Synthesis and antibacterial evaluation of (E)-1-(1H-indol-3-yl) ethanone O-benzyl oxime derivatives against MRSA and VRSA strains

Infections caused due to multidrug resistant organisms have emerged as a constant menace to human health. Even though numerous antibiotics are currently available for treating infectious diseases, a great number of bacterial strains have acquired resistance to many of them. Among these, infections caused due to Staphylococcus aureus are predominant in adult and paediatric population. Indole is a prominent chemical scaffold found in many pharmacologically active natural products and synthetic drugs. A number of oxime ether containing compounds have attracted attention of researchers owing to their interesting biological properties. Current work details the synthesis of indole containing oxime ether derivatives and their evaluation for antimicrobial activity against a panel of bacterial and mycobacterial strains. Synthesized compounds demonstrated good to moderate activity against drug-resistant S. aureus including resistant to vancomycin. Among all, compound 5h was found to possess potent activity against susceptible as well as MRSA and VRSA strains of S. aureus with MIC of 1 µg/mL and 2-4 µg/mL respectively. In addition, compound 5h was found to be non-toxic to Vero cells and exhibited good selectivity index of >40. Further, 5h, E-9a and E-9b possessed good biofilm inhibition against S. aureus. With these assuring biological properties, synthesized compounds could be potential prospective antimicrobial agents.