New Ionic Cu(II) and Co(II) DACH–Flufenamate Conjugate Complexes: Spectroscopic Characterization, Single X–Ray Studies and Cytotoxic Activity on Human Cancer Cell Lines

Abstract

AbstractNew ionic antitumor drug entities [{Cu(DACH)2(H2O)Cl}.(fluf)], 1 and [{Co(DACH)2(H2O)Cl}.(fluf)], 2 where DACH=1,2–diamminocyclohexane and fluf=flufenamate anion were prepared and characterized by spectroscopic studies and single X–ray crystallography. In order to evaluate the potential of these complexes to act as antitumor drug candidates, in vitro binding studies of 1 and 2 with ct–DNA have been carried out by biophysical methods which revealed electrostatic binding mode of these drug entities with ct–DNA preferably by external surface or groove binding mode contrary to other non–steroidal anti–inflammatory (NSAIDs) drugs which show intercalative binding. Comparative electron paramagnetic resonance (EPR) titrations were performed which revealed that there was no significant change in EPR spectra of complexes upon incubation with ct–DNA implicating that coordination geometry of metal ions does not alter. Validation of antitumor potential of 1 and 2 was done by cytotoxicity experiments against human cancer cell lines by Sulforhodamine B (SRB) assay. Complex 1 was active against all tested cell lines with an exceptionally low GI50 value=2.9 μg/ml against MCF–7 (breast cancer) cell line showing its preferential selectivity. On the contrary, complex 2 showed poor activity against all tested cancer cell lines.