Synthesis of ethyl cinnamate catalyzed by lipase B from Candida antarctica

Abstract

Cinnamic acid and its esters are widespread throughout plant kingdom and therefore, they are common components of our daily diet. Ethyl cinnamate has been approved by FDA for direct addition to food for human consumption. Enzyme synthesis is strongly preferred compared to chemically catalyzed esters synthesis when product quality is a main issue, as is the case for food production. The aim of this study was to examine possibilities for enzyme catalyzed synthesis of cinnamic acid esters and to optimize the synthesis of ethyl cinnamate in terms of selected parameters, including the type of the organic solvent and substrate initial molar ratio. All reactions were performed batchwise under pH and temperature control in vessels containing 5 mL of reaction medium, using cinnamic acid as limiting substrate (0.167 M). Each reaction mixture was supplemented with 75 mg of commercial immobilized lipase B from Candida antarctica, Novozyme 435. The antioxidant activity of obtained ester was measured by using chemical and electrochemical techniques. We have proven that ethyl cinnamate can be synthesized using lipase B from Candida antarctica with very high reaction yields in the simple bioreactor system.The best reaction yield (89%) was obtained in isooctane when substrate molar ratio of 1:3 was used. Both, DPPH assay and cyclic voltammetry measurement has shown that ethyl cinnamate has better antioxidant properties than cinnamic acid itself.