Metallo-Drugs in Cancer Therapy: Past, Present and Future

Cancer treatments which include conventional chemotherapy have not proven very successful in curing human malignancies. The failures of these treatment modalities include inherent resistance, systemic toxicity and severe side effects. Out of 50% patients administrated to chemotherapy, only 5% survive. For these reasons, the identification of new drug designs and therapeutic strategies that could target cancer cells while leaving normal cells unaffected still continues to be a challenge. Despite advances that have led to the development of new therapies, treatment options are still limited for many types of cancers. This review provides an overview of platinum, copper and ruthenium metal based anticancer drugs in clinical trials and in vitro/in vivo studies. Presumably, copper and ruthenium complexes have greater potential than Pt(II) complexes, showing reduced toxicity, a new mechanism of action, a different spectrum of activity and the possibility of non-cross-resistance. We focus the discussion towards past, present and future aspects.

New Cu+2 Complexes with N-Sulfonamide Ligands: Potential Antitumor, Antibacterial, and Antioxidant Agents

Nowadays, the discovery of a new non-toxic metal complex with biological activity represents a very active area of research. Two Cu⁺² complexes, [Cu(L1)₂(H₂O)₃] (C1) (HL1= N-(5-(4-methylphenyl)-[1,3,4]–thiadiazole–2-yl)-naphtalenesulfonamide) and [Cu(L2)₂(py)₂(H₂O)] (C2) (HL2= N-(5-ethyl-[1,3,4]–thiadiazole–2-yl)-naphtalenesulfonamide), with two new ligands were synthesized. The X-ray crystal structures of the complexes were determined. In both complexes, Cu⁺² is five-coordinated, forming a CuN₂O₃ and CuN₄O chromophore, respectively. The ligands act as monodentate, coordinating the metal ion through a single N_thiadiazole atom; for the C2 complex, the molecules from the reaction medium (pyridine and water) are also involved in the coordination of Cu⁺². The complexes have a distorted square pyramidal square-planar geometry. The compounds were characterized by FT-IR, electronic EPR spectroscopy, and magnetic methods. The nuclease activity studies confirm the complexes’ capacity to cleave the DNA molecule. Using a xanthine-xanthine oxydase system, the SOD mimetic activity of the complexes was demonstrated. Cytotoxicity studies were carried out on two tumor cell lines (HeLa, WM35) and on a normal cell line (HFL1) using the MTT method, with cisplatin used as a positive control. The antibacterial activity of the complexes was investigated against two Gram-positive and two Gram-negative bacteria, and compared with Amoxicillin and Norfloxacin using the disk diffusion method. Both complexes showed in vitro biological activity but the C2 complex was more active. A lack of in vivo toxicity was demonstrated for the C2 complex by performing hepatic, renal, and hematological studies on Swiss mice.