A δ-secretase inhibitor (IC50 = 0.7 µM); selective for δ-secretase over cathepsin S, cathepsin L, caspase-3, and caspase-8 (IC50s = >200, >200, 31.86, and 86.71 µM, respectively); inhibits δ-secretase in Pala cells (IC50 = 0.8 µM); inhibits glucose-oxygen deprivation-induced cell death in primary mouse neurons at 2 µM; inhibits brain δ-secretase in wild-type mice and transgenic mice expressing human tauP301S at 10 mg/kg per day; reduces the number of cortical and hippocampal tau N368-positive neurons, restores synaptic dysfunction, and improves spatial learning and memory in transgenic mice expressing human tauP301S; reduces hippocampal Aβ deposition and attenuates cognitive deficits in the 5XFAD transgenic mouse model of Alzheimer’s disease at 10 mg/kg