Advances in Copper Complexes as Anticancer Agents

The research on copper(I,II) coordination compounds as antiproliferative agents has increased as demonstrated by the high number of papers published in this field in the period 2008-2012. The first consideration which stems from the presented data concerns the large variety of ligands used to synthesize potentially active copper drugs. The reported copper complexes (mostly copper(II)) comprised ligands of different hapticity, from monodentate to hexadentate, and characterized by different donor atoms (O, N, S, P, and C) which gave rise to different geometrical arrangements and, in some cases, dimeric and polymeric species. Regarding the copper oxidation state, there is no direct correlation between the antiproliferative activity and reduced or oxidized forms of the metal. However, the few reported copper(I) complexes, featured by phosphine or heterocyclic carbene ligands generally showed a potent cytotoxic activity. Most of the studies with copper complexes continue to consider DNA as the main biological target.