Studies on the endocrine effects of the contents of Cimicifuga racemosa 2. In vitro binding of compounds to estrogen receptors.

The endocrine activity of compounds of the rhizome of CIMICIFUGA RACEMOSA can be demonstrated in the IN VIVO model of the ovariectomized rat as well as in the IN VITRO system of the estrogen receptor assay. A reduction of the serum levels of luteinizing hormone in ovariectomized rats takes place upon application of a methanol-extract. This extract contains substances, which are able to bind to estrogen receptors of rat uteri. Using the estrogen receptor assay as a pharmacological testsystem to determine the activity of different fractions, the chromatographic separation of the methanol-extract resulted in at least three different endocrine active compounds. One of these could be identified as the isoflavon Formononetine. The endocrine activity of this isoflavon was characterized in both described testsystems. It can be shown that Formononetine is a competitor in the estrogen receptor assay, but failed to reduce the serum levels of luteinizing hormone in overiectomized rats.