Comparison of acyl donors for lipase-catalyzed production of 1,3-dicapryloyl-2-eicosapentaenoylglycerol

Synthesis of 1,3-dicapryloyl-2-eicosapentaenoyl glycerol (CEC) catalyzed by Lipozyme IM (immobilized Rhizomucor miehui lipase) was performed by intere sterification of trieicosapentaenoylglycerol (ECD with caprylic acid ICA) ( acidolysis) and EEE with ethyl caprylate (EtC) (interesterification). Both methods involved two steps: (i) transesterification at an optimized water c ontent and temperature for the high yield conversion of the substrate to CE C, 1-capryloyl-2-eicosaptatacnoylglycerol (CEOH) and 2-eicosapentaenoylglyc erol (OHEOH), and (ii) reesterification of CEOH and OHEOH to CEC by water r emoval under reduced pressure. Interesterification had clear advantages ove r acidolysis. The reaction rates for interesterification were higher and th e reaction times shorter. The final yield of CEC by interesterification was higher, and the extent of acyl migration, indicated by the tricapryloylgly cerol content, was lower. The disadvantage of the higher price of EtC used for interesterification (approximately 10 times higher than the price of CA ) was overcome by synthesizing it directly in the same reaction vessel prio r to the interesterification step. EtC was rapidly synthesized by esterific ation of CA with ethanol in high yield (92% obtained in 2.5 h). The amount of water added to the reaction mixture and the reaction temperature influen ced the yields of CEC, CEOH, and OHEOH in the transesterification step for both interesterification and acidolysis methods. The regioisomeric purity o f CEC was 100% for both methods at temperatures of 40 degreesC or less. The highest yield of CEC (81%) was obtained for the interesterification of EEE with EtC, formed directly in the same reaction vessel, at a CA/EEE molar r atio of 20:1 and 30 degreesC.