Letter	Planta Med 2004; 70: 1240-1242 DOI: 10.1055/s-2004-835860
© Georg Thieme Verlag KG Stuttgart · New York
Catechin Gallates Inhibit Multidrug Resistance (MDR) in Staphylococcus aureus
Simon Gibbons1, Elisabeth Moser1, Glenn W. Kaatz2
1 Centre for Pharmacognosy and Phytotherapy, The School of Pharmacy, University of London, London, U.K. 2 Division of Infectious Diseases, Department of Internal Medicine, School of Medicine, Wayne State University and the John D. Dingell Department of Veterans Affairs Medical Center, Detroit, Michigan, U.S.A.

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 μg/mL, respectively). When incorporated into the growth medium at 20 μg/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 ≤ 20 μM both compounds paradoxically stimulated efflux. This phenomenon has not been encountered previously in the analysis of inhibitors of multidrug efflux.