Distribution of Δ5-olefinic acids in the triacylglycerols fromPinus koraiensis andPinus pinaster seed oils

Purified triacylglycerols (TAG) fromPinus koraiensis andP. pinaster seed oils, which are interesting and commercially available sources of Δ5-olefinic acids (i.e.,cis-5,cis-9,cis-12 18:3 andcis-5,cis-11,cis-14 20:3 acids) were fractionated by reversed-phase high-performance liquid chromatography, and each fraction was examined by capillary gas-liquid chromatography for its fatty acid composition. A structure could be assigned to more than 92% of TAG from both oils. In both instances, ca. 48% of the TAG were shown to contain at least one δ5-olefinic acid. In the great majority of TAG, our data showed that there is only one molecule of δ5-olefinic acid per molecule of TAG. This is compatible with theoretical calculations based on the proportion of total δ5-olefinic in the oils. Thecis-5,cis-9,cis-12 18:3 acid (14.2 and 8.6% of total fatty acids in the seed oils ofP. koraiensis andP. pinaster, respectively) and thecis-5,cis-11,cis-14 20:3 acid (1.1 and 8.1% of total fatty acids in the seed oils ofP. koraiensis andP. pinaster, respectively) are preferentially associated with two molecules of linoleic acid, and to a lesser extent, to one molecule of linoleic acid and one molecule of oleic acid, or two oleic acid molecules. However, several other combinations occur, each in low amounts. The distribution of δ5-olefinic acids in TAG is evidently not random. Combining these results with the known preferential esterification of δ5-olefinic acids to the 1,3-positions of TAG would suggest that most of these acids are present at only one of these positions at a time.     

cis-5-Monoenoic fatty acids in some chenopodiaceae seed oils

Methyl esters from seed oils of four Chenopodiaceae species are unusual in that they contain methylcis-5-hexadecenoate (4.6–12%) and methyl 5-octadecenoate (1.1–1.2%). There are indications of small amounts of 18∶2^5,9 and 18∶3^{5, 9, 12} along with unsaturated acids commonly found in seed oils-oleic (14–21%), linoleic (53–57%) and linolenic (3.5–7.8%). Fatty acid composition of the oils was determined by gas chromatography, and positions of the double bonds were established by application of gas chromatography-mass spectrometry to the methoxylated methyl esters. N. Market. Nutr. Res. Div., ARS, USDA.     

Positional distribution of Δ5-olefinic acids in triacylglycerols from conifer seed oils: General and specific enrichment in the sn-3 position

Triacylglycerols (TAG) were purified from the storage lipids extracted from the seeds of several conifer species (Taxus baccata, Larix decidua, Sciadopytis verticillata, and Juniperus communis), each species belonging to one of the four families Taxaceae, Pinaceae, Taxodiaceae, and Cupressaceae, respectively. Each species was characterized by a high content of 5,9-18:2, 5,9,12-18:3, 5,11,14-20:3, or 5,11,14,17-20:4 acids, respectively. TAG were partially deacylated with ethylmagnesium bromide, and the resulting 1,2-, 2,3-diacylglycerols (DAG), and 2-monoacylglycerols (MAG) were purified by thin-layer chromatography. 1,2- and 2,3-DAG were further fractionated by chiral column high-performance liquid chromatography of the 3,5-dinitrophenylurethane derivatives. Alternately, TAG were subjected to porcine pancreatic lipase, and the resulting 2-MAG were purified for further analysis. Gas-liquid chromatography of fatty acid methyl esters prepared from the separated DAG and MAG, coupled with appropriate calculations, indicated that the Δ5-olefinic acids, irrespective of the species, chainlengths and number of ethylenic bonds, were considerably enriched in the sn-3 position of TAG where they accounted for ca. 35 to 74 mole% of fatty acids esterified to this position (depending on the initial level of total Δ5-olefinic acids in TAG), which corresponded to 79–94% of Δ5-olefinic acids esterified to the three positions. On the other hand, Δ5-olefinic acids were less than 10% in the sn-2 position and less than 6% in the sn-1 position of TAG. This specific enrichment of Δ5-olefinic acids in the sn-3 position thus appears to be a general characteristic of conifer seed TAG. These results were extended to TAG from the seeds of two pine species (Pinus koraiensis and P. pinaster) that are rich in Δ5-olefinic acids and available commercially on a ton-scale.     

