Preparation, structure determination, and in silico and in vitro Elastase inhibitory properties of substituted N-([1,1′-Biphenyl]-2-ylcarbamothioyl)- Aryl/Alkyl benzamide Derivatives

Abstract

The preparation of a set of eight closely related biphenyl-thiourea conjugates with aromatic and aliphatic side chains (3a-3h) using a one-pot three-component strategy is reported. All the novel compounds were characterized by spectroscopic techniques (FTIR, 1H and 13C NMR) and elemental analysis. Moreover, the crystal structure of compounds 3f and 3h have been determined by X-ray diffraction. The common molecular skeleton can be closely superposed to each other and the 1-acyl thiourea groups show a nearly planar conformation favored by an intramolecular N–H•••O=C bond. In-vitro studies were carried out to test the elastase inhibition activity of the newly synthesized biphenyl-thiourea hybrid derivatives. Among the series, compound 3c (IC50 = 0.26 ± 0.05 μM) exhibited the maximum inhibition against elastase. The higher activity of aryl substituents over alkyl chains is evidenced, as well as the importance of electron withdrawing groups, as nitro (3b and 3c) and bromo (3d) to enhance the enzyme inhibitory activity. The compound 3c inhibits the enzyme in a competitive manner, with dissociation constant Ki = 0.84 µM. Molecular docking was also carried out within the enzyme active site to study enzyme-inhibitor interactions. Docking results correlate with experimental inhibition studies and show that compound 3c exhibits the highest binding energy (-7.70 kcal/mol) as compared with other compounds. The results of this study might help to develop new elastase inhibitors.