(+/-)-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. It is a weak estrogenic agonist, and competitive inhibitor of 17β-estradiol at the estradiol receptor. It inhibits 12-O-tetradecanoylphorbol 13-acetate (TPA)-induced neoplastic cell transformation by targeting the MEK/ERK/p90RSK/activator protein-1 signalling pathway. It functions as a DHT blocker.
B.Y.Tang; N.R.Adams. Effect of equol on oestrogen receptors and on synthesis of DNA and protein in the immature rat uterus. Journal of Endocrinology. 1980, 85,(2), 291-297.
R.S.Muthyala; Y.H Ju; S.Sheng; L.D.Williams; D.R.Doerge; B.S.Katzenellenbogen; W.G.Helferich; J.A.Katzenellenbogen. 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. 2004, 12,(6), 1559-1567.