A study of the antimicrobial activity of selected naturally occurring and synthetic coumarins.
The antimicrobial activities of 43 naturally occurring and synthetic coumarins were studied. Using a microtitre assay developed in-house, a range of Gram-positive and Gram-negative bacteria, including a hospital isolate of methicillin-resistant Staphylococcus aureus (MRSA),were utilised. The coumarins exhibiting good bioactivity (i.e. a low minimum inhibitory concentration) against two S. aureus strains were then assessed for their antimicrobial activities against a range of eight clinically isolated MRSA strains. The study showed that nearly one-half of the tested compounds displayed antimicrobial activity. Sixteen of these coumarins also possessed resistance-modifying activity, which reversed the resistance mechanism in MRSA allowing the antimicrobial oxacillin to exert an enhanced effect against an MRSA hospital strain. When tested in combination with oxacillin, 8-iodo-5,7-dihydroxycoumarin (32) had a similar activity to vancomycin, which is the current drug of choice for the treatment of MRSA infections.
Smyth
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T
School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, Co. Derry BT52 1SA, UK.
Ramachandran
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VN
Smyth
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WF
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003374:Coumarins / Q000494:pharmacology*; D004357:Drug Synergism; D006090:Gram-Negative Bacteria / Q000187:drug effects*; D006094:Gram-Positive Bacteria / Q000187:drug effects*; D006801:Humans; D016106:Methicillin Resistance / Q000187:drug effects; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure
D000900:Anti-Bacterial Agents; D003374:Coumarins