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Natural and synthetic conjugated linoleic acids (CLA) are reputed to have therapeutic properties that are specific to particular geometrical and positional isomers. Analysis of these has presented unique problems that have brought forward distinctive solutions, especially the use of gas chromatography-mass spectrometry and silver-ion high-performance liquid chromatography. In the analysis of CLA present at low levels in tissue samples, it is sometimes necessary to use concentration methods. In this review, the most useful and practical methods for the isolation and analysis of CLA isomers in tissues and in commercial CLA preparations are described.

We performed a retrospective case note review to identify the major complications of epidural analgesia occurring after surgery at our hospital. By cross-referencing the radiology, microbiology and patient information management system databases, we identified patients who had undergone either spinal magnetic resonance imaging or a lumbar puncture within 60 days of surgery in the period from January 2000 to December 2005. Review of these case notes identified six cases of epidural abscess, three of meningitis and three of epidural haematoma. Symptoms of epidural abscess or meningitis developed a median of 5 days after epidural catheter removal. Methicillin-resistant Staphylococcus aureus was the predominant pathogen. Epidural haematoma symptoms developed while the epidural catheter was in place. These symptoms were initially attributed to the epidural infusion. Diagnostic delays contributed to adverse neurological outcome in three patients. This study suggests that leg weakness is a critical monitor of spinal cord health. A national database is needed to establish a more accurate estimate of the incidence of major complications and to identify relevant risk factors.

The fatty acid composition of the lipids from the sponge Verongia aerophoba was investigated and 60 acids were identified. Two of them were new and their structures were elucidated by gas chromatography-mass spectrometry. These acids were identified as 20-methylhexacosanoic and Δ5, 9, 22-nonacosatrienoic. Only 13 sterols were present, and aplysterol predominated. In the volatile fraction 13 compounds were identified, mainly fatty acids, their esters and hydrocarbons, while in the n-butanol fraction we found mainly free fatty acids and free amino acids.

In view of the increasing interest of lipid researchers in the biological effects of all-cis A5-unsaturated polymethylene-interrupted fatty acids (Δ5-UPIFA) from vegetable origin, this paper is concerned with their occurrence in practical sources (gymnosperm seeds), structures, and identification by gas-liquid chromatography (GLC) and mass spectrometry (MS). The use of equivalent chain lengths (ECL) determined by calculations based on available standards, in close agreement with data determined with easily available commercial gymnosperm seeds specific for each A5-UPIFA, allows identification of all A5-UPIFA. These tentative identifications are supported by GLC-MS of the appropriate (4,4-dimethyloxazoline and picolinyl ester) derivatives. ECL are particularly useful to identify A5-UPIFA in tissue lipids from animals experimentally fed oils containing these acids, with no interference with polyunsaturated fatty acids of endogenous origin. Repondant a l'interet grandissant des chercheurs pour les effets biologiques des acides cis Δ5-olefiniques d'origine vegetale, cette etude traite de leur structure chimique, leur biosynthese et leur identification par chromatographie gaz-liquide et spectrometrie de masse. L'utilisation d'equivalents en longueur de chaines est particulierement utile pour identifier les acides cis Δ5-olefiniques dans les tissus d'animaux nourris par des huiles contenant ces acides sans interference avec les acides gras polyinsatures d'origine endogene.

The science of lipidomics may not be as new as many current practitioners believe, but the methods that are being applied today, especially those involving electrospray ionization mass spectrometry, are indeed novel and extremely powerful. They are enabling a much better understanding of the functions of lipids in tissues and of the relationship to human disease states. Shotgun lipidomics, i. e. direct mass spectrometric analysis of complex lipid extracts without chromatographic steps, gives rapid access to a great deal of compositional data. On the other hand, there are limitations to even this technique, and there are still occasions when chromatographic, and chemical and enzymatic degradative methods are necessary.

The fatty acid composition of Ginkgo biloba seed lipids was reinvestigated with particular emphasis on the polymethylene-interrupted octadecadienoic and eicosadienoic acids. Analysis of the picolinyl esters and 4,4-dimethyloxazoline derivatives by capillary gas-liquid chromatography on a highly polar cyanopropyl polysiloxane stationary phase coupled with mass spectrometry revealed the presence of three such acids, with the structures 5,9–18:2, 5,11–18:2, and 5,11–20:2. This indicated that in G. biloba seeds, cis-vaccenic (11–18:1) acid may be a substrate for the Δ5-desaturase characteristic of gymnosperms. The 5,11-18:2 acid was not limited to G. biloba, as it may occur in a few other species. The 5,11-20:2 acid is a common component of the seed lipids from almost all gymnosperm species analyzed so far.

