title: Pigments in green tea leaves (Camellia sinensis) suppress transformation of the aryl hydrocarbon receptor induced by dioxin.
abstract: Environmental contaminants such as dioxins enter the body mainly through diet and cause various toxicities through transformation of the aryl hydrocarbon receptor (AhR). We previously reported that certain natural flavonoids at the dietary level suppress the AhR transformation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In this study, we identified lutein and chlorophyll a and b from green tea leaves as the novel antagonists for AhR. These active compounds suppressed AhR transformation dose-dependently with the 50% inhibitory concentration (IC(50)) values against 0.1 nM TCDD-induced AhR transformation at 3.2, 5.0, and 5.9 microM, respectively. (-)-Epigallocatechin gallate, which is the most abundant flavonoid in green tea leaves, also showed stronger suppressive effects than did other major tea components, with the IC(50) value of 1.7 microM. Thus, these pigments of green tea leaves have the potential to protect from dioxin toxicity through the suppression of AhR transformation.
authors.affiliation: Laboratory of Food and Nutritional Chemistry, Faculty of Agriculture, Kobe University, Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan.
authors.forename: Itsuko
authors.initials: I
authors.lastname: Fukuda
authors.forename: Iwao
authors.initials: I
authors.lastname: Sakane
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Yabushita
authors.forename: Rie
authors.initials: R
authors.lastname: Kodoi
authors.forename: Shin
authors.initials: S
authors.lastname: Nishiumi
authors.forename: Takami
authors.initials: T
authors.lastname: Kakuda
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Sawamura
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kanazawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ashida
mesh_terms: D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002734:Chlorophyll / Q000494:pharmacology; D005419:Flavonoids / Q000032:analysis / Q000494:pharmacology; D014975:Lutein / Q000494:pharmacology; D010636:Phenols / Q000032:analysis / Q000494:pharmacology; D010860:Pigments, Biological / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D059808:Polyphenols; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D005419:Flavonoids; D010636:Phenols; D010860:Pigments, Biological; D010936:Plant Extracts; D000072317:Polychlorinated Dibenzodioxins; D059808:Polyphenols; D018336:Receptors, Aryl Hydrocarbon; D002734:Chlorophyll; D002392:Catechin; C045651:epigallocatechin gallate; D014975:Lutein