Lipophilization of phenolic compounds by lipase-catalyzed reactions

Enzymes are used more and more in various applications of different fields such as pharmaceutical, cosmetic or food industry. In the past years, a better understanding of enzymes functionalities and catalytic behaviors, together with the progress of molecular engineering has lead to new applications for various types of enzymes. Concerning lipases, they are used in various sectors, as pharmaceutical, food or detergency industry. Their advantages versus classical chemical catalysts is that they exhibit a improved substrate specificity and operate in milder reaction conditions. Moreover, the fact that they retain their activity in organic solvents extends their range of application. In the pharmaceutical industry, lipases can be used for racemic mixtures resolution or as biocatalysts for the synthesis of chiral synthesis intermediates. In the food sector, these enzymes are principally employed in oils and fats restructuration processes allowing the production of specific triacylglycerols with predetermined fatty acids composition and distribution.. Similar processes are also described for the synthesis of partial glycerides or fatty acids concentrates. Besides their application in oils and fats processes, these enzymes have proved to be very attractive for others lipase-catalyzed reactions with unusual substrates. In particular, they appear to be very effective for the synthesis of molecules involving the grafting of a lipophilic moiety or a hydrophilic one. The major example of this capacity is certainly the synthesis of glycolipids derivatives such as sugar esters that can be used as surfactants in the food, pharmaceutical or cosmetic industry. In this presentation, will be described and discussed some of the recent results in the field of the lipase assisted lipophilization of bioactive compounds such as phenolic derivatives in order to modify the hydrophilic/lipophilic properties of the initial molecules to obtain new products with multi-functionnal properties combining for example, microbial, antioxidant and emulsifying properties. More specifically, to illustrate this topic, will be presented in details the enzymatic lipophilization of phenolic acids from green coffee, namely chlorogenic acids, via esterification by fatty alcohols, in order to obtain new antioxidant molecules with improved activity in emulsified systems. (Texte intégral