Mass spectra of acetylenic fatty acid methyl esters and derivatives

A series of isomeric methyl octadecynoates was analyzed by mass spectrometry; each isomer gave a unique spectrum. The characteristic ions were those resulting from a McLafferty rearrangement of the allenic sites or of the already-rearranged allenic sites. The acetylenic esters were also subjected to oxymercuration whereupon a carbonyl group was formed at either of the original actylenic carbon atoms providing two oxostearates. Further reaction with NaBH₄ formed hydroxy esters which, after silylation, gave diagnostic mass spectra indicative of the triple bond location. Applied to esters with both double and triple bonds, this procedure permitted differentiation between the two types of unsaturation. Methoxyl groups marked the original double bond locations and hydroxyls did so for triple bonds. Presented at the 48th Fall Meeting of the American Oil Chemists’ Society, Philadelphia, PA, September 29–October 2, 1974.     

Mass spectra of the picolinyl esters of isomeric mono- and dienoic fatty acids

The picolinyl ester derivatives of the complete series of isomeric octadecenoates, methylene-interrupted octadecadienoates, and of octadec-9-ynoate have been subjected to gas chromatography-mass spectrometry. A fused-silica capillary column, coated with a cross-linked methyl silicone, was used for the separation. Electron impact spectra were determined at 70 eV. Earlier observations with a limited series of model compounds were confirmed, and it was shown that the picolinyl ester derivatives were of almost universal value in the location of double bonds in such isomers. Difficulties of interpretation arose mainly when the double bonds were close to the carboxyl group.     

Cross‐metathesis with fatty acid derivatives: Scope,challenges and perspectives

Plant oils are an important renewable resource for the chemical industry and will help to reduce CO₂ emissions and contribute to a sustainable development of our future. Chemically efficient as well as cost‐effective reactions and processes are now being developed to achieve this goal, metathesis being one of them. This feature briefly describes the possibilities of cross‐metathesis reactions with oleochemicals, discussing general aspects of cross‐metathesis reactions, evaluating current pros and cons, and highlighting recent developments.     

Analysis of novel hydroperoxides and other metabolites of oleic, linoleic, and linolenic acids by liquid chromatography-mass spectrometry with ion trap MSn

Linoleate is oxygenated by manganese-lipoxygenase (Mn-LO) to 11S-hydroperoxylinoleic acid and 13R-hydroperoxyoctadeca-9Z,11E-dienoic acid, whereas linoleate diol synthase (LDS) converts linoleate sequentially to 8R-hydroperoxylinoleate, through an 8-dioxygenase by insertion of molecular oxygen, and to 7S,8S-dihydroxylinoleate, through a hydroperoxide isomerase by intramolecular oxygen transfer. We have used liquid chromatography-mass spectrometry (LC-MS) with an ion trap mass spectrometer to study the MSⁿ mass spectra of the main metabolites of oleic, linoleic, α-linolenic and γ-linolenic acids, which are formed by Mn-LO and by LDS. The enzymes were purified from the culture broth (Mn-LO) and mycelium (LDS) of the fungus Gaeumannomyces graminis. MS³ analysis of hydroperoxides and MS² analysis of dihydroxy- and monohydroxy metabolites yielded many fragments with information on the position of oxygenated carbons. Mn-LO oxygenated C-11 and C-13 of 18∶2n−6, 18∶3n−3, and 18∶3n−6 in a ratio of ∼1∶1–3 at high substrate concentrations. 8-Hydroxy-9(10)expoxystearate was identified as a novel metabolite of LDS and oleic acid by LC-MS and by gas chromatography-MS. We conclude that LC-MS with MSⁿ is a convenient tool for detection and identification of hydroperoxy fatty acids and other metabolites of these enzymes.     

