Self-association of Coralyne: An ordered thermal destacking

Understanding DNA-ligand interactions is a prerequisite, for designing sequence/structure specific ligands. Generally, stabilization/destabilization of DNA structures as a function of ligand is studied using UV-thermal melting, and the data is usually interpreted by observing the hyperchromicity of DNA alone, without considering any contribution from free ligand. Herein, a temperature dependent hyperchromicity is reported for an antitumor drug Coralyne, in unbound state. The self-association has been investigated by UV-Visible absorption spectroscopy, UV- thermal melting and high resolution H-1 NMR. NMR spectra depict temperature dependent down field shifts of aromatic ring protons indicating self-association of Coralyne at 277 K, possibly stabilized by stacking of four aromatic rings. Following this data, it is suggested to have a detailed information on the solution state of the free ligand, before performing DNA interaction studies. To the best of our knowledge, temperature dependent hyperchromism of Coralyne has not been reported till date. Kindly incorporate Graphical Abstract (C) 2020 The Authors. Published by Elsevier B.V.