title: Structure-activity relationships of anthraquinones on the suppression of DNA-binding activity of the aryl hydrocarbon receptor induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin.
abstract: Anthraquinones are widely present in plant kingdom, and clinically used as laxatives. Environmental contaminants, dioxins, develop various adverse effects through transformation of a cytosolic aryl hydrocarbon receptor (AhR). We investigated the effects of 18 anthraquinones and 7 of their structurally related compounds on transformation of the AhR estimated by its DNA-binding activity in the cell-free system. 1,4-Dihydroxyanthraquinone (quinizarin), 1,5-dihydroxyanthraquinone (anthrarufin), 1,8-dihydroxyanthraquinone (danthron), and 5-hydroxy-1,4-naphthoquinone (juglone) strongly suppressed DNA-binding activity of the AhR induced by 0.1 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), with their IC(50) values around 1 muM. On the other hand, anthraquinone, 2,6-dihydroxyanthraquinone (anthraflavic acid), and 2-hydroxy-1,4-naphthalendione (lawsone) showed moderate effects. Quantitative structure-activity relationships analysis demonstrated that hydroxyl groups at C1 or C4 but not C3 position of anthraquinone structure are critical for the suppressive effects. In addition, all compounds except lawsone had no agonistic effect. The suppressive effects of anthraquinones in a cultured cell system were also confirmed. In human hepatoma HepG2 cells, chrysophanol, danthron, and rhein also suppressed the DNA-binding activity in a dose-dependent manner, although aloe-emodin showed a moderate effect. The findings of this study may be useful for the design of the novel antagonists of the AhR.
authors.affiliation: Research Center for Food Safety and Security, Graduate School of Agricultural Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo 657-8501, Japan. itsuko@silver.kobe-u.ac.jp
authors.forename: Itsuko
authors.initials: I
authors.lastname: Fukuda
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kaneko
authors.forename: Shin
authors.initials: S
authors.lastname: Nishiumi
authors.forename: Masaya
authors.initials: M
authors.lastname: Kawase
authors.forename: Rika
authors.initials: R
authors.lastname: Nishikiori
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Fujitake
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ashida
mesh_terms: D000880:Anthraquinones / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D021281:Quantitative Structure-Activity Relationship; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*
chemical_list: D000880:Anthraquinones; D004268:DNA-Binding Proteins; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon