Synthesis, Characterization, and Antimicrobial Activity of Some New 2,4-Dihydro-3H-1,2,4-Triazole-3-thione...

Antimicrobial resistance is a major problem in the treatment of infectious diseases. Therefore, it is important to develop new and effective antimicrobial agents. For this purpose, a new series of compounds with a 2,4-dihydro-3H-1,2,4-triazole-3-thione structure was synthesized.

2,4-dihydro-3H-1,2,4-triazole-3-thione compounds (T1-T8) were synthesized by heating thiosemicarbazide derivatives under alkaline conditions. Infrared (IR), ¹H-NMR, and ¹³C-NMR spectroscopic methods were used to elucidate the chemical structures of the compounds. The antimicrobial activity of the compounds against eight bacterial strains (five Gram-negative and three Gram-positive) and two fungal strains was evaluated using the microdilution method.

Compounds T4, carrying a benzoyl group, and T6, carrying a phenethyl group, showed the best antibacterial activity against Enterococcus faecalis ATCC 29212, with minimum inhibitory concentrations (MICs) of 41.79 mg/L and 81.25 mg/L, respectively. Compound T6 also demonstrated the strongest antibacterial activity against Staphylococcus epidermidis ATCC 12228, with an MIC of 40.62 mg/L. Antifungal activity assays revealed that compounds T4, T6, and T8 were the most potent against Candida albicans ATCC 90028, with MIC values of 40.62-83.59 mg/L, and that T6, T7, and T8 were the most potent against Candida glabrata ATCC 90030, with MIC values of 40.62-162.5 mg/L.

Among the compounds, T6 appears to exhibit significant antimicrobial activity against both Gram-positive bacteria (e.g., E. faecalis ATCC 29212 and S. epidermidis ATCC 12228) and fungi (e.g., Candida strains).