Synthesis, mitochondrial localization of fluorescent derivatives of cinnamamide as anticancer agents

Mitochondria are considered as a therapeutic target for new drug design toward all kinds of cancer. Hence in order to enhance the dosage in mitochondrial fraction of cinnamamides, the mitochondria-targeted derivatives were designed by the incorporation of cinnamamides into a fluorophore carrier of coumarin-3-carboxamide with a 1:1 stoichiometry. Using the amide linkers, twenty-one compounds were synthesized and the cytotoxicity against a panel of cancer cells (MCF-7, Hela, HepG2, HL-60) was tested. In particular, compound 18c displayed the potent cytotoxicity toward HL-60 leukaemia cells, which could quickly and efficiently entry into HL-60 cells and specifically localize within mitochondria. And 18c preferred enrichment in HL-60 cells than in PBMC normal cells, accounting for the higher toxicity to cancer cells than to normal cells. Moreover, the dissipations of mitochondrial membrane potential and enhancement of cellular ROS level were also preceded upon 18c treatment, leading to cell cycle arrest and apoptosis/necrosis in HL-60 cells. Besides, acted as a Michael acceptor, 18c initiated a thia-Michael addition reaction toward cysteamine (1:2 stoichiometry), detecting by the UV-Vis spectrum and HRMS analysis. This could result in the blue emission of 18c in mitochondria after the procedure of cell fixation, owing to the formation of covalent bond with mitochondrial thiols. Our study reported 18c might be useful for the further development into a mitochondria-targeted anti-leukemia agent and the Michael acceptor might be a versatile functional group.