(±)-Equol

Equol is a nonsteroidal estrogen produced from the metabolism of the isoflavonoid phytoestrogen daidzein by human intestinal microflora.^1,2 The estrogen receptor (ER) binding activity of the naturally occurring (S)-enantiomer demonstrates greater affinity toward ERβ while the (R)-enantiomer demonstrates greater affinity towards ERα.^1,2 Synthesized as a racemic mixture, (±)-equol exhibits EC₅₀ values of 200 and 74 nM for human ERα and ERβ, respectively and induces breast cancer cell proliferation in vitro at concentrations as low as 100 nM.^2,3

WARNING This product is not for human or veterinary use.

1. Setchell, K.D.R., Clerici, C., Lephart, E.D., et al. S-equol, a potent ligand for estrogen receptor β, is the exclusive enantiomeric form of the soy isoflavone metabolite produced by human intestinal bacterial flora. Am. J. Clin. Nutr. 81(5), 1072-1079 (2005).

2. Muthyala, R.S., Ju, Y.H., Sheng, S., et al. Equol, a natural estrogenic metabolite from soy isoflavones: Convenient preparation and resolution of R- and S-equols and their differing binding and biological activity through estrogen receptors alpha and beta. Bioorg. Med. Chem. 12(6), 1559-1567 (2004).

3. Liu, H., Du, J., Hu, C., et al. Delayed activation of extracellular-signal-regulated kinase ½ is involved in genistein- and equol-induced cell proliferation and estrogen-receptor-α-mediated transcription in MCF-7 breast cancer cells. J. Nutr. Biochem. 21(5), 390-396 (2009).