Synthesis, Structure and Antibacterial Evaluation of Some N-substituted 3-amino-5-hydroxy-4-phenyl-1H-pyrazole-1-carboxamides

N-substituted 3-amino-5-hydroxy-4-phenyl-1H-pyrazole-1-carboxamide derivatives have been prepared by heterocyclization of 1-cyanophenyl acetic acid hydrazide with isocyanates. Representative compounds were evaluated as potential antimicrobial agents. The most promising compound in this series, the N-(1-naphthyl)-3-amino-5-hydroxy-4- phenyl-1H-pyrazole-1-carboxamide 2f, was the most effective against the reference strains of pathogenic S. aureus ATCC 25923 and S. aureus ATCC 6538 or opportunistic S. epidermidis ATCC 12228 with MIC value of 7.81 μg/ml and against the other Gram-positive species with MIC values 15.63-31.25 μg/ml. This compound also showed high activity against clinical isolates of MSSA (methicillin-sensitive Staphylococcus aureus) with MIC of 0.98 - 31.25 μg/ml and MRSA (methicillin- resistant Staphylococcus aureus) with MIC of 1.96 – 7.81 μg/ml. Keywords: Antibacterial activity, pyrazole, synthesis, X-ray analysis, N-substituted, 3-amino, 5-hydroxy, 1H-pyrazole, 1-carboxamide derivatives