Hermes-Lima M, Nagy E, Ponka P, Schulman H M
Departamento de Biologia Celular, Universidade de Brasilia, DF, Brazil.
Free Radic Biol Med. 1998 Nov 15;25(8):875-80. doi: 10.1016/s0891-5849(98)00117-8.
Pyridoxal isonicotinoyl hydrazone (PIH) has previously been studied for use in iron chelation therapy in iron-overload diseases. It is an efficient in vitro antioxidant due to its Fe(III) complexing activity (Schulman, H. M., et al. Redox Report 1:373-378; 1995). Pathologies associated with iron-overload include hepatic and other cancers. Since oxidative alterations of DNA can be linked to the development of cancer, we decided to study whether PIH protects DNA against in vitro oxidative stress. We report here that pUC-18 plasmid DNA is damaged by *OH radicals generated from Fe(II) plus H2O2 or from Fe(II) plus hypoxanthine/xanthine oxidase. The DNA damage was quantified by determining the diminution of supercoiled DNA forms after oxidative attack using agar gel electrophoresis. Micromolar amounts of PIH (20-30 microM) were able to half-protect DNA from iron (1-7.5 microM)-mediated *OH formation. The antioxidant capacity of PIH was significantly higher than that of some of its analogs and desferrioxamine. PIH and some of its analogues could also inhibit the oxidative degradation of 2-deoxyribose caused by Fenton reagents. Since we observed that PIH enhances the Fe(II) autoxidation rate, measured by the ferrozine technique, PIH may limit *OH formation and consequently DNA damage by decreasing the amount of Fe(II) available to catalyze Fenton reactions.
吡啶醛异烟酰腙（PIH）此前已被研究用于铁过载疾病的铁螯合治疗。由于其铁（III）络合活性，它是一种有效的体外抗氧化剂（舒尔曼，H.M.等人，《氧化还原报告》1:373 - 378；1995年）。与铁过载相关的病理状况包括肝癌和其他癌症。由于DNA的氧化改变可能与癌症的发生有关，我们决定研究PIH是否能保护DNA免受体外氧化应激的影响。我们在此报告，pUC - 18质粒DNA会被由亚铁离子加过氧化氢或亚铁离子加次黄嘌呤/黄嘌呤氧化酶产生的羟基自由基所损伤。通过使用琼脂凝胶电泳测定氧化攻击后超螺旋DNA形式的减少来量化DNA损伤。微摩尔量的PIH（20 - 30微摩尔）能够使DNA免受铁（1 - 7.5微摩尔）介导的羟基自由基形成的一半损伤。PIH的抗氧化能力明显高于其一些类似物和去铁胺。PIH及其一些类似物也能抑制芬顿试剂引起的2 - 脱氧核糖的氧化降解。由于我们观察到PIH通过亚铁嗪技术测量会提高亚铁离子的自氧化速率，PIH可能通过减少可用于催化芬顿反应的亚铁离子量来限制羟基自由基的形成，从而减少DNA损伤。
