Synthesis, Biological Activity, and Docking Studies of the Fused Pyrazoline and Thiazole Hybrids

ABSTRACT Heterocyclic compounds containing thiazole embedded with pyrazoline moieties were designed via the Claisen‐Schmidt reaction followed by the condensation reaction with substituted phenacyl bromides. Structures of the synthesized compounds (5a–l) were confirmed by FTIR, 13 C‐NMR, 1 H‐NMR, and mass spectral analysis. All the compounds were screened for in vitro antimicrobial activity against Gram‐positive and Gram‐negative bacterial and fungal strains. Among the synthesized compounds, most of them showed good to moderate antimicrobial activity against Escherichia coli at different concentrations. The compound 4,5‐dihydro‐5‐(4‐nitrophenyl)‐1‐(5‐phenylthiazol‐2‐yl)‐3‐(4‐(prop‐2‐ynyloxy)phenyl)‐1H‐pyrazole (5i) and 4,5‐dihydro‐1‐(5‐(4‐methoxyphenyl)thiazol‐2‐yl)‐5‐(4‐nitrophenyl)‐3‐(4‐(prop‐2‐ynyloxy)phenyl)‐1H‐pyrazole (5 k) showed inhibitory potency against Candida albicans . Molecular docking studies were performed to check the insights of the activity experimentally and theoretically, which supported the in vitro activity results. The binding energy of −11.2 Kcal/mol for the compound 5‐(4‐fluorophenyl)‐4,5‐dihydro‐3‐(4‐(prop‐2‐ynyloxy)phenyl)‐1‐(5‐p‐tolylthiazol‐2‐yl)‐1H‐pyrazole (5g) showed the greater interaction towards the target Escherichia coli MurB enzyme (PDB code: 2MBR). The present study emphasizes the importance of the pyrazoline‐thiazole moiety in synthetic and medicinal chemistry with potential pharmacological activity.