Monounsaturated acids

MFPC multi-nutrient functional-peptide complex MNA monounsaturated acids... 

FIGURE 21-12 Routes of synthesis of other fatty acids. Palmitate is the precursor of stearate and ionger-chain saturated fatty acids, as well as the monounsaturated acids palmitoleate and oleate. Mammals cannot convert oleate to linoleate or a-linolenate (shaded pink), which are therefore required in the diet as essential fatty acids. Conversion of linoleate to other polyunsaturated fatty acids and eicosanoids is outlined. Unsaturated fatty acids are symbolized by indicating the number of carbons and the number and position of the double bonds, as in Table 10-1. 

Several monounsaturated phospholipid fatty acids exist in nature, but few cases are known of very long-chain monounsaturated acids longer than 22 carbons. However, marine sponges are unusual in that they have very long-chain fatty acids in their phospholipids. Sponges have provided the most interesting examples of long-chain phospholipid fatty acids since... 

Of the fatty acid in the fixed oil, most of which is contained in the polygonal cells in the seed endosperm, total monounsaturated acids account for 10% and total polyunsaturated fatty acids 2%. The main components of an expressed oil are petroselinic acid (up to 75%), oleic acid (up to 25%), linoleic acid (up to 15%) and palmitic acid (up to 5%) (Weiss, 2002). 

About one-fourth of the TFAs in ruminant fat is represented by RA, which is by far the predominant natural isomer of conjugated linoleic acid (CLA). The remaining TFAs are mainly trans monounsaturated acids of which vaccenic acid (VA /ra/iv-11-Cisi) is predominant. On the other hand, hydrogenated vegetable oils contain predominantly elaidic acid (trans-9-Ci8 i) and have a more even distribution of the other trans-C n acids, but contain little or no RA (Parodi, 2004). 

The reactions mentioned above account for many, but by no means all, pheromones whose biosynthesis is related to fatty acids. For example, the silkworm moth, Bombyx mori, has as its main pheromone component E, Z)-10,12-hexadecadien-l-ol (1). The corresponding diunsaturated fatty acid also is present in the gland (JjL), as is a large quantity of (Z) -11-hexadecenoic acid (15.). Recent studies have demonstrated that the monounsaturated acid is formed first, followed by what appears to be a 1,4-desaturation yielding the diunsaturated acid (1 ). 

FIGURE 6.36 Conversion of palmitic acid to an 18 1 fatty acid. Palmitic acid (16 0), a saturate, is converted in the body to the monounsaturate acid (18 1) by a two-step process involving initial conversion to stearic acid (18 0). 

Canola oil contains approximately 6% saturated acids, 2% monounsaturated acids, and 32% polyunsaturated acids see Table I. Additionally, sulfur-containing fatty acids may also be present as minor constituents. 

Another oil of interest for lubricants is jojoba oil as a replacement of sperm whale oil, the use of which is now banned. Jojoba oil is not a triglyceride but is a wax ester composed mainly of straight chain esters of C20-C22 monounsaturated acids and alcohols. The major constituents, shown in Fig. 6.11, are eicosenyl and docosenyl eicosenoates, where m = 9 and n = 10, 12 ... 

The physiological effects of vegetable oil are based on their fatty acid composition. Current US dietary guidelines recommend that diets contain less than 30% calories from fat, of which less than 10% is from saturated fat, 10-15% from monounsaturated acid, and 10% from polyunsaturated acids. The primary concerns with fatty acid consumption relate to two chronic diseases—coronary heart disease (CHD) and cancer. Research has shown that high levels of dietary saturated fatty acids are related to increased CHD and that dietary modification can lower plasma cholesterol. Consequent changes in cholesterol level can be predicted by the following relationship (Hegsted et al. 1993). 

