Antifolate activity of epigallocatechin gallate against Stenotrophomonas maltophilia.
The catechin epigallocatechin gallate, one of the main constituents of green tea, showed strong antibiotic activity against 18 isolates of Stenotrophomonas maltophilia (MIC range, 4 to 256 microg/ml). In elucidating its mechanism of action, we have shown that epigallocatechin gallate is an efficient inhibitor of S. maltophilia dihydrofolate reductase, a strategic enzyme that is considered an attractive target for the development of antibacterial agents. The inhibition of S. maltophilia dihydrofolate reductase by this tea compound was studied and compared with the mechanism of a nonclassical antifolate compound, trimethoprim. Investigation of dihydrofolate reductase was undertaken with both a trimethoprim-susceptible S. maltophilia isolate and an isolate with a high level of resistance. The enzymes were purified using ammonium sulfate precipitation, gel filtration, and methotrexate affinity chromatography. The two isolates showed similar levels of dihydrofolate reductase expression and similar substrate kinetics. However, the dihydrofolate reductase from the trimethoprim-resistant isolate demonstrated decreased susceptibility to inhibition by trimethoprim and epigallocatechin gallate. As with other antifolates, the action of epigallocatechin gallate was synergistic with that of sulfamethoxazole, a drug that blocks folic acid metabolism in bacteria, and the inhibition of bacterial growth was attenuated by including leucovorin in the growth medium. We conclude that the mechanism of action of epigallocatechin gallate on S. maltophilia is related to its antifolate activity.
Grupo de Investigación de Enzimología, Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
María Dolores
MD
Navarro-Martínez
Enma
E
Navarro-Perán
Juan
J
Cabezas-Herrera
Joaquín
J
Ruiz-Gómez
Francisco
F
García-Cánovas
José Neptuno
JN
Rodríguez-López
D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D005493:Folic Acid Antagonists / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008727:Methotrexate / Q000737:chemistry / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D020615:Stenotrophomonas maltophilia / Q000187:drug effects*; D013762:Tetrahydrofolate Dehydrogenase / Q000187:drug effects; D014295:Trimethoprim / Q000737:chemistry / Q000494:pharmacology; D014296:Trimethoprim Resistance
D000900:Anti-Bacterial Agents; D005493:Folic Acid Antagonists; D002392:Catechin; D014295:Trimethoprim; C045651:epigallocatechin gallate; D013762:Tetrahydrofolate Dehydrogenase; D008727:Methotrexate