ABSTRACT
Plants contain a great variety of phenolic compounds, derived from a range of biosynthetic pathways. This review focuses on those from the phenylpropanoid pathway, as these include most of the groups of compounds of current interest for human health studies and is the pathway for which there has been the most extensive plant metabolic engineering to date. Phenylpropanoids are a major group of plant secondary metabolites derived from phenylalanine (Davies and Schwinn, 2006; Boudet, 2007; Yu and Jez, 2008). They are of key importance for plant function both as structural compounds and for responses to the abiotic and biotic environment. It has been estimated that phenylpropanoids account for over 30% of all organic carbon in the biosphere, principally in the form of lignin, and they are therefore a common dietary component (Kyle and Duthie, 2006).