The metabolism of fatty acids in cheese by Penicillium spp. involves four main steps (Fig. 4) (1) release of fatty acids by the lipolytic systems discussed above (Sections IVD2-IVD4), (2) oxidation to )3-ketoacids, (3) decarboxylation to methyl ketone with one less carbon atom, and (4) reduction of methyl ketones to the corresponding secondary alcohol (Hawke, 1966) step 4 is reversible under aerobic conditions (Adda et al., 1982). The concentration of methyl ketones is related to lipolysis. Methyl ketones can also be formed by the action of the mould on the ketoacids naturally present at low concentrations in milk fat (ca. 1% of total fatty acids). They could also be formed by the oxidation of monounsaturated acids, but Adda et... 

Higher desaturase activity is found in the liver of genetically fat strains of domestic fowl compared with genetically lean strains (Legrand Lemarchal, 1992). The synthesis of a higher proportion of monounsaturated acids in the genetically fat line is thought to facilitate their incorporation into very low density lipoproteins (VLDL), which leads to a... 

Fatty acids such as oleic acid, which contain only one double bond, are referred to as monounsaturated acids. One of the unsaturated acids, linoleic acid, is an essential fatty acid. The human body cannot produce this acid, but... 

The seasonal variation in milk fat composition is demonstrated in Table 3.153, winter milk fat being more saturated than summer milk fat. The trans fatty acid content is not frequently recorded. Literature values vary between 2 and 11% with higher values in the summer. The determined values are very method-dependent and values in the range 4-8% are probably realistic (Deman and Deman, 1983). The main trans monounsaturated acid is tran -vaccenic acid (18 1 n-1) (Hay and Morrison, 1970 Lund and Jensen, 1983). 

Monounsaturated acids are prepared from three units ... 

Discrimination between cyclopropane and monounsaturated acid methyl esters was possible by chemical ionization-MS with use of mixtures of methane or isobutane with vinyl methyl ether as reactant gas only... 

Although increased levels of lipid peroxidation endproducts are found in most human diseases, the occurrence of lipid peroxidation does not always imply a state of disease. For example, increased levels of lipid peroxidation also occur in fasting human subjects, by the breakdown of fat (65). A certain level of lipid peroxidation may actually be expected after exposure to CIA, as most polyunsaturated fatty acids are more susceptible to the attack of oxygen radicals than monounsaturated fatty acids or saturated fatty acids (66). For example, supplementation with fish oil significantly increased plasma lipid peroxides in women (67, 68). Work by Banni et al. showed that CLA does not behave differently under oxidative stress than regular polyunsaturated fatty acids (51). The control oil used in the studies by Riserus et al. (35) and Basu et al. (64) was olive oil, which contains high levels of the monounsaturated acid oleic acid and has been shown to work as an anti-oxidant (69). 

Description C16 palmitic 8.0% palmitoleic C18 stearic 2.0% oleic, 82.0% linoleic, 8.0% linolenic total saturated acids 14% total monounsaturated acids 77% total polyunsaturated acids 9%... 

Plant lipids are of two main types structural and storage. The structiu lipids are present as constituents of various membranes and protective surface layers and make up about 7 per cent of the leaves of higher plants. The surface lipids are mainly waxes, with relatively minor contributions from long-chain hydrocarbons, fatty acids and cutin. The membrane lipids, present in mitochondria, the endoplasmic reticulmn and the plasma membranes, are mainly glycolipids (40-50 per cent) and phosphoglyc-erides. Plant storage lipids occur in fruits and seeds and are, predominantly, triacyl-glycerols. Over 300 different fatty acids have been isolated from plant tissues, but only about seven are of common occurrence. The most abundant is a-linolenic acid the most common saturated acid is palmitic acid and the most common monounsaturated acid is oleic acid. 

The cis-monounsaturated acids might also resnlt from the desaturation of a fatty acid with 16 carbons which would undergo desaturation prior to the elongation by acetyl-CoA. 

Pancreatic lipase hydrolysis has proved (Coleman, 1963a Fedeli et al., 1965 Gunstone and Padley, 1965 Mattson and Volpenhein, 1961 Vander Wal, 1960) that acids are not randomly distributed on the three positions of glycerol with very few exceptions, the 2-posi-tion is predominantly occupied by unsaturated acids, whereas the saturated and C20-22 monounsaturated acids are predominantly distributed in the 1,3-positions of glycerol. 

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