Spectroscopic and molecular modeling methods to investigate the interaction between 5-Hydroxymethy1-2-furfural and calf thymus DNA using ethidium bromide as a probe

In this work, the interaction of 5-Hydroxymethyl-2-furfural (5-HMF) with calf thymus DNA (ctDNA) under simulated physiological conditions (Tris-HCl buffer of pH 7.40), was explored by UV absorption spectroscopy, fluorescence spectroscopy and molecular modeling method, using ethidium bromide (EB) as a fluorescence probe of DNA. The fluorescence quenching mechanism of EB-ctDNA by 5-HMF was confirmed to be a static quenching, which derived from the formation of a new complex. The binding constants of 5-HMF with DNA in the presence of EB were calculated to be 2.17 x 10(3), 4.24 x 10(3) and 6.95 x 10(3) L mol(-1) at 300, 305 and 310 K, respectively. The calculated thermodynamic parameters, enthalpy change Delta H and entropy change Delta S, suggested that both hydrophobic interactions and hydrogen bonds played a predominant role in the binding of 5-HMF to DNA. According to the UV absorption spectroscopy and melting temperature (T-m) curve results, the binding mode of 5-HMF with DNA was indicative of a non-intercalative binding, which was supposed to be a groove binding. The molecular modeling results showed that 5-HMF could bind into the hydrophobic region of ctDNA and supported the conclusions obtained from the above experiments. (C) 2013 Elsevier B.V. All rights reserved.