The interaction of pyridoxal isonicotinoyl hydrazone (PIH) and salicylaldehyde isonicotinoyl hydrazone (SIH), two important biologically active chelators, with iron has been investigated by spectrophotometric methods. High iron(III) affinity constants were determined for PIH, logβ₂ = 37.0 and SIH, logβ₂ = 37.6. The associated redox potentials of the iron complexes were determined using cyclic voltammetry at pH 7.4 as + 130 mV (vs normal hydrogen electrode, NHE) for PIH and + 136 mV(vs NHE) for SIH. These redox potentials are much higher than those corresponding to iron chelators in clinical use, namely deferiprone, − 620 mV; desferasirox, − 600 mV and desferrioxamine, − 468 mV. Although the positive redox potentials of SIH and PIH are similar to that of EDTA, namely + 120 mV, the iron complexes of these two hydrazone chelators, unlike the iron complex of EDTA, do not redox cycle in the presence of vitamin C. These properties render PIH and SIH as excellent scavengers of iron, under biological conditions. Both SIH and PIH scavenge mononuclear iron(II) and iron(III) rapidly. These fast kinetic properties of the hydrazone-based chelators provide a ready explanation for the adoption of SIH in fluorescence-based methods for the quantification of cytosolic iron(II).

通过分光光度法研究了吡two醛异烟酰ino（PIH）和水杨醛异烟酰ino（SIH）这两种重要的生物活性螯合剂与铁的相互作用。高铁（III）的亲和常数测定为PIH，logβ ₂  = 37.0和SIH，logβ ₂  = 37.6。铁络合物的相关氧化还原电势是使用循环伏安法在pH 7.4下测定的，对于PIH为+ 130 mV（相对于正常氢电极，NHE），对于+ 136 mV（相对于正常氢电极，NHE）NHE）。这些氧化还原电位远高于临床上与铁螯合剂相对应的电位，即去铁酮-620 mV；去铁胺-600 mV和去铁胺-468 mV。尽管SIH和PIH的正氧化还原电势与EDTA相似，即+ 120 mV，但这两种螯合剂的铁络合物与EDTA的铁络合物不同，在存在维生素C的情况下不会进行氧化还原循环。这些性质在生物条件下，使PIH和SIH成为铁的优良清除剂。SIH和PIH都能快速清除单核铁（II）和铁（III）。基螯合剂的这些快速动力学性质为在荧光定量胞质铁（II）的方法中采用SIH提供了现成的解释。