Iron(III)-Chelating Properties of the Novel Catechol O-Methyltransferase Inhibitor Entacapone in Aqueous Solution

摘要: The iron(III) complex formation of entacapone, a novel catechol O-methyltransferase (CoMT) inhibitor, has been studied at 25 °C in aqueous 0.1 mol/L NaCl solution by using the electromotive force titration method. Entacapone functions as bidentate ligand chelating through catecholate oxygen atoms and forms stable complexes with constant tris complex: log s-613 ([FeL33־][H]6 +/ [Fe3+][H2L]3) = -6.9 ± 0.1. Distribution curves show that entacapone is highly effective for iron (III) moderately dilute (10—3 mol/L) whereas very (10- 6 hydroxo together FeL33— dominate under physiological pH 7.4. Comparison species distribution competitive two-ligand entacapone- system reveals complexation favored high low dilution.