title: Catechin gallates inhibit multidrug resistance (MDR) in Staphylococcus aureus.
abstract: Epicatechin gallate (1) and epigallocatechin gallate (2) were evaluated for their antibacterial and efflux inhibitory activity against a wild-type and three multidrug-resistant (MDR) strains of Staphylococcus aureus. Compound 2 was more active than 1 based on minimum inhibitory concentrations (MICs; 32-64 versus 64->512 microg/mL, respectively). When incorporated into the growth medium at 20 microg/mL, both compounds exhibited a four-fold potentiation of the activity of norfloxacin against a norfloxacin-resistant strain of S. aureus overexpressing the NorA multidrug efflux pump. Against this strain 1 was moderately more potent than 2 as an inhibitor of ethidium efflux, but at < or = 20 microM both compounds paradoxically stimulated efflux. This phenomenon has not been encountered previously in the analysis of inhibitors of multidrug efflux.
authors.affiliation: Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, London, UK. simon.gibbons@ulsop.ac.uk
authors.forename: Simon
authors.initials: S
authors.lastname: Gibbons
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Moser
authors.forename: Glenn W
authors.initials: GW
authors.lastname: Kaatz
mesh_terms: D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D002392:Catechin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology* / Q000627:therapeutic use; D018432:Drug Resistance, Multiple; D006801:Humans; D008826:Microbial Sensitivity Tests; D008517:Phytotherapy; D010946:Plants, Medicinal; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: D000900:Anti-Bacterial Agents; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate