ANTIOXIDANT AND PROOXIDANT PROPERTIES OF SOME DI-SCHIFF BASE COPPER(II) COMPLEXES

The di-schiff base complexes, [N,N' -bis(2-pyridyl)methylene-1,2-diami noethane]- (N,N',N'',N''')-copper(II) (1), and ene-1,3-diaminopropane] -(N,N',N'',N''')-copper(II) (2), were prepared in the perchlorate form , and characterized using elemental analysis, UV/Vis, infrared (IR) an d electronic paramagnetic resonance (EPR) spectroscopies. The relative thermodynamic stabilities of these complexes were estimated by circul ar dichroism (CD), using bovine albumin as the competitive ligand. The ir antioxidant properties were verified by their catalytic activities in the dismutation of superoxide radicals (SOD activity), and in the d isproportionation of hydrogen peroxide (catalase activity). The determ ined SOD-activities were comparable to that of known SOD mimics, with IC50 = 0.447 for (1) and 0.0902 mu M for (2), in comparison to 0.0054 mu M for the native Cu2Zn2-SOD. The determined rate constants for the catalase activity were k = 0.098 mol(-1) dm(3) s(-1), and 1.10 mol(-1) dm(3)s(-1) to compounds (1) and (2), respectively. (C) 1998 Elsevier Science Inc. All rights reserved.