Enzymatic synthesis of structured lipid containing arachidonic and palmitic acids

Abstract

AbstractHuman milk fat contains 20–25% palmitic acid, and about 70% of the fatty acid is esterified to the 2‐position of triglycerides. It was also reported that arachidonic acid (AA) accelerated the growth of preterm infants. Thus, we attempted the synthesis of 1,3‐arachidonoyl‐2‐palmitoyl‐glycerol by acidolysis of tripalmitin with AA using 1,3‐specific Rhizopus delemar lipase. When a mixture of 10 g tripalmitin/AA (1∶5, w/w) and 0.7 g immobilized Rhizopus lipase was incubated at 40°C for 24 h with stirring, the AA content in glycerides reached 59 mol%. The immobilized lipase could be used five times without a decrease in the extent of acidolysis. Glycerides were extracted 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 were 56.9 and 3.2 mol%, respectively. It was therefore confirmed that the fatty acids at the 1,3‐positions of triglyceride were exchanged for AA. High‐performance liquid chromatography showed that the contents of triarachidonin, 1,3‐arachidonoyl‐2‐palmitoyl‐glycerol, and 1(3)‐arachidonoyl‐2,3(1)‐palmitoyl‐glycerol were 7.3, 75.9, and 12.4 wt%, respectively.