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  • 182541 - Aromatase Inhibitor II, Letrozole - CAS 112809-51-5 - Calbiochem

182541 Sigma-Aldrich

Aromatase Inhibitor II, Letrozole - CAS 112809-51-5 - Calbiochem

The Aromatase Inhibitor II, Letrozole, also referenced under CAS 112809-51-5, controls the biological activity of Aromatase.

Synonym: 4,4ʹ-(1H-1,2,4-Triazol-1-ylmethylene)dibenzonitrile, 1-( bis-(4-Cyanophenyl)methyl)-1,2,4-triazole

  • CAS Number 112809-51-5

  • Empirical Formula (Hill Notation) C17H11N5

  • Molecular Weight 285.30



Related Categories Bioactive Small Molecules, Biochemicals and Reagents, Cell Biology More...
packaging   25 mg in Glass bottle (182541-25MG)
color   white
form   powder
shipped in   ambient
solubility   DMSO: 50 mg/mL, clear, colorless
  ethanol: <5 mg/mL (partially soluble)
storage condition   OK to freeze
  protect from light
brand family   Calbiochem
purity   ≥99% by HPLC
storage conditions   +2C to +8C


General description

An orally bioavailable non-steroidal triazole compound that acts as a potent and selective inhibitor of aromatase (IC50 = 140, 350 and 450 pM in Dex-treated fibroblasts, MCF-7Ca, and JEG-3 cells, respectively). Competitively, but reversibly binds to the heme iron of aromatase. Does not affect the synthesis of adrenal mineralocorticoid or glucocorticoids. Reported to be highly effective as an anti-estrogenic and anti-proliferative agent in estrogen-rich tumors. Also delays the fusing of the growth plates in adolescents and enhances the effectiveness of growth hormone. Shown to synergistically induce apoptosis and cause tumor regression when combined with IGF-1R inhibitors.

Other Notes

Hou, X., et al. 2011. Cancer Res.71, 7597.
Lisztwan, J., et al. 2008. Breast Cancer Res.10, R56.
Miller, W.R., et al. 2002. Cancer Invest.20 (Suppl 2), 15.
Long, B.J., et al. 1998. J. Steroid Biochem. Molec. Biol.67, 293.


25 mg in Glass bottle

Packaged under inert gas


Following reconstitution, aliquot and freeze (-20°C). Stock solutions are stable for up to 6 months at -20°C.


Standard Handling (A)

Safety & Documentation

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Certificate of Analysis

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