A ruthenium(II) complex containing a p-cresol group induces apoptosis in human cervical carcinoma cells through endoplasmic reticulum stress and reactive oxygen species production.

The chemical structures of Ru (II) complexes are known to affect their cellular behavior and toxicity. In this study, three new luminescent Ru (II) complexes, [Ru(bpy)₂(HIPMP)](ClO₄)₂ (Ru1, bpy = 2,2'-bipyridine, HIPMP = 2-(1H-imidazo-[4,5-f] [1,10] phenanthrolin-2-yl)-4-methylphenol), [Ru(phen)₂(HIPMP)](ClO₄)₂ (Ru2, phen = 1,10-phenanthroline), [Ru(dmb)₂(HIPMP)](ClO₄)₂ (Ru3, dmb = 4,4'-dimethyl-2,2'-bipyridine), were synthesized, and their anticancer activities were examined. All three complexes displayed anticancer activities against various cancer cells, with Ru2 exhibiting the highest cytotoxic activities. Ru2 was shown to accumulate specifically in the endoplasmic reticulum (ER) and induce ER stress-mediated apoptosis. In addition, Ru2 could generate reactive oxygen species (ROS) and trigger mitochondrial membrane potential depolarization. These results demonstrated that Ru2 induced apoptosis in HeLa cells through ER stress and ROS production.