Phenanthroline derivatives with improved selectivity as dna-targeting anticancer or antimicrobial drugs

Phenanthroline derivatives are of interest due to their potential activity against cancer, and viral, bacterial, and fungal infections. In a search for highly specific antitumor and antibacterial compounds, we report the activities of 1,10-phenanthroline-5,6-dione (phendione or L1), dipyrido[3,2-a:2’,3’-c]phenazine (dppz or L2), and their corresponding platinum complexes ([PtL1Cl2] and [PtL2Cl2]), and provide the solid-state 3D structure for [PtL1Cl2]. It is generally known that a toxic metal ion coordinated to an active organic moiety leads to a synergistic effect; however, we report herein that the platinum complexes [PtL1Cl2] and [PtL2Cl2] have weaker activities relative to those of the free ligands, especially against bacteria. Testing these agents against a variety of human cancer cell lines revealed that L1 and [PtL1Cl2] were at least as active as cisplatin against several of the cell lines (including a cisplatin-resistant cell line). The absence of antibacterial activity of [PtL1Cl2] removes the detrimental effect of phenanthrolines toward intestinal flora, suggesting a highly promising new strategy for the development of anticancer drugs with reduced side effects.