E linoleic acid

Dietary fatty acids will influence the cardiac phospholipid composition of the rat but to a lesser extent than the cardiac neutral lipids (Carroll, 1965). Dietary fatty acids may be incorporated as saturated and monounsaturated fatty acids, or they may be incorporated and converted to more polyunsaturated fatty acids (PUFA), i.e., linoleic acid to 20 4 n-6, 22 4 n-6, and 22 5 n-6 and linolenic acid to 20 5 r/-3, 22 5 n-3, and 22 6 n-3 (see Chapter 16). Dietary saturated and monounsaturated fatty acids are incorporated to a small extent into cardiac phospholipids (Carroll, 1965). On the other hand, dietary 18 2 n-6 and 18 3 n-3 cause a significant increase in the pentaenoic and hexaenoic acids which is greater in the heart than in any other organ of the rat (Rieckehoff et aL, 1949 Widmer and Holman, 1950). With this background it may be useful to discuss changes in the composition of the different cardiac phospholipids with diet. 

There are numerous varieties of sunflower which are identifiable in part on the basis of height but also on the basis of oil composition, i.e. linoleic acid-rich and oleic acid-rich. The flower heads are harvested mechanically, ideally when the moisture content has dropped to approximately 9-10%. Mechanical drying is frequently necessary. Yields of 1300-2000 kg/ha are obtained. Oil content of seed 20-32% old strains, 40% new strains. 

Figure 1. Chemical structures of a) palmitic acid (16 0) b) stearic acid (18 0) c) arachidic acid (20 0) d) oleic acid (18 1) e) linoleic acid (18 2) f) linolenic acid (18 3).

The antagonisms that exist between unsaturated fatty acids, and carotene and vitamin E are compHcated and largely undefined. Linoleic acid acts as an antivitamin to i7/-a-tocopherol [59-02-9, 1406-18-9, 10191-41-0] (vitamin E) by reducing availabiHty through direct intestinal destmction. Various Hpoxidases destroy carotenes and vitamin A (73). Dicoumarol [66-76-2] (3,3 -methylenebis(4-hydroxycoumarin)) is a tme antimetaboHte of vitamin K [12001 -79-5] but seems to occur only in clover and related materials that are used primarily as animal feeds (74). 

Organisms differ with respect to formation, processing, and utilization of polyunsaturated fatty acids. E. coli, for example, does not have any polyunsaturated fatty acids. Eukaryotes do synthesize a variety of polyunsaturated fatty acids, certain organisms more than others. For example, plants manufacture double bonds between the A and the methyl end of the chain, but mammals cannot. Plants readily desaturate oleic acid at the 12-position (to give linoleic acid) or at both the 12- and 15-positions (producing linolenic acid). Mammals require polyunsaturated fatty acids, but must acquire them in their diet. As such, they are referred to as essential fatty acids. On the other hand, mammals can introduce double bonds between the double bond at the 8- or 9-posi-tion and the carboxyl group. Enzyme complexes in the endoplasmic reticulum desaturate the 5-position, provided a double bond exists at the 8-position, and form a double bond at the 6-position if one already exists at the 9-position. Thus, oleate can be unsaturated at the 6,7-position to give an 18 2 d5-A ,A fatty acid. 

Sodium dodecyl sulfate and hydrogen dodecyl sulfate have been used as catalysts in the denitrosation iV-nitroso-iV-methyl-p-toluenesulfonamide [138]. The kinetics of condensation of benzidine and p-anisidine with p-dimethylamino-benzaldehyde was studied by spectrophotometry in the presence of micelles of sodium dodecyl sulfate, with the result that the surfactant increases the rate of reaction [188]. The kinetics of reversible complexation of Ni(II) and Fe(III) with oxalatopentaaminecobalt(III) has been investigated in aqueous micellar medium of sodium dodecyl sulfate. The reaction occurs exclusively on the micellar surface [189]. Vitamin E reacts rapidly with the peroxidized linoleic acid present in linoleic acid in micellar sodium dodecyl sulfate solutions, whereas no significant reaction occurs in ethanol solution [190]. 

