Polyunsaturated Fatty Acids PUFAs

The fatty acid, s )ecifically AA (20 4, i)-6), has a key functional role in platelet-mediated hemostasis and thrombosis because of its rapid conversion to TxAj upon platelet activation. Over the last few years, we have seen a tremendous interest on AA metabolism within the scientific community. Certainly the interest on PUFAs, has 

Dietary linoleic acid (18 2, o-6) is the indirect precursor for both the eicosanoid 1 and 

FIgura S. Hm fatty add tumovar pathway, showing tha ralaata, uptaka and convafslen of fatty adds 

Platelet phospholipid and fatty acid composition was first reported in some detail by two groups (11, 12). Subsequently, our laboratory fully characterized individual fatty acid specific molecular species in human platelet phospholipids (13), in addition to documenting the molar concentration of individual phospholipids (Table 1). This work 

Mhomo-gamma Unotanlc Add (DOLA) AnehldonieAdd(AA) Elcosapantasnolc Add (EPi  

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Lipid peroxidation is a radical-mediated chain reaction resulting in the degradation of polyunsaturated fatty acids (PUFAs) that contain more than two covalent carbon-carbon double bonds (reviewed by Esterbauer et al., 1992). One of the major carriers of plasma lipids is LDL, a spherical molecule with a molecular weight of 2.5x10 . A single LDL particle contains 1300 PUFA molecules (2700 total fatty-acid molecules) and is... 

It is now widely appreciated that polyunsaturated fatty acids (PUFAs) are highly susceptible to oxidative damage. Indeed, the process of lipid peroxidation was broadly defined as the oxidative deterioration of polyunsaturated lipids by Tappel (1979). The presence of a double... 

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... 

FIGURE 32-6 Lipid peroxidation leads to fragmentation or oxidation of polyunsaturated fatty acids (PUFA). HO, hydroxyl radical LO, lipid alkoxylradical LOO, lipid peroxyl radical 0 2, superoxide radical O, atomic oxygen radical. (From Hall in [3].)... 

Dietary polyunsaturated fatty acids (PUFAs), especially the n-3 series that are found in marine fish oils, modulate a variety of normal and disease processes, and consequently affect human health. PUFAs are classified based on the position of double bonds in their lipid structure and include the n-3 and n-6 series. Dietary n-3 PUFAs include a-linolenic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) whereas the most common n-6 PUFAs are linoleic acid, y-linolenic acid, and arachidonic acid (AA). AA is the primary precursor of eicosanoids, which includes the prostaglandins, leukotrienes, and thromboxanes. Collectively, these AA-derived mediators can exert profound effects on immune and inflammatory processes. Mammals can neither synthesize n-3 and n-6 PUFAs nor convert one variety to the other as they do not possess the appropriate enzymes. PUFAs are required for membrane formation and function... 

Polyunsaturated fatty acids (PUFAs), 5 33t 10 830 17 663-666 health effects of, 17 665-666 Polyunsaturates, 10 814 Polyurea, colloidal suspensions, 7 275 Polyurea greases, 15 243 Polyurethane (PU). See also Polyurethanes (PUs)... 

Arachidonic acid (C20 4 n-6) is the precursor for the synthesis of prostaglandin molecules (Section 4.4.4), which have a wide range of biochemical effects on for example, the perception of pain, inflammation, blood clotting and smooth muscle contraction. Docosahexaenoic acid (DHA, C22 6) and eicosapentaenoic acid (EPA, C20 5) are both n-3 long-chain polyunsaturated fatty acids (PUFA) which have been shown to have significantly beneficial effects on intellectual development and inflammatory conditions such as asthma and cardiovascular disease. 

The main action of vitamin E in human tissue is to prevent oxidation of polyunsaturated fatty acids (PUFA), thereby protecting lipid and phospholipids in membranes. Vitamin E interacts syn-ergically with other nutrients, such as vitamin C, selenium, and zinc, which are also involved in the oxidation pathway. The recommended intake is strongly related to the quantity of PUFA consumption. Some studies [454-456] on animal models and epidemiological trials in human suggest... 

