Synthesis, characterization; DNA binding and antitumor activity of ruthenium(II) polypyridyl complexes

•Ru(II) polypyridyl complexes shown an excellent DNA binding results.•These complexes bind to DNA through intercalative mode.•Complexes were shown good photocleavage results against plasmid DNA.•Three complexes shown different cytotoxic activity toward the HeLa cell line.•From uptake studies, complexes entered into the cell and accumulate in the nuclei.

Three new ruthenium(II) polypyridyl complexes [Ru(phen)2BrIPC]2+ (1), [Ru(bpy)2 BrIPC]2+ (2) and [Ru(dmb)2BrIPC]2+ (3) where, BrIPC = (6-bromo-3-(1H-imidazo[4,5-f] [1,10]-phenanthroline, phen = 1,10-phenanthroline, bpy = 2,2′ bipyridine, dmb = 4,4′-dimethyl 2,2′ bipyridine, were synthesised and characterised. DNA-binding nature was investigated by spectroscopic titrations and mode of binding was assessed by viscosity measurements. The DNA-binding constants Kb of complexes 1, 2 and 3 were determined to be in the order of 105. Experimental results showed that these complexes interact with CT-DNA by intercalative mode. Photocleavage and antimicrobial activities were complex concentration dependent, at high concentration, high activity and vice versa. MTT assay was performed on HeLa cell lines, IC50 values of complexes in the order of 3 > 2 > 1 > cisplatin. From comet assay, cellular uptake studies, we observed that complexes could enter into the cell membrane and accumulate inside the nucleus. Molecular docking studies support the DNA binding affinity with hydrogen bonding and van der Waals attractions between base pairs and phosphate backbone of DNA with metal complexes.

Graphical abstractDNA binding and anti tumor activity of Ru(II) polypyridyl complexes.Figure optionsDownload full-size imageDownload as PowerPoint slide