Investigations on the interactions of diclofenac sodium with HSA and ctDNA using molecular modeling and multispectroscopic methods

A tentative study on interaction of diclofenac sodium (DF-Na) with human serum albumin (HSA) and calf thymus DNA (ctDNA) was conducted by using multi-spectroscopic and molecular modeling techniques under simulative physiological conditions. The results of spectroscopic measurements suggested that the quenching mechanisms were static quenching. Three-dimensional fluorescence spectroscopy clearly demonstrated the occurrence of conformational changes of HSA with addition of DF-Na. In addition, competitive studies with ethidium bromide (EB) have shown that DF-Na can bind to ctDNA relatively strong via groove binding. Based on the values of thermodynamic parameters and the results of molecular modeling, it was confirmed that hydrophobic forces and hydrogen bond were the mainly binding forces in DF-Na–HSA and DF-Na–DNA systems. The binding distance between DF-Na and HSA was also determined using the theory of the Förster energy transference.

Molecular modeling studies of the interactions of diclofenac sodium with HSA/ctDNA were investigated.Figure optionsDownload as PowerPoint slideHighlights
► It is the first time to analyze the influence DF-Na of on ctDNA and HSA.
► Bonding modes are ascertained from spectral techniques and molecular modeling.
► Displaying the conformational change of HSA employing 3D fluorescence spectroscopy.
► Hydrophobic force and hydrogen bond played a very important role in DF-Na bindings.
► Groove mode in the system of DF-Na–ctDNA was investigated using EB as probe.