Silymarin Protects Against Daunorubicin-Induced DNA Damage in an In Vivo Comet Assay

Daunorubicin is an anthracycline chemotherapy drug that is active against leukemias but has significant effects on normal cells, leading to long-term toxicity. The flavanolignan silymarin, which is extracted from milk thistle, has well-known antioxidant and cytoprotective effects. This study examined the protective activity of silymarin against daunorubicin-induced primary damage to DNA in lymphocytes of rats. Adult Wistar rats were divided into four groups and administered silymarin by oral gavage and daunorubicin by a single intraperitoneal injection. Isolation of peripheral-blood lymphocytes was followed by alkaline single-cell gel electrophoresis (comet assay). The amount of DNA damage was determined as the percentage of DNA in the comet tail and was analyzed at the animal level using parametric and nonparametric statistics. DNA migration was extensive when treated with daunorubicin. The administration of silymarin in combination significantly reduced this damage, and it changed the profile of cellular damage from extreme to mostly moderate. There was no significant increase in DN damage in animals given silymarin. Silymarin has a clear antigenotoxic effect in vivo in the presence of daunorubicin, and it could be a useful chemoprotective adjuvant.