Topo I inhibition, DNA photocleavage, Molecular docking and cytotoxicities of two new phenanthroline-based ruthenium complexes

Two ruthenium complexes containing a new phenanthroline-based ligand pai (pai = 2-(5-(1, 10- phenanthroline))-1H-acenaphtho[1′,2′:4,5]imidazole) were synthesized and characterized. Two ruthenium complexes were found to cleave DNA under irradiation, interact with CT-DNA by intercalation. Furthermore, DNA topoisomerase inhibition experiments indicated that complex 2 exhibited higher topoisomerase I inhibition activity (IC 50 = 10 μM) than complex 1 (IC 50 = 40 μM). Molecular modeling studies revealed that complex 2 stabilized Top1cc complex via π-π interaction and the formation of hydrogen bond. The cytotoxicity of complexes 1 and 2 against Eca-109 and A549 cells was also evaluate by MTT method, indicating that complex 2 exhibited good anticancer activity against Eca-109 cells (IC 50 = 17.23 ± 0.22 μM), but two ruthenium complexes displayed weak anticancer activity against A549 cells.