Synthesis, Antibacterial and Antifungal Activities of Novel 1,2,4-Triazolium Derivatives

A series of novel 1,2,4-triazolium derivatives was synthesized starting from commercially available 1H-1,2,4-triazole, 2,4-dichlorobenzyl chloride, or 2,4-difluorobenzyl bromide. Their antibacterial and antifungal activities were evaluated against Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922, Bacillus proteus, Bacillus subtilis, Pseudomonas aeruginosa, Candida albicans ATCC 76615, and Aspergillus fumigatus. All structures of the new compounds were confirmed by NMR, IR, and MS spectra, and elemental analyses. The antimicrobial tests showed that most of synthesized triazolium derivatives exhibit significant antibacterial and antifungal activities in vitro. 1-(2,4-Difluorobenzyl)-4-dodecyl-1H-1,2,4-triazol-4-ium bromide and 1-(2,4-Dichlorobenzyl)-4-dodecyl-1H-1,2,4- triazol-4-ium bromide were the most potent compounds against all tested strains with the MIC values ranging from 1.05 to 8.38 microM. They exhibited much stronger activities than the standard drugs chloramphenicol and fluconazole which are in clinical use. The results also showed that the antimicrobial activities of triazolium derivatives depend upon the type of substituent, the length of the alkyl chain, and the number of triazolium rings.