Synthesis, In-Vitro Antibacterial, Antifungal, and Molecular Modeling of Potent Anti-Microbial Agents with a Combined Pyrazole and Thiophene Pharmacophore

Abstract

Ethyl 5-acetyl-4-methyl-2-(phenylamino)thiophene-3-carboxylate (2) and there derivatives 3a–c, 4, 6a–c and 9a–f were synthesized. The structure of compound 2 was deduced by 1H-NMR, 13C-NMR, FT-IR, MS, microanalysis, and single-crystal X-ray crystallography. The compound crystallized in the monoclinic system, with space group P21/c and cell coordinates a = 8.5752(16) Å, b = 21.046(4) Å, c = 8.2941(12) Å, β = 101.131(6)°, V = 1468.7(4) Å3, and Z = 4. Compounds 2, 3a–c, 4, 5a–c and 9a–f were subjected into in vitro antimicrobial activity tests. Compounds 3a and 3c were more potent than standard drug amphotericin B, showing MIC values of 23.8 ± 0.42 and 24.3 ± 0.68, respectively, against Aspergillus fumigatus while the standard drug MIC was 23.7 ± 0.1. Compound 3c was also more potent (MIC 24.8 ± 0.64) than the standard drug amphotericin B (MIC 19.7 ± 0.2) against Syncephalastrum racemosum. Compounds 4 and 9f also showed promising anti-microbial activity. Molecular modeling was performed for the most active compounds.

Keywords

• thiophene
• enaminone
• [2+3] cycloaddition
• anti-microbial activity
• molecular modeling