Biosynthesis of 7,8-dihydroxyflavone glycosides via OcUGT1-catalyzed glycosylation and transglycosylation.

Herein, a flavonoid glycosyltransferase (GT) OcUGT1 was determined to be able to attack C-8 position of 7,8-dihydroxyflavone (7,8-DHF) via both glycosylation and transglycosylation reactions. OcUGT1-catalyzed glycosylation of 7,8-DHF resulted in the formation of two monoglycosides 7-O-β-D-glucosyl-8-hydroxyflavone (1a), 7-hydroxy-8-O-β-D-glucosylflavone (1b), as well as one diglycoside 7,8-di-O-β-D-glucosylflavone (1c). Under the action of OcUGT1, inter-molecular trans-glycosylations from aryl β-glycosides to 7,8-DHF to form monoglycosides 1a and 1b were observable.