TABLE 5

Inhibition of human cytosolic aldehyde oxidase-catalyzed phthalazine oxidation activity by estrogen antagonists and selective estrogen receptor modulators

IC50 values are means ± S.E.


Agent

IC50
μM
Clomifene 2.5 ± 0.6
Coumestrol 0.48 ± 0.03
Diethylstilbestrol 0.46 ± 0.05
Droloxifene 0.79 ± 0.11
Estradiola 0.29 ± 0.07
Estrone 0.43 ± 0.09
Ethinyl estradiola 0.57 ± 0.15
Fulvestrantb 0.66 ± 0.10
Genistein 0.34 ± 0.03
GW5638c 57 ± 39
4-Hydroxytamoxifen 0.45 ± 0.07
Levormeloxifene 1.0 ± 0.1
Nafoxidine 0.50 ± 0.14
Raloxifened 0.0057 ± 0.0004
Tamoxifena
2.2 ± 1.5
  • a Denotes data from Obach et al. (2004).

  • b The inhibition demonstrated by fulvestrant topped out at 74% at concentrations above 1.5 μM. This could be due to solubility limitations. Data gathered at fulvestrant concentrations above 5 μM were not included in the calculation of IC50.

  • c Estimated value. The highest concentration tested was 50 μM.

  • d Combined value from previously reported values and additional measurements.