Structure Activity Relationship of Antitumor Palladium Complexes

Abstract

The discovery of cisplatin1 as an antineoplastic agent has sparked a tremendous interest in the development of new platinum complexes and complexes of other metals as anticancer drugs. Recently, a number of platinum(II.) complexes have been shown to be highly active as broad-spectrum antitumor agents. However, there are several drawbacks associated with the use of platinum complexes to treat tumors. Generally, the platinum complexes are highly nephrotoxic, sparingly soluble in water and are relatively inactive against gastro-intestinal tumors.2 It was, therefore, of interest to explore the possibility of developing antitumor palladium complexes as the coordination chemistry of palladium(II) and platinum(II) is usually similar. In all instances reported in the literature the palladium complexes tested had either little or marginal antitumor activity. The low activity of the palladium complexes has been attributed to the rapid formation of aquated complexes in. vivo3. By suitable choice of the ligands, a variety of palladium complexes have been synthesized whose antitumor activities are comparable to, and in some instances greater than, the platinum complexes currently in widespread use in cancer chemotherapy.