Iron(III) and aluminum(III) complexes with hydroxypyrone ligands aimed to design kojic acid derivatives with new perspectives

With the aim to design new chelators for the clinical treatment of different diseases involving the trivalent metal ions Fe(III) and Al(III), we present the equilibria of kojic acid and its derivative 6-[5-hydroxy-2-hydroxymethyl-pyran-4-one]-5-hydroxy-2-hydroxymethyl-pyran-4-one with these two metal ions. Potentiometric and spectrophotometric techniques for iron, and potentiometry and 1H NMR for aluminum were used, supported by X-ray, electrospray ionization-mass spectrometry (ESI-MS), calorimetry and quantum chemical calculations. In this work, evidence is given on the formation of MeL, MeL2, and MeL3 complexes of both metal ions with kojic acid, confirmed by the X-ray structure of the FeL3 complex, and of variously protonated Me2L2 and MeL2 complexes of 6-[5-hydroxy-2-hydroxymethyl-pyran-4-one]-5-hydroxy-2-hydroxymethyl-pyran-4-one. The extremely good pFe value for this second ligand gives confidence to, and opens perspectives for, the search of new kojic acid derivatives.

Graphical abstractWith the aim to design new chelators for the clinical treatment of diseases involving iron(III) and aluminum(III), the complex formation equilibria of a kojic acid derivative with these two metal ions are here presented. The extremely good pFe value for this ligand opens perspectives for the search of new kojic acid derivatives.Figure optionsDownload full-size imageDownload as PowerPoint slide