Synthesis and Antibacterial Evaluation of Rhodanine and Its Related Heterocyclic Compounds against S.†aureus and A.†baumannii.

Antimicrobial resistance is a serious challenge to modern medicine. Besides imposing high financial burden, multidrug resistant infections are directly responsible for high morbidity and mortality. Even though a number of antibiotics are currently available to treat infections caused by ESKAPE organisms, more and more bacterial strains are becoming resistant to these drugs. Prevailing circumstances pose an urgent unmet need for the development of newer antimicrobials to treat the infections caused by MDR organisms. Rhodanine and structurally related 5-membered heterocycles possess wide range of pharmacological activities. A number of these derivatives have shown good to potent inhibition against various microorganisms. They are reported to alter the function of DNA gyrase B, metallo-ß-lactamases, penicillin binding protein (PBP), Mur ligases, RNA polymerase, Enoyl ACP reductases, 1-deoxy-d-xylulose-5-phosphate reductoisomerase. etc which are vital in bacterial growth, survival and replication. In this study, we have generated a library of Rhodanine and related 5 membered heterocyclic derivatives and screened them against a panel of pathogens. Among all the compounds, 2a-i, 3a-b, 3g, 4, 6b-c, 6e, 6g, 12a-b and 14b-c have demonstrated good to moderate inhibition against S. aureus (MIC 0.125-8 µg/mL). Further, compound 17b demonstrated moderate activity against A. baumannii (MIC 8 µg/mL). In addition, compounds 2a, 2e, 4, 6c, 6g and 14b have shown good to mild inhibition against MDR S. aureus including VRSA (MIC 0.5-16 µg/mL) with good selectivity index 20-1600. In addition, compound 2e inhibited the growth gradually after 6 h in time kill kinetic studies and not antagonized with the tested FDA approved drugs.

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.