Synthesis, characterization and crystal structure of cobalt(III) complexes containing 2-acetylpyridine thiosemicarbazones: DNA/protein interaction, radical scavenging and cytotoxic activities

•Structure of complex has been determined from single crystal XRD studies.•Complexes were proved to have good DNA interaction properties.•Binding ability of complexes with BSA have been evaluated.•Complexes were found to have high antioxidant and cytotoxic activity.

The synthesis, structure and biological studies of cobalt(III) complexes supported by NNS-tridentate ligands are reported. Reactions of 2-acetylpyridine N-substituted thiosemicarbazone (HL1–3) with [CoCl2(PPh3)2] resulted [Co(L1–3)2]Cl (1–3) which were characterized by elemental analysis and various spectral studies. The molecular structure of the complex 1 has been determined by single crystal X-ray diffraction studies. In vitro DNA binding studies of complexes 1–3 carried out by fluorescence studies and the results revealed the binding of complexes to DNA via intercalation. The binding constant (Kb) values of complexes 1–3 from fluorescence experiments showed that the complex 3 has greater binding propensity for DNA. The DNA cleavage activity of the complexes 1 and 3 were ascertained by gel electrophoresis assay which revealed that the complexes are good DNA cleavage agents. Further, the interactions of the complexes with bovine serum albumin (BSA) were also investigated using fluorescence spectroscopic method, which showed that the complexes 1–3 could bind strongly with BSA. The antioxidant property of the complexes was evaluated to test their free-radical scavenging ability. Furthermore, in vitro cytotoxicity of the complexes against MCF-7 and A431 cell lines was assayed which showed higher activity and efficiently vanished the cancer cells even at low concentrations.

Graphical abstractCobalt(III) 2-acetylpyridine thiosemicarbazone complexes were synthesized and characterized. Crystal structure has been determined by X-ray diffraction. The DNA binding, cleavage and BSA binding properties have been studied. The new complexes were found to have good antioxidant and cytotoxic activities.Figure optionsDownload full-size imageDownload as PowerPoint slide