Abstract: Objective To explore the antioxidant activities of puerarin on aged rats.Methotds Ten 2-month-old SD rats were selected as control group.Thirty 12-month-old SD rats were divided into negative control group,positive control group and puerarin group.Rats in medication were given an oral administration of 25 mg/kg puerarin and 15 mg/kg U-74006F,while other rats were given an administration of same volume of distilled water.Two months later,all the rats were sacrificed and blood was collected,and serum level of malondialdehyde (MDA) and activities of total antioxidant activity (T-AOC),superoxide dismutase (SOD) and glutathione (GSH-Px) were measured.The levels of MAD and activities of T-AOC,SOD and GSH-Px in liver and brain were also detected.Besides,the mRNA expressions of SOD and CAT in liver were analyzed in all the groups.Results The serum level of MDA and the activities of T-AOC,SOD and GSH-Px in aged rat group were significantly lower than young rat group.After the treatment of puerarin and U-74006F,the serum and liver levels of MDA decreased and the activities of SOD,T-AOC and GSH-Px increased significantly,and were significantly higher than aged rat group.The level of MDA decreased and the activities of SOD,T-AOC and GSH-Px increased significantly in brain after the treatment of U-74006F.Puerarin had no effects on MAD,SOD and GSH-Px except increased the activity of T-AOC.The mRNA expression of SOD and CAT of aged rat were significantly lower than young rat group,and after puerarin treatment this phenomenon was weakened.Conclusion Puerarin can increase the activities of antioxidant factors and had notable antioxidant functions on aged rats.