Fatty acids in animal tissues

Figure 1. Pathways of oxygenation of unsaturated fatty acids in animal tissue.

Octadecanoic Stearic 69.6 Major fatty acid in animal tissues and some fungi, usually minor in plants, major only in a few plant species (e.g., cocoa butter). 

Bezard. J.. Blond, J.P., Bernard, A., and Clouet, P. (1994) Availability of Essential Fatty Acids in Animal Tissues, Re-prod. Nutr. Dev. 34,539-568. 

Very little is known about the oxidative reactions which lead to the production of acetyl-coenzyme A from fatty acids in animal tissues, but, since it is likely that these oxidations utilize the same electron transfer system as Krebs cycle oxidations, and since fatty acid oxidation takes place in the same enzyme preparations which are used for the study of oxidative phosphorylation, it would seem likely on a priori grounds that the over-all P/0 ratio for fatty acid oxidation must be similar to that observed for the complete oxidation of pyruvate. 

C.,g and C20 fatty acids of the (n-9), (n-6) and (n-3) families are the most abundant trienoic fatty acids in animal tissues they elute in this order on polar stationary phases and some ECL data are contained in Table 5.3. All of the eight possible geometrical isomers of 9,12,15-octadecatrienoic acid (a-linolenic acid) have been prepared by nitrous oxide-catalysed elaidinisation [21-23,815] and by total synthesis [747]. Ackman and Hooper [21-23] were able to predict their ECL values, from data for the appropriate monoenes obtained on a WCOT column coated with Silar 5CP , by applying diethylenic... 

Using the serial data for the cerebral cortex, plasma, and erythrocytes, we constructed accumulation and decay curves for several key fatty acids in these tissues, which provided gross estimates of their turnover times after fish-oil feeding to n-3 fatty acid-deficient monkeys (Table 2). For cerebral cortex, a steady state was reached after 12 wk of fish-oil feeding for DHA, but 22 5n-6 took longer to decline to the low levels found in the cortex of control animals. The half-lives of DHA in cerebral phospholipids ranged from 17 to 21 d 21 d for phosphatidylethanolamine, 21 d for phosphatidylserine, 18 d for phosphatidylinositol, and 17 d for phosphatidylcholine. The corresponding values for 22 5n-6 in these same phospholipids were 32,49,14, and 28 d, respectively. The half-lives of linoleic acid, EPA, and DHA in plasma phospholipids were estimated to be 8,18, and 29 d, respectively. In the phospholipids of erythrocytes, linoleic acid, arachidonic acids, EPA, and DHA had half-lives of 28, 32, 14, and 21 d, respectively. 

The role of fatty adds in the etiology of atherosclerosis is far from clear. It has often been suggested that excess saturated fats or carbohydrates in the diet are related to the development of atherosclerosis. Animals that live free in the woodland areas where they eat a great variety of foods including nuts, berries, seeds, etc., get a more oil-rich diet and have considerably moM polyunsaturated fatty acid in their tissues than animals in captivity. Fatty acid analysis was made of abdominal sucutaneous adipose tissue of men that died suddenly and the coronary disease evaluated under standardized procedures. The analyzed fatty acids listed in order of their relative contributions to the extent of the disease are stearic, lauric, palmltolelc, myrlstlc, and llnolelc. 

The use of radioactive tracers in the study of reaction mechanisms has been steadily increasing over the last two decades. Radioactive tracers have been used to elucidate the mechanism of complex laboratory reactions, in photosynthetic chemistry and, in particular, to follow metabolic pathways of substances, synthetic and natural, in both plants and animals. In fact, the first reported use of an in-line radioactivity detector fitted directly to a gas chromatograph was in a paper by James and Piper (51) who developed the detector to study the synthesis of lipids, glycerides and fatty acids in plant tissue. James and his... 

The most abundant saturated fatty acids in animal and plant tissues are straight-chain compounds with 14, 16 and 18 carbon atoms, but all the possible odd and even numbered homologues with 2 to 36 carbon atoms have been found in nature in esterified form. They are named systematically from the saturated hydrocarbon with the same number of carbon atoms, the final -e being changed to -oic. Thus, the fatty acid with 16 carbon atoms and the stmctural formula -... 

Lipid analysts soon acquire an intuitive understanding of the relationship between the retention times of peaks on a GC trace and their identity. For example, a typical fingerprint of the fatty acids from animal tissue phospholipids would have the 16 0 component standing in relative isolation, followed by the three peaks for the Cis components (18 0, 18 1 and 18 2), then a gap to the next substantial peak for 20 4(n-6), followed by a further gap to the C22 components, the last of which is 22 6(17-3). Many of the minor peaks can be identified tentatively according to their proximity to these major components. 

As isomers differing in ECL value by about 0.04 should be separable on most WCOT column, it would be expected that those fatty acids with central double bonds (about 4-18 1 to 9-18 1) will not be easily resolved petroselinic (6-18 1) and oleic acids occur together in some seed oils and are not readily resolved by GC (although this is possible with reversed-phase HPLC [168]). In the monoenoic fatty acids from animal tissues, there tend to be isomers in which the double bond positions are two carbon atoms apart, because they are formed... 

It is the author s opinion then that picolinyl esters are the best general purpose derivative for locating double bonds by GC-MS. They have been used in analyses of fatty acids of animal tissues [173,184,363,365,979], a fish oil [173,184], marine invertebrates [175] and bacteria [960],... 

