Cis- and trans-platinum and palladium complexes: a comparative study review as antitumour agents

A large body of novel platinum and palladium complexes, in both the cis- and trans-forms, with various donor ligands, e.g. beta-carboline alkaloids, pyrazoles, DMSO, ferrocenylphosphines,...... have been tested for their antitumour activity against number of fluid suspension (P388, L1210, K562, and Raji) and solid tumour (KB, T47D, SW948, HeLa, A549, L929, Hep-2, RD,...) cell lines. Remarkable cytotoxic effects against these cell lines were observed by some of these complexes. The preliminary results indicated that most of the trans-palladium complexes showed a better activity than the cis-platinum isomers and superior activity than that of the cis-palladium isomers. More importantly they showed activities equal to (or superior than) those of cisplatin, carboplatin and oxaliplatin (the anti-cancer drugs) in vitro. Although these results are preliminary, however, encouraging since they are in a disagreement with the previous studies that cis-isomers are more active than trans-ones; the complexes which have not received the required attention from the vast number of researchers in this field.