In this paper are presented the features of copper (II) and zinc (II) heteronuclear complexes of the cyclic peptide-c(HKHGPG)2. The coordination properties of ligand were studied by potentiometric, UV-Vis and CD spectroscopic methods. These experiments were carried out in aqueous solutions at 298 K depending on pH. It turned out that in a physiological pH dominates Cu(II)/Zn(II) complex ([CuZnL]4+) which could mimic the active center of superoxide dismutase (Cu,ZnSOD). In next step we performed in vitro research on Cu,ZnSOD activity for [CuZnL]4+ complex existing in 7.4 pH by the method of reduction of nitroblue tetrazolium (NBT). Also mono- and di-nuclear copper (II) complexes of this ligand were examined. The ability of inhibition free radical reaction were compared for all complexes. The results of these studies show that Cu(II) mono-, di-nuclear and Cu(II)/Zn(II) complexes becoming to new promising synthetic superoxide dismutase mimetics, and should be considered for further biological assays.
Keywords: Cu ZnSOD mimetics; Heteronuclear copper(II) and zinc(II) complexes; Potentiometry; SOD activity; Stability constants.