Ionic liquids: a green solution to enzymatic lipophilisation of bioactive compounds

Flavonoids are found in a variety of foods and beverages. They are commonly regarded as antioxidants or bio-antioxidants for lipids in food or biological systems. Flavonoids are water-soluble compounds and limited in antioxidative functions due to limited mass transfer and/or insufficient partitioning in the real heterophasic food or biological systems. Therefore, lipophilisation of the compounds is one of the best solutions to improve their functions. Enzymatic approach offers the best possibility for the lipophilisation of flavonoids due to milder conditions and specificity. However no traditional organic solvents are suitable to provide an efficient reaction system due to lower solubility and other aspects. Ionic liquids have been emerged in sight recently as green solvent due to negligible vapour pressure. Thus ionic liquids provide a potential solution for the system development in enzymatic flavonoids lipophilisation. In this project, the major objectives are to develop an efficient system for the acylation of flavonoids to obtain flavonoids esters as well as process optimisation for product separation and purification. A few interesting flavonoids will be selected for the process development. In order to reduce the experimental workload for the screening of numberless ionic liquids, activity coefficient model will be validated to predict the related properties, acting as pre-screening. To better understand the impact of ionic liquids on the enzyme activity, water distribution in the reaction system will be evaluated through NIR and 1H-NMR. Eventually a preliminary product evaluation will be conducted also concerning antioxidation performance of the products in LDL and liposome model systems.