Biochemical and molecular mechanisms of beneficial effects for human health by phytoestrogens

在这项研究中，双酚A和植物雌激素，如染料木素，比较了雌激素对人乳腺癌MCF-7细胞的雌激素活性。我们还建立了在MCF-7细胞暴露于具有雌激素活性的化学物质后，诱导雌激素应答基因PS2基因的表达。大豆苷元、柚皮素、山奈酚的雌激素活性弱于染料木素。对于雌激素类化合物的解毒途径，双酚A和植物雌激素的磺化偶联反应是由人肝微粒体催化的。在Km值的基础上，双酚A对磺基转移酶的亲和力似乎高于植物雌激素。一种耐热的苯酚-磺化转移酶ST1A3被鉴定为双酚A-磺化转移酶。然而，植物雌激素和双酚A在雌激素作用机制上没有差别。通过分析MCF-7细胞暴露于植物雌激素和双酚A后的基因表达是可能的，双酚A的毒性作用被怀疑是由于其雌激素作用。

In this study, estrogenicity of bisphenol A and phytoestrogens such as genistein was compared in human breast cancer MCF-7 cells using so called E-screen assay. We also established induction of expression of pS2 gene, an estrogen-resposive gene, after exposure of MCF-7 cells to chemicals with estrogenicity. Estrogenic activities of daidzein, naringenin, kaempfenol were weaker than that of genistein. For detoxification pathway of estrogenic compounds, sulfoconjugation of bisphenol A and phytoestrogens was catalyzed by human hepatic microsomes. On the basis of Km values, affinity of bisphenol A to sulfotransferase seemed to be higher than that of phytoestrogens. A form of thermostable phenol-sulfating sulfotransferase, ST1A3, was identified as a bisphenol A-sulfating sulfotransferase.Difference in the mechanisms of estrogenicity between phytoestrogens and bisphenol A was not, however, achieved. It would be possible by analyses of gene expression after exposure of MCF-7 cells to phytoestrogens, and bisphenol A whose toxic action is suspected due to its estrogenic action.