Daidzein-d₄is intended for use as an internal standard for the quantification of daidzein by GC- or LC-MS. Daidzein is an isoflavone phytoestrogenic compound that has been found in soybeans and other legumes.¹It binds to estrogen receptor β (ERβ; K_i= 2.8 µM) but not ERα at concentrations up to 1 mM.²It is estrogenicin vitro, increasing gene transcription mediated by the estrogen response element (ERE) in a reporter assay in an ERβ-dependent manner (EC₅₀= 2.8 µM for MCF-7 cells expressing ERβ).¹Daidzein is an inhibitor of carbonic anhydrase (CA) that is selective for carbonic CAVII and CAXII (K_is = 4.2 and 56 nM, respectively) over CAI, II, and IV (K_is = >10,000, >10,000, and 718.7 nM, respectively).³It reduces tumor growth in a PC3 prostate cancer mouse orthotopic model when administered at a dose of 50 mg/kg per day and potentiates the effects of radiation therapy.⁴

1.Harris, D.M., Besselink, E., Henning, S.M., et al.Phytoestrogens induce differential estrogen receptor alpha- or beta-mediated responses in transfected breast cancer cellsExp. Biol. Med. (Maywood)230(8)558-568(2005) 2.Zhao, L., and Brinton, R.D.Structure-based virtual screening for plant-based ERβ-selective ligands as potential preventative therapy against age-related neurodegenerative diseasesJ. Med. Chem.48(10)3463-3466(2005) 3.Karioti, A., Ceruso, M., Carta, F., et al.New natural product carbonic anhydrase inhibitors incorporating phenol moietiesBioorg. Med. Chem.23(22)7219-7225(2015) 4.Singh-Gupta, V., Zhang, H., Yunker, C.K., et al.Daidzein effect on hormone refractory prostate cancer in vitro and in vivo compared to genistein and soy extract: Potentiation of radiotherapyPharm. Res.27(6)1115-1127(2010)