Pulse radiolytically determined superoxide dismutase mimicking activity of copper-putrescine-pyridine, a diSchiff base coordinated copper complex

Abstract

In order to exclude possible interferences in the many indirect superoxide dismutase (SOD) activity measurements using the copper-putrescine-pyridine complex (Cu-PuPy) a pulse radiolytic study on this diSchiff base copper complex has been devised and sucessfully performed. The reaction kinetics and rate constants of pulse radiolytically generated superoxide in the presence of Cu-PuPy reveal pseudo first-order characteristics. The rate constant (k 2 = 6 + 1 • l0 s ~1 -! s -t) is comparable to that of an Fe-SOD and is approximately a factor of 3 lower than that of bovine Cu2Zn2-SOD. The superoxide dismutating activity of Cu-PuPy shows a more pronounced temperature dependence compared with that of Cu2Zn2-SOD. Arrhenius analyses yielded activation energies of 7.8 +_0.3 and 4.6 +_ 0.2 kcalmo1-1 for Cu-PuPy and Cu2Zn2-SOD, respectively. The rate constant of the reaction of superoxide and Cu-PuPy is highest at pH 5.0. The possible application of Cu-PuPy for new therapeutic strategies on all types of inflammatory diseases appears to be promising.

Superoxide dismutase mimetic activity of a cyclic tetrameric Schiff base N-coordinated Cu(II) complex

“…This rate constant is very similar to those observed for other Cu(ll) chelates (Younes et al 1978, Lengfelder et al 1979, Felix et al 1993. The second-order rate constant was obtained by dividing the pseudo first-order rate constants over the respective Cu(TAAB) 2+ concentrations and has been calculated to be (2.9 + 0.5) x 10 s mol 1 s ~ dm 3.…”

The analogous reaction of diSchiff base coordinated copper and Cu2Zn2 superoxide dismutase with nitric oxide

“…The produced superoxide is efficiently eliminated by Cu-PuPy (Felix et al 1993). The possible interferences of hydrogen peroxide during the dismutation of superoxide anions are excluded in the presence of catalase (10/,gml-1).…”

“…It is formed upon neutralization from NO and it delivers NO when acidified. In addition to its well known superoxide dismutase (Felix et al 1993) and Fenton reactivity (Miesel et al 1990, Steinkiihler et al 1990, 1991, Cu-PuPy appears to be a remarkably efficient moderator of the biochemical reactivity of nitrogen monoxides.…”

“…4-butanediamine (N,N',N",N'")-Cu(II)-di-perchlorate] was prepared according to the method of Felix et al (1993). The diSchiff base ligand PuPy was prepared by the addition of 2 ml pyridine-2-aldehyde (21 mmol) to 1.05 ml putrescine (1,4-diaminobutane, 10.5 mmol) in 30 ml ethanol under constant stirring.…”

“…Cu(I)-PuPy was formed by the addition of CuC1 to the ligand under anaerobic conditions. Oxidation of this complex yielded a Cu(II) compound with the same EPR spectrum obtained from Cu(II)-PuPy which was prepared according to the method of Felix et al (1993). Sodium cr-oxyhyponitrite (Angeli's salt, Na2N203), which served as a source for NO , was prepared by a modified method of Angeli (Hunt et al 1962).…”