Bisbenzoxazole Derivatives: Design, Synthesis, in Vitro Antimicrobial, Antiproliferative Activity, and Molecular Docking Studies

Abstract

Four series of bisbenzoxazole derivatives were designed, synthesized, and screened for antiproliferative and antimicrobial activities. Generally, all synthesized bisbenzoxazoles (9–24) displayed significant antiproliferative activity; these effects were shown to be related to oxazole rings and substituents in bisbenzoxazole compounds. Especially, the series bearing chloro-substituent (9–12) exhibited better antiproliferative activity with higher selectivity than the other series (13–24); the IC50 values were observed in the range of 0.045–0.342 µM. Interestingly, only the compound with a nitro substituent (22) showed maximum potency with an IC50 value of 0.011 µM, which is two-fold more active than the standard drug methotrexate, with moderate selectivity. The compounds bearing fluoro-substituent (14–16) were found to exhibit potent antibacterial activity against the Gram-positive Enterococcus faecalis, with a MIC value of 62.5 μg/mL, and moderate activity against Gram-negative bacteria and fungi. Only the compound 23 showed potent activity against Escherichia coli, with a MIC value of 62.5 μg/mL. In order to better evaluate the activity results, crystal structures of five different proteins Human Anaplastic Lymphoma Kinase (PDB ID: 2XP2), CYP2C8dH complexed (PDB ID: 2NNI), factor-human kinase-β enzyme IKK-β enzyme (PDB ID: 4KIK), a tubulin heterodimer complex containing α and β sub-units (PDB ID: 1Z2B) and penicillin-binding protein 4 (PBP4) from Enterococcus faecalis (PDB ID: 6MKI) were used in the docking study to examine antiproliferative and antimicrobial activity. Finally, an ADMET screening test was applied to determine the drug-like, toxicological, and optimum physicochemical properties for all of the synthesized compounds. The strategy applied in this research may act as a perspective for the rational design of potential anticancer drugs. Highlights Four series of sixteen bisbenzoxazole derivatives has been designed and synthesized. All compounds were evaluated to be antiproliferative and antimicrobial activity. The series bearing chloro-substituent exhibited better antiproliferative activity. The compounds bearing fluoro-substituent were found to exhibit potent antibacterial activity. ADMET screening test was applied to determine the drug-like, toxicological, and optimum physicochemical properties for all of the synthesized compounds.