Effects of three metal ions (Cu 2+ ,Pb 2+ and Cd 2+ ) on antioxidant enzyme activities in buckwheat seed extracts (BSE) were reported. The results showed that the enzyme activities of superoxide dismutase (SOD), catalase (CAT) and glutathion peroxidase (GSH Px) in BSE were inhibited partly in the presence of Cu 2+ ,Pb 2+ and Cd 2+ ions, and the inhibition in common buckwheat extracts (CBE) was greater than that in tartary buckwheat extracts (TBE). Antioxidant enzymes activities were seriously inhibited by Cd 2+ in BSE. When the concentration of Cu 2+ was 50mmol/L in the reaction system, the activities of SOD, CAT and GSH Px in CBE were 60 0%, 24 6% and 11 6% of the initial values respectively, and in TBE,they were 63 0%, 28 2% and 17 1%. While the concentration of Cd 2+ was 20 mmol/L, the remaining activities of three enzymes in CBE were 49 1%, 4 6% and 1 4%, and in TBE the remaining activities of three enzymes were 50 0%,6 2%and 3 9% respectively. SOD in BSE was heat stable remarkably, but the enzyme activity was lost partly in the presence of the three ions. These results suggested that these metal ions mightbe substituted for the zinc in SOD, and effected the enzyme stability.
