Synthesis, structure and in vitro cytotoxic studies of novel paramagnetic palladium(III) complexes with hematoporphyrin IX

Two coordination compounds of PdIII with hematoporphyrin IX ((7,12-bis(1-hydroxyethyl)-3,8,13,17-tetramethyl-21H-23H-porphyn-2, 18-dipropionic acid), Hp), dinuclear [PdIII2(Hp -3H)Cl3(H2O)5]·2PdCl 2, 1 and mononuclear [PdIII(Hp-2H)Cl(H 2O)]·H2O, 2 were obtained and structurally characterized in solid state and solution using spectroscopic, thermal and magnetic methods. In the dinuclear complex, 1 one of the PdIII ions is coordinated to the deprotanated COO- groups from the side chains of the porphyrin ligand and the second PdIII ion - to two adjacent pyrrole N-atoms on the top of the porphyrin ring and a PdIII-Hp- PdIII system was formed. The PdIII ion in the mononuclear complex, 2 is incorporated in the porphyrin core. The PdIII centers in both complexes have a distorted octahedral coordination filled with additional donor species such as Cl- and H2O. The studied compounds showed in vitro cell growth inhibitory effects at micromolar concentration against a panel of human tumor cell lines. A DNA fragmentation assay indicated that the growth inhibitory effects are at least partly mediated by induction of apoptosis. © 2013 Elsevier Inc.