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

• Stable paramagnetic PdIII hematoporphyrin IX complexes, mononuclear and dinuclear.
• Their structures were characterized by spectroscopic, thermal and magnetic methods.
• The PdIII centers have low-spin distorted octahedral coordination.
• N,O-porphyrin donors and H2O, Cl− ligands fill the inner coordination sphere.
• The complex 1 showed antiproliferative activity and ability to trigger apoptosis.

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]·2PdCl2, 1 and mononuclear [PdIII(Hp-2H)Cl(H2O)]·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.

Stable dinuclear and mononuclear PdIII coordination compounds of hematoporphyrin IX have been synthesized and structurally characterized. The compounds showed significant antiproliferative activity at micromolar concentration against spectrum of human tumor cell lines. A DNA fragmentation assay indicated that the growth inhibitory effects are mediated by induction of apoptosis.Figure optionsDownload as PowerPoint slide