Teratogenic effects of silymarin on mouse fetuses

Silybum marianum has been used for centuries in herbal medicine for treatment of liver diseases. Currently, there is no data available on the possible effects of silymarin on fetal development. This study aimed to investigate the teratogenic effect of silymarin on BALB/c mice fetuses.
A total of 40 pregnant mice were divided into 4 groups of 10 mice each. Three groups received silymarin at three different doses of 50, 100 and 200 mg/kg/day during gestational days (GDs). The control group received normal saline and tween (solvent). Dams were sacrificed on GD 18 and all fetuses were examined for gross malformations, size and body weight. Malformed fetuses were double stained with alizarin red and alcian blue.
Silymarin administration at all doses resulted in reduction of the mean fetal body weights. The abnormalities included limb, vertebral column and craniofacial malformations. Craniofacial malformations were the most common abnormalities, but they were not observed in a dose-dependent manner. The percentage of fetal resorption significantly increased (up to 15%) in all treatment groups.
Based on our results, silymarin, especially at high doses can lead to fetal resorption, intrauterine growth retardation and limb, vertebral column and craniofacial abnormalities. More precise studies should be conducted about the teratogenic effects of herbal medicine investigating the underlying mechanisms. Thus, caution should be taken when administering S. marianum to pregnant woman.