Rapid access to structured triacylglycerols acylated with n-3 polyunsaturated fatty acids for nutritional applications

International audienceIn order to better understand the metabolic fate of n-3 polyunsaturated fatty acids (PUFAs), an efficient access to symmetrical and unsymmetrical triacylglycerols (TGs), esterified with PUFAs, with known high purity, is required. In this context, we optimized the esterification of a mixture of glycerols protected as dioxane and dioxolane with PUFAs. The kinetics of this reaction depends on various factors, such as the fatty acid chain length and the stereochemistry of the dioxane. Then, one-pot acetal hydrolysis and esterification of hydroxyl groups led to the desired structured TGs without either double bond isomerization or acyl migration (except when symmetrical TGs are acylated with long-chain saturated fatty acids in external positions). PUFAs location on the glycerol backbone was assayed by NMR, HPLC and pancreatic lipase hydrolysis

The Fraction of a-Linolenic Acid Present in the sn-2 Position of Structured Triacylglycerols Decreases in Lymph Chylomicrons and Plasma Triacylglycerols during the Course of Lipid Absorption in Rats 1-3

International audienceLittle is known about the ability of a-linolenic acid (Ln) to remain in the sn-2 position of TG during the absorption process. The goal of this study was to determine the Ln distribution in the lymph (Study 1) and plasma (Study 2) TG of rats fed a single i.g. load of structured TG [300 mg/rat of either oleic acid (O)/Ln/O TG (OLnO) or Ln/O/O TG (LnOO), n = 7 rats]. In an early fraction (3-4 h) of lymph (OLnO group; 100%Ln in the sn-2 position), 46 6 2%Ln was maintained in this position in lymph TG. There was even less (29 6 6%) in the last fraction (7-24 h) (P , 0.05). Ln was also found (9 6 3%) in the sn-2 position of lymph TG in the LnOO group. The Ln content in lymph phospholipids was twice as high in rats when they were fed LnOO (4.2 6 0.1%) than OLnO (2.3 6 0.2%) (P , 0.005). Six hours postprandially (Study 2), 21 6 3% of the Ln incorporated into plasma TG was located in the sn-2 position in the OLnO group compared to 13 6 2%in the LnOO group (P , 0.001). Overall, these results indicate that the amount of Ln that moved fromthe sn-2 position of structured TG to the sn-1(3) position of lymph TG increased during absorption. This may account for a substantial hydrolysis of the 2-monolinolenylglycerols in enterocytes, leading to the intramolecular redistribution of Ln in lymph TG and, consequently, in plasma TG