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1.
Theerythro andthreo isomers of methyl 9,10-dihydroxyoctadecanoate and thethreo isomer of methyl 12,13-dihydroxy-cis-9-octadecenoate were converted into methylcis- andtrans-9-octadecenoate and methylcis-9,rans-12-octadecadienoate, respectively, by reaction of the dihydroxy ester with triethyl orthoformate to give the 2-ethoxy-1,3-dioxolane
which was thermally decomposed to the unsaturated ester. 相似文献
2.
A new method for the synthesis ofcis-3,cis-5- andtrans-3,cis-5-tetradecadienoic acids, pheromone constituents of the dermestid beetlesAttagenus elongatulus andA. megatoma, was developed. The syntheses are based upon the formation oftrans-2-tetradecen-5-ynoic acid by reaction of 4-bromo-2-butenoic acid with 1-decynylmagnesium bromide. The enynoic acid undergoes
alkali-induced isomerization to yield a mixture of acids from whichcis-3- andtrans-3-tetradecen-5-ynoic acids were separated in 31% and 34% yields, respectively. Methyltrans-2-tetradecen-5-ynoate was similarly prepared and isomerized to furnish methylcis-3-tetradecen-5-ynoate in 8% yield. Reduction of the tetradecenynoic acids with dicyclohexylborane gavecis-3,cis-5-andtrans-3,cis-5-tetradecadienoic acids in 4% and 39% yields, respectively. A better yield (49%) in the reduction ofcis-3-tetradecen-5-ynoic acid tocis-3,cis-5-tetradecadienoic acid was obtained by hydrogenation over Lindlar's catalyst. Similarly, reduction of methylcis-3-tetradecen-5-ynoate with disiamylborane gave 22% methylcis-3,cis-5-tetradecadienoate. 相似文献
3.
R. O. Adlof W. E. Neff E. A. Emken E. H. Pryde 《Journal of the American Oil Chemists' Society》1977,54(10):414-416
Medium chain length aldehydic acids and esters (C8-C13) were synthesized by ozonolysis of readily available cyclic and straight chain alkenoate esters followed by rearrangement
or reduction of the ozonide. The acetal esters, prepared by reaction of the aldehydic acids with CH3OH-HC1, were characterized by gas liquid chromatography, proton magnetic resonance, carbon magnetic resonance, thin layer
chromatography, and infrared analysis. Selective hydrolysis of the acetal esters to aldehyde esters was conveniently accomplished
with H2O-HC1-CH3CN to give 95% or higher yields in less than 30 min. Development of this simple and effective hydrolysis procedure allows
these medium chain length esters to be safely stored as their acetal esters, which retards their oxidation, trimerization,
and decomposition. 相似文献
4.
E. A. Emken H. J. Dutton W. K. Rohwedder Henry Rakoff R. O. Adlof R. M. Gulley J. J. Canary 《Lipids》1980,15(10):864-871
Triglycerides containingcis- andtrans-12-octadecenoic acid (12c-18∶1 and 12t-18∶1) andcis-9-octadecenoic acid (9c-18∶1) labeled with deuterium were fed to 2 young adult male subjects. These fatty isomers each contained a different number
of deuterium labels, which allowed mass spectrometric analysis to distinguish among them after they were fed as a mixture.
This approach results in a direct comparison of the absorption and distribution of these 3 monoenoic acids into blood plasma
and lipoprotein lipids. Plasma lipid data indicated that all phospholipid fractions selectively incorporate 12c-18∶1 and 12t-18∶1 in preference to 9c-18∶1. Discrimination against 12c-18∶1 and 12t-18∶1 compared to 9c-18∶1 was found in the plasma neutral lipids, with a strong discrimination against 12t-18∶1 incorporation into the cholesteryl ester fraction. Considerable reduction in the percentage of linoleic and arachidonic
acid was observed when 12–18∶1 isomers were incorporated in plasma triglyceride, phosphatidylcholine and sphingomyelin samples.
Chylomicron lipid analyses indicated that all isomers were well absorbed. Variation was observed in the relative distribution
of 12c-18∶1, 12t-18∶1 and 9c-18∶1 between the very low density, low density and high density lipoprotein lipid classes. No desaturation of 12c-18∶1 to linoleic acid was detected. 相似文献
5.
