Reduced amino acid Schiff base containing ruthenium(III) complexes: Synthesis, characterization, DNA interaction, and in vitro cytotoxicity

A number of reduced amino Schiff base ligands and corresponding ruthenium(III) complexes were designed and prepared based on the fact that amino acids not only possess multiple coordinate atoms but also improve the solubility of drugs in the body. The interaction of the complexes with calf thymus DNA was analyzed with spectroscopic methods of ultraviolet-visible absorption spectra, DNA competitive binding with ethidium bromide, circular dichroism spectra, and DNA melting experiments, and DNA viscosity measurements, indicating that the complexes bind to DNA primarily in the grooving mode. With respect to the ligands, the cytotoxicity in vitro of the complexes against Hela, A549, and MCF-7 cells was much enhanced, with most of the IC50 values less than 50 mu M or even comparable with those of cisplatin.