Synthesis, characterization and anticancer effect of the ruthenium (II) polypyridyl complexes on HepG2 cells

As one of the major cell regulated center, mitochondria are closely associated with cell proliferation, apoptosis of tumor cell. In this work, four new ruthenium (II) polypyridyl complexes [Ru(bpy)₂(FTTP)](ClO₄)₂ (1) (FTTP=11-(3-fluoro-naphthalen-2-yloxy)-4,5,9,14-tetraaza-benzo[b]triphenylene, bpy=2,2'-bipyridine), [Ru(phen)₂(FTTP)](ClO₄)₂ (2) (phen=1,10-phenanthroline), [Ru(bpy)₂(PTTP)](ClO₄)₂ (3) (PTTP=2-phenoxy-1,4,8,9-tetraazatriphenylene) and [Ru(phen)₂(PTTP)](ClO₄)₂ (4) were synthesized and characterized by elemental analysis, ESI-MS, ¹H NMR and ¹³C NMR. The cytotoxic activity, ability of inhibiting cell invasion, cell cycle arrest and apoptosis-inducing mechanism of these Ru(II) complexes have been investigated in detail by MTT (3-(4,5-dimethylthiazole)-2,5-diphenyltetrazolium bromide) method, invasion assay, comet assay as well as western blotting techniques. Notably, complexes 1-4 displayed high cytotoxic activity against liver carcinoma HepG2 cells and the IC₅₀ values of complexes 1-4 against HepG2 cells are 10.4±1.2, 9.3±0.6, 29.1±1.5 and 5.6±1.2μM, respectively. The comet assay showed that the complexes can induce DNA damage. The acridine orange (AO) and ethidium bromide (EB) staining method indicated that the complexes can cause apoptosis in HepG2 cells. Further studies showed that complexes 1-4 caused cell cycle arrest at G0/G1 phase and induced HepG2 cells apoptosis through a ROS-mediated mitochondrial dysfunction pathway, which involved an increase in the levels of reactive oxygen species (ROS), a decrease in the mitochondrial membrane potential, activation of caspases and Bcl-2 family proteins.