Activation of estrogen receptor-β by a special extract of Rheum rhaponticum (ERr 731®), its aglycones and structurally related compounds

The special extract ERr 731® from the roots of Rheum rhaponticum is the major constituent of Phytoestrol® N which has been used for the treatment of climacteric symptoms for decades. However, the molecular mode of action of ERr 731® underlying its proven clinical efficacy is not completely clarified. Therefore, we addressed the question whether ERr 731® and its aglycones trans-rhapontigenin and desoxyrhapontigenin exert their biological action via estrogen receptor-alpha -beta (ERa, ERb). The effects were compared to the structurally related compounds cis-rhapontigenin, resveratrol and piceatannol. As controls,…