Novel ethyl 1,5-disubstituted-1H-pyrazole-3-carboxylates as a new class of antimicrobial agents

Abstract

A series of pyrazole derivatives 9-22 were designed and synthesized. All the newly synthesized compounds were assayed for their antimicrobial activity against the Gram-positive bacteria Staphyllococcus aureus and Bacillius subtilis and the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, in addition to the fungi organisms, Candida albicans, C. parapsilosis and C. tropicalis. Ethyl 5-(2,5-dimethylthiophen-3-yl)-1-phenyl-1H-pyrazole-3-carboxylate (21) (MICE.coli =0.038 µmol mL–1, MICP. aerug = 0.067 µmol mL–1) is nearly as active as ampicillin (MIC = 0.033 and 0.067 µmol mL–1, respectively). Ethyl 5-(4-bromo-2-chlorophenyl)-1-phenyl-1H-pyrazole-3-carboxylate (16) (MIC = 0.015 µmol mL–1) is more active than fluconazole (0.020 µmol mL–1) as a reference drug against C. parapsilosis