Characterization of the groove binding between di-(2-ethylhexyl) phthalate and calf thymus DNA

In this study, the interaction between di-(2-ethylhexyl) phthalate (DEHP) and calf thymus DNA (ctDNA) was investigated by a combination of multispectroscopic methods, chemometrics algorithm, cyclic voltammetry and molecular simulation. The concentration profiles of the components obtained from resolving the UV-vis absorption data by multivariate curve resolution-alternating least-squares (MCR-ALS) provided a basic evidence for the formation of DEHP-ctDNA complex. Furthermore, the groove binding of DEHP to ctDNA was evidenced by the results from iodide quenching effect, single-stranded DNA quenching effect, melting studies, viscosity measurements and cyclic voltammetry. The binding constant of the complex was in the order of magnitudes of 10⁴Lmol^-1, and hydrophobic forces were inferred to drive the binding process. Analysis of Fourier transform infrared spectra suggested that DEHP preferentially bound to A-T rich region of ctDNA in the minor groove, and these results further confirmed by molecular docking. The circular dichroism spectra indicated that DEHP induced a decrease in base stacking degree and an increase in right-handed helicity of ctDNA, but did not cause a significant damage in DNA. This study may improve the understanding of interaction between DEHP and ctDNA and help evaluate the toxicological effect of DEHP.