BACE1 and Alzheimer disease: Since the advent of cholinesterase inhibitors (ChEIs) and N-methyl-d-aspartate (NMDA) receptor antagonist, the two drug classes currently available for AD treatment, extensive research has been conducted to find out novel therapeutic targets to treat AD, including butyrylcholinesterase (BuChE), β-secretase (BACE1), tau protein and related enzymes (e.g., GSK-3β), and oxidative stress [123].