Coordination Chemistry of Palladium(II) Ternary Complexes with Relevant Biomolecules

Cisplatin, cis-Diamminedichloroplatinum (II), is one of the most effective anticancer agents (Rosenberg, 1969). It has demonstrated a remarkable chemotherapeutic potential in a large variety of human solid cancers, such as, testicular, ovarian, bladder, lung and stomach carcinomas (Wong and Giandomenico, 1999; Guo and Sadler, 2000). The successful use of platinum (II) complexes as potent anticancer drugs has attracted the interest of many scientists. It was observed that the nature and arrangement of the ligands can affect the mode of action and metabolism of the drug while crossing the cell membrane and inside the cell. Despite the widespread use of cis-platin as an anticancer drug there is still scope for improvement, with respect to: i) reduced toxicity; ii) increased clinical effectiveness; iii) broader spectrum of action; iv) elimination of side effects (e.g., nausea, hearing loss, vomiting, etc); v) increased solubility and vi) ability to use them in combination with other drugs, limited by severe toxicities so far. Replacement of the chloro ligands by carboxylate groups in carboplatin, cis-diamine(1,1cyclobutanedicarboxylate)platinum(II), is a widely used second-generation platinum anticancer drug showing less side effects than cis-platin. The development of several new anticancer platinum drugs including Carboplatin, Nedaplatin, Lobaplatin and Oxaliplatin (Scheme 1) still have draw-backs and offer no more clinical advantages over the existing cisplatin (Gill, 1984; Galanski et al., 2005; Momekov et al., 2005). Furthermore, the development of acquired resistance to cis-platin is frequently observed during chemotherapy (Heim, 1993).