Structured lipids triacylglycerols

Sanders, T.H. (1979) Varietal differences in peanut triacylglycerol structure. Lipids, 14, 630-633. 

Structural lipids and triacylglycerols contain primarily fatty acids of at least sixteen carbons. 

Lawson, L.D. and Hughes, B.G. (1988) Triacylglycerol structure of plant and fungal oils. Lipids, 23,... 

The major differences between the lipids of bovine and human milk are in fatty acid composition and triacylglycerol structure. Bovine milk contains substantial quantities of C4 o-Ci0 o, about 2% Cis 2 and almost no other long-chain polyunsaturated fatty acids. The fatty acid composition is not altered by ordinary changes in diet. Human milk contains very little C4 o-C10 o, 10-14%i (w/w of fat) Ci8 2, and small quantities of other polyunsaturates. The triacylglycerol structure differs, with much of the sn-2 position in human milk lipids occupied by C16 0 and the sn-2 position of bovine milk-fat occupied by C4 o-Ci0 o-... 

The lipase-catalyzed interesterification process can be used for the production of triacylglycerols with specific physical properties, and it also opens up possibilities for making so-called structured lipids. An example is a triacylglycerol that carries an essen-... 

Various fatty acids are used in the production of structured lipids these may include both n-3 and n-6 fatty acids. Structured lipids containing MCFA and LCFA may modify the absorption rates because MCFA are rapidly oxidized for energy, whereas LCFA are oxidized very slowly. These specialty lipids are strucmrally and metabolically different from simple physical mixtures of medium-chain and long-chain triacylglycerols. 

Jennings, B.H., and Akoh, C.C. (1999) Enzymatic Modification of Triacylglycerols of High Eicosapentaenoic and Docosahexaenoic Acids Contents to Produce Structured Lipids, /. Am. Oil Chem. Soc. 76,1133 1137. 

Yli-Jokipii K, Kallio H, Schwab U, et al. Effeets of palm oil and transesterified palm oil on chylomicron and VLDL triacylglycerol structures and postprandial lipid... 

As in plants, animal lipids can be conveniently classified as storage or structural . Storage lipids are, with few exceptions, triacylglycerols, and the structural lipids are mainly phospholipids and cholesterol. The fatty acid compositions of these types of lipids are markedly different. 

Vegetable oils or fats have also been used as starting materials for the enzymatic synthesis of structured lipids with valuable dietetic or nutritional properties. Milk fat substitutes for use in baby foods have been produced enzymatically from pahn oil mid-fractions (King and Padley, 1990). Using the same enzymatic process, long-chain saturated fatty acids (which have been implicated in atherogenesis) at the sn-2 position of peanut oil triacylglycerols have been replaced with oleic acid (Sridhar et al, 1991). 

Despite the lack of selectivity, some structured lipid-like products have been synthesized by chemicals methods. The catalyst most often used for chemical interesterification of triacylglycerols or for alcoholysis between triacylglycerols and fatty acids is sodium methoxide, which is more active than other base, metal or acid catalysts. In general, sodium alkoxides are easy to use as catalysts. They are inexpensive, active at relatively low temperatures (50-90°C), and are effective at low concentrations. Although no regioselectivity or fatty acid selectivity occurs, the chemically synthesized commercial products listed in Table 2 contain sTAG with the desired nutritional function. 

To promote uses of rapeseed ( Brassica. nopus) oil, some new oil fatty acid profiles are needed. In this paper, we report the development of low linolenic acid (Cl8 3) iines. The triacylglycerol (TAG) lipid structure of high and low Cl8 3 rapeseed oils has been determined to test Sn-2 specific acyltransferase activities. No differences were detected among the lines for the TAG lipid structure even with a 0.9% Cl8 3 content. 

HDL and VLDL are assembled primarily in the endoplasmic reticulum of the liver (with smaller amounts produced in the intestine), whereas chylomicrons form in the intestine. LDL is not synthesized directly, but is made from VLDL. LDL appears to be the major circulatory complex for cholesterol and cholesterol esters. The primary task of chylomicrons is to transport triacylglycerols. Despite all this, it is extremely important to note that each of these lipoprotein classes contains some of each type of lipid. The relative amounts of HDL and LDL are important in the disposition of cholesterol in the body and in the development of arterial plaques (Figure 25.36). The structures of the various... 

Triacylglycerols are the major energy-storing lipids, whereas phosphoglycerols, sphingomyelin, and gly-cosphingolipids are amphipathic and have structural functions in cell membranes as well as other specialized roles. 

Using PTLC six major fractions of lipids (phospholipids, free sterols, free fatty acids, triacylglycerols, methyl esters, and sterol esters) were separated from the skin lipids of chicken to smdy the penetration responses of Schistosoma cercaria and Austrobilharzia variglandis [79a]. To determine the structure of nontoxic lipids in lipopolysaccharides of Salmonella typhimurium, monophosphoryl lipids were separated from these lipids using PTLC. The separated fractions were used in FAB-MS to determine [3-hydroxymyristic acid, lauric acid, and 3-hydroxymyristic acids [79b]. 

The one and only distinctive feature of lipids is that they are all totally hydrophobic (water fearing), or nearly so. They generally will not chemically interact with water and therefore will not dissolve in water. Chemically, lipids fit into several categories, each of which is structurally unique. Common types of lipids include triacylglycerols, phospholipids, and steroids. 

---