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

Abstract

Hepatitis C virus (HCV), first described in 1989, is now recognized as one of the main causes of chronic liver disease worldwide. HCV infection becomes chronic in the majority of cases. All current treatment protocols for hepatitis C are based on the use of interferon alpha and ribavirin (RBV). Moreover, RBV alone was used in treatment of various viral infections as influenza A and B, lower respiratory tract disease caused by respiratory syncytial virus, Crimean-Congo hemorrhagic fever and rift valley fever. Despite RBV broad spectrum in treatment of various viral infections, recently several reports revealed genotoxic effects ofRBV in vivo and in vitro. This genotoxicity was correlated with the production of reactive oxygen species (ROS). This study aimed to evaluate RBV genotoxicity and investigate the role of the natural antioxidant silymarin (SL) to modulate RBV genotoxicity. In the present study, RBV was injected i.p. at three dose levels (20, 75 and 130 mglkg) either as a single injection (acute treatment) or multiple injections for 5 consecutive days (subacute treatment). Other groups were treated with SL (70 mglkg) lhr before RBV injection. Mice were sacrificed at different sampling time (24, 48 and 72 hr) after RBV treatment. Micronucleus (MN) and SSCP assays were used as cytogenetic assay and molecular end point to assess genotoxic and cytotoxic effects ofRBV and to evaluate SL pretreatment protection. In the present study, RBV induced structural chromosomal damage hence producing the fragments for the micronucleus formation. Also it decreased the PIN ratio indicating that it prevents cell division in mouse bone marrow. SL pretreatment decreased RBV genotoxicity using the MN assay. On the other hand, when using SSCP assay, no mutations could be detected in the two studied sites of mtDNA D-loop. In conclusion, RBV is a potent genotoxic and cytotoxic agent in mice in vivo. Furthermore, the present study revealed the protective effect of SL pretreatment against RBV-induced chromosome damage in mice bone marrow. Key Words: HCV, ribavirin, silymarin, cytotoxicity, genotoxicity, MN, SSCP.