Galaris, D., Sevanian, A., Caelenas, E. and Hochstein, P. (1990). Ferrylmyoglobin catalysed linoleic acid peroxidation. Arch. Biochem. Biophys. 281, 163-169. 

Guyan et al. 1990) have used several markers of lipid peroxidation (9-cis-, 11-tmns-isomer of linoleic acid, conjugated dienes and ultraviolet fluorescent products) to demonstrate significant increases in the duodenal aspirate after secretin stimulation in patients with acute and clinic pancreatitis. They interpreted this as indicating induction of hepatic and pancreatic drug-metabolizing enzymes in the face of a shortfidl of antioxidant defences, more marked in chronic pancreatitis. Subsequent studies in patients with chronic pancreatitis have confirmed decreased serum concentrations of selenium, -carotene and vitamin E compared with healthy controls (Uden et al., 1992). Basso aol. (1990) have measured increases in lipid peroxides in the sera of patients with chronic... 

The essential fatty acids in humans are linoleic acid (C-18 2 N-6) and a-linolenic acid (C18 3 N-3). Arachidonic acid (C20 4 N-6) is also essential but can be synthesized from linoleic acid. Administration of 2% to 4% of total daily calories as linoleic acid should be adequate to prevent essential fatty acid deficiency in adults (e.g., infusion of 500 mL of 20% intravenous lipid emulsion once weekly).7 Biochemical evidence of essential fatty acid deficiency can develop in about 2 to 4 weeks in adult patients receiving lipid-free PN, and clinical manifestations generally appear after an additional... 

As mentioned earlier, both MCTs and LCTs are used in tube feeding products. Corn, soy, and safflower oils have been the mainstay sources of fat in these products, providing mainly co-6 polyunsaturated fatty acids (PUFAs). On the other hand, some newer EN products contain higher quantities of co-3 PUFAs from sources such as fish oil [i.e., docosahexenoic acid (DHA) and eicosapentenoic acid or (EPA)]. Still other formulas contain higher quantities of monounsaturated fatty acids from canola oil and high-oleic safflower or sunflower oils. The essential fatty acid (EFA) content (mainly linoleic acid) of EN... 

Essential fatty acid deficiency Deficiency of linoleic acid, linolenic acid, and/or arachidonic acid, characterized by hair loss, thinning of skin, and skin desquamation. Long-chain fatty acids include trienes (containing three double-bonds [e.g., 5,8,11-eicosatrienoic acid, or Mead acid trienoic acids) and tetraenes (containing four doublebonds [e.g., arachidonic acid]). Biochemical evidence of essential fatty acid deficiency includes a trieneitetraene ratio greater than 0.4 and low linoleic or arachidonic acid plasma concentrations. 

Vulcain, E. et al. (2005). Inhibition of the metmyoglobin-induced peroxidation of linoleic acid by dietary antioxidants Action in the aqueous vs. lipid phase. Free Rad. Res. 39(5) 547-563. 

Jones E L, Shingfield K J, Kohen C, Jones A K, Lupoli B, Grandison A S, Beever D E, Williams C M, Calder P C and Yaqoob P (2005), Chemical, physical, and sensory properties of dairy products enriched with conjugated linoleic acid , Journal of Dairy Science, 88, 2923-2937. 

Tricon S, Burdge G C, Kew S, Banerjee T, Russell J J, Jones E L, Grimble R F, Williams C M, Calder P C and Yaqoob P (2004), Effects of cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acid on immune function in healthy humans , American Journal of Clinical Nutrition, 80, 1626-1633. 

