Anti-MRSA (Multidrug Resistant Staphylococcus aureus) Activity of 3-Substituted Coumarins

Background: Infectious pathogenic bacteria are the key virulence in our daily life. Especially diseases produced by multidrug resistant Staphylococcus aureus (MRSA) still contributing in morbidity and mortality in humans. Discovery of new and safer antibiotics is an upmost task in current medicinal research. Methods: By keeping in mind the considerable antimicrobial activities of coumarin scaffold, 3-substituted coumarin derivatives 1-24 were synthesized by Knoevenegel condensation reaction. Different aryl aldehydes were treated with β-keto esters in the presence of organic base piperidine. All synthetic compounds were characterized by different spectroscopic techniques such as EI-MS, HREI-MS, 1H-NMR, and 13C-NMR. Compounds were screened to check for their in vitro anti- MRSA (multidrug resistant Staphylococcus aureus) activity against different strains of bacteria such as MRSA-252, EMRSA-16, EMRSA-17 and local clinical isolate. Micro-plate alamar blue assay (MABA) was used for this activity. Oxacillin, streptomycin, clindamycin and vancomycin were used as standards. Results: Results were reported as percent inhibition at 20 μg/mL concentration. Amongst all four standard drugs, only vancomycin was showed 19%, 24%, 21% and 40% inhibitions in case of MRSA-252, EMRSA-16, EMRSA-17 and local clinical isolate, respectively, at 20 μg/mL concentration. Most of the synthetic compounds were showed a weak to good inhibition as compared to standard, vancomycin. Conclusion: Newly identified compounds may serve as lead for future research in order to get the more powerful antibacterial agents.