E Group active derivatives of tocol and tocotrienol most active is RRR-a-tocoferol = (d)-a-tocoferol Vegetable oils and cereals, vegetables, fruit Depending on the amount of polyunsaturated fatty acids (PUFA) in the diet <1/2 yr 2.9 a-TE 1/2-1 yr 3.6 a-TE 1-19 yr 5.5 up to 13.3 a-TE >19 yr 13 down to 8.3 a-TE pregnancy 0.6 a-TE extra lactating women 2.7 a-TE extra... 

Lipids that contain polyunsaturated fatty acids (PUFA) have therapeutic value. Supercritical CO2 extraction was chosen as an alternative method to recover these valuable compounds from the lower fungus, Pythium irregu-lare (Walker et al., 1999). 

Lipid emulsions are essential components of parenteral nutrition. However, due to the amount of polyunsaturated fatty acids (PUFA), it is possible that chemical degradation occurs, forming hydroperoxides. 

Cabanes, A., Wang, M., Olivo, S., Gustafsson, J., and Hilakivi-Clarke, L. (2003). Effect of n-3 polyunsaturated fatty acids (PUFAs) on breast cancer progression. Cancer Epidemiol. Biomarkers Prev. 12 (1305S). 

Long-chain fatty acids are hydrophobic substances in plasma they occur in the esterified state or bound to protein (mainly albumin). As a consequence, long-chain fatty acids are not excreted into the urine and are measured either in the plasma or in erythrocytes, where they are part of the membrane. Erythrocyte levels of polyunsaturated fatty acids (PUFA) are fairly constant and may reliably reflect the longterm availability or deficiency of the essential fatty acids. A list of fatty acids that can be separated and analysed by GC is shown in Table 3.3.1. 

Enzymes present in the ER are responsible for desaturating fatlyj j acids (that is, adding cis double bonds). Termed mixed-function oxidases, the desaturation reactions require NADPH and 02. A van-l ety of polyunsaturated fatty acids (PUFA) can be made through addi-l tional desaturation combined with elongation. [Note Humans laal the ability to introduce double bonds between carbon 9 and the col... 

E9 10. Polyunsaturated fatty acids (PUFAs) have several carbon-carbon double bonds as present in /3-carotene. Why are PUFAs not colored like fi-carotene ... 

Lipids are susceptible to oxidation and, therefore, analytical protocols are required to measure their quality. Not all lipids have the same degree of susceptibility to oxidation. Many factors are responsible for a lipid s tendency to oxidize, including the presence of catalysts, oxidative enzymes, radiation, and a lipid-air interface, as well as the oxygen partial pressure, the incorporation of oxygen into the product, and the presence of metal ions. The most important factor is the degree of unsaturation of the lipid itself. The majority of a food product s polyunsaturated fatty acids (PUFAs) are generally contained in phospholipids, which are consequently more prone to autoxi-dation than the triacylglycerol fraction. 

Figure D2.1.2 Different types of conjugated and nonconjugated double bonds in fatty acids. (A) A polyunsaturated fatty acid (PUFA). (B) A PUFA nonhydroperoxide with a conjugated diene (CD). (C) A PUFA hydroperoxide with a CD. and R2 indicate the remaining alkyl portions of the PUFA. Reprinted from Corongiu and Banni (1994) with permission from Academic Press.

Interest in w-3-polyunsaturated fatty acids initially was prompted by observations that Greenland Eskimos experienced a significantly lower incidence of death from ischemic heart disease than Western populations. Results of subsequent studies indicated that this alleged or potential health benefit and other physiological effects were due to a diet high in marine oils containing esterifed w-3-polyunsaturated fatty acids (PUFAs). 

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