes were restored to normal levels in fish fed with vitamin C and vitamin C combined with chitosan following exposure to paraquat. Increased levels of malondialdehyde were observed in liver after exposure to paraquat, while glucose-6-phosphate dehydrogenase and catalase activities and the total antioxidant levels decreased. Administration of vitamin C combined with chitosan significantly reduced malondialdehyde levels and increased the total antioxidant capacity, glucose-6-phosphate dehydrogenase and catalase activities.

Conclusion: Administration of vitamin C is effective in reducing liver toxicity of paraquat. However, administrating both vitamin C and chitosan is more effective. In other words, chitosan and vitamin C have a synergic effect. They could be used as hepatoprotective agents against paraquat-induced hepatotoxicity in fish.