Stereospecific ligands and their complexes. Part VII. Synthesis, characterization and in vitro antitumoral activity of platinum(II) complexes with O,O′-dialkyl esters of ( S,S)-ethylenediamine- N,N′-di-2-(4-methyl)pentanoic acid

Platinum(II) complexes ( 1–4) with bidentate N,N′-ligands, O,O′-dialkyl esters (alkyl = ethyl, n-propyl, n-butyl and n-pentyl), of ( S,S)-ethylenediamine- N,N′-di-2-(4-methyl)pentanoic acid were synthesized and characterized by IR, 1H NMR and 13C NMR spectroscopy and elemental analysis. DFT calculations were performed for the complexes and it was found that only one diastereoisomer could be formed. Cytotoxic activity of complexes 1–4 was determined against chronic lymphocytic leukemia cells (CLL) and compared to the activity of ligand precursors L1·2HCl– L4·2HCl and corresponding palladium(II) complexes, [PdCl 2 L] ( L = L1– L4). The complexes were found to exhibit significantly higher antitumor activities than cisplatin on CLL cells. Cytotoxic effect of platinum(II) complexes on CLL cells was higher compared to corresponding palladium(II) complexes. In addition the mode of cell death induced by platinum(II) complexes was determined. Platinum(II) complexes ( 1– 4) exhibited higher antitumoral activity than ligand precursors, corresponding palladium(II) complexes and cisplatin on chronic lymphocytic leukemia cells (CLL). [Display omitted] ► Platinum(II) complexes from this study are more active than corresponding palladium(II) complexes and ligand precursors. ► Platinum(II) complexes expressed higher activity than cisplatin. ► Investigated complexes induced apoptotic mode of cell death on CLL cells.