The fatty acid compositions of the seeds from three Taxus (yew) species and one Torreya species belonging to the Taxaceae family [Taxus cuspidata (Japanese yew), T. chinensis (Chinese yew), T. baccata (English yew), and Torreya grandis (Chinese nutmeg yew)] have been established. These compositions were compared with those previously published for T. canadensis (Canadian yew) and Torreya nucifera. In Taxus species, as well as in Torreya species, Δ5-olefinic acids are present in the seed lipids from all species analyzed. In Taxus, 5,9-18:2 (taxoleic) acid is the prominent Δ5-olefinic acid. It represents between 9.5 and 16.2% of total fatty acids. Other Δ5-olefinic acids that occur in low amounts are 5,9,12-18:3 (

A new conjugated trans,trans-diunsaturated acetylenic acid (17%), found for the first time in nature as a main component of the seed oil of Tanacetum (Chrysanthemum) corymbosum, was shown to be octadeca-8t,10t-dien-12-ynoic acid. Another already known naturally occurring acetylenic acid, crepenynic acid (10%), was found also in the seed oil. The structure of this new unusual fatty acid was confirmed by chromatographic (thin-layer chromatography, gas chromatography, high-performance liquid chromatography) and spectroscopic (infrared, ultraviolet, mass spectrometry) methods by using different chemical derivatizations (deuteration, preparation of picolinyl ester, dimethyloxazoline, and maleic anhydride adduct).

Procedures for structural analysis of fatty acids are reviewed. The emphasis is on methods that involve gas chromatography-mass spectrometry and, in particular, the use of picolinyl ester and dimethyloxazoline derivatives. These should be considered as complementing each other, not simply as alternatives. However, additional derivatization procedures can be of value, including hydrogenation and deuteration, and preparation of dimethyl disulfide and 4-methyl-1,2,4-triazoline-3,5-dione adducts. Sometimes complex mixtures must be separated into simpler fractions prior to analysis by gas chromatography-mass spectrometry. Silver ion and reversed-phase high-performance liquid chromatography are then of special value. In particular, a novel application of the latter technique, involving a base-deactivated stationary phase and acetonitrile as mobile phase, is described that is suited to the separation of fatty acids in the form of picolinyl ester and dimethyloxazoline derivatives, as well as methyl esters.

Four procedures have ben developed to simplify routine analysis of large numbers of plant lipid samples. First, a rapid extraction method has been devised in which the key step consists of washing propan-2-ol-chloroform extracts with an aqueous phase impregnating solid SephadexTM G-25-300. The extracts are then separated by high performance liquid chromatography (HPLC) with evaporative light-scattering detection, using a complex gradient that permits separation of most of the important simple lipid, glycolipid and phospholipid classes in sequence. An example of an application to the analysis of a newly generated mutant is illustrated. In addition, a novel solid-phase extraction procedure with a bonded propylamine phase allows separation of four broad classes, simple lipids, glycolipids, zwitterionic phospholipids and acidic phospholipids (plus sulphoquinovosyldiacylglycerol), for further analysis. Finally, base-catalysed transesterification followed by HPLC analysis, permits identification of those lipids that do not contain conventional ester bonds. © 1998 John Wiley & Sons, Ltd.

The conjugated linoleic acid methyl cis-9,trans-11-octadecadienoate has been prepared on a large scale from methyl ricinoleate. Methyl ricinoleate was purified from castor esters by a partition method. It was converted to the mesylate, which was reacted with a base (1,8-diazabicyclo[5,4,0]-undec-7-ene) to give a product that contained 66% of the desired ester. Two urea crystallizations produced a product containing 83% methyl cis-9,trans-11-octadecadienoate, the identity of which was confirmed by gas chromatography linked to mass spectrometry and by Fourier transform infrared spectroscopy. The remaining impurities were methyl cis-9,cis-11- and cis-9-,trans-12-octadecadienoate.

