A two-step O- to C-glycosidic bond rearrangement using complementary glycosyltransferase activities

Abstract

An efficient 2'-O- to 3'-C-β-d-glucosidic bond rearrangement on the dihydrochalcone phloretin to convert phlorizin into nothofagin was achieved by combining complementary O-glycosyltransferase (OGT) and C-glycosyltransferase (CGT) activities in a one-pot transformation containing catalytic amounts of uridine 5'-diphosphate (UDP). Two separate enzymes or a single engineered dual-specific O/CGT were applied. Overall (quantitative) conversion occurred in two steps via intermediary UDP-glucose and phloretin.

Enzymatic Synthesis of Acylphloroglucinol 3‐C‐Glucosides from 2‐O‐Glucosides using a C‐Glycosyltransferase from Mangifera indica

“…However, this conversion of 1 into 1 a was not observed with only MiCGT (Figure S3 in the Supporting Information) or Os CGT . These unique results inspired our interest in how this enzymatic conversion of 2‐ O ‐ into 3‐ C ‐glucoside occurred: through chemical Fries‐type O / C ‐glucosidic bond rearrangement or an aglycone intermediate followed by a Friedel–Crafts‐like reaction . To verify these predictions, a mixture of 1 , UDP and MiCGTb was incubated at 30 °C from 10 to 60 min, and the time course of the reaction was monitored by HPLC, which clearly indicated the formation of aglycone phloretin ( 1 b , Figure B).…”

“…The same result was also obtained when MiCGTb and 1 were incubated with UDP (Figure ). However, this conversion of 1 into 1 a was not observed with only MiCGT (Figure S3 in the Supporting Information) or Os CGT . These unique results inspired our interest in how this enzymatic conversion of 2‐ O ‐ into 3‐ C ‐glucoside occurred: through chemical Fries‐type O / C ‐glucosidic bond rearrangement or an aglycone intermediate followed by a Friedel–Crafts‐like reaction .…”

Creating a Water‐Soluble Resveratrol‐Based Antioxidant by Site‐Selective Enzymatic Glucosylation

“…Resveratrol triglucoside was also not formed. As pH could influence resveratrol glucosylation (by affecting reaction kinetics or thermodynamics),26 we carried out reactions over pH 6.0–8.0: optimum conversion was around pH 8.0. The pH‐dependent distribution of glucosylated products (Figure S2) can be explained by the increased reaction rate at high pH.…”

Probing the Catalytic Promiscuity of a Regio‐ and Stereospecific C‐Glycosyltransferase from Mangifera indica

“…It demonstrated that MiCGT appeared to generate only C-glycosides with 2,4,6-tri-hydroxy acceptors at the Aring (1-13), both Cand O-glycosides with 2,4-di-hydroxyl acceptors at the Aring (14)(15)(16), and only O-glycosides with 2-or 4-mono-hydroxy acceptors at the Aring (38, 39). Thes ame results were observed with simple phenolics (26-36).…”