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Redox Properties of the Iron Complexes of Orally Active Iron Chelators CP20, CP502, CP509 , and ICL670
Author(s) -
Merkofer Martin,
Kissner Reinhard,
Hider Robert C.,
Koppenol Willem H.
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490272
Subject(s) - chemistry , redox , cyclic voltammetry , hydrogen peroxide , stoichiometry , inorganic chemistry , chelation , superoxide , voltammetry , electrode , nuclear chemistry , electrochemistry , organic chemistry , enzyme
Redox cycling of iron is a critical aspect of iron toxicity. Reduction of a low‐molecular‐weight iron(III)‐complex followed by oxidation of the iron(II)‐complex by hydrogen peroxide may yield the reactive hydroxyl radical (OH . ) or an oxoiron(IV) species (the Fenton reaction). Complexation of iron by a ligand that shifts the electrode potential of the complex to either to far below −350 mV (dioxygen/superoxide, pH=7) or to far above +320 mV (H 2 O 2 /HO . , H 2 O pH=7) is essential for limitting Fenton reactivity. The oral chelating agents CP20, CP502, CP509 , and ICL670 effectively remove iron from patients suffering from iron overload. We measured the electrode potentials of the iron(III) complexes of these drugs by cyclic voltammetry with a mercury electrode and determined the dependence on concentration, pH, and stoichiometry. The standard electrode potentials measured are −620 mV, −600 mV, −535 mV, and −535 mV with iron bound to CP20, ICL670, CP502 , and CP509 , respectively, but, at lower chelator concentrations, electrode potentials are significantly higher.