Ruthenium(II) Phosphine/Mercapto Complexes: Their in Vitro Cytotoxicity Evaluation and Actions as Inhibitors of Topoisomerase and Proteasome Acting as Possible Triggers of Cell Death Induction

Inorg Chem. 2020 Oct 19;59(20):15004-15018. doi: 10.1021/acs.inorgchem.0c01835. Epub 2020 Sep 30.

Abstract

In this paper, a series of new ruthenium complexes of the general formula [Ru(NS)(dpphpy)(dppb)]PF6 (Ru1-Ru3), where dpphpy = diphenyl-2-pyridylphosphine, NS ligands = 2-thiazoline-2-thiol (tzdt, Ru1), 2-mercaptopyrimidine (pySm, Ru2), and 4,6-diamino-2-mercaptopyrimidine (damp, Ru3), and dppb = 1,4-bis(diphenylphosphino)butane, were synthesized and characterized by elemental analysis, spectroscopic techniques (IR, UV/visible, and 1D and 2D NMR), and X-ray diffraction. In the characterization, the correlation between the phosphorus atoms and their respective aromatic hydrogen atoms of the compounds in the assignment stands outs, by 1H-31P HMBC experiments. The compounds show anticancer activities against A549 (lung) and MDA-MB-231 (breast) cancer cell lines, higher than the clinical drug cisplatin. All of the complexes are more cytotoxic against the cancer cell lines than against the MRC-5 (lung) and MCF-10A (breast) nontumorigenic human cell lines. For A549 tumor cells, cell cycle analysis upon treatment with Ru2 showed that it inhibits the mitotic phase because arrest was observed in the Sub-G1 phase. Additionally, the compound induces cell death by an apoptotic pathway in a dose-dependent manner, according to annexin V-PE assay. The multitargeted character of the compounds was investigated, and the biomolecules were DNA, topoisomerase IB, and proteasome, as well as the fundamental biomolecule in the pharmacokinetics of drugs, human serum albumin. The experimental results indicate that the complexes do not target DNA in the cells. At low concentrations, the compounds showed the ability to partially inhibit the catalytic activity of topoisomerase IB in the process of relaxation of the DNA plasmid. Among the complexes assayed in cultured cells, complex Ru3 was able to diminish the proteasomal chymotrypsin-like activity to a greater extent.

MeSH terms

  • Antineoplastic Agents / chemical synthesis
  • Antineoplastic Agents / pharmacology*
  • Apoptosis / drug effects
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Coordination Complexes / chemical synthesis
  • Coordination Complexes / pharmacology*
  • DNA Topoisomerases, Type I / metabolism*
  • Drug Screening Assays, Antitumor
  • G1 Phase Cell Cycle Checkpoints / drug effects
  • Humans
  • Phosphines / chemical synthesis
  • Phosphines / pharmacology
  • Proteasome Inhibitors / chemical synthesis
  • Proteasome Inhibitors / pharmacology*
  • Ruthenium / chemistry
  • Sulfhydryl Compounds / chemical synthesis
  • Sulfhydryl Compounds / pharmacology
  • Topoisomerase I Inhibitors / chemical synthesis
  • Topoisomerase I Inhibitors / pharmacology*

Substances

  • Antineoplastic Agents
  • Coordination Complexes
  • Phosphines
  • Proteasome Inhibitors
  • Sulfhydryl Compounds
  • Topoisomerase I Inhibitors
  • Ruthenium
  • DNA Topoisomerases, Type I
  • TOP1 protein, human