title: Activation of estrogen receptor-beta by a special extract of Rheum rhaponticum (ERr 731), its aglycones and structurally related compounds.
abstract: The special extract ERr 731 from the roots of Rheum rhaponticum is the major constituent of Phytoestrol N which is used for the treatment of climacteric symptoms in menopausal women. However, the molecular mode of action of ERr 731 was unknown. For the first time, ERr 731 and its aglycones trans-rhapontigenin and desoxyrhapontigenin were investigated with regard to the activation of the estrogen receptor-alpha or estrogen receptor-beta (ERalpha, ERbeta). The related hydroxystilbenes cis-rhapontigenin, resveratrol and piceatannol were studied as comparators. As controls, 17beta-estradiol or the selective ERalpha-(propylpyrazoltriol) or ERbeta-agonists (diarylpropionitril) were used. Neither in ERalpha-expressing yeast cells, in the ERalpha-responsive Ishikawa cells, nor in human endometrial HEC-1B cells transiently transfected with the ERalpha an activation of ERalpha by ERr 731 or the other single compounds was detected. Furthermore, an antiestrogenic effect was not observed. In contrast in human endometrial HEC-1B cells transiently transfected with the ERbeta, 100 ng/ml ERr 731 and the single compounds significantly induced the ERbeta-coupled luciferase activity in a range comparable to 10(-8)M 17beta-estradiol. All effects were abolished with the pure ER antagonist ICI 182780, indicating an ER-specific effect. The ERbeta agonistic activity by ERr 731 could be of importance for its clinical use, as central functions relevant to climacteric complaints are proposed to be mediated via ERbeta activation.
authors: Molekulare Zellphysiologie und Endokrinologie, Technische Universität Dresden, 01062 Dresden, Germany.
authors: Jannette
authors: J
authors: Wober
authors: Frank
authors: F
authors: Möller
authors: Tobias
authors: T
authors: Richter
authors: Catharina
authors: C
authors: Unger
authors: Carmen
authors: C
authors: Weigt
authors: Anett
authors: A
authors: Jandausch
authors: Oliver
authors: O
authors: Zierau
authors: Reinhard
authors: R
authors: Rettenberger
authors: Marietta
authors: M
authors: Kaszkin-Bettag
authors: Günter
authors: G
authors: Vollmer
mesh_terms: D045744:Cell Line, Tumor; D047629:Estrogen Receptor beta / Q000819:agonists*; D006801:Humans; D015394:Molecular Structure; D010936:Plant Extracts / Q000494:pharmacology*; D012250:Rheum / Q000737:chemistry*
chemical_list: D047629:Estrogen Receptor beta; D010936:Plant Extracts