A Convenient One-Pot Synthesis of Novel Benzimidazole-Thiazinone Derivatives and Their Antimicrobial Activity.

Background

The increasing prevalence of antimicrobial resistant highlights the urgent need for the new therapeutic agents. This study aimed to design and synthesize fused tricyclic benzimidazole-thiazinone derivatives (CS1-CS10) through a convenient method and evaluate their antimicrobial activity against various microorganisms.

Methods

A series of fused tricyclic benzimidazole-thiazinone derivatives was rationally designed and synthesized in one pot by the reaction between trans substituted acrylic acids and 1H-benzo[d]imidazole-2-thiol using coupling reagent TBTU (2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate). The structure of these compounds was confirmed through various spectroscopic techniques like IR, 1H and 13C NMR, the DEPT and 2D-HMQC NMR techniques were also performed to confirm the relation of both carbon and proton. Further, the compounds were in vitro evaluated for their effectiveness against the Candida species and a panel of standard bacterial isolates.

Results

The synthesized compounds showed moderate antimicrobial activity. Among all of the compounds, CS4 exhibited potent inhibition against Pseudomonas aeruginosa and Escherichia coli at 256 and 512 μg/mL concentrations, respectively. Additional research indicated that compound CS4 demonstrated a synergistic effect after combining with the standard antibacterial drug ciprofloxacin.

Conclusions

These results suggest that CS4 is the best-synthesized antibacterial agent particularly in combination therapies. These findings highlight its promise for further development as a novel antibacterial agent.