Effect of cobalt(II) complexes with dipyridylamine and salicylaldehydes on cultured tumor and non-tumor cells: Synthesis, crystal structure investigations and biological activity

The synthesis of eight mixed-ligand cobalt(II) complexes with 2,2′-dipyridylamine (dpamH) and substituted salicylaldehydes (X-saloH) was undertaken in an effort to discover new compounds with anticancer activity. The complexes with the general formula [Co(dpamH)2(X-salo)]Y, (Y = Br or Cl) were characterized by elemental analyses, FT-IR and UV–visible spectroscopy, magnetic and conductivity measurements. The structures of two of them [Co(dpamH)2(5-CH3-salo)]Br and [Co(dpamH)2(3-OCH3-salo)]Cl, as well as of the precursors [Co(dpamH)3]Br2 and [Co(dpamH)2Cl(H2O)]Cl, were determined by X-ray crystallography revealing octahedral coordination of cobalt(II) and mononuclear complexes. The complexes were thermally stable up to 200 °C in nitrogen atmosphere, studied by simultaneous TG/DTG–DTA technique. The two precursor Co compounds, as well as four of the title compounds, were evaluated for their efficacy as anticancer agents against different cancer and normal human cell lines. The in vitro chemosensitivity of various human cell lines to these Co complexes was evaluated by measuring cell growth inhibition by employing the SRB colorimetric assay. A series of experiments showed a dose-dependent cytotoxic activity of the complexes against all cell lines used. These findings represent a prompting to search for possible interaction of these complexes with other cellular elements of fundamental importance in cell proliferation.

Graphical abstractEight mixed-ligand complexes [Co(X-salo)(dpamH)2]+ and the precursors [Co(dpamH)3]Br2 and [Co(dpamH)2Cl(H2O)]Cl were characterized by spectroscopy and X-ray crystallography. The in vitro evaluation for their efficacy as anticancer agents, against different cancer human cell lines, was undertaken using the SRB method.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of mixed-ligand Co(II) cationic complexes [Co(X-salo)(dpamH)2]+ ► Synthesis of the precursors [Co(dpamH)3]Br2 and [Co(dpamH)2Cl(H2O)]Cl ► Spectroscopic and crystallographic characterization ► Thermal studies (TG/DTG–DTA) ► In vitro evaluation for their efficacy as anticancer agents by the SRB method