Synthesis and Evaluation of the in vitro Antimicrobial Activity of Triazoles, Morpholines and Thiosemicarbazones

Background: Microbial infections is a global public health problem. The aim of this work was to synthesize and evaluate the antimicrobial activity of novel triazoles, morpholines and thiosemicarbazones. Methods: Compounds were synthesized using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. The antimicrobial activity of these compounds against bacteria and yeast was evaluated by the broth microdilution method. Results: The proposed route for synthesis gave high to moderate yields, moreover these compounds were successfully characterized by 1H NMR, 13C NMR and LC-MS. Antimicrobial testing indicated that the thiosemicarbazone and morphine derivatives had the best antimicrobial activity against the microorganisms tested with minimum inhibitory concentrations (MIC) between 0.29 and 5.30 μM. Thiosemicarbazone derivative (12) was able to inhibit the growth of C. tropicalis, with minimum fungicidal concentration (MFC) of 0.55 μM. In addition, this compound was active against E. coli, S. aureus and S. epidermidis, with MIC values ranging from 0.29 to 1.11 μM. Moreover, the morpholine derivative (15) had an MIC value of 0.83 μM against C. albicans and E. coli. Conclusion: We have efficiently synthesized a series of eleven novel triazoles, thiosemicarbazones and morpholine derivatives using 2,4-Dihydroxyacetophenone and 4-hydroxybenzaldehyde as starting materials. Thiosemicarbazone derivative (12) showed promising antifungal and antibacterial activity and these findings suggest that this compound can be used as scaffolds to design new antimicrobial drugs.