title: Binding of natural and synthetic polyphenols to human dihydrofolate reductase.
abstract: 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.
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
authors.forename: Luís
authors.initials: L
authors.lastname: Sánchez-Del-Campo
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
authors.forename: Magalí
authors.initials: M
authors.lastname: Sáez-Ayala
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
authors.forename: Soledad
authors.initials: S
authors.lastname: Chazarra
authors.affiliation: Servicio de Análisis Clínicos, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Cabezas-Herrera
authors.affiliation: Departamento de Bioquímica y Biología Molecular A, Facultad de Biología, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
authors.forename: José Neptuno
authors.initials: JN
authors.lastname: Rodríguez-López
mesh_terms: 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
chemical_list: 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