Spectroscopic, voltammetric and computational approaches shed light on the combination characteristics of an anticancer agent, bexarotene with human serum albumin

Abstract

The combination process of bexarotene (BEX) with the primary transporter protein in blood plasma, human serum albumin (HSA) was explored to comprehend the anticancer agent’s transport in the circulatory system. The HSA fluorescence spectrum was discovered to be successively quenched by BEX. Involvement of static quenching process as well as the BEX–HSA complexation were suggested by the bimolecular quenching rate constant (kq) values. This finding was further corroborated by ultraviolet absorption spectral analysis. The binding affinity of BEX–HSA interaction was found as moderate on the basis of Ka values (Ka = 3.19–8.72 × 104 M−1) for the system. Thermodynamic particulars (ΔS = 175.93 J mol−1 K−1; ΔH = 25.85 kJ mol−1) revealed that the stabilizing intermolecular forces associated in the reaction were hydrophobic interactions and hydrogen bonds. BEX binding altered the microenvironment near Trp and Tyr residues of HSA, but it improved the protein’s resistance to heat stress. Both site-specific ligand displacement and computational docking outcomes indicated that Sudlow’s Site II was detected as the position for BEX binding to HSA with higher priority. The BEX–HSA complex constancy was demonstrated by the complex maintaining equilibrium during the course of the simulations, according to analysis of the molecular dynamics simulation results.