Biosynthesis of the novel fatty acid, 17-methyl-cis-9,10-methyleneoctadecanoic acid,by the parasitic protozoan,Herpetomonas megaseliae

Herpetomonas megaseliae, a flagellate protozoan parasite of the gut of a dipteran,Megaselia scalaris, is shown by chromatographic, spectrometric and radiotracer methods to synthesize de novo aniso-branched chain cyclopropane fatty acid, 17-methyl-cis-9,10-methyleneoctadecanoic acid.     

Reactions of fatty aldehydes with fatty alcohols: Formation of acetals,hemiacetals and alk-1-enyl alkyl ethers

A convenient method for the synthesis of acetals of fatty aldehydes and fatty alcohols by transacetatlation between fatty aldehyde dimethyl acetals and fatty alcohols is described. The acetals undergo decomposition to the alk-1-enyl alkyl ethers during GLC. Equimolar mixtures of fatty aldehydes and fatty alcohols show hemiacetal structure as evidenced by IR spectra in KBr discs but are dissociated completely into their components in solution and during TLC. They do not undergo dehydration and conversion to alk-1-enyl alkyl ethers during GLC under conditions of dealcoholization of acetals but are dissociated into aldehydes and alcohols. Presented at the AOCS Meeting, San Francisco, April 1969.     

Separation and quantitation of hydroxy and epoxy fatty acid by high-performance liquid chromatography with an evaporative light-scattering detector

A new high-performance liquid chromatography technique with an evaporative light-scattering detector (ELSD) has been developed for the separation and quantitative analysis of hydroxy and epoxy fatty acids. This method employs a gradual binary gradient (hexane/isopropanol) and ELSD detection. The minimum limit of detection is about 1 μg and ratio of mass to signal is essentially linear in the range of 10 to 200 μg. This high-performance liquid chromatography (HPLC) technique is able to separate various positional isomers of mono-hydroxy and dihydroxy fatty acids and can also discriminate between monohydroxy, epoxy, epoxyhydroxy, dihydroxy and trihydroxy fatty acids.     

A comparison of the ethoxylation of a fatty alcohol,fatty acid,and dimethiconol

Knowing that dimethiconols or silanols condense under acid or alkaline catalysis, a study was undertaken to determine if these compounds could be successfully ethoxylated under conditions similar to those used to ethoxylate fatty alcohols and acids. It was anticipated that the condensation reaction would take precedent over ethoxylation reaction. We determined that ethoxylation reaction occurs preferentially to condensation reaction. In addition, kinetics of ethoxylation are similar to kinetics observed when fatty alcohols are ethoxylated. This reaction gives rise to a new class of hydrolyzable silicone compounds that have applications in industrial as well as in personal-care products.     

Uses of fats,fatty oils,and derivatives in the petroleum industry

Conclusion The use of fats, fatty oils, and derivatives is extensive in the petroleum industry to improve its lubricants in their wetting ability or oiliness. Fats and their derivatives serve to carry active elements such as chlorine, sulfur, and phosphorus for the improvement of load-carrying capacity, resistance to oxidation, inhibiting corrosiveness, and preventing wear during use. Greases are compounded from whole fats and fatty acids which serve under suitable conditions to gel lubricating oil and thus fulfill lubricating requirements which the liquid oils cannot themselves satisfy. Greases and their components may be tested for skin hardening in storage by means of an oxygen absorption test which distinguishes between satisfactory and unsatisfactory ingredients and products. Presented in a symposium on the Industrial Applications of Fats & Fatty Acids at the Fall Convention of the American Oil Chemists Society, Chicago, Oct. 1939.     

