Interaction studies of cholinium-based ionic liquids with calf thymus DNA: Spectrophotometric and computational methods

Ionic liquids (ILs) are emerging class of low-melting solid which have potential to replace conventional solvents. DNA is one of the primary targets of many synthetic agents which are classified as carcinogens; most of them bind to the DNA irreversibly causing mutation of the genome. Thus, it is essential to study the nature and mode of binding of new molecules to predict its toxicity. In the present study, we carried out photo-physical and computational studies on interaction of aqueous cholinium-based ILs (cholinium chloride, cholinium dihydrogen citrate, cholinium bicarbonate, cholinium bromide) with calf thymus DNA (ct-DNA). The experimental (absorption and fluorescence) and docking studies indicated weak interaction between the cholinium-based ILs and double stranded ct-DNA, mainly through minor grooves. Since the strength of binding was quite weak, a safe nature of cholinium-based ILs could be expected. However, COSMO-RS studied carried out using individual DNA bases (A, T, G & C) and cholinium-based ILs showed propensity of the latter class of chemicals with the biomolecules.