Unusual fatty acids, with up to 34 carbon atoms and containing one or two bis-methylene-interrupted double- bond systems, have been identified in the sponge Haliclona cinerea from the Black Sea. These include the dienes-5, 9-16:2, 7, 11-18:2, 9, 13-20:2, 13, 17-24:2, 15, 19-26:2, 17, 21-28:2, 19, 23-30:2 and 21, 25-32:2 ; trienes-5, 9, 23-30:3, 5, 9, 24-31:3, 5, 9, 25-32:3, and 5, 9, 27-34:3 ; and the tetraenes-5, 9, 19, 23-30:4, 5, 9, 21, 25-32:4, and 5, 9, 23, 27-34:4. In addition, 5, 9, 13-eicosatrienoic acid was present. Many of these do not appear to have been described before, and only 5, 9-16:2 and 5, 9, 23-30:3 are found often in sponges. They were identified by using silver-ion high-performance liquid chromatography to simplify the complex mixture of fatty acids for subsequent analysis by gas chromatography/mass spectrometry as picolinyl ester derivatives. Deuteration with Wilkinson's catalyst in homogeneous solution confirmed the structures. We speculate that the di- and tetraenoic fatty acids arise by chain elongation of 5, 9-hexadecadienoic acid, also a major component of the lipids, followed by further insertion of double bonds in the 5 and 9 positions. The trienes may be formed from 9-hexadecenoic acid by similar mechanisms.

The fatty acid composition of seeds ofGinkgo biloba has been examined by a combination of capillary gas chromatography, silver ion high-performance liquid chromatography and gas chromatography/mass spectrometry. Some of the fatty acids identified are unusual in plants and were rather different from those reported earlier. These include ananteiso-methyl branched fatty acid, 14-methylhexadecanoic acid, 5,9-octadecadienoic acid, and 5,9,12-octadecatrienoic acid. Fourier-transform infrared spectroscopy confirmed that all of the double bonds were of thecis-configuration.

A method is proposed for the determination of petroselinic, oleic and cis-vaccenic acids in plants of the Umbelliferae by using silver ion thin layer chromatography and densitometry. The fatty acids are first converted into phenacyl esters and this enables base line separation at ambient temperature on a plate impregnated with 1% methanolic silver nitrate. Conditions were found for the simultaneous determination of the saturated and dienoic fatty acids while maintaining the resolution of petroselinic and oleic acids. The procedure is suitable for screening plants of the Umbelliferae in phytochemical and selection studies, and may be of value as a small-scale preparative technique.

Triacylglycerols of the seed oil ofTrichosanthes kirilowii have been resolved by high-performance liquid chromatography (HPLC) in the silver-ion and reverse-phase modes. The fatty acids were identified by gas chromatography/mass spectrometry as the picolinyl esters. The main components arecis,cis-C18:2n-6 (38.2 mole%), C18:39c,11t,13c (punicic acid, 38.0 mole%), andcis-C18:1n-9 (11.8 mole%). Small amounts of C18:39c,11t,13t (α-eleostearic acid) and C18:39t,11t,13c (catalpic acid) were detected. Silver-ion HPLC exhibited excellent resolution in which fractions were resolved on the basis of the number and configuration of double-bonds. In this instance, the strength of interaction of a conjugated trienoic double-bond system with silver ions seemed to be between that of dienoic and monoenoic double bond systems. The triacylglycerols were also separated into 20 fractions by reverse-phase HPLC, and the fractionation was achieved according to the partition number in which a conjugated trienoic double bond was not equivalent to three monoenoic double bonds in a molecule with a given chainlength. The principal triacylglycerol species are (C18:2n-6) (C18:39c,11t,13c )2 (28.3 mol% of total), (C18:1n-9)(C18:2n-6) (C18: 39c,11t,13c ) (19.0 mol%), and (C18:2n-6)2(C18:39c,11t,13c ) (16.2 mol%), while simple triacylglycerols such as (C18:39c11t,13c )3 and (C18:2n-6)3 were present as minor components only (

The wax esters of the roe oil of the amber fish,Seriola aureovittata, have been resolved by high-performance liquid chromatography (HPLC) in the silver-ion mode. Each of the fractions collected was transmethylated, and the fatty acids and alcohols were identified by gas chromatography/mass spectrometry (GC/MS) as the picolinyl esters and nicotinates, respectively. Their compositions were determined by GC. The fatty acid composition is complex, and the main components are C18:1n-9 (35.5 mol%), C22:6n-3 (20.3 mol%), and C16:1n-7 (10.7 mol%), while fatty alcohols are limited to saturated (C16:0, 60.3 mol%; C18:0, 15.3 mol%; C14:0, 5.1 mol%) and monoenoic alcohols (C18:1n-9, 6.5 mol%; C16:1n-7, 4.5 mol%) with traces (

