Enzymatic synthesis cf structured lipid containing arachidonic and palmitic acids

Human milk fat contains 20-25% palmitic acid, and about 70% of the fatty ac id is esterified to the 2-position of triglycerides. It was also reported t hat arachidonic acid (AA) accelerated the growth of preterm infants. Thus, we attempted the synthesis of 1,3-arachidonoyl-2-palmitoyl-glycerol by acid olysis of tripalmitin with AA using 1,3-specific Rhizopus delemar lipase. W hen a mixture of 10 g tripalmitin/AA (1:5, w/w) and 0.7 g immobilized Rhizo pus lipase was incubated at 40 degrees C for 24 h with stirring, the AA con tent in glycerides reached 59 mol%. The immobilized lipase could be used fi ve times without a decrease in the extent of acidolysis. Glycerides were ex tracted from the reaction mixture with n-hexane, and regiospecific analysis was performed. As a result, the AA contents at the 1,3- and 2-positions we re 56.9 and 3.2 mol%, respectively. It was therefore confirmed that the fat ty acids at the 1,3-positions of triglyceride were exchanged for AA. High-p erformance liquid chromatography showed that the contents of triarachidonin , 1,3-arachidonoyl-2-palmitoyl-glycerol, and 1(3)-arachidonoyl-2,3(1)-palmi toyl-glycerol were 7.3, 75.9, 1 palmitoyl-glycerol were 7.3, 75.9, and 12.4 wt%, respectively.