Daidzein belongs to the isoflavone class of flavonoids. It is also classified as a phytoestrogen since it is a plant-derived nonsteroidal compound that possesses estrogen-like biological activity. Daidzein has been found to have both weak estrogenic and weak anti-estrogenic effects. Daidzein is the aglycone (aglucon) of daidzin. The isoflavone is found naturally as the glycoside daidzin and as the glycosides 6"-O-malonylgenistin and 6"-O-acetyldaidzin. Daidzein and its glycosides are mainly found in legumes, such as soybeans and chickpeas. Soybeans and soy foods are the major dietary sources of these substances. Daidzein glycosides are the second most abundant isoflavones in soybeans and soy foods; genistein glycosides are the most abundant. Nonfermented soy foods, such as tofu, contain daidzein, principally in its glycoside forms. Fermented soy foods, such as tempeh and miso, contain significant levels of the aglycone. Daidzein is Used to treat climacteric syndrome, prostatic cancer, breast cancer, cardiac disease, angiocardiopathy