Dipyridophenazine Complexes of Cobalt(III): DNA Photocleavage and Photobiology

Abstract

The UV-visible spectroscopy and photochemistry of [Co(en)2(DPPZ)](ClO4)3 (DPPZ = dipyrido[3,2-a:2´,3´-c]-phenazine) in the presence of plasmid DNA and the nucleoside 2´-deoxygaunosine have been investigated. Evidence for the intercalation of the complex with DNA and photoinduced DNA strand breakage is found. The structurally related complexes [Co(en)2(DPPN)]Cl3 and [Co(en)2(DPPA)]Cl2, where DPPN = benzo[i]dipyrido[3,2-a:2´,3´-c]phenazine and DPPA = dipyrido[3,2-a:2´,3´-c] phenazine-11-carboxylic acid, have also been synthesized and characterized. In vitro cytotoxicity studies and photocytotoxicity studies of the complexes using the C6 rat glioma cell line are reported and indicate significant increases in toxicity following irradation.