Abstract

In recent years, helicates have been studied for different applications, such as potential anticancer agents, due to their ability to bind DNA and cause structural changes in the conformation of the double-stranded helix, thus avoiding its replication. In the present work, two new bimetallic Fe(II) helicates with ligands derived from bis-phenanthroline are presented. In addition, a monometallic complex whose structure is related to the helicates was included, in order to study the role of the nuclearity, charge and size on the interaction with plasmidial DNA. The set of paramagnetic complexes was structurally characterized in solution and solid phase by UV-Vis, mass spectroscopy and X-Ray diffraction. The nature and magnitude of interaction between complexes and DNA was determined by electrophoresis and UV-vis spectroscopy. Results indicate that the bimetallic helicates exhibit high affinity for DNA and produce changes in the conformation of supercoiled plasmid to induce both relaxed and linear forms. The double-nick on the plasmid is responsible of the linear form, whereas higher concentrations of complex cause the degradation of the DNA. These observations are discussed in terms of a possible mechanism of action where the paramagnetic Fe(II) atom is involved.