Gold coordination complexes as anticancer agents

Metal ions are known to bind with nucleic acids and thereby alter their conformation and biological function. The metal ion-base interaction depends on the nature of both metal and bases; a certain site of coordination is preferred. One of the most notable successes for inorganic drugs has been the effectiveness of platinum complexes against cancer. These advances have spurred a surge of investigations to identify new inorganic agents for use in chemotherapy with improved specificity and decreased toxic side effects. Gold(I) and gold(III) complexes, the last isostructural and isoelectronic with platinum(II) complexes, are potentially attractive as anticancer agents. The design of an effective anticancer agent is a complicated game that must encompass not only the drug's inherent inhibitory properties but also its delivery, dosage, and residence time in vivo. Gold(I) and gold(III) complexes overcome some of these challenges by forming strong covalent attachments to targets. Au(III) isoelectronic with Pt(I1)-d8 system usually forms square planar complexes in solution. Since the square planar geometry of Pt(II) is important for its action as an anticancer drug, Au(III) compounds also can be used for the same purpose with the added advantage of decreased toxicity. This, together with the recent finding that certain transitional metal complexes like Au and Pt complexes have been found to be potentially useful in cancer chemotherapy, created a renewed interest in the study of the interactions of metal ions with respect to the site of binding and the structure and stability of the complexes. This work was motivated by the thought that information on the variety of Au(III) complexes and their effects can be obtained by studying the properties of Au complexes with various ligands. Various studies in the past have shown that Au complexes are very attractive in view of their application as anticancer agents.