An overview of important fatty acids with an even number of carbon atoms in the molecule is given in Table 3.1. Besides the systematic names derived from the corresponding hydrocarbons, trivial names are also given, and these are used predominately in routine practice, especially in the nomenclature of common fatty acids. In the Hterature, for brevity, various short designations predominate, such as an N M ratio, where N is the number of carbon atoms in the molecule and M the number of double bonds. The most abundant saturated fatty acids in animal and plant tissues... 

The most widespread unsaturated fatty acid is oleic acid (3-4), which occurs, at least in a small amount, in virtually all animal and plant lipids. Oleic acid constitutes 30 0% of the total fatty acids in adipose tissue of animals and 20 80% of the total fatty adds in vegetable fats and oils. For example, ohve oil contains up to 78% oleic add. 

Linoleic acid (3-7) is the most common polyenoic fatty add. It is present, at least in traces, in aU fats. For example, sunflower and soybean oils usually contain 50-60% of linoleic add safflower oil contains 75% linoleic acid. In the fat of animals, where this essential fatty add gets from plant food, its content is typically 15-25%, but maybe higher (cardioUpin of heart muscle contains 75% linoleic acid). Linolenic acid (3-11) is the main component of leaves, especially in the photosynthesising apparatus of algae and higher plants. Linolenic acid is present in linseed oil in amounts of up to 65%. Soybean and rapeseed oils only contain up to 10% linolenic acid. In animal tissues, it is usually a minor component (up to 1%), although the adipose tissue of horses contains up to 10% of this essential fatty acid. 

We must conclude from the manner in which the isotope of fatty acids is incorporated into acetoacetic acid, as well as from other lines of evidence (see Section VII), that the formation of 2-carbon fragments is a fundamental step in the oxidation of fatty acids by animal tissues. 

Palmitoleic acid is commonly found at low levels in animal and plant tissues (Gunstone, 1994). It is present in most fish oils at levels of around 10% (w/w) of total fatty acids. In animal depot fat, the level of palmitoleic acid varies between 3% and 10%, depending on location and animal species. In human and animal milk, the proportion of palmitoleic acid, together with other 16 1 isomers, is typically 2-6%, with exceptionally high levels found in grey seal milk (16%) and camel colostrum (14%) and milk (10%) (Gorban and Izzeldin, 2001). 

Fats in animal tissue Fat substitutes Fatty acid... 

Phosphatidylcholine, commonly known as lecithin, is the most commonly occurring in natnre and consists of two fatty add moieties in each molecule. Phosphati-dylethanolamine, also known as cephahn, consists of an amine gronp that can be methylated to form other compounds. This is also one of the abundant phospholipids of animal, plant, and microbial origin. Phosphatidylserine, which has weakly acidic properties and is found in the brain tissues of mammals, is found in small amounts in microorganisms. Recent health claims indicate that phosphatidylserine can be used as a brain food for early Alzheimer s disease patients and for patients with cognitive dysfunctions. Lysophospholipids consist of only one fatty acid moiety attached either to sn-1 or sn-2 position in each molecule, and some of them are quite soluble in water. Lysophosphatidylchohne, lysophosphatidylserine, and lysophos-phatidylethanolamine are found in animal tissues in trace amounts, and they are mainly hydrolytic products of phospholipids. 

Fatty Acids in Archaeological Skeletal and Soft Tissue Remains and Experimental Animals... 

In Box 7.13 we saw that the widely used analgesic aspirin exerted its action by acetylating the enzyme cyclooxygenase (COX) which is involved in the production of prostaglandins. Prostaglandins are modified C20 fatty acids synthesized in animal tissues and they affect a wide variety of physiological processes, such as... 

Cholesterol is present in all animal tissues, and particularly in neural tissue. It is a major constituent of cellular membranes, in which it regulates fluidity (see p. 216). The storage and transport forms of cholesterol are its esters with fatty acids. In lipoproteins, cholesterol and its fatty acid esters are associated with other lipids (see p.278). Cholesterol is a constituent of the bile and is therefore found in many gallstones. Its biosynthesis, metabolism, and transport are discussed elsewhere (see pp. 172, 312). 

The fatty acids could be carried by proteins by a process similar to the way in which serum albumin binds fatty acid in the bloodstream of mammals. Other types of lipid might be formed into complexes analogous to low-density lipoproteins of the type found in animal tissues, where the lipid core of the lipoprotein is surrounded by a hydrophilic cortex made up of protein, phospholipid, and cholesterol (87). This allows the lipid to be moved in an aqueous environment. The protein of the lipoprotein shell could also act as possible ligands for particular receptors at the membrane of the cell at which the export occurs. The lipoproteins, if they are present, would probably be formed within the endomembrane lumen and would receive the proteins at the endoplasmic reticulum. 

Triacylglycerol. Triglyceride a compound consisting of three molecules of fatty acids esterified to glycerol. It is a neutral fat synthesized from carbohydrates for storage in animal adipose cells. On enzymatic hydrolysis, it releases free fatty acids in the blood. Tuberculosis. Any of the infectious diseases of man and animals caused by species Mycobacterium and characterized by the formation of tubercles and caseous necrosis in the tissues. 

Absorption and Deposition of CLA in Animal Tissues. Miller etal (27) described a method employing the methyl ester of conjugated dienes prepared from com oil as tracers of fat metabolism. It was postulated that the conjugated dienoic isomers could be differentiated from other fatty acids in body fat by spectrophotometric absorbance at 233 nm. 

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