In vitro effects of the Cimicifuga racemosa extract BNO 1055.
Level 5 - mechanism / opinion, no new human data
In vitro bench research
PubMed 12609557 · doi:10.1016/s0378-5122(02)00346-8
What was done
Researchers evaluated the in vitro binding properties of the Cimicifuga racemosa (black cohosh) extract BNO 1055. They performed subtype-specific ligand-binding assays using recombinant estrogen receptors (ERalpha and ERbeta) and recombinant dopamine D2 receptor protein. They also tested the extract's ability to displace radiolabeled estradiol from porcine and human endometrial cytosol preparations and performed countercurrent chromatography to fractionate the extract.
What was found
The abstract reports no numerical binding constants or concentrations. Qualitatively, Cimicifuga racemosa extract BNO 1055 displaced radiolabeled estradiol from binding sites in porcine and human endometrial cytosol, but failed to displace tracer from recombinant ERalpha or ERbeta proteins. The extract demonstrated binding activity at the dopamine D2 receptor. Countercurrent chromatography separated the endometrial estrogenic-binding activity and the dopaminergic activity into two distinct fractions.
Why it matters
These findings suggest that black cohosh does not bind classical recombinant ERalpha or ERbeta despite binding to endometrial cytosol, and that dopaminergic pathways may contribute to its clinical effects in climacteric complaints.
Limits
This was an entirely in vitro binding study using tissue extracts and recombinant proteins with no living cell functional assays, animal models, or human clinical outcomes. The abstract provides no quantitative data (such as IC50 or Ki values), concentrations tested, or chemical identification of the active substances.
Cited by
- context Clinical studies show black cohosh acts on serotonin and dopamine pathways in the hypothalamus to aid in temperature regulation and mood.