Investigation of interaction between dexamethasone/pheniramine and trypsin by fluorescence, UV-vis, CD, and molecular docking

Antihistamines and glucocorticoids are commonly used to treat allergy symptoms and the inflammatory conditions. In present study, the in-vitro binding interactions a glucocortikoid, dexamethasone/an antihistamine, pheniramine with TSN (TSN) secreted from pancreas to small intestine for protein digestion were investigated by fluorescence emission spectroscopy (FES), UV-Vis spectroscopy, synchronous fluorescence spectroscopy (SFS), CD spectroscopy, FT-IR and molecular modeling methods. Also, the effect of these drugs on the catalytic activity of trypsin (TSN) was determined. The fluorescence quenching experiments indicated that each drugs quenched the intrinsic fluorescence of TSN with their increased concentrations. The results of SFS and UV-Vis spectra proved the interaction of dexamethasone and pheniramine with TSN. CD spectra showed that the secondary structure of enzyme was altered in the presence of the drugs. All these spectroscopy results were validated and explained by molecular docking and molecular dynamic simulation (MD) studies. The IC50 values were determined as 0.0049 mM and 0.0038 mM for dexamethasone and pheniramine, respectively. So, both drugs have inhibition effect on the catalytic activity of TSN. The results of this study can provide valuable information in the field of pharmacokinetics and pharmacodynamics. Communicated by Ramaswamy H. Sarma