Abstract: To study the preparation and the effect of peanut polypeptide on antioxidative system of mice with oxidative injury model induced by D-galactose, forty kunming mice were divided into four groups, namely contral group, oxidative injury model group, low or high dosage of peanut polypeptide treatment group. Except the control group, all other groups were subcutaneously injected with D-galactose solution (40mg/ml, 0.1ml/10g bw) daily for successive 32 days. At the same time, mice in the peanut polypeptide treatment groups were orally given peanut polypeptide in the dosage of 400mg/kg bw and 800mg/kg bw, respectively. Then the malondialdehyde (MDA) contents, superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities in serum and in liver were assayed respectively. In addition, the spleen and thymus gland were also separated to dtermine their indices. The results showed that thymus index and spleen index significantly decreases. While MDA content significantly increases and the activity of GSH-Px significantly decreases both in serum and in liver of oxidative injury mouse model. Both 400mg/kg and 800mg/kg peanut polypeptide administrations have made thymus index and spleen index significantly increase, MDA content significantly decreased and GSH-Px activity significantly increase in serum and in liver. The dosage of 800mg/kg also significantly increased the liver SOD activity. It showed that polypeptide has significantly antioxidative activity with the mechanism probably connected with rising immunity, oxygen free radicals elimination and antilipoperoxidation.

Key words: peanut polypeptide, D-galactose, mice, antioxidative effect