E. A. Emken 《Lipids》2001,36(9):965-973
The use of stable isotope tracers for investigating fatty acid metabolism in human subjects has increased substantially over
the last decade. Advances in analytical instrumentation, commercial availability of labeled substrates, and safety considerations
are major reasons for this increased use of stable isotope tracers. Several experimental design options are available for
using either deuterium or carbon-13 as tracers for fatty acid and lipid studies. Options include feeding a pulse dose of labeled
fat or a mixture containing two or more labeled fats. Multiple doses of the labeled fat can be fed at timed intervals to increase
enrichments. Administration by injection or continuous intravenous infusion is an alternative. Another option is to use diets
containing foods from plants that have slightly higher natural carbon-13 enrichment. Each basic experimental design has its
specific strengths, and the best choice of experimental design depends on the study objectives. Stable isotope studies have
been used to address a variety of questions related to unsaturated fatty acid metabolism in humans. Examples are provided
that illustrate the use of stable isotopes to investigate oxidation of docosahexaenoic acid, desaturation of linoleic and
linolenic acids in infants and adults, incorporation of long-chain n−6 and n−3 fatty acids, bioequivalency of linolenic acid
in primates, 13C nuclear magnetic resonance spectra of arachidonic acid in living rat brain, and effect of triacylglycerol structure on absorption.
Radioisotope and stable isotope tracer studies in animals and humans are responsible for much of our understanding of fatty
acid and lipid metabolism. However, tracer studies have limitations, and there are some unresolved issues associated with
isotope studies. Examples of unresolved issues are quantification of isotope data, validity of in vivo fatty acid metabolite results, kinetic modeling, subject variability, and use of blood lipid data as a reflection of tissue
lipid metabolism. Resolving these issues, developing novel methodology, and applying stable isotope tracer methods to questions
related to PUFA metabolism are broad areas of interesting and challenging research opportunities. 相似文献
6.
E. A. Emken 《Journal of the American Oil Chemists' Society》1978,55(4):416-421
The high specificity and activity of lipoxygenase (EC 1.13.1.13) have not been widely exploited in commercial applications. An analytical application of substrate specificity is exemplified by the Canadian Food and Drug Official Method FA 59 for determining unisomerized linoleic acid in hydrogenated fats. An attractive potential application of lipoxygenase is the lipoxygenase oxidation of linoleic acid for conversion of a renewable resource into a valuable chemical intermediate. Hydroxy-conjugated octadecadienoic acids (HCD) have been prepared by oxidation of a 10% soybean soapstock solution with an aqueous soy flour extract followed by reduction of the hydroperoxide. High yields and a 20-min reaction time are features of this procedure. These laboratory-scale experiments indicate that the processing cost to produce hydroxy-conjugated octadecadienoic acids can be estimated at 21 cents per lb. This cost does not include the cost of the soapstock. The combined hydroxy, conjugated diene, and fatty acid groups in HCD give it the potential of being a versatile chemical intermediate. HCD is readily converted to hydroxystearate or conjugated triene and can compete directly with tung oil acids or hydrogenated castor oil acids. Other reactions can be visualized based on functional group modification to yield products with potential application in the formulation of coatings, lubricants, emulsifiers, and plasticizers. 相似文献
7.
A sensitive and accurate method for detection and quantitation of deuterated fatty acids in the presence of large amounts
of unlabeled fatty acids is described using mass fragmentography in combination with the preparation of tertiarybutyldimethylsilyl
esters (t-BDMS). The method has been applied to determination of deuterated stearic, oleic, elaidic and linoleic acids in human plasma
lipoproteins following duodenal perfusion with a micellar mixture of acids. Over a concentration range of 10–1000 ng/ml, the
average coefficient of variation for the linoleate was 3% and for the oleate (elaidate) ester was 2%. 相似文献
8.
Thetrans 16∶1, 18∶1 and 18∶2 fatty acid composition of various human organ lipids was studied to determine if isomers accumulated
in specific tissues. “Trans” isomers are defined as those fatty acids containing one or moretrans double bonds. Adipose, kidney, brain, heart and liver tissue lipids were analyzed. Gas chromatography with a 100-SP2560 capillary
column was used to characterize the various positional and/or geometrical isomers. The distribution ofrans 16∶1 and 18∶1 isomers ranged from 0.3% in the brain to 4.0% in adipose tissue, whiletrans 18∶2 isomers ranged from 0.0% in the brain to 0.4% in adipose tissue. Notrans 18∶3 isomers were detected. Positional isomer ratios forcis 16∶1 (Δ9 vs Δ7) andcis 18∶1 (Δ11 vs Δ9) were also determined. Since these ratios are reproducible from one individual to the next, they might be
useful for diagnosis of human metabolic disorders. 相似文献
9.