Electrochemical and spectroscopic investigations of carboxylic acid ligand and its triorganotin complexes for their binding with ds.DNA: In vitro biological studies

A carboxylic acid ligand, (Z)-4-(4-acelylphenylamino)-4-oxobut-2-enoic acid (APA-1), and its triphenyl(APA-2) and tributyl-tin(IV) (APA-3) compounds have been synthesized and investigated for their binding with ds.DNA using UV-visible spectroscopy, fluorescence spectroscopy, cyclic voltammetry, and viscosity measurements under physiological conditions of pH and temperature. The experimental results from all techniques i.e. binding constant (K-b), binding site size (n) and free energy change (Delta G) were in good agreement and inferred spontaneous compound-DNA complexes formation via intercalation. Among all the compounds APA-3 showed comparatively greater binding at pH 4.7 as evident from its greater K-b values {APA-3: K-b: 5.63 x 10(4) M-1 (UV); 7.94 x .10(4) M-1 (fluorescence); 9.91 x 10(4) M-1 (CV)}. Electrochemical processes of compounds before and after the addition of DNA were found diffusion controlled. Among all compounds, APA-3 exhibited best antitumor activity. (C) 2013 Elsevier B.V. All rights reserved.