Abstract
Bacterial infectious diseases, such as tuberculosis, are among the leading causes of mortality worldwide. Some of the major contributing factors behind the high mortality rate are the overuse and misuse of antimicrobials, which often lead to the emergence of drug resistance. The prevalence of drug resistance makes it difficult to treat infectious diseases using commercially available drugs. Therefore, the discovery and development of novel antibacterial agents to treat these critical illnesses is urgently required.
This study reports on the synthesis of pyrimidine N-acylhydrazones analogues as potential antibacterial agents. The pyrimidine N-acylhydrazones analogues were synthesized through the condensation of N-acylhydrazides with benzaldehydes. The products were identified and confirmed by FT-IR, NMR, and HRMS analysis. Conformational studies NMR revealed that the resulting pyrimidine N-acylhydrazones with an ortho-substituted hydroxyl (OH) group exist in two conformational stereoisomers, major syn-E and minor anti-E, in CDCl3. Furthermore, the biological activity of the target compounds was assessed using the broth microdilution technique to determine the minimum inhibitory concentration (MIC) against five gram-positive (Bacillus substilis (BS), Mycobacterium smegmatis (MS), Staphylococcus epidermis (SE), Staphylococcus aureous (SA), Enterococcus faecalis (EF)) and seven gram-negative (Enterobacter cioacea (ECL), Escherischia coli (EC), Proteus vulgaris (PV), proteus mirabilis (PM)), pseudomonas aeruginosa (PA), Klebsiella oxytoca (KO, Klebsiella aerogenes (KA)) bacterial strains. All the pyrimidine N-acylhydrazones exhibited good antibacterial activity against all the bacterial strains, with MIC values ranging from 3.9 μg/mL to 7.8 μg/mL.