Oleic acid synthesis

The Calgene company has also produced the expression of an antisense gene encoding a B. rapa stearoyl-ACP desaturase in both B. mpus and B. rapa. This has led to the inhibition of oleic acid synthesis for the benefit of the stearic acid concentration in the oil of up to 40% (Knutzon et al., 1992). 

Changes in agronomic practices and the inroduction of new cultivars in recent years have been shown to affect tree nut composition. For example, it has been demonstrated that irrigation retarded oleic acid synthesis in filberts (hazel nuts) and reduced its proportion at all stages of ripening. Heaton et al. (1966) showed that nitrogen application to pecan trees caused oleic acid to decrease and linoleic acid to increase in nut kernels. Heaton et al. (1975) reported that variations in fatty acid composition of pecan nuts were associated with cultivar and year of production. These variations in fatty acid composition may influence the nutritional value and storage stability of tree nuts. Listed in Table 6.5 are the total oil content and fatty acid composition of 13 types of tree nut kernels. 

To obtain polyunsaturated fatty acids, the double bonds are introduced by a stepwise process. A fundamental difference exists between mammals and plants. In the former, oleic acid synthesis is possible, and, also, additional double bonds can be inserted towards the carboxyl end of the fatty acid molecule. For example, y-hnolenic acid can be formed from the essential fatty acid linoleic acid and, also, arachidonic acid (Fig. 3.5) can be formed by chain elongation of y-linolenic acid. In a diet deficient in linoleic acid, oleic acid is dehydrogenated to isolinoleic acid and its derivatives (Fig. 3.5), but none of these acquire the physiological function of an essential acid such as linoleic acid. 

The obtained results showed that total fatty acids, triacylglycerols and oleic acid accumulation during olive fruit ripening decreased when NaCl concentrations augmented in Irrigation water. This oleic acid synthesis decrease could be explained by a photosynthetic acitivity inhibition because the chloroplast is an important site of oleic acid production in plant cells (Stumpf and al,, 1980). 

The effects of methyl sterculate on R gracilis were also studied via the use of (l- C]acetate and ammonium [ 1- C]stearate as possible precursors for oleic acid synthesis (Table 2). When labelled stearate was the precursor molecule, methyl sterculate was able to decrease the conversion of stearate to oleate from approximately 40% to 4%, whilst In samples In which (1- x]acetate was the precursor, very little Inhibition was observed. Such evidence Implies that the conversion of acetate to oleate Is by a route which Is not susceptible to sterculate Inhibition. Similar observations have been reported for both plant and mammalian" desaturase systems. 

In work performed by Jeffcoat and Pollard, the Inhibitory form of stercullc acid In mammalian tissue was reported to be sterculoyl-CoA. If this Is also true for R. gracilis, we may tentatively propose that the alternative route of oleic acid synthesis In the presence of methyl sterculate Is via a A9 desaturase system that Is capable of desaturatlng stearate when attached to a complex lipid. Further desaturation of phospholipid substrate to llnoleate and then llnolenate would explain the lack of sterculate Inhibition of the latter s S3rnthesls. These possibilities are being Investigated. 

The participation of this tritium in oleic acid synthesis is not negligible and is of the same order of magnitude as that observed in case of stearic acid. More intensive participation of the NADPH hydrogen in oleic acid synthesis is rather improbable, but the high ratio... 

Cyanide Wastes. Ozone is employed as a selective oxidant in laboratory-scale synthesis (7) and in commercial-scale production of specialty organic chemicals and intermediates such as fragrances, perfumes (qv), flavors, antibiotics (qv), hormones (qv), and vitamins (qv). In Japan, several metric tons per day (t/d) of piperonal [120-57-0] (3,4-methylenedioxybenzaldehyde) is manufactured in 87% yield via ozonolysis and reduction of isosafrole [93-16-3], Piperonal (or heHotropine [120-57-0]) has a pleasant odor and is used in perfumery. Oleic acid [112-80-1/, CH3(CH2 )7CH—CH(CH2 ). C02H, from tall oil (qv) is ozonated on a t/d scale to produce pelargonic, GgH2yG02H, and azelaic, H02G(GH2)yG02H, acids. Oleic acid also is ozonated in Japan... 

