In vitro exploration of interaction behavior between calf thymus DNA and fenhexamid with the help of multi-spectroscopic methods and molecular dynamics simulations

As an amide fungicide, fenhexamid has been extensively used to control botrytis and sclerotinia as well as antagonize the resistant bacteria produced by other pesticides. But because of the accumulation of residues in fruit and vegetable products, it may have an adverse effect on the health of human and animals. In this work, the exploration of the interaction between fenhexamid and calf thymus DNA (ct-DNA) was carried out by fluorescence spectroscopy , UV–vis spectroscopy, circular dichroism, viscosity measurement, melting measurements, molecular docking and molecular dynamics simulation . The results implied that fenhexamid bound onto ct-DNA in terms of groove binding. And the outcomes from circular dichroism measurements demonstrated a slight change in the ct-DNA helical structure during the binding process. In addition, the combination ratio of fenhexamid with ct-DNA was 1:1 and the association constant was 2.52 × 10 3  M −1 at 298 K. The measured thermodynamic parameters indicated that hydrogen bonding interaction and van der Waals forces become more dominant during interacting fenhexamid with ct-DNA, which was further confirmed through computer simulation technique.