Synthesis, DNA-binding, and antitumor activity of polypyridyl-ruthenium(II) complexes [Ru(L)2(DClPIP)] (L = bpy, phen; DClPIP=2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline)

Two new ruthenium(II) complexes, [Ru(bpy)(2)(DClPIP)](ClO4)(2) (1) and [Ru(phen)(2)(DClPIP)](ClO4)(2) (2) (bpy = 2,2 '-bipyridine, phen = 1,10-phenanthroline, and DClPIP = 2-(2,4-dichlorophenyl)-1H-imidazo[4,5-f][1, 10]phenanthroline), have been prepared in high yield by using microwave-assisted synthesis technology. The anticancer activity of the two ruthenium(II) complexes against A549, C6, CNE-1 and MDA-MB-231 cell lines has been evaluated by MTT assay and results showed that 2 exhibited higher antitumor activity than 1 toward all the selected tumor cell lines. Besides, A549 cell line was sensitive to both ruthenium(II) complexes, especially to 2 (IC50 = 8.01 +/- 0.36 mu M). Meanwhile, 2 showed low toxicity against MCF-10A human normal cells. Furthermore, the DNA-binding properties of the two new ruthenium(II) complexes with CT-DNA have been investigated by electronic absorption titration, luminescence spectra, circular dichroism spectra and viscosity measurements. The results suggested that 1 and 2 were able to interact with CT-DNA via intercalative mode with a strong binding affinity in the order 2 > 1. All of these results suggested that anticancer activity of both ruthenium(II) complexes could be closely related to their interaction with DNA.