Synthesis and biological evaluation of some new heterocyclic compounds incorporating sulfapyridine as potential antimicrobial agents

This study investigated the cyanoacylation of the sulfapyridine moiety using cyanoacetyl pyrazole as a key synthetic intermediate for the construction of diverse bioactive scaffolds. The intermediate, 2-cyano-N-(4-(N-pyridin-2-yl) sulfamoyl) phenylacetamide, served as a valuable precursor for the synthesis of acrylamide, thiophene, thiazole, chromene, pyridone, 1,2,4-triazine, and hydrazone derivatives all incorporating the sulfapyridine core. The structural elucidation of the synthesized compounds was achieved using infrared (IR), nuclear magnetic resonance (1H 1 H and 13 C), and mass spectrometry techniques. The biological activity of the newly synthesized compounds was evaluated against a panel of microorganisms, including Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis), Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa), and the fungus Candida albicans. Notably, the thiol derivative (compound 12), the pyrazole derivative (compound 15), and the 1,2,4-triazine derivatives (compound 21) exhibited significant to good antibacterial and antifungal activity. Interestingly, compounds 12 and 15 displayed a broader spectrum of activity, demonstrating efficacy against all tested microbial strains.