In Vitro and Computational Approaches to Untangle the Binding Mechanism of Galangin with Calf Thymus DNA

Flavonoids have potential applications in the nutraceutical, medicinal, pharmaceutical and cosmetic fields. The binding of flavonoids with DNA could unravel essential information required for the design of novel and effective chemical agents. The present paper describes the interaction of a flavonoid and a potent anticancer drug, galangin (GAL) with calf thymus DNA (ct-DNA) by fluorescence, UV absorption, melting studies, viscosity measurements and molecular docking studies. A hyperchromic effect was noticed in the absorption spectra of ct-DNA in the presence of the GAL system, indicating the presence of a groove mode of binding. Furthermore, GAL persuaded the minor changes in ct-DNA viscosity, indicating a non-intercalative mode of binding. Fluorescence studies revealed that the GAL quenched the fluorescence intensity of ct-DNA-Hoechst, thereby indicating the interaction between GAL and ct-DNA. Fluorescence results obtained at 298, 308 and 318 K revealed that the fluorescence quenching of ct-DNA-Hoechst-GAL occurred through the static quenching mechanism. Thermodynamic parameters for ct-DNA-Hoechst-GAL were computed and suitable conclusions were drawn. The changes noticed in the conformation of ct-DNA upon interaction with GAL were evaluated in terms of molar ellipticity. It indicated a plausible interaction between ct-DNA and GAL. The molecular docking studies also confirmed the groove mode of binding in the ct-DNA-GAL system. Thus, this work helped to unravel the binding mechanism between GAL and ct-DNA.