Anti- and pro-mutagenic effects of silymarin in the Ames bacterial reverse mutation assay.

Silymarin, a polyphenolic flavonoid isolated from milk thistle (Silybum marianum), is being used clinically in Europe and Asia for the treatment of liver diseases. Silymarin has a strong antioxidative action capable of scavenging both free radicals and reactive oxygen species responsible for cancer. Silymarin, a powerful hepatoprotective and antioxidant, was chosen in the present study and was tested for its antimutagenic activity using an in vitro test, the Ames bacterial reverse mutation assay. The results indicated that silymarin showed a significant mutagenicity in frame shift mutant strains (TA97a and TA98) with metabolic activation. This compound also showed stronger antimutagenic effect against 2-aminofluorene and 4-nitroquinoline N-oxide induced mutation. When pre-, co- and post-treatment of silymarin was carried out, it showed stronger antimutagenic activity in the post-treatment with 2-aminofluorene and 4-nitroquinoline N-oxide in TA97a and TA98 strains.