Binding of natural and synthetic polyphenols to human dihydrofolate reductase.
Dihydrofolate reductase (DHFR) is the subject of intensive investigation since it appears to be the primary target enzyme for antifolate drugs. Fluorescence quenching experiments show that the ester bond-containing tea polyphenols (-)-epigallocatechin gallate (EGCG) and (-)-epicatechin gallate (ECG) are potent inhibitors of DHFR with dissociation constants (K(D))of 0.9 and 1.8 microM, respectively, while polyphenols lacking the ester bound gallate moiety [e.g., (-)-epigallocatechin (EGC) and (-)-epicatechin (EC)] did not bind to this enzyme. To avoid stability and bioavailability problems associated with tea catechins we synthesized a methylated derivative of ECG (3-O-(3,4,5-trimethoxybenzoyl)-(-)-epicatechin; TMECG), which effectively binds to DHFR (K(D) = 2.1 microM). In alkaline solution, TMECG generates a stable quinone methide product that strongly binds to the enzyme with a K(D) of 8.2 nM. Quercetin glucuronides also bind to DHFR but its effective binding was highly dependent of the sugar residue, with quercetin-3-xyloside being the stronger inhibitor of the enzyme with a K(D) of 0.6 microM. The finding that natural polyphenols are good inhibitors of human DHFR could explain the epidemiological data on their prophylactic effects for certain forms of cancer and open a possibility for the use of natural and synthetic polyphenols in cancer chemotherapy.
Sánchez-Del-Campo
Luís
L
Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
Sáez-Ayala
Magalí
M
Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
Chazarra
Soledad
S
Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
Cabezas-Herrera
Juan
J
Servicio de Análisis Clínicos, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain.
Rodríguez-López
José Neptuno
JN
Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
D000595:Amino Acid Sequence; D001665:Binding Sites; D002392:Catechin / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry; D005493:Folic Acid Antagonists / Q000737:chemistry* / Q000494:pharmacology; D020719:Glucuronides / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D045563:Indolequinones / Q000737:chemistry / Q000494:pharmacology; D062105:Molecular Docking Simulation; D008969:Molecular Sequence Data; D059808:Polyphenols / Q000737:chemistry* / Q000494:pharmacology; D011485:Protein Binding; D011794:Quercetin / Q000737:chemistry; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry* / Q000378:metabolism
C529447:3-O-(3,4,5-trimethoxybenzoyl)epicatechin; D005493:Folic Acid Antagonists; D020719:Glucuronides; D045563:Indolequinones; D059808:Polyphenols; C068040:quinone methide; D002392:Catechin; D011794:Quercetin; D013762:Tetrahydrofolate Dehydrogenase