Novel vanadyl complexes of acetoacetanilide: Synthesis, characterization and inhibition of proteintyrosine phosphatase

Three novel vanadyl complexes, [VO(OH)(aa)(Haa)]·Haa (1), [VO(aa)2(H2O)] (2) and [VO(OH)(aa)(Haa)] (3), were synthesized in the reaction between vanadyl sulfate and acetoacetanilide (Haa), with a stoichiometry of 1:2, in water/ethanol solution. These complexes have been characterized by elemental analysis, ESR, IR, UV–Vis spectroscopy and cyclic voltammetry. Their composition depends on pH and on the ethanol to water ratio. All the complexes contain two acetoacetanilide ligands in the coordination sphere, in the anionic form (2) or anionic and neutral form (1 and 3), and have a distorted tetragonal bipyramidal geometry. The ligand alone does not cause PTP1B inhibition, while the activity of the synthesized complexes is comparable or higher than that of [VO(mal)2], which is known as a strong inhibitor.

Graphical abstractThe reaction between vanadyl sulfate and acetoacetanilide gives three complexes. Their composition depends on the synthesis conditions (pH and ethanol to water ratio). Equal amounts of ethanol and water give [VO(OH)(aa)(Haa)]⋅Haa (1) at pH 4 and [VO(OH)(aa)(Haa)] (3) at pH 9.4. In solution with an excess of ethanol (H2O: EtOH of 1: 8, v/v) [VO(aa)2(H2O)] (2) is formed at pH 4.Figure optionsDownload full-size imageDownload as PowerPoint slide