Genotoxic and Antigenotoxic Activity of Silymarin by an In Vivo Bone Marrow Micronucleus Assay and Comet Assay

Introduction: Silymarin is obtained from Silybum marianum (milk thistle), an edible plant that has long been used medicinally for the treatment of liver-related disorders. Silymarin is a powerful hepatoprotective and antioxidant but the anticlastogenic activity, which is an important aspect of its cancer chemoprevention is not known; hence the present investigation was carried out to study its anticlastogenic and DNA protective activity in Balb/c Mouse.Material & Methods: After silymarin injections, the mice were administered either cyclophosphamide (CP) or mitomycin C (MMC) intraperitoneally and were sacrificed at 24 hrs, 48 hrs and 72 hrs after the last dose. In vivo bone marrow micronucleus assay and Comet assay in whole blood were performed.Results: Silymarin produced an increased number of micronucleated polychromatic erythrocytes in in vivo bone marrow micronucleus assay. Similarly it showed anticlastogenic activity against mutagens cyclophosphamide (CP) and mitomycin C (MMC) and caused significant reduction in the number of micronucleated polychromatic erythrocytes. In comet assay, it produced DNA damage, however silymarin showed DNA protective action against mutagens CP and MMC.Conclusion: Silymarin has chemopreventive potentials against CP and MMC induced clastogenicity in Balb/c mice. Ironically, it has also been found to induce clastogenicity and DNA damaging effects. Hence, large-scale investigations are essential to confirm the clastogenic effect before continuing the use of silymarin for therapeutic purposes