Chemoenzymatic and Protecting-Group-Free Synthesis of 1,4-Substituted 1,2,3-Triazole-α-d-glucosides with Potent Inhibitory Activity toward Lysosomal α-Glucosidase.

α-Glucosyl triazoles have rarely been tested as α-glucosidase inhibitors, partly due to inefficient synthesis of their precursor α-d-glucosylazide (). Glycosynthase enzymes, made by nucleophile mutations of retaining β-glucosidases, produce in chemical rescue experiments. glucosyl hydrolase 116 β-glucosidase (GH116) E441G nucleophile mutant catalyzed synthesis of from sodium azide and NP-β-d-glucoside (NPGlc) or cellobiose in aqueous medium at 45 °C. The NPGlc and azide reaction product was purified by Sephadex LH-20 column chromatography to yield 280 mg of pure (68% yield). was successfully conjugated with alkynes attached to different functional groups, including aryl, ether, amine, amide, ester, alcohol, and flavone via copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry reactions. These reactions afforded the 1,4-substituted 1,2,3-triazole-α-d-glucoside derivatives without protection and deprotection. Several of these glucosyl triazoles exhibited strong inhibition of human lysosomal α-glucosidase, with IC values for and more than 60-fold lower than that of the commercial α-glucosidase inhibitor acarbose.