Nonvolatile α-branched chain fatty acid derivatives: III. Addition of acid chlorides,anhydrides and amides to terminal olefins

At-butyl peroxide initiated free radical reaction was employed for the preparation of α-branched fatty acid chlorides, which were then converted in situ to methyl esters. Similarly prepared were an α-branched fatty acid amide and an α-branched acid anhydride. The latter was converted to the methyl ester. The use of the acid chloride and acid anhydride permitted reduction in the molar ratio of reactants to half or less than that used in the addition of esters to terminal olefins without affecting the yield. The resulting increase of α-branched product concentration in the reaction mixture also made isolation of the product easier. The direct addition of a variety of stearic acid derivatives to 1-decene under the same conditions (20:4:1.2 molar ratio of reactants at 160 C) gave the following olefin based yield order: stearoyl chloride > stearic anhydride > stearamide and methyl stearate > stearic acid. Presented at the AOCS Meeting, Chicago, October 1967. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Sterol and fatty acid composition of the clam,Codakia orbicularis,with chemoautotrophic symbionts

Codakia orbicularis may obtain nutrients from chemoautolithotrophic bacteria. The chemical composition of theC. orbicularis was investigated because of this unusual source of nutrition, and because it is a human food source in the Caribbean. The lipid fraction of these molluscs is discussed in detail. Polyunsaturated fatty acids account for only 11–15% of the total fatty acids, and non-methylene interrupted dienes are present as high as 9.5%. Cholesterol represents about 45% of the total sterols present. Mention of a commercial company or product does not constitute an endorsement by NOAA, National Marine Fisheries Service.     

The mass spectra of the 4,4-dimethyloxazoline derivatives of some conjugated hydroxy ene-yne C17 and C18 fatty acids

The mass spectra of the 4,4-dimethyloxazoline derivatives from various fatty acids with a hydroxy group in conjugation with conjugated double-triple bonds (7-hydroxy-trans-10-heptadecene-8-ynoic acid; 7-hydroxy-trans-10, 16-heptadecadiene-8-ynoic acid; 8-hydroxy-rans-11-octadecene-9-ynoic acid; 8-hydroxy-trans-11, 17-octadecadiene-9-ynoic acid) have been examined and compared with their analogous nonhydroxy derivatives. The position of the hydroxy group was unequivocally proven by characteristic odd-numbered fragment peaks, explainable by α-cleavage at the hydroxy group at the oxazoline end of the molecule. The weak ions produced by α-cleavage at the other side of the hydroxy group indicated that the hydroxy group must be in conjugation with the ene-yne system. Fragments that allow one to distinguish between ene-yne or yne-ene systems were absent. In conjunction, the weak molecular ion and the more intense M-18 ion could confirm the molecular weight of each fatty acid. This work was presented in parts at the Second International Symposium of Natural Products and Their Applications in Concepción/Chile (30.11.-2.12.94). (Title of the symposium in Spanish is II Simposio internacional de productos naturales y sus applicaciones.)     

Cuticular lipids of the booklouse,Liposcelis bostrychophila: hydrocarbons,aldehydes, fatty acids,and fatty acid amides

The booklouse, Liposcelis bostrychophila, is an increasingly common pest of stored food products worldwide. We report here the cuticular lipid composition of this pest (the first report of the hydrocarbons of any member of the Order Psocoptera and the first report of fatty acid amides as cuticular components for any insect). No unsaturated hydrocarbons were present. A homologous series of n-alkanes (C₂₁–C₃₄), monomethyl alkanes (3-, 4-, 5-, 7-, 9-, 11-, 12-, 13- and 15-methyl-) with a carbon chain range of C₂₈–C₄₂, and dimethyl alkanes (3, 7-; 9, 13-; 11, 15-; 13, 17-; 9, 21-; 11, 19-; and 13, 21-); with a carbon number range of C₃₁–C₄₃ were identified. The relative abundances of these hydrocarbons were low, comprising approximately 0.0125% of total biomass. The amides were a homologous series (C₁₆–C₂₂ in chain length), with the major amide being stearoyl amide. In addition to the amides, free fatty acids (C_16:1, C_16:0, C_18:2, C_18:1, and C_18:0 in chain length) and three straight chain aldehydes (C₁₅, C₁₆, and C_17:1 in chain length) also occurred as cuticular components. These findings are discussed in terms of the chemical and physiological ecology of this species.     

