Copper-Ligand Interactions and Physiological Free Radical Processes. pH-Dependent Influence of Cu2+ Ions on Fe2+-Driven OH- Generation

Prior to comparative studies on the reactivity of various copper complexes with respect to OH radicals, the influence of free Cu2+ ions on the superoxide-independent generation of OH radicals through Fenton assays and water gamma radiolysis has been tested in the present work.Cu2+ ions have been shown to behave in a distinct manner towards each of these two production systems. As was logically expected from the noninvolvement of copper in OH- radical production through gamma radioiysis, no influence of Cu2+ ions has been observed on the amount of radicals detected in that case. In contrast, Cu2+ ions do influence OH- radical generation through iron-driven Fenton reactions, but differently depending on copper concentration.When present in high concentrations, Cu2+ ions significantly contribute to OH- radical production, which confirms previous observations on the reactivity of these in the presence of hydrogen peroxide. At lower levels corresponding to copper/iron ratios below unity on the contrary, Cu2+ i...