Anticancer Activity, Attenuation on the Absorption of Calcium in Mitochondria, and Catalase Activity for Manganese Complexes of N-Substituted Di(picolyl)amine

In order to find multifunction anticancer complexes, three Mn(II) complexes of N-substituted di(2-pyridylmethyl)amine were characterized and used as agents to interfere with the functions of mitochondria and the metabolite of O<sub>2</sub> in cancer cells. It was found that carboxylate-bridged dimanganese(II) systems are good models of catalase and exhibit good inhibition of the proliferation of U251 and HeLa cells. The inhibiting activity of these manganese(II) complexes on the tumor cells in vitro was related to their disproportionating H<sub>2</sub>O<sub>2</sub> activity. The reaction of carboxylate-bridged dimanganese Mn(II) complex with H<sub>2</sub>O<sub>2</sub> forms a stable Mn(III)–(μ-O)<sub>2</sub>–Mn(IV) complex. Extensive experimental results show that chloride-bridged dimanganese(II) complexes could inhibit the swelling of calcium(II) overloaded mitochondria, and carboxylate-bridged manganese(II) complexes enhance the swelling of calcium(II) overloaded mitochondria. These results indicate that the interactions between Mn(II) complexes of N-substituted di(picolyl)amine and mitochondria are influenced by the structure and conformation of the complexes. Mn(II) complexes of N-substituted di(picolyl)amine could be developed as multifunctional anticancer complexes to interfere with the absorption of calcium(II) in mitochondria and the metabolite of O<sub>2</sub> through the H<sub>2</sub>O<sub>2</sub> or ROS involved signaling induced apoptosis of cancer cells.