Synthesis, molecular docking and antibacterial activity of new benzimidazole compounds derived from 3,4-diaminobenzophenone containing 1,3,4-thiadiazole ring

The aim of this present study was to synthesize new benzimidazole compounds derived from 3,4-diaminobenzophenone, which include a 1,3,4-thiadiazole ring. The final compounds 4(A-E) were synthesized by a multistep procedure: First, 2-mercapto-5-benzoylbenzimidazole was prepared by reaction of 3,4-diaminobenzophenone with CS2 in C2H5OH. Then various 2-amino-5-substituted-1,3,4-thiadiazole were prepared through reacting thiosemicarbazide with various benzoic acids using POCl3. These compounds were reaction with chloroacetylchloride to yielded 2-chloroacetamide derivatives. Finally, nucleophilic substitution reaction between these intermediates and compound (1) in the presence of K2CO3/DMF, reflux, yielded the target compounds. The structural authenticity of the targeted compounds was confirmed using spectral data obtained from FT-IR and 1H and 13C-NMR. Subsequently the antibacterial activity of the final target compounds 4(A-E) was examined in vitro against four types of bacterial isolates: two gram-positive (Staphylococcus aureus and Staphylococcus epidermidis) and two gram-negative (Pseudomonas aeruginosa and Escherichia coli). Compounds 4(B, C, D, and E) demonstrated promising pharmacological activity in vitro when compared to the standard antibacterial agent, azithromycin. The synthesized molecules underwent molecular docking studies specifically with DNA gyrase subunit b (PDB ID:1KZN).The outcomes of these molecular docking studies offer support for the antibacterial activity of the compounds, demonstrating notable inhibition constants and binding energies. KEY WORDS: Benzimidazole, 1,3,4-Thiadiazole, Molecular docking, Antibacterial activity, 3,4-Diaminobenzophenone Bull. Chem. Soc. Ethiop. 2025, 39(9), 1807-1818. DOI: https://dx.doi.org/10.4314/bcse.v39i9.12