Evaluation of the role of the antioxidant silymarin in modulating the in vivo genotoxicity of the antiviral drug ribavirin in mice

► We confirmed ribavirin genotoxic effect in mice as indicated by significant increase in MNPCEs compared to the negative control. ► We revealed ribavirin cytotoxic effect in bone marrow cells as indicated by decrease in the rate of erythropoiesis. ► We revealed the ameliorating effect of silymarin pretreatment for different ribavirin treated groups. ► SSCP patterns showed no abnormal bandshifts for PCR product for ribavirin treated groups in the two selected sites in the D-loop of mtDNA. Ribavirin (1-β-d-ribofuranosyl-1,2,4-triazole-3-carboxamide) is a widely used broad-spectrum antiviral drug. Recently, several reports revealed genotoxic effects of ribavirin in vivo and in vitro, which were correlated with the production of reactive oxygen species (ROS). This study aimed to evaluate the genotoxicity of ribavirin and to investigate the role of the natural antioxidant silymarin to modulate this genotoxicity. Male albino mice (age, 8–10 weeks) were injected intraperitoneally (i.p.) with ribavirin at three dose levels (20, 75 and 130mg/kgbw) either in a single injection (acute treatment) or in multiple injections on five consecutive days (sub-acute treatment). Other comparable groups were treated with silymarin (70mg/kgbw) 1h before the injection with ribavirin. Mice were sacrificed at different sampling times (24, 48 and 72h) after the last ribavirin treatment. Micronucleus (MN) and single-strand conformation polymorphism (SSCP) assays were used to assess genotoxic and cytotoxic effects of ribavirin and to evaluate the protective effect of the pre-treatment with silymarin. Our results reveal genotoxic and cytotoxic effects of ribavirin in the MN assay. Pre-treatment with silymarin reduced the toxicity of ribavirin. In the SSCP assay, ribavirin treatment did not induce any mutations in the two selected sites in the D-loop of mitochondrial DNA (mtDNA).