The organic osmolyte betaine effectively counteracts the deleterious effect of diclofenac on protein structure and stability

Understanding the physicochemical properties of pharmacy and the concept of pharmacophore is essential to devise guidelines for the synthesis of target-oriented drugs. In the present study, thermal denaturation, circular dichroism, intrinsic fluorescence, and docking were employed for studying the effects of the non-steroidal anti-inflammatory drug, diclofenac sodium, on the stability and structure of bovine pancreatic ribonuclease (RNase A) taken as a model of an enzyme. Since drug-protein interaction is an important pharmacokinetic parameter of a drug, it was deemed significant to study the effects of diclofenac on protein structure and stability. When the thermodynamic parameters were assessed, it was shown that RNase-A was destabilized in the presence of diclofenac sodium in terms of Tm and ΔGD°, while the addition of osmolytes stabilized the protein. In the presence of diclofenac sodium and osmolyte, there was a change in a tertiary structure of the protein but not in its secondary structure. Spectral results revealed a decrease in fluorescence intensity confirming fluorescence quenching of RNase-A by diclofenac sodium and osmolytes. Molecular docking analysis suggested that hydrogen bonds and Van der Waals are involved in the binding of RNase-A to diclofenac sodium. The RNAse-A activity is decreased in the presence of diclofenac sodium while osmolyte can restore the RNase-A activity and the indices kcat increase and Km values decrease. This study presents new combination of drug therapy comprising diclofenac sodium and osmolytes to reduce the risk of adverse effects of diclofenac sodium.

RNase-A, thermal denaturation, osmolytes, diclofenac