A comparison of the effects of thymoquinone, silymarin and N-acetylcysteine in an experimental hepatotoxicity

This study investigated the effects of thymoquinone, silymarin, and N-acetylcysteine in a rat model with carbon tetrachloride (CCl4)-induced hepatotoxicity. Although numerous similar studies are available, we aimed to compare the efficacy of these agents by considering N-acetylcysteine as a reference compound. A total of 50 male Wistar albino rats were randomly designated as 5 groups: Group I, CCl4; group II, thymoquinone and CCl4; group III, silymarin and CCl4; group IV, N-acetylcysteine and CCl4; group V, control group. CCl4 was administered intraperitoneally at a dose of 1.5 mL/kg (a mixture of CCl4: olive oil, 1:2) twice a week. Thymoquinone was administered at a dose of 10 mg/kg, silymarin was administered at a dose of 100 mg/kg, and N-acetylcysteine was administered at a dose of 100 mg/kg by daily intraperitoneal injection. At the end of four weeks, blood and liver tests were analyzed. The results were evaluated statistically via the one-way ANOVA test. A p-value < 0.05 was considered statistically significant. Thymoquinone, silymarin, and N-acetylcysteine improved the levels of alanine aminotransferase, tumor necrosis factor-alpha, platelet-derived growth factor-BB, and interleukin-6, which were increased by CCl4. Thymoquinone and silymarin showed the positive increase in liver glutathione levels. Thymoquinone, silymarin, and N-acetylcysteine improved blood total oxidant status. In the histological examinations of liver tissue, thymoquinone decreased necrosis, and inflammation. The most positive decrease in the alpha-smooth muscle actin-stained hepatic stellate cell count was only observed with thymoquinone. These findings suggest that thymoquinone, silymarin, and N-acetylcysteine have potential for the treatment of diseases causing liver injury. Among these agents, thymoquinone showed the best results on most of the parameters. Since TQ appears to be at least as effective as SM and NAC in our in-vitro study, we propose that it is time for clinical studies with thymoquinone on hepatotoxicity.