Synthesis, structures, and antimalarial activities of some silver(I), gold(I) and gold(III) complexes involving N-heterocyclic carbene ligands

A series of mono-and dinuclear silver(I) and mononuclear gold(I) complexes containing bis(N-heterocyclic carbene) (NHC) or N-functionalized NHC ligands were synthesized and fully characterized by spectroscopic methods and, in some cases, by single crystal X-ray diffraction. The in vitro antiplasmodial and antifungal activities of a previously described family of N-functionalized bis(imidazolium) proligands and their corresponding silver(I), gold(I) and gold(III) complexes but also the new here described compounds were investigated in a chloroquine-resistant strain of Plasmodium falciparum, and against two Candida strains, respectively. For the first family, interesting antiplasmodial and antifungal activities were found for the dinuclear silver(I) species but they also showed strong hemolytic properties. Pharmaco-modulations leading to the second series of complexes allowed notably increase in the antiplasmodial activity, in particular of the mononuclear gold(I) complexes with IC50 values up to 330 nM, without any hemolysis.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New silver and gold complexes have been synthesized and characterized. ► Their antiplasmodial and antifungal activities have been tested. ► The antiplasmodial activity of an Au-complex is close to value of control drugs.