In this research, the effect of oral administration of different doses of hydroalcoholic extract of silymarin on the status of trace elements with antioxidant properties (Se, Cu, Zn, Mn and Fe) was studied. Fifty male rats were randomly used in five groups including healthy control group (treated by saline), diabetic control group (treated by saline) and three diabetic groups that were daily treated by different oral dose of silymarin (100, 175 and 250 mg kg-1). Diabetes was induced by intraperitoneal injection of streptozotocin (50 mg kg-1) in rats. Rats were orally treated for 14 days by gavage. Weight was measured before STZ injection, 7 and 14 days after treatment. The blood glucose was measured before injection of STZ, 3 days after injection and 7 and 14 days after diabetes was induced (under treatment by silymarin). At the end of the study, blood samples were taken by heart puncture. Results showed that the average weight increased during the 14 days of treatment with silymarin and the blood glucose was decreased. Hydroalcoholic extract of silymarin increased trace elements levels in treated groups by dose-dependent manner. The present study showed that in diabetic rats, high therapeutic doses of silymarin had a major effect on serum antioxidant factors. Results also showed that hydroalcoholic extract of silymarin increased the body weight and decreased serum glucose concentration at the end of the treatment period. Silymarin in a dose dependent manner could improve trace element levels in diabetic rats. Therefore, it may cause reduction of oxidative stress in the diabetic rats.