Molecular species composition of phosphatidylinositol from the brain,retina, liver and muscle of cod (Gadus morhua)

The molecular species composition of phosphatidylinositol (PI) purified from four different tissues from cod was found to show large tissue-specific differences. In brain 18∶0/20∶5 was the most abundant species (40.8%) followed by 18∶1/20∶5 (13.5%). In retina, 24–26% each of PI was the 16∶0/22∶6 and 18∶0/20∶4 species with 16–18% each of 18∶0/20∶5 and 18∶0/22∶6. In liver, almost half of the PI was 18∶0/20∶4 with 18% 18∶1/20∶4. In contrast, muscle contained almost 40% of 18∶0/22∶6 with 10–14% each of 18∶0/20∶4, 18∶0/20∶5 and 18∶1/22∶6. Molecular species are abbreviated as follows:e.g., 18∶0/20∶4 PI is 1-stearoyl-2-eicosatetraenoyl-sn-glycero-3-phosphoinositol.     

Alcoholysis,saponification and the preparation of fatty acid methyl esters

Evidence is offered to support the contention that methanolysis precedes the saponification of esters in methanolic solutions of sodium hydroxide. This results from the hydroxide-alkoxide equilibrium which greatly favors methoxide formation even in the presence of rather considerable amounts of water. Saponification-reesterification methods of methyl ester formation are shown to be actually extensions of methanolysis procedures. A simplified method is proposed for the preparation of fatty acid methyl esters. Scientific Journal Series 7706, Agricultural Experiment Station, University of Minnesota, St. Paul, Minnesota 55101.     

Polyunsaturated fatty acids,vitamine E,and the proliferation of aortic smooth muscle cells

Smooth muscle cell cultures were obtained from the aortas of prepubertal guinea pigs. Cell proliferation in these cultures was inhibited by 8,11,14-eicosatrienoic acid, 5,8,11,14-eicosatetraenoic acid, and their prostaglandin E derivatives, PGE₁ and PGE₂. Prostaglandin F derivatives, PGF_1α and PGF_2α, stimulated cell proliferation. Cell proliferation was also inhibited by 5,8,11-eicosatrienoic acid and 11,14,17-eicosatrienoic acid. The monoene and diene precursors of the triene acids, 9-octadecenoic acid and 9,12-octadecadienoic acid, did not inhibit cell, proliferation. Indomethacin alone had no effect on cell proliferation, and indomethacin did not suppress the inhibition of cell proliferation with a triene acid. The antioxidant α-naphthol alone stimulated cell proliferation and suppressed prostaglandin E formation. α-Naphthol in the presence of either triene or tetraene acids also stimulated cell proliferation and suppressed prostaglandin E formation. The antioxidants butylated hydroxy toluene and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid either alone or in the presence of triene and tetraene acids stimulated cell proliferation and had no effect on prostaglandin E formation. Vitamin E either alone or in the presence of triene or tetraene acids stimulated cell proliferation and had no effect on prostaglandin E formation. More prostaglandin E was formed from 8,11,14-eicosatrienoic acid than from 5,8,11,14-eicosatetraenoic acid in the presence of antioxidants. Vitamin E suppressed the inhibitory effects of both PGE₂ and palmitic acid on cell proliferation. The cyclic nucleotide phosphodiesterase inhibitors, caffeine and papaverine, suppressed the stimulatory effect of vitamin E on cell proliferation and enhanced the inhibitory effect of a triene acid on cell proliferation. Substrate and inhibitor specificities are consistent with the oxidative regulation of cell proliferation through the formation of hydroperoxy fatty acids. We propose that hydroperoxy fatty acids may regulate both cyclase and cyclic nucleotide phosphodiesterase enzymes through sulfhydryl-disulfide interconversions. We suggest that this regulatory mechanism may help to explain the acculation of 5,8,11-eicosatrienoic acid in essential fatty acid deficiency, the effects of antioxidants on cell proliferation, and one of the several effects of polyunsaturated fatty acids in proliferative disorders such as cancer and atherosclerosis.     

