great interest because of various pharmacological effects of these FAs. These include
several health benefits on cardiovascular diseases, immune disorders and inflamma-
tion, renal disorders, allergies, diabetes, cancer, etc. (Akoh, 1995; Gill and Valivety,
1997a,b). These FAs may be also essential for brain and retina development in hu-
mans.
Among sTAGs containing PUFA, sTAGs containing one molecule PUFA and two
molecules of medium-chain fatty acids are very noticeable. Several studies have
been performed for the synthesis of sTAG containing PUFA at specific sites of
the glycerol backbone (Lee and Akoh, 1996; Shimada et al., 1996a; 1999; Souma-
nou et al., 1997). The absorption of PUFA into the body depends upon the position of
PUFA along the glycerol backbone, i.e. atsn-1 (or 3) orsn-2 position (Christensen et
al., 1995). sTAG containing PUFA atsn-2 position and MCFA atsn-1 and–3 posi-
tions can be hydrolyzed into 2–monoacylglycerol (2-MAG) containing PUFA and
FA by pancreatic lipase and are efficiently absorbed into intestinal mucosa cells in
normal adults. It is to be noted that mammalian pancreatic lipases hydrolyze the ester
linkages at thesn-1 andsn-3 positions with a preference for MCFA over long-chain
ones (Battino et al., 1967; Yang et al., 1990). Therefore, for dietary supplement for
adult health, sTAG containing PUFA atsn-2 position and MCFA at thesn-1 andsn- 3
positions may be suitable. On the other hand, due to the antiatherogenic, antineo-
plastic, and anti-inflammatory effects of the n-3 PUFAs, their intake is important for
newborns for eicosanoid synthesis as well as for normal neonatal brain nervous
development and cell membrane structure. Although PUFA are essential to the neo-
nate for both normal growth and metabolism, neonatal intestinal function is imma-
ture, resulting in reduced levels of pancreatic lipase and bile acid salts. In addition,
pancreatic lipase does not hydrolyze ester bonds containing long-chain n-3 PUFA
(Iverson et al., 1992). Therefore, in the case of the newborn, PUFA absorption
by pancreatic lipase is not feasible. However, for neonatal adsorption of PUFA,
there is an alternative mechanism. PUFA are released from gastric digestion, and
gastric lipase exhibits stereospecificity for thea-position of TAG and hydrolyzes
thesn-3 position twice as fast as thesn-1 position (Iverson et al., 1992; Harmosh
and Harmosh, 1996). Therefore, for PUFA therapy for neonates, sTAG containing
PUFA atsn-1 (or -3) position and MCFA at the other sites may be suitable.
sTAG can be synthesized either chemically or enzymatically. However, an enzy-
matic synthesis of sTAG is more advantageous over a chemical process with regard
to several aspects. Enzymes are generally specific, giving rise to less or no bypro-
9.1 Introduction 149
Table 1.Classification of structured triacylglycerols (sTAG).
No. of different FA Type Chirality Stereoisomer
Monoacid- AAA Achiral
Diacid- ABA Achiral
AAB, BAA Chiral EnantiomersTriacid- ABC, CBA Chiral Enantiomers
BCA, ACB Chiral Enantiomers
CAB, BAC Chiral Enantiomers