Miroestrol is a

phytoestrogen A phytoestrogen is a plant-derived xenoestrogen (see estrogen) not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it is a diverse group of naturally occurring nonstero ...

, a plant-derived chemical that mimics the biological activity of the hormone

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

. Miroestrol was first reportedly isolated from the Thai herb ''

Pueraria mirifica ''Pueraria mirifica'', also known as กวาวเครือ Kwao Krua (among other names), is a plant found in northern and north eastern Thailand and Myanmar. In Thailand, the plant is known as “Kwao Krua Kao”, the 'Kao' meaning white ...

'' in 1960 and thought to be responsible for the supposed rejuvenating properties of the plant. However, more recent studies have suggested that the active ingredient may actually be the closely related chemical compound deoxymiroestrol (shown below), and the reported presence of miroestrol may only have been an artifact of the isolation procedure. When deoxymiroestrol is exposed to the oxygen in air, it is converted to miroestrol.

A comparative study of the estrogenic properties of phytoestrogens found that both deoxymiroestrol and miroestrol were comparable in activity ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called " test-tube experiments", these studies in biology ...

'' to other known phytoestrogens such as

coumestrol Coumestrol is a natural organic compound in the class of phytochemicals known as coumestans. Coumestrol was first identified as a compound with estrogenic properties by E. M. Bickoff in ladino clover and alfalfa in 1957. It has garnered research ...

as 17β-oestradiol agonists. Because of their estrogenic activities, miroestrol, deoxymiroestrol, and other related compounds have been the targets of scientific research including

total synthesis Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes i ...

. Extracts of ''

'' reportedly containing miroestrol are marketed as dietary supplements intended to lead to breast enhancement in women. However, there is a lack of conclusive evidence for such claims. The Federal Trade Commission has taken legal action against marketers for these unproven claims.

References

{{Estrogen receptor modulators Phytoestrogens Natural phenols