The wide range of lipid classes found in plant tissues, including simple lipids, glycolipids, and phospholipids, have been resolved by gradient high performance liquid chromatography with evaporative light-scattering detection. The lipids from potato tubers were used to optimize the separations. Adsorption chromatography with silica gel gave disappointing results for the plant glycolipids. Much better separations were obtained with chemically bonded stationary phases, e.g. those with propionitrile or polymeric vinyl alcohol as the functional moiety. With careful calibration, good reproducibility was possible. Only highly acidic lipids such as phosphatidylserine still present some problems.

The triacylglycerol composition of olive oil samples has been determined by stereospecific analysis after partial hydrolysis with ethyl magnesium bromide, derivatization, preparative chiral HPLC, transesterification, and GC quantitation of fatty acid methyl esters. The data obtained for position sn-2 were compared with those from capillary GC analysis of monoacyl sn-2-glycerols after enzymatic lipolysis of triacylglycerols. The determination of triacylglycerols collected by silver ion HPLC and quantified (as fatty acid methyl esters) by GC, together with direct GC analysis on a polar column, have then furnished a comprehensive picture of the triacylglycerol content of olive oil.

A rapid procedure has been developed for the isolation of methyl esters of trans-monoenoic fatty acids by silver ion high-performance liquid chromato- graphy. The combined saturated plus trans-monoene fraction was collected for analysis by gas chromatography and comparison with the composition of the unfractionated sample. The trans-monoene contents of partially hydrogenated vegetable oils, determined in this way, are compared with data obtained by Fourier-transform infrared spectroscopy. Alternative methods of base-line correction are discussed. The infrared technique gave values that were a little higher than the chromatographic ones, presumably because the former also detected trans unsaturation in di- and polyunsaturated fatty acids.

The fatty acid composition of the sponge,Dysidea fragilis, from the Black Sea has been determined by analytical gas chromatography, silver ion high-performance liquid chromatography and gas chromatography/mass spectrometry. More than a hundred different fatty acids were identified, of which many were similar to those in sponges from tropical seas. On the other hand, some of the fatty acids identified have not been found previously in sponges or other marine sources and perhaps are new to science. These include 13-methyl-tetradec-4-enoic and 14-methyl-hexadec-6-enoic acids, together with demospongic acids,i.e. 5,9,17-tetracosatrienoic, 5,9,17-pentacosatrienoic and 5,9,19-pentacosatrienoic acids. From the elution behavior on silver nitrate chromatography, all the double bonds were of thecis-configuration.

The compositions of positionssn-1,sn-2 andsn-3 of triacylglycerols from “extra-virgin” olive oil (Olea europaea) were determined. The procedure involved preparation of diacyl-rac-glycerols by partial hydrolysis with ethyl magnesium bromide; 1,3-, 1,2- and 2,3-diacyl-sn-glycerols as (S)-(+)-1-(1-naphthyl)ethyl urethanes were isolated by highperformance liquid chromatography (HPLC) on silica, and their fatty acid compositions were determined. The same procedure was also carried out on the five main triacylglycerol fractions of olive oil after separation according to the degree of unsaturation by HPLC in the silver ion mode. Although stereospecific analysis of the intact triacyl-sn-glycerols indicated that the compositions of positionssn-1 andsn-3 were similar, the analyses of the molecular species demonstrated marked asymmetry. The data indicate that the “1-random, 2-random, 3-random” distribution theory is not always applicable to vegetable oils.

The electron impact mass spectra have been obtained for isomeric C14 and C18 allenic fatty acids in the form of the methyl and picolinyl ester derivatives. When the allene moiety was in positions 3 to 9, the mass spectra of the methyl esters gave spectra with diagnostic ions that appeared to be formed by beta cleavage on the distal side of the molecule; otherwise hydrocarbon ions were dominant. With the picolinyl ester derivatives, distinctive fragmentations beta to the allene moiety on each side were observed for each isomer.

