DNA binding and cytotoxicity of two Cu(II) complexes containing a Schiff base ligand along with 1,10-phenanthroline or imidazole as a coligand

We report the synthesis, characterization and biological activities of the compounds [CuL(o-phen)] (1) and [CuL(Imz)] (2), (H2L = o-HOC6H4C(H)= NC6H4OH-o, o-phen = 1,10-phenanthroline, and Imz = imidazole). Both the compounds 1 and 2 have been characterized by X-ray crystallography. A four-line EPR pattern originating from the interaction of the unpaired electron with the central Cu-63/65 nucleus (I = 3/2) with A(iso) values of 7.3 and 8.5 mT, respectively for 1 and 2 in DMF at RT suggests their monomeric nature in solution. These compounds undergo irreversible oxidation-reduction. Biological studies show inter-calative DNA binding and remarkable cell cytotoxicity as well as anticancer activity. IC50 values of 1 and 2 for the human lung cancer A549 cell line (0.67 and 0.59 mu M, respectively) and for the breast cancer MCF7 cell line (6.30 and 8.88 mu M, respectively) are found to be very promising. Compounds 1 and 2 appear to be more potent for the human lung cancer A549 cell line than some anticancer drugs tested for this cell line. Most importantly, 1 and 2 are found to be remarkably less toxic for the human lung embryonic normal cell line L132 as evident from the cell viabilities in presence of these two compounds. (C) 2018 Elsevier B.V. All rights reserved.