Rare-earth complexes with anti-inflammatory drug sulindac: Synthesis, characterization, spectroscopic and in vitro biological studies

Abstract

New rare-earth complexes with the general formula [LnIII(sul)3]∙nH2O, where sul− is the anti-inflammatory drug sulindac and Ln3+ = Ce3+, Pr3+, Gd3+, Tb3+, and Ho3+, were synthesized, characterized, and had their cytotoxic activity and anti-inflammatory profile assessed. Characterization employing elemental analysis, thermogravimetry, complexometric titration using EDTA, and differential scanning calorimetry provided the complexes stoichiometric ratio, whereas FTIR data results suggest that the carboxylate groups of sulindac molecules are coordinated to the lanthanide ions in a bidentate chelate fashion, with no sulfinyl groups (S[dbnd]O) coordinated to the metal centers. Diffuse reflectance spectroscopy was employed in order to study the electronic properties of the synthesized complexes, revealing the presence of a metal-to-ligand charge-transfer on the Ce3+ complex. Additionally, cell viability and anti-inflammatory activities of the [Ln(sul)3]∙nH2O compounds were studied employing human peripheral blood mononuclear cells (PBMC), and the results indicated that the treatment with [Ce(sul)3]∙4H2O significantly increased the PMBC viability at lower concentrations, and [Gd(sul)3]∙3H2O and [Ho(sul)3]∙3H2O displayed a high production of H2O2 was observed without a decrease in cell viability.