UDP-glucose: glucosyltransferase activity involved in the biosynthesis of flavonol triglucosides in Pisum sativum L. seedlings.

From young, light-grown seedlings of Pisum sativum L. an enzyme activity catalyzing the glucosylation of kaempferol and quercetin in the 3-position to form the 3-0-triglucoside derivative has been demonstrated. The reaction proceeds from the aglycone via the mono- and diglucoside intermediates. The triglucoside can be produced from any of the less substituted derivatives with uridine diphosphate-D-glucose (UDPG) as the glucosyl donor. Young leaf tissues had much higher levels of glucosyltransferase activity than the petioles and internodes. This is the first report of the synthesis of flavonol-3-0-triglucosides in vitro.