“…Malamas et al designed 22 ( Figure 6 ), a type of BACE1 inhibitor with a pyrazolyl ring and a pyrimidine as well, which enhanced the selectivity against BACE2 and cathepsin D [ 45 ]. Moreover, Volgraf and Chen made the phenyl ring and the Ar 2 connect with an oxygen atom respectively, and this could also increase the inhibitory effect (compound 23 with an IC 50 value of 110 nM and compound 24 with an IC 50 value 0.9 nM) [ 43 , 46 ]. Besides, different structure modifications were made in pentatomic rings (compounds 25 , 26 , 27 , Figure 6 ), and these compounds all showed good BACE1 inhibitory activities as their IC 50 values ranged from 0.05 μM to 5.96 μM [ 47 , 48 ].…”