Aromatase Inhibitor II, Letrozole Product information 
Form  White powder 
Molar mass  285.3 
Protect from Light  Yes 
Packaged under inert gas  Yes 
Purity  ≥99% by HPLC 
Solubility  DMSO 
Chemical formula  C17H11N5 
CAS number  112809-51-5 
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