The compositions of positionssn-1, 2 and 3 of triacylglycerols can be determined by partial hydrolysis with ethyl magnesium bromide, derivatization of the total products with (S)-(+)-1-(1-naphthyl)ethyl isocyanate and isolation of the diacyl-sn-glycerol urethane derivatives by chromatography on solid-phase extraction columns containing an octadecylsilyl phase. The diastereomericsn-1,2-and 2,3-diacylglycerol derivatives are separated by high-performance liquid chromatography on silica for determination of their fatty acids by gas chromatography. Each step in the process has been evaluated rigorously. The compositions of all three positions can be calculated with good accuracy from the analyses of these compounds and that of the total triacylglycerols. Although the 1,3-sn-diacylglycerol derivatives can also be isolated easily, they do not give reliable results for the composition of positionsn-2 because acyl migration occurs during their generation. The stereospecific analysis procedure has been applied to some plant and animal triacyl-sn-glycerols of commercial and scientific interest, containing predominantly C16 and C18 fatty acids,i.e. safflower, sunflower, olive and palm oils, tallow, egg and rat adipose tissue. The method is not at present suited to the analysis of more complex triacylglycerols, such as milk fat or fish oils, and problems associated with these are discussed.

Picolinyl and methyl ester derivatives of all the isomeric thialaurates and thiastearates, together with some dithiastearates, have been characterized by gas chromatography/mass spectrometry. The picolinyl ester derivatives give simple electron impact mass spectra in which ions formed by cleavage at the sulphur atom and containing the sulphur atom are especially distinctive. The methyl ester derivatives have much more complex mass spectra, again dominated by ions formed by cleavage at the sulphur atoms, although all possible fragments are seen. With both derivatives, the spectra are readily interpretable in terms of the positions of the sulphur atoms. The position of the sulphur atom can also have a marked effect on the abundance of the McLafferty rearrangement ion.

Triacylglycerols from North Atlantic herring (Clupea harengus) were separated according to the degree of unsaturation by high performance liquid chromatography (HPLC) in the silver ion mode. Each of the eleven fractions collected was then separated by reversed- phase HPLC, which in these circumstances separated the molecules according to the combined chain- lengths of the fatty acyl residues only. One hundred thirty fractions were obtained for fatty acid analysis. Almost 50% of the triacylglycerol molecules had six or more double bonds in their fatty acyl residues. Saturated-dimonoenes and disaturated- monoenes, 18.9% and 10.4%, respectively, were the most plentiful fractions of the more saturated species. Such a complex mixture of molecules was present that the most abundant subfractions from reversed- phase HPLC represented less than 5% of the total. Indeed, the largest single molecular species [16:0- 22:l- 22:6(n− 3)] represented only 2.8% of the total. These sequential analyses by complementary techniques made it possible to obtain a considerable amount of information on the composition of molecular species, but it was still not possible to identify all components.

We report here the finding that normal, young cartilages, in distinction from all other tissues examined, have unusually high levels of n-9 eicosatrienoic (20:3 cis-delta 5,8,11) acid and low levels of n-6 polyunsaturated fatty acids (n-6 PUFA). This pattern is identical to that found in tissues of animals subjected to prolonged depletion of nutritionally essential n-6 polyunsaturated fatty acids (EFA). This apparent deficiency is consistently observed in cartilage of all species so far studied (young chicken, fetal calf, newborn pig, rabbit, and human), even though levels of n-6 PUFA in blood and all other tissues is normal. The n-9 20:3 acid is particularly abundant in phosphatidylethanolamine, phosphatidylinositol, and the free fatty acid fractions from the young cartilage. Several factors appear to contribute to the reduction in n-6 PUFA and the appearance of high levels of the n-9 20:3 acid in cartilage: 1) limited access to nutritional sources of EFA due to the impermeability and avascularity of cartilage, 2) rapid metabolism of n-6 PUFA to prostanoids by chondrocytes, and 3) a unique fatty acid metabolism by cartilage. Evidence is presented that each of these factors contributes. Previously, EFA deficiency has been shown to greatly suppress the inflammatory response of leukocytes and rejection of tissues transplanted into allogeneic recipients. Because eicosanoids, which are derived from EFA, have been implicated in the inflammatory responses associated with arthritic disease, reduction of n-6 PUFA and accumulation of the n-9 20:3 acid in cartilage may be important for maintaining normal cartilage structure.

