Novel ruthenium(II) complexes with cimetidine: DFT calculations and in vitro cytotoxic activities against glioblastoma cell lines

Herein, four novel ruthenium(II) complexes containing cimetidine as a ligand were obtained, [RuCl(CIM)(dppb) (bipy)]Cl (1), [RuCl(CIM)(dppb)(4,4'-Me-bipy)]Cl (2), [RuCl(CIM)(dppb)(5,5'-Me-bipy)]C1 (3), [RuCl(CIM) (dppb)(phen)]Cl (4), where CIM (cimetidine) = cyano-2-methyl-3-[2-[(5 methyl-1H-imidazol-4-y1) methylsulfanyl] ethyl] guanidine], dppb = 1,4-bis(diphenylphosphine)butane, bipy = 2,2'-bipyridine, 4,4'-Mebipy = 4,4'-dimethyl-2,2'-bipyridine, 5,5'-Me-bipy = 5,5'-dimethyl-2,2'-bipyridine and phen = 1,10-phenanthroline. The complexes were characterized by elemental analysis; molar conductivity measurements; infrared and UV-Vis spectroscopy; P-31{H-1}, C-13 and H-1 NMR; mass spectrometry and cyclic voltammetry. Density functional theory (DFT) calculations were performed and compared with experimental data. Coordinated cimetidine cleavage was also observed. The cytotoxicity profiles of compounds (1-4) were determined in a glioblastoma cell line (U251-MG), and compared to the free ligand cimetidine, these compounds were able to reduce the viability of U251-MG cells.