Belkner et al. [32] demonstrated that 15-LOX oxidized preferably LDL cholesterol esters. Even in the presence of free linoleic acid, cholesteryl linoleate continued to be a major LOX substrate. It was also found that the depletion of LDL from a-tocopherol has not prevented the LDL oxidation. This is of a special interest in connection with the role of a-tocopherol in LDL oxidation. As the majority of cholesteryl esters is normally buried in the core of a lipoprotein particle and cannot be directly oxidized by LOX, it has been suggested that LDL oxidation might be initiated by a-tocopheryl radical formed during the oxidation of a-tocopherol [33,34]. Correspondingly, it was concluded that the oxidation of LDL by soybean and recombinant human 15-LOXs may occur by two pathways (a) LDL-free fatty acids are oxidized enzymatically with the formation of a-tocopheryl radical, and (b) the a-tocopheryl-mediated oxidation of cholesteryl esters occurs via a nonenzymatic way. Pro and con proofs related to the prooxidant role of a-tocopherol were considered in Chapter 25 in connection with the study of nonenzymatic lipid oxidation and in Chapter 29 dedicated to antioxidants. It should be stressed that comparison of the possible effects of a-tocopherol and nitric oxide on LDL oxidation does not support importance of a-tocopherol prooxidant activity. It should be mentioned that the above data describing the activity of cholesteryl esters in LDL oxidation are in contradiction with some earlier results. Thus in 1988, Sparrow et al. [35] suggested that the 15-LOX-catalyzed oxidation of LDL is accelerated in the presence of phospholipase A2, i.e., the hydrolysis of cholesterol esters is an important step in LDL oxidation. 

Odor and color stability problems were also related to the alkyl chains used for SAI. These could be traced to the oxidation of unsaturated carbons, such as oleic acid (Ci8 fatty acid with a single double bond between carbon 9 and 10, i.e. bond position 9 counted from the carboxyl carbon), linoleic acid (Cis fatty acid with two double bonds at position 9 and 12), and linolenic acid (Cis fatty acid with three double bonds at position 9, 12, and 15). Natural coconut fatty acid contains about 6% oleic acid, about 3% linoleic acid, and less than 1% linolenic acid. Tallow fatty acid contains nearly 44% oleic and about 6% of other unsaturates [20]. Partial hydrogenation of the coconut fatty acid used in the manufacture of SCI served to eliminate linoleic and linolenic acids for improved odor stability, while not eliminating oleic acid, which is important for good lather. 

The omega (<0) numbering system is also used for unsaturated fatty acids. The co-family describes the position of the last double bond relative to the end of the chain. The omega designation identifies the major precursor fatty add, e.g., arachidonic add is formed from linoleic acid (co-6 family). Arachidonic acid is itself an important precursor for prostaglandins, thromboxanes, and leukotrienes. 

M. Meurens, V. Baeten, S.H. Yan, E. Mignolet and Y. Larondelle, Determination of the conjugated linoleic acids in cow s rmlk fat by Eourier transform Raman spectroscopy, J. Agric. Food Chem., 53, 5831-5835 (2005). 

Unsaturated fatty acids usually contain a cis double bond at position 9 or 12—e.g., linoleic acid (18 2 9,12). As with saturated fatty acids, degradation in this case occurs via p-oxida-tion until the C-9-ds double bond is reached. Since enoyl-CoA hydratase only accepts substrates with trans double bonds, the corresponding enoyl-CoA is converted by an iso-merase from the ds-A, cis- A isomer into the trans-A, cis-A isomer [1]. Degradation by p-oxidation can now continue until a shortened trans-A, ds-A derivative occurs in the next cycle. This cannot be isomerized in the same way as before, and instead is reduced in an NADPH-dependent way to the trans-A compound [2]. After rearrangement by enoyl-CoA isomerase [1 ], degradation can finally be completed via normal p-oxidation. 

E,Z, Z,E- or Z,Z-) can be assigned with the help of retention time considerations and DA-UVD . Examples of the analytical process reqnired for the peroxides derived from linoleic acid are shown in Scheme 20, Section VUI.E and for cholesteryl esters (191) in Section VIII.C.3. 

---