Reactions of copper complexes with oxygen radicals generated by human neutrophils

Abstract

The intensity of the chemiluminescence of unstimulated human neutrophils in the presence of luminol was used to investigate the effects of low-molecular-weight copper complexes at the cellular level. In different models (superoxide dismutase mimetic activity, inhibition of haematoporphyrin derivative/light-induced lysis of cells), the biological activity of the complexes exceeded the activity of the ligands alone.

Modulation of polymorphonuclear leukocyte responsiveness by copper (II)2 (niflumate)4

“…These observations have been confirmed and extended by others using electron spin resonance and NBT reduction in hydroxyl radical generating systems [35], CL of either non-stimulated [26] or phorbol diester stimulated [37] human PMNLs, as well as hematoporphorin and light stimulated systems [36]. Stimulation of CL with still higher concentrations of tetrakis-g-salicylatodicopper(II) [Cu(II)2(salicylate)2 ] [26] can be attributed to the myeloperoxidase-mimetic activity of this complex and not an assumed deleterious effect [26] of this complex. The modulation of protein kinase C activity by copper complexes is also consistent with the possibility that Cu(II)z(salicylate)4 prevents the reduction of spin-labeled cell membranes by 02-following phorbol diester activation of PMNLs [37].…”

“…This myeloperoxidase-mimetic activity of copper complexes may account for the increase in CL observed for increasing concentrations of Cu(II)2(salicylate)4 following inhibition of CL due to 02 disproportionation with lower concentrations of this complex [26]. An increase in myeloperoxidase-mimetic activity would also facilitate PMNL function and would not represent a deleterious action due to the presence of copper as assumed by Haseloff et al [26] whereas PMNL respiratory burst and candidacidal activity are reversibly depressed by the lack of copper [27,28].…”

Nitroxides Increase the Detectable Amount of Nitric Oxide Released from Endothelial Cells

“…(15), provides a model system for evaluation of the interaction of both species and the influence of SOD-mimetic compounds. Among SOD-mimetic compounds, low molecular weight copper or iron complexes were found to be very effective (16,17). Cytoprotection, at least partly due to SOD-like activity, was also reported for nitroxides, a class of free radicals widely applied as tools in electron paramagnetic resonance (EPR) spectroscopy (18).…”