4-hydroxy Estrone is a metabolite of the endogenous estrogen estrone .1 It is formed from estrone primarily by the cytochrome P450 (CYP) isoforms CYP1B1, CYP1A2, and CYP1A1. 4-hydroxy Estrone (5 µM) induces nuclear translocation of phosphorylated p53 and is protective against glutamate-induced oxidative death in HT22 hippocampal neuronal cells.2 It reduces neurodegeneration induced by kainic acid in the rat hippocampus and improves working memory in the Y-maze in rats when administered at a dose of 10 µg/animal. 4-hydroxy Estrone also inhibits proliferation of MCF-7 and MDA-MB-231 breast cancer cells with IC50 values of 30 and 38 µM, respectively.3
1.Cribb, A.E., Knight, M.J., Dryer, D., et al.Role of polymorphic human cytochrome P450 enzymes in estrone oxidationCancer Epidemiol. Biomarkers Prev.15(3)551-558(2006) 2.Choi, H.J., Lee, A.J., Kang, K.S., et al.4-Hydroxyestrone, an endogenous estrogen metabolite, can strongly protect neuronal cells against oxidative damageSci. Rep.10(1)7283(2020) 3.Seeger, H., Huober, J., Wallwiener, D., et al.Inhibition of human breast cancer cell proliferation with estradiol metabolites is as effective as with tamoxifenHorm. Metab. Res.36(5)277-280(2004)