Tea polyphenol epigallocatechin-3-gallate inhibits ergosterol synthesis by disturbing folic acid metabolism in Candida albicans.
OBJECTIVE
Elucidation of the mechanism of action of epigallocatechin-3-gallate (EGCG) against Candida albicans and demonstration of the connection between its antifolate activity and other metabolic pathways involved in C. albicans survival are the major objectives of this study.


METHODS
C. albicans ATCC 10231 and 12 clinical isolates were used. MICs of EGCG against C. albicans were determined according to NCCLS. C. albicans dihydrofolate reductase (DHFR) was purified using methotrexate-affinity chromatography and its inhibition by EGCG studied by spectroscopic techniques. Synergy experiments were performed by chequerboard tests by combining eight doubling concentrations of EGCG with another eight dilutions of azole compounds or terbinafine. Reversion experiments with leucovorin or S-adenosylmethionine were carried out, and the content of ergosterol was determined by a spectrophotometric method.


RESULTS
EGCG is an efficient inhibitor of C. albicans DHFR (K(i) = 0.7 microM). As with other antifolates, the effects of EGCG on C. albicans can be highly attenuated by growing the cells in the presence of leucovorin. EGCG showed synergy with inhibitors of the ergosterol biosynthesis pathway in C. albicans such as azole antifungals and terbinafine. We demonstrate that by disturbing the folate metabolism, EGCG can inhibit ergosterol production. The molecular connection between the pathways is discussed.


CONCLUSIONS
EGCG acts as an antifolate compound on C. albicans, disturbing its folic acid metabolism. This effect could explain the molecular mechanism for the synergy between EGCG and azole antifungals, and could represent a starting point for therapies involving antifolates and azoles used as an alternative for the treatment of C. albicans infections.
Navarro-Martínez
María Dolores
MD
Grupo de Investigación de Enzimología, Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
García-Cánovas
Francisco
F
Rodríguez-López
José Neptuno
JN
D000935:Antifungal Agents / Q000494:pharmacology*; D001393:Azoles / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism; D002177:Candidiasis / Q000382:microbiology; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004875:Ergosterol / Q000096:biosynthesis*; D005492:Folic Acid / Q000378:metabolism*; D005493:Folic Acid Antagonists / Q000494:pharmacology*; D005656:Fungal Proteins / Q000302:isolation & purification / Q000378:metabolism; D002955:Leucovorin / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008954:Models, Biological; D009281:Naphthalenes / Q000494:pharmacology; D012436:S-Adenosylmethionine / Q000378:metabolism; D013057:Spectrum Analysis; D000077291:Terbinafine; D013762:Tetrahydrofolate Dehydrogenase / Q000302:isolation & purification / Q000378:metabolism; D014803:Vitamin B Complex / Q000494:pharmacology
D000935:Antifungal Agents; D001393:Azoles; D004791:Enzyme Inhibitors; D005493:Folic Acid Antagonists; D005656:Fungal Proteins; D009281:Naphthalenes; D014803:Vitamin B Complex; D012436:S-Adenosylmethionine; D002392:Catechin; D005492:Folic Acid; C045651:epigallocatechin gallate; D013762:Tetrahydrofolate Dehydrogenase; D000077291:Terbinafine; D002955:Leucovorin; D004875:Ergosterol