Antibacterial Assessment of Heteroaryl, Vinyl, Benzyl, and Alkyl Tetrazole Compounds

Background: In previous reports, the antibacterial properties of certain tetrazole derivatives have been described. We have previously reported the antibacterial properties of aryl 1Htetrazole compounds. Objective: To study the antibacterial activity of 5-substituted heteroaryl, vinyl, benzyl, and alkyl 1H-tetrazole derivatives. Methods: The antibacterial properties of heteroaryl, vinyl, benzylic, and aliphatic tetrazole derivatives were investigated against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. The activity was assessed by determining the minimum inhibitory concentration of these tetrazole derivatives and comparing them to the known antibiotics amoxicillin, trimethoprim and sulfamethoxazole. Results: The tetrazole compounds were prepared utilizing cerium(III) chloride heptahydrate catalysis at 160 °C for 1-4 h in a microwave reactor using an aqueous solvent mixture. The most active derivatives exhibited minimum inhibitory concentration values between 125-250 μg/mL against Escherichia coli. More importantly, these compounds were considerably more active when used in combination with trimethoprim and a significant synergistic effect was observed (MIC = 0.98-7.81 μg/mL) against E. coli and S. aureus. Conclusion: The tetrazole derivatives were synthesized in high yield and short reaction times in water. Several of the tetrazole compounds showed a significant synergistic antibacterial effect when used with trimethoprim.