Black cohosh

Although the mechanism by which black cohosh relieves menopausal symptoms is unknown, several hypotheses have been made. It is believed to act through the following mechanisms/effects:

1) as a selective estrogen receptor modulator 2) through serotonergic pathways 3) as an antioxidant 4) on inflammatory pathways

The primary active component of the black cohosh root is believed to be the terpene glycoside fraction, including actein and cimifugoside. The triterpenes are one of the most ubiquitous and diverse groups of plant natural products. They are classified as complex molecules that are beyond the reach of chemical synthesis in the laboratory. Simple triterpenes are constituents of surface waxes and specialized plant membranes and may possibly serve as signaling molecules. More complex glycosylated triterpenes (also known as saponins) provide protection against pathogens and pests. The rhizome (stem portion of the plant) also contains other potentially biologically active substances, including alkaloids, flavonoids, and tannins. The therapeutic activity of black cohosh was initially believed to be the activation of estrogen receptors; however, more recent studies show that although some components of the extract bind to at least one subtype of estrogen receptor, the receptor binding produces very little (if any) estrogenic effect, and may selectively block some of the effects.

An early study reported that treatment with black cohosh leads to a decrease in luteinizing hormone (LH) levels consistent with its purported estrogenic effect. Despite this, more recent studies have shown no effect on levels of LH, follicle-stimulating hormone (FSH), or prolactin. To this day it is unclear whether black cohosh exerts its effect via estrogen receptors or through another mechanism.

One study observed that while the most prominent triterpene in black cohosh, known as 23-epi-26-deoxyactein, inhibits cytokine-induced nitric oxide production in brain microglial cells, the complete black cohosh extract demonstrated to enhance this pathway. A variety of activities have been reported for black cohosh and its compounds, however, the absorption and tissue distribution of these compounds is not known.

Cimicifuga racemosa (black cohosh) is used most often to treat symptoms occurring during menopause. However, in recent years, several concerns regarding its safety have been voiced.