Modifying the acylation of flavonols in Petunia hybrida

The potential for chemically-regulating the acylation of natural products in whole plants has been determined by treating petunia leaves with phenylpropanoid acyl donors supplied as the respective methyl esters. Treatment with derivatives of the naturally-occurring acylating species caffeic acid resulted in a general increase in flavonol derivatives, notably caffeoylated quercetin-3-O-diglucoside (QDG) and kaempferol-3-O-diglucoside (KDG). Similarly, methyl ferulate increased the content of feruloylated KDG 40-fold. Treatment with methyl coumarate resulted in the appearance of a coumaroylated derivative of quercetin-3-O-glucuronyl-glucoside (QGGA). When the feeding studies were repeated with the equivalent phenylpropanoid isosubstituted with fluorine groups a semi-synthetic 4-fluorocinnamoyl ester of QGGA was observed. Our results demonstrate the potential to regulate the acylation of flavonols and potentially other natural products by treating whole plants with methyl esters of natural and unnatural acyl donors.