Spectroscopic and molecular docking investigation of the binding of a bioactive mercaptobenzimidazole-functionalized Schiff base to human serum albumin

This study was conducted to examine the binding of a newly synthesized Schiff base derived from 2-hydroxy-1-naphthaldehyde and 5-amino-2-mercaptobenzimidazole with human serum albumin (HSA) employing various biophysical techniques. The thermal-based fluorescence quenching data indicated that static quenching occurred between the ligand and HSA. The fluorescence results expose that ligand quenches the intrinsic fluorescence of HSA through a static quenching procedure. The thermodynamic parameters of the binding interaction, obtained using van't Hoff equation indicated the spontaneity of the reaction. The stability of the HSA–ligand complex resulted from hydrogen bonding and hydrophobic interactions, which afforded a substantial binding affinity between ligand and HSA. UV–Vis and circular dichroism data indicated that ligand binding induced conformational changes in HSA. The energy transfer efficiency determined according to Fӧorster's theory. Absorption, distribution, metabolism, and excretion (ADME) and Lipinski’s drug likeness of the ligand was predicted, revealing that it had auspicious physicochemical properties for oral bioavailability. Furthermore, molecular modeling was also employed to determine the location of the ligand in HSA binding sites, which revealed that the ligand interacted with polar and apolar residues of site I (subdomain IIA) of HSA, predominantly through hydrophobic and hydrogen bonding interactions.