Biotransforming Phenylpropanoids derived from Biorefining:A Toolkit Approach

Phenylpropanoids (PPs) are a group of metabolites found in all terrestrial plants which are used in nature to make a range polyphenolic compounds, which serve important dietary functions as flavourings and antioxidants. In this project, we propose to effectively copy the pathways which exist in nature and take PPs left over as low value by products of biofuel and plant fibre production and biotransform them into high value chalcone, aurone and stilbene polyphenolics. This biosynthetic process would be carried out in fermentable microbes, using enzyme pathways which can be assembled together in a modular manner to generate a wide range of end products from the limited range of PPs available from biorefining. In addition to generating existing known antioxidants and flavourings, the ability to increase the production of unusually biologically active intermediates, such as dihydrochalcones, has the potential to produce unique flavourings and neutraceutical agents. To illustrate the technology, we will generate glycosylated dihydrochalcones which are 100s of time sweeter than sucrose and used as flavour enhancers, without resorting to harsh chemical reactions.
The proposed process involves a series of individual enzyme steps , each of which serves as a module which can then be linked to the next biosynthetic step to produce the compounds of interest. The first committed step in the pathway involves the generation of a common precursors (Work package 1= WP1) which can then be converted to a range of polyphenolic metabolites depending on the enzyme used (WP2). The resulting compounds can then be structurally modified with sugars (WP3) to give the biologically active end products. Then to illustrate how this approach can fast forward the biological production of unusual and low abundance neutraceuticals, we will use the same WP1-3 linked approach to generate a second generation of polyphenolics based on benzoic acid precursors which are also extracted from plants. The programme would be conducted at Durham University over a three year period in the interdisciplinary Centre for Bioactive Chemistry .
In addition to expanding the existing markets for plant-derived chemicals used in high value food applications, the project has the potential to generate completely new products which have good chemical precedence as being biologically active and usable by industry. In addition the project further improves the sustainability of biofuels and other mainstream ‘green’ refined plant products by increasing the value of the main process by transforming low value waste-streams into high value chemicals for food applications.