Black cohosh

One of the principal cycloartanol-type triterpene glycosides regarded as a marker for black cohosh activity. It has been associated with vasoactive (hypotensive, peripheral vasodilatory) effects and, in vitro, with modulation of cell signalling; it does not bind classical estrogen receptors, consistent with the herb's largely non-estrogenic mechanism.

A dominant, chemically stable triterpene glycoside widely used to standardise commercial extracts. Contributes to the triterpene fraction credited with the extract's climacteric-symptom activity.

Members of the cimicifugoside/cimiracemoside series of cycloartane glycosides characteristic of the genus. Part of the triterpene complex implicated in the herb's central and vasomotor effects rather than direct estrogenic stimulation.

Cimigenol-based glycosides form part of the diverse triterpene glycoside pool. They are of interest chiefly as chemotaxonomic and quality-control markers and contribute to the overall bioactive triterpene content.

Caffeic/ferulic-acid-derived esters unique to Cimicifuga. They show antioxidant activity and mild weak-estrogenic/serotonergic-related activity in vitro and serve as authentication markers distinguishing genuine Actaea racemosa from Asian adulterant species.

Simple phenolic acids contributing antioxidant and anti-inflammatory activity to the whole extract.

Serotonin-like constituents that bind and act as partial agonists at 5-HT7 (and 5-HT1A) receptors in vitro, providing a mechanistic basis for the proposed serotonergic contribution to relief of hot flushes and mood/sleep symptoms.

Early reports described the isoflavone formononetin, but subsequent analyses of authenticated material have generally failed to confirm its presence; its absence supports the view that black cohosh is not meaningfully phytoestrogenic.

Commercial products are typically standardised isopropanolic or ethanolic dry extracts delivering roughly 20-40 mg extract (about 1 mg triterpene glycosides as 23-epi-26-deoxyactein) once or twice daily. Because rare idiosyncratic liver injury has been reported, use is generally limited to 6 months, liver-related symptoms should prompt discontinuation, and use is discouraged in existing liver disease or during pregnancy.

Traditionally the dried root was simmered as a decoction or prepared as an ethanolic tincture. The fresh root and overdoses can cause frontal headache, nausea, dizziness and slowed heart rate, so only modest amounts of well-identified dried material were used. Should not be confused with toxic 'blue cohosh' (Caulophyllum thalictroides), a different plant.

Eighty-four early post-menopausal women received 6.5 mg/day of dried black cohosh root extract or placebo for 8 weeks. Greene Climacteric Scale total scores fell significantly more with black cohosh at weeks 4 and 8 (about 12.9 points greater reduction at week 8), with improvement across vasomotor, psychological and somatic subscales and no reported side effects.

In women (many with a history of breast cancer) black cohosh 20 mg twice daily produced a mean 20% reduction in hot-flash score versus 27% for placebo, a non-significant difference. The trial found no evidence that black cohosh reduced hot flashes more than placebo, illustrating the mixed efficacy data for this indication.

This Cochrane review of 16 trials (>2000 women) concluded there was insufficient evidence to support the use of black cohosh for menopausal symptoms, citing heterogeneity and methodological limitations while noting the herb was generally well tolerated in the short term.

The knotty black root was decocted for rheumatism, fatigue, fever, sore throat, gynaecological and childbirth complaints, and snakebite; this Indigenous use introduced the plant to European settlers.

Eclectic physicians valued 'macrotys' (Cimicifuga racemosa) as a leading remedy for acute rheumatism, neuralgia, myalgia and gynaecological/menstrual complaints, cementing its reputation in American botanical medicine.

Approved black cohosh rhizome for premenstrual discomfort, dysmenorrhoea and climacteric (menopausal) neurovegetative complaints, underpinning its modern European use for menopausal symptoms.