In vitro and in vivo Anticancer Effects of a Novel 9-Phenyldibenzo[a,c]phenazin-9-ium Cation and Its Ligands

Background: Multidrug resistance (MDR) is a major problem in cancer treatment. Cu complexes possess the ability to overcome MDR in cancer. Therefore, the search for new Cu complexes is of great clinical significance and we address the anticancer effects of a previously synthesized novel 9-phenyldibenzo[a,c]phenazin-9-ium cation [1 + ] as [1] [CuCl 2 ] and as [1] [I]. Methods: The existence of the monovalent Cu(I) in [1] [CuCl 2 ] was proven by electron paramagnetic resonance (EPR) studies and in vivo anticancer effects were studied in animals. Results: The monovalent nature of the Cu ion in [1] [CuCl 2 ] was determined through EPR. The mean survival time of mice bearing doxorubicin-resistant Ehrlich ascites carcinoma cells is longer when [1] [I] is injected intraperitoneally whereas [1] [CuCl 2 ] does not significantly increase the median survival in tumor-bearing mice. Compounds do not follow the immunomodulatory route and only [1] [I] shows cytotoxic activity in both MDR and drug-sensitive leukemia cell lines. Conclusion: An organic iodide complex rather than a cupric complex possesses direct cytotoxic potential.