Miroestrol is a phytoestrogen, a plant-derived chemical that mimics the biological activity of the hormone estrogen. Miroestrol was first reportedly isolated from the Thai herb Pueraria mirifica 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 deoxymiroestrol was similar in activity to other known phytoestrogens, such as coumestrol, but that miroestrol was significantly less active. Because of their estrogenic activities, miroestrol, deoxymiroestrol, and other related compounds have been the targets of scientific research including total synthesis.
Extracts of Pueraria mirifica reportedly containing miroestrol are marketed as dietary supplements intended to lead to breast enhancement in women. However, there is no scientific basis for such claims. The Federal Trade Commission has taken legal action against marketers for these fraudulent claims.
^Chansakaow, S.; Ishikawa, T.; Seki, H.; Sekine, K.; Okada, M.; Chaichantipyuth, C. (2000). "Identification of Deoxymiroestrol as the Actual Rejuvenating Principle of "Kwao Keur", Pueraria mirifica. The Known Miroestrol may be an Artifact". Journal of Natural Products63 (2): 173–175. doi:10.1021/np990547v. PMID10691701.
^Matsumura, A.; Ghosh, A.; Pope, G. S.; Darbre, P. D. (2005). "Comparative Study of Estrogenic Properties of eight Phytoestrogens in MCF7 Human Breast Cancer Cells". Journal of Steroid Biochemistry and Molecular Biology94 (5): 431–443. doi:10.1016/j.jsbmb.2004.12.041. PMID15876408.
^Ito, F.; Kumamoto, T.; Yamaguchi, K.; Ishikawa, T. (2009). "Synthetic Studies toward Miroestrols: Trials for Elongation of the Methyl Group of 5-Substituted 2-Methyl-2-Cyclohexanone to 3-Methyl-2-Butenyl Function". Tetrahedron65 (4): 771–785. doi:10.1016/j.tet.2008.11.055.