Exploiting the hydrophobic terrain in fucosidases with aryl-substituted pyrrolidine iminosugars

Fucosidase inhibition shows potential in numerous therapeutic contexts. Substitution of fucose-like iminosugars with hydrophobic "aglycons" yields significant improvements in potency of fucosidase inhibition. Here we have prepared three new 2-aryl-3,4-dihydroxy-5-methylpyrrolidines featuring phenyl substituents in variable orientations with respect to the iminocyclitol core and at various distances from it to explore the key binding interactions that stabilise the enzyme-inhibitor complex. The presence of a triazole linker in one structure resulted in nanomolar inhibition of the fucosidase from bovine kidney (Ki =4.8 nM), thus giving rise to one of the most potent pyrrolidine-type inhibitors of this enzyme known to date.