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 AdCGT also displays O- or C-glycosylation activity to other coumarins and flavonoids. When phloretin and 2,4,6-trihydroxyacetophenone were fed as substrates, AdCGT catalyzed the formation of di-C-glycosides. Therefore, AdCGT is a multifunctional glycosyltransferase with a broad substrate acceptability. This work highlights the potential of AdCGT 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.