Molecular species composition of the major diacyl glycerophospholipids from muscle,liver, retina and brain of cod (Gadus morhua)

The molecular species composition of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) from white muscle, liver, retina and brain of cod (Gadus morhua) were determined by high-performance liquid chromatography of the respective 1,2-diacylglycerol 3,5-dinitrobenzoyl derivatives. A minimum of 69 diacyl species was identified. In muscle and liver saturated fatty acid/polyunsaturated fatty acid (PUFA) and monounsaturated fatty acid/PUFA molecular species were predominant, particularly 16∶0/20∶5 and 16∶0/22∶6 in PC, 16∶0/22∶6 and 18∶1/22∶6 in PE and 18∶0/22∶6 and 18∶1/22∶6 in PS. Didocosahexaenoyl species were major components of PC, PE and PS from retina, comprising 29.3, 71.8 and 59.7% of the respective totals. Didocosahexaenoyl species were also abundant in PE and PS from brain, accounting for 13.8 and 24.0% of the totals, respectively. DiPUFA species were important in muscle, totalling 21.2% in PC and 38.3% in PE. PC from all tissues had the largest amounts of species containing only saturated or monounsaturated fatty acids, accounting for 59.8% of PC from brain, including 12.8% of 18∶1/24∶1 plus 24∶1/18∶1.     

Analysis of fatty acid methyl esters with high accuracy and reliability. V. Validation of theoretical relative response factors of unsaturated esters in the flame lonization detector

Because unsaturated fatty acid methyl esters (FAME) are subject to autoxidation, it is virtually impossible to obtain and maintain high purity standards. Accordingly, it is not possible to determine flame ionization detector response factors by the usual technique of analyzing standard mixtures of known composition. In an alternative approach, the response factors of methyl oleate, methyl linoleate, methyl linolenate, methyl arachidonate and methyl 4,7,10,13,16,19-docosahexaenoate relative to methyl stearate were estimated by determining the peak areas before and after quantitative hydrogenation in the presence of an internal standard. The estimates showed excellent agreement in all cases with the theoretical factors predicted by Ackman and Sipos and thus constitute an independent and unambiguous proof that the theoretical factors are highly accurate for all olefinic unsaturated FAME. Whereas it is common practice to determine an empirically derived correction factor for each FAME by analyzing standard mixtures of known composition, the thesis is now proposed that, for both saturated and olefinic unsaturated FAME, the proper approach to accurate analysis requires that peak areas be corrected using the theoretical response factors as the only correction factors. If the correct result cannot be obtained when analyzing a primary standard of saturated FAME, it is an indication of faulty technique or equipment, and the only acceptable resolution of the problem is to locate and correct the fault(s).     

Effect of growth conditions on the fatty acid composition ofListeria monocytogenes and comparison with the fatty acids ofErysipelothrix andCorynebacterium

Six strains ofListeria monocytogenes belonging to four different serotypes all had similar fatty acid profiles when grown at 37 C, with C₁₅ and C₁₇ branched chain acids as major components. The proportion of 17∶0 br decreased markedly as the growth temperature was lowered from 37 C to 4 C, and a reduction of 18∶1 with increasing age of cultures was observed in cells harvested at different stages of the growth curve. The fatty acid composition was also affected by the nature of the culture medium. Two other genera of the family Corynebacteriaceae were analyzed for fatty acid composition. Strains ofErysipelothrix rhusiopathiae isolated from human, turkey, dog and pig had rather similar patterns, consisting mainly of straight chain, even-numbered fatty acids from C₁₀ to C₁₈. The three species ofCorynebacterum analyzed each had quite different fatty acid patterns.C. poinsettiae bore some resemblance toL. monocytogenes butC. pseudodiphtheriticum had much higher proportions of 16∶0 and 18∶1 andC. equi contained a rather complex mixture of fatty acids. Part of this work was carried out in the Collip Medical Research Laboratory.