Abstract:

The kinetic behavior of two antioxidative peptides, His-Asp-His-Pro-Val-Cys (HDHPVC) and His-Glu-Lys-
Val-Cys (HEKVC), as well as glutathione (GSH) for their DPPH radical scavenging activity was investigated. Three
kinetic parameters of the two antioxidative peptides, including second-order rate constant (k2), antiradical power (ARP)
and stoichiometry were calculated and compared with those of GSH. Results showed that the antioxidative capacity was
sequenced as HEKVC＜HDHPVC＜GSH. All of them were considered to belong to slow kinetics behavior and showed a 3–5
folds higher EC50 than at the steady state. It is concluded that HDHPVC and HEKVC are excellent natural antioxidants.

Key words: His-Glu-Lys-Val-Cys, His-Glu-Lys-Val-Cys, DPPH free radical, antioxidant, kinetics