Investigation on the interaction of 1-amino-4-hydroxy-9,10-anthraquinone with calf thymus DNA and CTAB micelles

Abstract

The interaction of 1-amino-4-hydroxy-9,10-anthraquinone (AHAQ), a simple analogue of anthracycline anticancer drugs with calf thymus DNA (ct-DNA) and cationic surfactant cetyltrimethylammonium bromide (CTAB) was investigated in aqueous solution at physiological pH (7.4) by cyclic voltammetry and UV–vis absorption spectroscopy. Both aspects of affinity of AHAQ molecule to DNA and cationic surfactant micelle, a model system for a biological membrane, are important in determining its biological action. By using different nonlinear fitting procedures, the intrinsic binding constant and the binding site size were evaluated for AHAQ–ct-DNA interaction and the results indicate a significant affinity of AHAQ towards ct-DNA. Binding constant, partition coefficient and the stoichiometry were determined for AHAQ–CTAB micelles interaction. The results showed that the hydrophobic interaction plays a major role in the binding of AHAQ to CTAB micelles. In addition, the hydrophobic interaction has an important role in the distribution of AHAQ between CTAB micelle — water phases. Gibbs free energy for the binding and distribution of AHAQ between the bulk aqueous medium and surfactant micelles were calculated.