DNA binding mode of transition metal complexes, a relationship to tumor cell toxicity

Transition metal-based compounds constitute a distinct class of chemotherapeutics extensively used in the clinic as antitumor and antiviral agents. However, drug resistance and side effects of established antitumor metallodrugs such as cisplatin [cis-diamminedichloroplatinum(II)] and its analogues, carboplatin and oxaliplatin, have limited their clinical utility. These limitations have prompted a search for more effective and less toxic metal-based antitumor agents. The unique properties of metal ions, such as redox transfer/electron shuttling, and versatile coordination geometries arising from various oxidation states, result in metal ions and complexes that have potential medicinal applications that could be complementary to organic compounds and which are widely sought in drug discovery efforts. This review summarizes the results that show that transition metal complexes exhibit antitumor effects that differ from cisplatin or its analogues.