γ-secretase inhibitor; inhibits proteolytic cleavage of amyloid precursor protein (APP) over the Notch pathway. Reduces levels of Aβ in the brain (inhibits Aβ40 and Aβ42 in SH-SY5Y neuroblastoma cells with an IC50 of 0.65 nM); attenuates plaque deposition. Orally bioavailable. Purity 99%. MW (observed): 517.92