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Updated: Jul 17, 2026

Visualization of Bacterial Resistance using Fluorescent Antibiotic Probes
Published on: March 2, 2020
N-caffeoylphenalkylamide derivatives as bacterial efflux pump inhibitors
Serge Michalet1, Gilbert Cartier, Bruno David
1DPM UMR 5063 CNRS-UJF, Equipe de Pharmacognosie, UFR de Pharmacie de Grenoble, Domaine de La Merci, 38706 La Tronche cedex, France. sergemichalet@yahoo.fr
Abstract:
As part of an ongoing project to identify plant natural products as efflux pump inhibitors (EPIs), bioassay-guided fractionation of the methanolic extract of Mirabilis jalapa Linn. (Nyctaginaceae) led to the isolation of an active polyphenolic amide: N-trans-feruloyl 4'-O-methyldopamine. This compound showed moderate activity as an EPI against multidrug-resistant (MDR) Staphylococcus aureus overexpressing the multidrug efflux transporter NorA, causing an 8-fold reduction of norfloxacin MIC at 292 microM (100 microg/mL). This prompted us to synthesize derivatives in order to provide structure-activity relationships and to access more potent inhibitors. Among the synthetic compounds, some were more active than the natural compound and N-trans-3,4-O-dimethylcaffeoyl tryptamine showed potentiation of norfloxacin in MDR S. aureus comparable to that of the standard reserpine.
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