Screening and Mechanism-Based Evaluation of Estrogenic Botanical Extracts
Pp. 159-186 (28)
Cassia R. Overk and Judy L. Bolton
Symptoms associated with menopause can greatly affect the quality of life for
women. Botanical dietary supplements have been viewed by the public as safe and effective
despite a lack of evidence indicating an urgent necessity to standardize these supplements
chemically and biologically. Seventeen plants were evaluated for estrogenic biological
activity using standard assays: competitive estrogen receptor (ER) binding assay for both
alpha and beta subtypes, transient transfection of the estrogen response element (ERE)
luciferase plasmid into MCF-7 cells expressing either ER alpha or ER beta, and the Ishikawa
alkaline phosphatase induction assay for both estrogenic and antiestrogenic activities. Based
on the combination of data pooled from these assays, the following was determined: a) a
high rate of false positive activity for the competitive binding assays, b) some extracts had
estrogenic activity despite a lack of ability to bind the ER, c) one extract exhibited selective
estrogen receptor modulator (SERM) activity, and d) several extracts show
additive/synergistic activity. Taken together, these data indicate a need to reprioritize the
order in which the bioassays are performed for maximal efficiency of programs using
bioassay-guided fractionation. In addition, possible explanations for the conflicts in the
literature over the estrogenicity of Cimicifuga racemosa (black cohosh) are suggested.
Botanicals, estrogen, dietary supplements, menopause, selective
estrogen receptor modulators.
UIC/NIH Center for Botanical Dietary Supplements Research and Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago, 833 S. Wood St., M/C 781, Chicago, IL 60612, USA.