The iron chelator pyridoxal isonicotinoyl hydrazone inhibits mitochondrial lipid peroxidation induced by Fe(II)–citrate

Pyridoxal isonicotinoyl hydrazone (PIH) is able to prevent iron-mediated hydroxyl radical formation by means of iron chelation and inhibition of redox cycling of the metal. In this study, we investigated the effect of PIH on Fe(II)–citrate-mediated lipid peroxidation and damage to isolated rat liver mitochondria. Lipid peroxidation was quantified by the production of thiobarbituric acid-reactive substances (TBARS) and by antimycin A-insensitive oxygen consumption. PIH at 300 μM induced full protection against 50 μM Fe(II)–citrate-induced loss of mitochondrial transmembrane potential ( Δψ) and mitochondrial swelling. In addition, PIH prevented the Fe(II)–citrate-dependent formation of TBARS and antimycin A-insensitive oxygen consumption. The antioxidant effectiveness of 100 μM PIH (on TBARS formation and mitochondrial swelling) was greater in the presence of 20 or 50 μM Fe(II)–citrate than in the presence of 100 μM Fe(II)–citrate, suggesting that the mechanism of PIH antioxidant action is linked with its Fe(II) chelating property. Finally, PIH increased the rate of Fe(II) autoxidation by sequestering iron from the Fe(II)–citrate complex, forming a Fe(III)–PIH 2 complex that does not participate in Fenton-type reactions and lipid peroxidation. These results are of pharmacological relevance since PIH is a potential candidate for chelation therapy in diseases related to abnormal intracellular iron distribution and/or iron overload.