Diacylglycerols have been separated as their (S)-(+)-or (R)-(-)-1-(1-naphthyl)ethyl urethanes by high performance liquid chromatography (HPLC) on a column of silica gel with 0.5% 2-propanol in hexane as the mobile phase. The elution order of components derivatized with the (S)-form of the reagent was 1,3-, followed by 1,2-, and finally 2,3-diacyl-sn-glycerols. The elution order of 1,2- and 2,3-diasteromers was reversed when the (R)-form of 1-(1-naphthyl)ethyl isocyanate was used for derivatization. Single-acid 1,2- and 2,3-diastereomers were separated to the baseline with a resolution factor from 5.2-5.7, and the resolution factor between 1,3- and 1,2- or 2,3-diacyl-sn-glycerol derivatives was more than 23. Molecular species of single-acid diacylglycerol derivatives were separated in the sequence 18:1 less than 18:0 less than 18:2 less than 16.0. In order to assess this methodology as part of a procedure for the stereospecific analysis of triacyl-sn-glycerols, we prepared diacyl-rac-glycerols from maize oil, evening primrose oil and egg yolk triacylglycerols by partial hydrolysis with ethyl magnesium bromide. The 1,3-, 1,2- and 2,3-diacyl-sn-glycerols as (S)-(+)-1-(1-naphthyl)ethyl urethanes were isolated and their fatty acid compositions were determined. Although this only permitted an indirect determination of the compositions of positions sn-1, -2 and -3, it was sufficient to indicate the potential of the methodology because results comparable to those published earlier were achieved.

Triacylglycerols from Atlantic herring (Clupea harengus), sandeel (Ammodytes sp.) and Baltic herring (Clupea harengus membras) have been fractionated by silver ion high-performance liquid chromatography. An ion exchange column loaded with silver ions was the stationary phase, and a gradient in the mobile phase from 1,2-dichloroethane/dichloromethane (1∶1, v/v) to acetone and then to acetone/acetonitrile (2∶1, v/v) was used to effect the separation with light-scattering (i.e., mass) detection. Fractions were collected via a streamsplitter, and fatty acid methyl esters were prepared by transesterification in the presence of an internal standard for identification and quantification by gas liquid chromatography. Triacylglycerols were separated according to the number of double bonds in the fatty acyl residues. Resolution was excellent at first, when the least unsaturated molecules eluted (trisaturated to dimonoene-monodiene fractions). Base-line resolution could no longer be achieved when molecules containing trienoic or more highly-unsaturated fatty acids began to elute because of overlapping components. Nonetheless, some valuable separations of species containing two saturated and/or monoenoic fatty acids and one polyenoic fatty acid were achieved. Double bond indices (average number of double bonds in each triacylglycerol molecule) were calculated to estimate the separations possible. Fractions containing at least 11–14 double bonds per molecule were obtained.

The triacylglycerols of meadowfoam oil have been resolved by HPLC in the silver ion and reversed-phase modes, and by the two techniques used in a complementary fashion. The fractions obtained were collected and quantified by gas chromatography of their methyl esters in the presence of an internal standard. Silver ion chromatography gave a distinctive resolution in which fractions differing solely in the position and chain-length of a single monoenoic fatty acyl group were resolved, the order of elution being 11−20∶1, 5−20∶1, 13−22∶1, 5−18∶1 and 9−18∶1. Reversed-phase chromatography also gave fractions containing single positional isomers, (11−20∶1

Solid phase extraction columns packed with a stationary phase with bonded benzene sulphonate groups can be converted to the silver ion form and utilised for the separation of molecular species of triacylglycerols. Stepwise elution with dichloromethane/methyl acetate mixtures gave pure trisaturated- and disaturated-monoene species, together with a mixed fraction containing saturated-dimonoene and disaturated-diene; the remaining more highly unsaturated species were recovered by elution with a solvent containing a high proportion of acetonitrile. Fractions were identified and quantified by gas chromatography after transmethylation in the presence of an internal standard. This permitted calculation of the relative proportions of the two species in the third fraction. The procedure was applied to cocoa butter, palm oil and sheep subcutaneous adipose tissue.

The seed oil of Arum maculatum has been found to contain 13-phenyltridec-9-enoic (0.4%) and 15-phenyl-pentadec-9-enoic (1%) acids, detected by gas chromatography-mass spectrometry of the picolinyl ester and related derivatives.

