Evaluation of DNA binding, antioxidant and cytotoxic activity of mononuclear Co(III) complexes of 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde thiosemicarbazones

Four new 2-oxo-1,2-dihydrobenzo[h]quinoline-3-carbaldehyde N-substituted thiosemicarbazone ligands (H2-LR, where R = H, Me, Et or Ph) and their corresponding new cobalt(III) complexes have been synthesized and characterized. The structures of the complexes 2 and 3 were determined by single crystal X-ray diffraction analysis. The interactions of the new complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Antioxidant studies of the new complexes showed that the significant antioxidant activity against DPPH radical. In addition, the in vitro cytotoxicity of complexes 1–4 against A549 cell line was assayed which showed higher cytotoxic activity with lower IC50 values indicating their efficiency in killing the cancer cells even at very low concentrations.

Graphical abstractFour new Co(III) complexes of 2-oxo-1,2-dihydro-benzo[h]quinoline-3-carbaldehyde thiosemicarbazones have been synthesized and characterized. The DNA interaction, antioxidant and cytotoxic properties of the synthesized complexes have been evaluated.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The new Co(III) complexes can interact with CT-DNA via intercalation. ► Co(III) complexes can displace Ethidium Bromide from EB-DNA complex. ► The new complexes show moderate antioxidant activities compared to standards. ► The new complexes showed considerable cytotoxic activity against A549 cell line.