Manini, Paola, Napolitano, Alessandra, Camera, Emanuela, Caserta, Teresa, Picardo, Mauro, Palumbo, Anna, and d'Ischia, Marco
Ni2+, a toxic, carcinogenic and allergenic agent, affected both the kinetic and chemical courses of the Fe2+-induced oxidation of arachidonic acid (AA) in 0.05 M phosphate buffer (pH 7.4) and at 37 °C. At 10 μM concentration, Ni2+ decreased the rate of oxidation of peroxide-free AA (200 μM) promoted by 50 μM Fe2+, as determined by measurement of thiobarbituric acid reactive species (TBARS) and 1H NMR analysis. However, in the presence of low levels of peroxides (e.g. 2%), Ni2+ exerted a significant stimulatory effect on Fe2+-induced AA oxidation and TBARS formation. 1H NMR analysis showed that Ni2+ (10 μM) enhanced formation of genotoxic alkenals including 4-hydroxy-2-nonenal (4-HNE, GC/MS evidence) by Fe2+-promoted degradation of both AA and 15-hydroperoxy-5,8,11,13-eicosatetraenoic acid (15-HPETE) methyl esters. The observed stimulatory effects of Ni2+ on peroxide breakdown and cytotoxic aldehyde formation provide an attractive explanation to the enhanced sensitization capacity of nickel in inflammatory states compared to normal states. [Copyright &y& Elsevier]