Effect of Thymoquinone on Diclofenac-Induced Liver Injury

Background and Objective: Thymoquinone (TQ) is an active phenolic compound obtained from Nigella sativa L. It has anti-inflammatory and antioxidant activity by inhibiting the overproduction of certain inflammatory molecules and lipid peroxidation. TQ also has a hepatoprotective effect. This study, it was aimed to biochemically investigate the effect of TQ on diclofenac (DC)-induced liver damage in rats. Materials and Methods: The animals were divided into healthy control (HG), only diclofenac (DG), only thymoquinone (TQG) and diclofenac+thymoquinone (DTQG) groups. The DC was injected intraperitoneally at a dose of 25 mg kg(-1). The TQ was administered orally to the stomach at a dose of 20 mg kg(-1). This procedure was repeated once a day for 7 days. Results: Biochemical test results showed that TQ significantly prevented the increase in oxidant parameters and the decrease in antioxidants in liver tissue, which is formed by DC. Also, DC and TQ inhibited the increase of proinflammatory cytokines in liver tissue. The TQ also prevented the decrease of COX-1 activity by DC and increased the inhibition of COX-2. The TQ also significantly suppressed the elevation of liver function markers such as Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST) with DC. Conclusion: These findings indicated that the hepatotoxic effect of DC was due to oxidative stress and inhibition of cytoprotective structural COX-1 enzyme. It suggested that TQ may be useful in the treatment of DC-related liver injury.