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.