Flavonoids and stilbenes have attracted much attention as potential targets for nutraceuticals,cosmetics, and pharmaceuticals. We have de-veloped a system for producing ‘‘unnatural’’ fla-vonoids and stilbenes in Escherichia coli. The artificial biosynthetic pathway included three steps. These included a substrate synthesis step for CoA esters synthesis from carboxylic
acids by 4-coumarate:CoA ligase, a polyketide synthesis step for conversion of the CoA esters into flavanones by chalcone synthase and chal-cone isomerase, and into stilbenes by stilbene synthase, and a modification step for modifica-tion of the flavanones by flavone synthase, fla-vanone 3b -hydroxylase and flavonol synthase.Incubation of the recombinant E. coli with exog-enously supplied carboxylic acids led to pro-duction of 87 polyketides, including 36 unnatu-ral flavonoids and stilbenes. This system is promising for construction of a larger library by employing other polyketide synthases and modification enzyme