Forming coumarin C-glycosides via biocatalysis: Characterization of a C-glycosyltransferase from Angelica decursiva

A glycosyl transferase , isolated from Angelica decursiva a medical herb rich in coumarin , shows C-glycosyl transferase activity by in vitro activity assay using 5,7-dihydroxycoumarin as substrate, producing a C-glycosylated product at position C′8 along with the main product at C′6 position. Catalytic promiscuity assay shows that Ad CGT also displays O- or C-glycosylation activity to other coumarins and flavonoids . When phloretin and 2,4,6-trihydroxyacetophenone were fed as substrates, Ad CGT catalyzed the formation of di-C-glycosides. Therefore, Ad CGT is a multifunctional glycosyltransferase with a broad substrate acceptability. This work highlights the potential of Ad CGT as a catalyst for glycosylation of coumarin and reveals a new regio-selective C-glycosyltransferase, providing a basis for exploring the mechanism of coumarin glycosylation.