Fatty acid pyrrolidides have been found to have unusual gas chromatographic properties on a polar stationary phase of the Carbowax type. In particular, exceptional resolution of positional isomers was achieved, and in contrast to methyl esters, unsaturated isomers with double bonds in position 5 or earlier eluted before the corresponding saturated fatty acid derivative. Les derives pyrrolidides des acides gras ont ete les premiers derives contenant de l'azote decrits par la spectrometrie de masse. Les pyrrolidides ont des proprietes non usuelles en chromatographie gazeuse sur la phase stationnaire polaire de type Carbowax. En particulier, une resolution exceptionnelle des isomeres de position est reussie. Les resultats montrent que la chromatographie gazeuse des derives pyrrolidides sur des colonnes polaires pourrait etre recherchee systematiquement pour determiner leur potentiel total pour la separation d'acides gras isomeriques. Les pyrrolidides peuvent apporter des informations complementaires a l'utilisation des methyls esters dans de nombreuses applications.

Triacylglycerols from evening primrose oil have been resolved by HPLC in the silver ion mode on a stationary phase consisted of an ion exchange medium, i.e. a silica gel matrix with boned sulphonic acid moieties, loaded with silver ions. The mobile phase was a gradient of acetone into 1,2-dichloroethane-dichloromethane initially, before acetonitrile was introduced. A mass detector was employed to monitor separations. Fractions were collected via a stream-splitter for identification and quantification by gas chromatography as methyl esters. Excellent resolution was obtained, and species differing in saturation from disaturated- monoenoic to monodienoic-ditrienoic were resolved and quantified. Fraktionierung der Triglyceride von Nachtkerzenol mittels Hochdruckflussigchromatographie an einer mit Silberionen beladenen Saule Die Triglyceride von Nachtkerzenol wurden durch HPLC an einer mit Silberionen beladenen stationaren Phase fraktioniert. Die stationare Phase bestand aus einem lonenaustauscher, einer Silicagelmatrix mit gebundenen Sulfonsauregruppen, beladen mit Silberionen. Die mobile Phase bestand anfangs aus einem Gradienten von Aceton in 1,2-Dichlorethan-Dichlormethan, bevor Acetonitril verwendet wurde. Ein Massendetektor diente zur Beobachtung der Trennungen. Zur Identifizierung und Quantifizierung der Triglyceride durch Gaschromatographie als Methylester wurden die Fraktionen mittels Stromungsteiler gesammelt. Es konnte eine ausgezeichnete Auftrennung erzielt werden. Es konnte eine ausgezeichnete Auftrennung erzielt werden. Es wurden Triglyceride getrennt und quantifiziert, die sich in ihrem Gesattigtheitsgrad unterschieden.

[1-14C]-Trans-9-octadecenoic acid was obtained in 60 per cent overall yield and [9,10-3H]-trans-9-octadecenoic acid in 30 percent yield by stereomutation of the double bonds in the corresponding cis -compounds with nitrous acid in toluene. The products were purified by silver nitrate chromatography and contained no detectable positional isomers.

Low resolution mass spectra of pyrrolidides of isomeric octadecadienoic acids and other polyunsaturated straight chain fatty acids are presented and discussed. The spectra of the pyrrolidides contain mainly ions from the polar part of the molecule and give spectra that are specific for each isomer. The interpretation follows, in most cases, the rule developed for monounsaturated fatty acid pyrrolidides.

Lipids were isolated from the adrenals of non-pregnant, pregnant and foetal sheep (ca 30 days pre-parturition). The lipid content of the adrenals from the pregnant sheep was higher than that of the other groups, and most of this was accounted for by triacylglycerols. Little difference was observed in the fatty acid compositions of the various lipid classes between the pregnant and non-pregnant animals. All the lipids of the foetal adrenals contained substantial amounts of the 20:3(n–9) fatty acid, which is often associated with essential fatty acid deficiency, but only the cholesterol ester fraction contained a higher level of polyunsaturated fatty acids than was present in the adult groups. The adrenals of the pregnant sheep contained significant levels of glycerolether diesters and neutral plasmalogens, which were fully characterised, and four unknown components that were tentatively identified as steroidal esters. These components were present at barely detectable levels in the adrenals of non-pregnant sheep. The triacylglycerols, glycerolether diesters and phosphatidylcholines from each group were, where possible, subjected to stereospecific analysis. The triacylglycerols were distinctive and resembled those of plasma and lymph in structure. The results are discussed in terms of a putative direct role for cholesterol esters in corticosteroidogenesis.

