Fenton-like 5,7-dibromo-2-methyl-8-hydroxyquinoline Mn2+ complex acting as a probe for mitochondrial imaging and chemodynamic therapy

Complex 1-Mn acting as probe for mitochondrial imaging and chemodynamic therapy. [Display omitted] •New Mn complex (1-Mn) with 5,7-dibromo-2-methyl-8-hydroxyquinoline and dipyridophenazine as the ligands was firstly synthesized and characterized.•1-Mn could be enriched in the mitochondria of HepG-2 cells and show blue fluorescence.•1-Mn is accompanied by a fenton-like reaction that producing ·OH in mitochondria and ultimately leading to cell death. Although the antitumor activities of 8-hydroxyquinoline complexes have been reported, their applications in the mitochondrial imaging and chemodynamic therapy of tumors have been rarely studied. In this work, we received a manganese complex: Mn(L)2(DPPZ) (1-Mn), by using 5,7-dibromo-2-methyl-8-hydroxyquinoline (HL) as the active ligand together with dipyridophenazine (DPPZ) as the auxiliary ligand reacting with manganese chloride. It was found that 1-Mn had well antitumor activity on HepG-2 cells with IC50 value of 7 ± 0.26 µM, which was accompanied by the generation of large amounts of ·OH via 1-Mn-mediated Fenton-like reaction of H2O2, thereby stimulating oxidative stress in the mitochondria and leading to cell death ultimately. In addition, confocal imaging showed that 1-Mn could be enriched in the mitochondria of HepG-2 cells and show blue fluorescence. Studies have shown that 1-Mn can be potentially used in the biomedical imaging and CDT anticancer drug.