Novel phosphine sulphide gold(i) complexes: topoisomerase I inhibitors and antiproliferative agents

Abstract

This work describes the synthesis of the gold(I) complexes of phosphine sulphides. The formation of these new derivatives has been confirmed by X-ray crystallography. The coordination of gold(I) with the sulphur atom of the phosphine sulphides favors the inhibition of topoisomerase I as well as a high cytotoxicity of the gold(I)-complexed compounds against the cancer line A549 with IC₅₀ values in the nanomolar range and IC₅₀ values below 5 μM against the SKOV3 cell line. It should be noted that the cytotoxicities observed for the new gold(I) complexes are higher than those observed for phosphine sulphide ligands before binding to gold. Furthermore, the results also indicate that the presence of a nitrogenated heterocycle, such as tetrahydroquinoline or quinoline, is also necessary for the TopI inhibition to be maintained. In addition, no toxicity was observed when the non-cancerous lung fibroblast cell line (MRC5) was treated with the new phosphine sulphide gold(I) complexes prepared.