Impact of metal on the DNA photo-induced cleavage activity of a family of Phterpy complexes

A family of Phterpy complexes, [Mn(Phterpy)2][N(CN)2]2·0.5H2O (1), [Fe(Phterpy)2](NO3)2 (2), [Ni(Phterpy)2](NO3)2 (3), [Ni(Phterpy)2]Cl2·10H2O (4), [Cd(Phterpy)2](NO3)2·2H2O (5) and [Zn(Phterpy)Cl2] (6) (Phterpy = 4′-phenyl-2,2′:6′,2″-terpyridine), have been synthesized and structurally characterized, and their DNA binding and photo-induced DNA cleavage activities have been investigated. These complexes display binding propensity to the CT-DNA giving a relative order: 1 > 4 > 3, 5, 2, 6. Under dark or ambient lighting conditions, all complexes show no efficient DNA cleavage activity to pBR322 DNA. While on irradiation with UV-A light of 365 nm, complexes of 1, 3 and 4 exhibit significant cleavage activities. In the presence of H2O2 as a revulsant or an activator, the cleavage ability of complex 2 is obviously enhanced. Complexes 5 and 6 do not exhibit any apparent chemical nuclease activities under irradiation conditions or with the addition of H2O2. The DNA photo-induced cleavage activities are consistent with the number of single-electron in the central metal ion of complexes and singlet oxygen and hydroxyl radical are found as the reactive oxygen species.

In attempt to obtain more insight on the selectivity and efficiency of DNA cleavage with different transition metal complexes, herein, we have prepared a series of mononuclear d-metal complexes and investigated their DNA cleavage activities.Figure optionsDownload as PowerPoint slideHighlights
► A family of Phterpy complexes have been synthesized and structurally characterized.
► Their DNA binding and photo-induced DNA cleavage activities have been studied.
► Singlet oxygen and hydroxyl radical are found as the reactive oxygen species.