Possible Interaction: Tamoxifen and Daidzein

“At a concentration of 100 microM, Da enhanced 1 microM E(2)-induced VTG transcription by …)-induced VTG mRNA expression in a dose-dependent fashion from 1 to 100 microM. Tamoxifen … daidzein , alone or in combination with 1 microM of E(… 10 microM E(2)-induced VTG mRNA expression.”

“Interestingly, coadministration of TAM with either daidzein or genistein produced tumors of greater size than with TAM alone.”

“Moreover, tamoxifen , though known as the antiestrogen compound, was found to only partly block the binding of daidzein to nAChRs.”

“Moreover, the ameliorating effects of daidzin or daidzein were antagonized by tamoxifen (1 mg/kg), the nonspecific estrogen receptor antagonist.”

“Results showed that DAI (10 microg/mL) increased germ cell numbers, which were inhibited by cotreatment with the estrogen receptor antagonist tamoxifen at 0.1 microg/mL. Exposure to A1254 (10 microg/mL) reduced superoxide dismutase activity and glutathione content but increased lipid peroxidation significantly.”

“Results showed that DAI significantly increased the number of germ cells (P<0.05) and this stimulating effect was inhibited by tamoxifen in a dose-dependent manner.”

“This study conclusively shows for the first time the combination of daidzein with tamoxifen produces increased protection against mammary carcinogenesis, while the combination of genistein with tamoxifen produces an opposing effect when compared with tamoxifen alone.”

“Moreover, the effect of daidzein (10(-5) M) in elevating cellular protein content and alkaline phosphatase activity was inhibited completely by the presence of tamoxifen (10(-6) M), suggesting that the effect of the isoflavone is mediated partly through estrogen action.”