The ability of lipases to synthesize the amide bond has been shown (26). Mucor miehei lipase (NOVO tipozyme) has been used in the reaction of laurylamine and oleic acid at 60°C. Water was shown to inhibit the synthesis of this Ai-lauryloleamide (27). 

There has been only one major use for ozone today in the field of chemical synthesis the ozonation of oleic acid to produce azelaic acid. Oleic acid is obtained from either tallow, a by-product of meat-packing plants, or from tall oil, a byproduct of making paper from wood. Oleic acid is dissolved in about half its weight of pelargonic acid and is ozonized continuously in a reactor with approximately 2 percent ozone in oxygen it is oxidized for several hours. The pelargonic and azelaic acids are recovered by vacuum distillation. The acids are then esterified to yield a plasticizer for vinyl compounds or for the production of lubricants. Azelaic acid is also a starting material in the production of a nylon type of polymer. 

Oleic acid, structure of, 1062 Oligonucleotide, 1114 synthesis of, 1114-1116 Olive oil, composition of, 1062 -otie. ketone name ending, 697 -otdtrile, nitrile name ending, 754 Optical activity, 294-296 measurement of, 295 Optical isomers. 297 Optically active, 295 Orbital. 4... 

In this in vitro system, the presence of serum in cell culture medium is not necessary, but the type of transwell is important (the total amount of H-triglycerides secreted was two-fold higher when using 3 pm versus 1 pm pore size transwells), and oleic acid supplementation is required for the formation and secretion of CMs as well as the transport of 3-carotene through Caco-2 cells. Finally, the presence of Tween 40 does not affect CM synthesis and secretion in this in vitro cell culture system. Thus, CMs secreted by Caco-2 cells were characterized as particles rich in newly synthesized H-triglycerides (90% of total secreted) containing apolipoprotein B (30% of total secreted) and H-phospholipids (20% of total secreted) and with an average diameter of 60 nm. These characteristics are close to those of CMs secreted in vivo by enterocytes. ... 

This study could be extended to the synthesis of iron nanoparticles. Using Fe[N(SiMe3)2]2 as precursor and a mixture of HDA and oleic acid, spherical nanoparticles are initially formed as in the case of cobalt. However, a thermal treatment at 150 °C in the presence of H2 leads to coalescence of the particles into cubic particles of 7 nm side length. Furthermore, these particles self-organize into cubic super-structures (cubes of cubes Fig. ) [79]. The nanoparticles are very air-sensitive but consist of zerovalent iron as evidenced by Mossbauer spectroscopy. The fact that the spherical particles present at the early stage of the reaction coalesce into rods in the case of cobalt and cubes in the case of iron is attributed to the crystal structure of the metal particles hep for cobalt, bcc for iron. 

In 2000, Sun and co-workers succeeded in synthesis of monodispersed Fe/Pt nanoparticles by the reduction of platinum acetylacetonate and decomposition of Fe(CO)5 in the presence of oleic acid and oleylamine stabilizers [18]. The Fe/Pt nanoparticle composition is readily controlled, and the size is tunable from 3 to 10 nm in diameter with a standard deviation of less than 5%. For practical use, we developed the novel symthetic method of FePt nanoparticles by the polyol reduction of platinum acetylacetonate (Pt(acac)2) and iron acetylacetonate (Fe(acac)3) in the presence of oleic acid and oleylamine stabilizers in di- -octylether [19,20]. The Fe contents in FePt nanoparticles can be tuned from 23 to 67atomic%, and the particle sizes are not significantly affected by the compositions, retaining to be 3.1 nm with a very narrow size distribution, as shown in Figure 6. 

