(E/Z)-4-hydroxy Tamoxifen-d₅

(E/Z)-4-hydroxy Tamoxifen-d₅ is intended for use as an internal standard for the quantification of (E/Z)-4-hydroxy tamoxifen (Item No. 17308) by GC- or LC-MS. (E/Z)-4-hydroxy Tamoxifen is a mixture of (E)-4-hydroxy tamoxifen and (Z)-4-hydroxy tamoxifen.¹ (Z)-4-hydroxy Tamoxifen is an active metabolite of the estrogen receptor antagonist tamoxifen (Item Nos. 13258 | 11629) and is formed from tamoxifen by the cytochrome P450 (CYP) isoform CYP2D6. (Z)-4-hydroxy Tamoxifen (100 nM) inhibits 17β-estradiol-induced increases in the mRNA encoding progesterone receptor in MCF-7 breast cancer cells.² (Z)-4-hydroxy Tamoxifen inhibits the proliferation of MCF-7 and MDA-MB-231 breast cancer cells (IC₅₀s = 27 and 18 µM, respectively).³

WARNING This product is not for human or veterinary use.

1. Desta, Z., Ward, B.A., Soukhova, N.V., et al. Comprehensive evaluation of tamoxifen sequential biotransformation by the human cytochrome P450 system in vitro: Prominent roles for CYP3A and CYP2D6. J. Pharmacol. Exp. Ther. 310(3), 1062-1075 (2004).

2. Y.C., L., Desta, Z., Flockhart, D.A., et al. Endoxifen (4-hydroxy-N-desmethyl-tamoxifen) has anti-estrogenic effects in breast cancer cells with potency similar to 4-hydroxy-tamoxifen. Cancer Chemother. Pharmacol. 55(5), 471-478 (2005).

3. Seeger, H., Huober, J., Wallwiener, D., et al. Inhibition of human breast cancer cell proliferation with estradiol metabolites is as effective as with tamoxifen. Horm. Metab. Res. 36(5), 277-280 (2004).