Imidazo[1,2-b]Pyrazole-1,2,4-oxadiazole Linked 1,2,3-Triazoles: Synthesis, Antibacterial, Biofilm, and In Silico Studies.

The growing incidence of bacterial resistance, especially in gram-positive infections, emphasizes how urgently new antibacterial medicines must be developed. This study presents the rational design and synthesis of a series of fused imidazo[1,2-b]pyrazole-1,2,4-oxadiazole-1,2,3-triazole hybrids (8a-8n) employing a multi-step synthetic approach that includes oxidative cyclisation, amidoxime formation, Vilsmeier-mediated cyclodehydration, and Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The synthesized compounds were assessed for their in vitro antibacterial efficacy against Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis. Multiple derivatives displayed notable antibacterial activity, with compounds 8j and 8l identified as the most effective (MIC = 1.56 µg/mL), exhibiting antibacterial efficacy comparable to or surpassing that of the reference medication dicloxacillin. Biofilm inhibition tests further indicated that compounds 8j and 8l exhibit substantial antibiofilm action. Molecular docking analyses targeting penicillin-binding protein (PDB ID: 1MWT) demonstrated advantageous binding affinities, with compound 8k displaying the most favorable binding score (-9.10 kcal/mol), corroborating the experimental results. Structure-activity relationship (SAR) research revealed that the inclusion of electron-withdrawing substituents, especially dihalogen groups, markedly increases antibacterial efficacy. These results underscore the therapeutic potential of fused imidazo[1,2-b]pyrazole-1,2,4-oxadiazole-1,2,3-triazole hybrids as effective antibacterial and antibiofilm agents against gram-positive bacterial infections.