Biosynthesis of Unsaturated Fatty Acids. In the mammalian tissues, the forma-tion of monoene fatty acids is only possible. Oleic acid is derived from stearic acid, and palmitooleic acid, from palmitic acid. This synthesis is carried out in the endoplasmic reticulum of the liver cells via the monooxigenase oxidation chain. Any other unsaturated fatty acids are not produced in the human organism and must be supplied in vegetable food (plants are capable of generating polyene fatty acids). Polyene fatty acids are essential food factors for mammals. 

Fatty acids have also been converted to difunctional monomers for polyanhydride synthesis by dimerizing the unsaturated erucic or oleic acid to form branched monomers. These monomers are collectively referred to as fatty acid dimers and the polymers are referred to as poly(fatty acid dimer) (PFAD). PFAD (erucic acid dimer) was synthesized by Domb and Maniar (1993) via melt polycondensation and was a liquid at room temperature. Desiring to increase the hydrophobicity of aliphatic polyanhydrides such as PSA without adding aromaticity to the monomers (and thereby increasing the melting point), Teomim and Domb (1999) and Krasko et al. (2002) have synthesized fatty acid terminated PSA. Octanoic, lauric, myristic, stearic, ricinoleic, oleic, linoleic, and lithocholic acid acetate anhydrides were added to the melt polycondensation reactions to obtain the desired terminations. As desired, a dramatic reduction in the erosion rate was obtained (Krasko et al., 2002 Teomim and Domb, 1999). 

SILAR has been used for the synthesis of CdS/ZnS coatings for CdSe quantum dots. The precursor solutions were prepared by dissolving CdO, ZnO, and S in oleic acid and octadecane. The final coating consisted of three layers of CdS and three additional layers of ZnS. The photonic band structure of the photonic crystal had a modifying influence on the photoluminescence of the embedded quantum dots.90... 

It has been found that the catalytic activity of PKC is enhanced by a lipid component of the cell membrane, namely phosphatidylserine. This activity is further stimulated by sn-1,2-diacylglycerol. Oleic acid also activates the enzyme in the presence of 1,2-diacylglycerol, and thus it is presumed to mimic phosphatidylserine. In order to identify that modulating binding site for oleic acid on PKC, a photoaffinity analogue was devised. A carbene generating photophore, diazirine was placed in the apolar terminus of the unsaturated fatty acid ligand (30, Fig. 12). The synthesis and the photochemical activation properties were reported by Ruhmann and Wentrup [113]. 

Plants have apparently adopted the dead-ant signal to induce ants to pick up seeds that contain the signal. Evolutionarily, this development should have involved a minimal cost in energy, since plants were already making and using oleic acid as a constituent of their fats. Here then, the critical step would have been not the synthesis of oleic acid, but the incorporation of oleic acid into the seed s elaiosome. 

While the extracts of SPMDs are generally less difficult to purify than are extracts of tissue or sediment, certain interferences can be problematic for some types of analyses. The most important of these potential interferences are codialyzed polyethylene oligomers (i.e., the so-called polyethylene waxes), oleic acid, and methyl oleate. The latter two interferences are residual from the synthesis of the triolein. Also, oxidation products of triolein may be present in dialysates of SPMDs that have been exposed (especially in the presence of light) to air for periods exceeding 30 d. For a standard 1-mL triolein SPMD, the mass of all these interferences in dialysates is generally <30 mg or about 6 mg g of SPMD (Huckins et al., 1996). Another potential interference is elemental sulfur, which is often present in sediment pore water and is concentrated by SPMDs. However, both polyethylene waxes and elemental sulfur are readily removed using the previously described SEC procedure. 

The synthesis of carboxylic acids by the oxidation of alkenes is a two-step process. In the first step, a hot basic potassium permanganate (KMnO ) solution oxidizes an alkene, and in the second step, the oxidized alkene is acidified. The process cleaves the Ccirbon backbone at the carbon-carbon double bond to produce two smaller carboxylic acid molecules. For example, oleic acid (CH3(CH2)yCH=CI-l(CI-l2)yCOOH) yields of mixture of nonanoic acid (CH3(CH2)7C00H) and nonadioic acid (HOOC(CH2)7COOH). 

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