As part of a study of the contribution of the intestinal lymph lipoproteins and their lipid constituents to the plasma lipids in sheep, the positional distributions of the fatty acids in the triacyl-sn-glycerols and phosphatidylcholines in very low density/low density lipoprotein and high-density lipoprotein fractions were determined by stereospecific analysis procedures. The triacyl-sn-glycerols of these lipoprotein fractions in intestinal lymph did not differ appreciably in structure and resembled the plasma triacyl-sn-glycerols in the composition of position sn-2 especially. However, there were appreciable amounts of the essential fatty acid, linoleic acid, in positions sn-1 and sn-3 of the triacylglycerols in lymph but not in plasma. This result is discussed in terms of the metabolism of the triacylglycerols of lymph after they enter the plasma as part of a mechanism for the conservation of essential fatty acids in ruminants. No differences of metabolic note were observed in the structures of the phosphatidylcholines between lipoprotein fractions and among tissues.

Dietary manipulation has been used to produce a range of milk fats differing substantially in fatty acid composition. These fats have then been fractionated by preparing the mercuric acetate adducts to produce the trisaturated glyceride components. The method produced fractions having a very low unsaturated fatty acid content. Calculations suggest that the trisaturated fractions contained appreciably less 4:0 than would be predicted; with a compensating increase in the relative proportion of long-chain fatty acids. The triglyceride distributions of the parent fats were shown to be markedly bimodal in nature, whereas those of the trisaturated glycerides were unimodal or exhibited fairly small second peaks. Calculations based on the proportion of unsaturated fatty acids present in the milk fat suggest that the strategy of triglyceride synthesis within the bovine mammary gland is not to reduce the production of trisaturated glycerides to a minimum unless only small amounts of unsaturated fatty acid are available. The melting spectra, determined by differential scanning calorimetry, of the parent milk fats were quite different from those of the trisaturated components, with the latter fraction having little material melting below 0°C, but complete melting occurred at slightly higher temperatures. The positions of the major endotherms in the melting spectra of the parent fats on the one hand and the trisaturated fractions on the other indicate that extensive solid solution occurred between the unsaturated and trisaturated components of the parent fat. The heat of melting of the trisaturated glycerides was much greater than that of the parent fats.

This study reports on the plasma lipid compositions of sheep fed either a control diet (C), a control diet supplemented with tallow (A) or polyunsaturated fatty acid (B) that had been protected against hydrolysis and hydrogenation in the rumen, or a control diet supplemented with maize oil (D). Diet B considerably increased the 18∶2 content of all the major plasma lipid fractions. Although the feeding of diet D also resulted in an increase in the 18∶2 contents within the cholesteryl ester, unesterified fatty acid, and phospholipid fractions the increases were considerably less than those observed with diet B; the levels of 18∶2 within the triglyceride fraction remained similar to that for the sheep which received the control diet. The effect of feeding diet A was confined solely to the triglyceride fraction where the concentrations of 16∶0 and 18∶1 were increased. The lipoproteins of the plasma were separated into very low density lipoproteins (d

The lipids and lipoproteins of intestinal lymph in the sheep make a contribution to the corresponding fractions in plasma and thence affect lipid compositions in other tissues. As a first step towards assessing this contribution, the lipoproteins of intestinal lymph, peripheral (popliteal lymph) and plasma have been isolated for compositional studies. Popliteal lymph and the plasma were similar in the distributions of lipids among the major lipoprotein fractions with high-density lipoproteins accounting for just over half of the total lipid present. In intestinal lymph, 80 per cent of the total lipid was associated with the very low-density lipoprotein fraction. Whereas triacylglycerols comprised the principal lipid component of the very low-density lipoprotein and low-density lipoprotein fractions of the intestinal lymph and were present in the high-density lipoprotein fraction, they were present in essence only in the very low-density lipoprotein fraction of popliteal lymph and plasma, where high concentrations of cholesteryl esters and phospholipids were found in all the lipoprotein fractions. The fatty acid compositions of each lipid class were also determined. The most distinctive feature of the results was the distribution of the essential fatty acid, linoleic acid, among the lipid components. In all lipid classes in each of the body fluids, the concentration of this component was highest in the high-density lipoproteins and lowest in the very low-density lipoproteins. Higher concentrations tended to be present in the triacylglycerols and phosphatidylcholine fractions of intestinal lymph than of plasma and popliteal lymph, but the opposite was true of the cholesteryl esters. The results are discussed in terms of the sources of the linoleic acid in the lipids of intestinal lymph of ruminant animals.