Rational drug design, synthesis, and in vivo biological activity of new indolyl-imidazolone hybrids as potential and safer non-steroidal anti-inflammatory agents

Abstract

ObjectivesThe study aimed to synthesize and evaluate the potential anti-inflammatory and analgesic activities of rationally designed hybrid molecules of imidazolone and indole nuclei linked through a methylene bridge. MethodsIndolyl-imidazolone hybrids were synthesized in three simple steps starting from 2-phenyl-1H-indole (1). In the first step, compound 1 was converted to 2-phenyl-1H-indole-3-carbaldehyde (2) using standard conditions of the Vilsmeier Haack reaction. Benzoyl glycine was reacted with 2 (step 2) followed by treatment with aromatic/aliphatic amines (step 3) to furnish the indolyl-imidazolone hybrids. In vivo anti-inflammatory and analgesic activity along with ulcerogenicity of the prepared hybrids were evaluated in experimental animals. Molecular properties and pharmacokinetic profile were also predicted using online computational software. Cyclooxygenase-2 (COX-2) enzyme (PDB: 3pgh) was used for molecular docking studies. Indomethacin and aspirin were used as reference compounds for the comparison purpose. ResultsThe percentage inhibition in edema in rats and reduction in frequency of acetic acid induced writhes in mice indicated that two compounds namely 3-(3-Hydroxpropyl)-2-phenyl-5-[(2-phenyl-1H-indol-3-yl)methylene]-4H-imidazol-4-one (4g) and 3-(2,4-Dinitrophenyl)-2-phenyl-5-[(2-phenyl-1H-indol-3-yl) methylene]- 4H-imidazol-4-one (4b) could be useful in treating pain and inflammatory conditions. Both the hybrid molecules exhibited better biological spectrum than the standard drug indomethacin. Additionally, both the potent compounds were noted to be less ulcerogenic than indomethacin. Pharmacokinetic profile predicted using ADMETsar and SwissADME cheminformatic software indicated compound 4g to be orally bioavailable with high blood brain barrier permeability. However, molecular docking studies revealed that compound 4b binds to COX-2 enzyme more strongly than 4g as indicated by a lower binding energy and formation of hydrogen bond interactions with amino acid residues in the binding pocket. ConclusionsIt could be concluded that hybrid compounds 4b and 4g are promising lead candidates and should be further studied to develop compounds for the treatment of inflammatory conditions.