Synthesis, DNA binding and antitumor activities of some novel polymer–cobalt(III) complexes containing 1,10-phenanthroline ligand

The novel water-soluble polymer–cobalt(III) complex samples, cis-[Co(phen)2(BPEI)Cl]Cl2 · 4H2O (phen = 1,10-phenanthroline, BPEI = branched polyethyleneimine), with different amounts of cobalt complex content in the polymer chain, were prepared by ligand substitution method in water–ethanol medium and characterized by Infra-red, UV–Vis, 1H NMR spectral and elemental analysis methods. The interaction of these polymer–cobalt(III)-phenanthroline complex samples with calf thymus DNA has been explored using electronic absorption spectroscopy, emission spectroscopy and gel electrophoresis techniques. The presence of multiple small size molecular binding sites, namely, the cobalt(III)–phenanthroline complex moieties, and free amino groups in a single big sized polymer molecule enhanced both the electrostatic and/or van der Waals interaction and partial intercalative bindings with calf thymus DNA. The antitumor activity of a sample of polymer–cobalt(III) complex was determined using HEp-2 cell line and different cell death indicator stains and MTT assay. Many of the cultured HEp-2 cells treated with this complex suffered loss of viability and death mostly through apoptosis as evidenced by the nuclear and cytoplasmic morphology.

Some polymer–cobalt(III) complex samples (containing 1,10-phenanthroline ligand) with varying degree of cobalt(III) complex content in the polymer chain were prepared and characterized. DNA binding properties of these complex samples have been carried out using different physico-chemical methods. A sample of this polymer–cobalt(III) complex was tested for its antitumor activity. The antiproliferative and morphological effects of polymer–cobalt(III) complex sample with high degree of coordination appear to be target-specific killing of cells.Figure optionsDownload as PowerPoint slide