“…A number of small molecule inhibitors against β- N -acetylhexosaminidases have been reported. These include PUGNAc 15 ( 1 ), Nagstatin 16 ( 2 ), NAG-thiazoline 17 ( 3 ), pyrimethamine 18 ( 4 ), iminocyclitols 19 , 20 , and naphthalimides 21–24 . Among these, PUGNAc, Nagstatin, and NAG-thiazoline are the three classic potent inhibitors, which however show non-selectivity between GH20 and GH84 β- N -acetylhexosaminidases 4 , 25 .…”