Influence of Rheum rhaponticum, Cimicifuga racemosa and Trifolium pratense extracts on breast cancer cell proliferation

Abstract

<b>Background:</b> Extracts from the Siberian rhubarb (<i>Rheum rhaponticum</i>) as well as those from red clover (<i>Trifolium pratense</i>) contain phytoestrogens, while black cohosh (<i>Cimicifuga racemosa</i>) may alternatively modify estrogen receptor activity. They have been used for the treatment of menopausal symptoms. Little is known about their effects on estrogen-dependent tumor cells. <b>Materials and Methods:</b> The influence of a standardized preparation of <i>Rheum rhaponticum</i> (ERr 731®), a well described preparation of <i>Trifolium pratense</i> (Menoflavon® extra) and a commercial preparation of <i>Cimicifuga racemosa</i> (Cefakliman® mono) on proliferation of breast cancer cells was analyzed by the crystal violet assay in estrogen-receptor (ER) dependent (MCF-7) and ER independent (MDA-MB-231) cell-based systems. As positive control for the proliferation of MCF-7 cells we used 17 β-estradiol. The estrogen specificity was demonstrated by applying the ER antagonist ICI182,780 to the cell culture. <b>Results:</b> <i>Rheum rhaponticum</i> and <i>Cimicifuga racemosa</i> did not induce cell proliferation of MCF-7 or MDA-MB-231 cells. High concentration (100 µg/mL) of <i>Rheum rhaponticum</i> and <i>Trifolium pratense</i> extract were toxic to both cell lines. <i>Trifolium pratense</i> slightly increased proliferation of MCF-7 cells in a dose dependent manner, but this effect was not estrogen specific. <b>Conclusion:</b> Our results demonstrate that the used extracts have no estrogen specific impact on the proliferation of ER dependent and ER independent breast cancer cells.