cis-5,cis-9,cis-12-octadecatrienoic and some unusual oxygenated acids inXeranthemum annuum seed oil

Seed oil ofXeranthemum annuum (family Compositae) contains a number of unusual fatty acids in addition to palmitic, stearic, oleic, linoleic and linolenic. These acids includecis-5,cis-9,cis-12-octadecatrienoic, 5%;cis-9-l,10-l-epoxyoctadecanoic, 3%;cis-9-l,10-l-epoxy-cis-12-octadecenoic (coronaric), 8%; andcis-12-d,13-d-epoxy-cis-9-octadecenoic (vernolic), 2%; as well as a mixture of two hydroxy acids, 11%. The absolute configurations of the two 9,10-epoxy acids are established for the first time. Presented in part at the AOCS Meeting in Cincinnati, October 1965. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Autoxidation rates of 5-olefinic monoenoic and denoic fatty acids from sea urchin lipids and meadoefoam oils

Autoxidation rates of the 5-olefinic monoenoic and dienoic fatty acids from sea urchin lipids and meadow-foam oils were compared with those of normal monoenoic and dienoic fatty acids by gas-liquid Chromatographic determination of the unoxidized fatty acid methyl esters remaining through the autoxidation period. The fatty acids are classified into five groups shown below according to the oxidation rate of their methyl esters: I 5-olefinic monoenoic acids (c5-18:l, c5-20:l and c5-22:1), II normal monoenoic acids (c9-18:l, cll-18:l, c9-20:1, cl3-20:l and cl3-22:l), III 5-olefinic dienoic acids (c5,cll-20:2, c5,cl3-20:2 and c5,cl3-22:2), IV 7-olefinic dienoic acids (c7,cl3-22:2 and c7,cl5-22:2) and V normal dienoic acids (c6,c9-18:2, c9,cl2-18:2 and cll,cl4-20:2). The oxidation rates of these groups increased during autoxidation in order from I to V. These results show that the 5-olefinic monoenoic and dienoic acids are more stable to autoxidation than the normal monoenoic and dienoic acids, respectively. The higher stabilities of the 5-olefinic monoenoic and dienoic acids in organisms are shown from these results.     

Composition of triacylglycerols containing cyclopropene fatty acids in seed lipids of Munguba (Bombax munguba Mart.)

The seed lipids of Munguba (Bombax munguba Mart., Bombacaceae) were found to contain substantial proportions (ca. 30%) of cyclopropene acyl moieties (sterculoyl and malvaloyl). In a novel approach to the analysis of glycerolipids containing cyclopropene acyl moieties, the triacylglycerols of Munguba seed were first treated with silver nitrate in acetonitrile-acetone (1:1, v/v), in order to convert the cyclopropene groups to the correspondingα,β-unsaturated ketones. The resulting triacylglycerols were fractionated by thin layer chromatography into molecular species containing none, one and two keto (corresponding to none, one and two cyclopropene) acyl moieties per molecule. Each of these molecular species was further fractionated according to carbon numbers by gas chromatography, and the positional distribution of the acyl moieties in each species was determined. Both sterculoyl and malvaloyl moieties were found predominantly at thesn-2 position of the triacylglycerols. The major triacylglycerols of Munguba seed were found to be 1,3-dipalmitoyl-2-oleoylglycerol, 1,3-dipalmitoyl-2-linoleoylglycerol and 1,3-dipalmitoyl-2-sterculoylglycerol.     

OxygenatedTrans-3-olefinic acids in aStenachaenium seed oil

Interesting differences were found in oils from two samples ofStenachaenium macrocephalum (Compositae) seed with dissimilar storage histories. One contained significant amounts of epoxy acids (6.5%) and hydroxy conjugated dienoic acids (5.6%), but the other contained no more than 1% of these oxygenated acids. Characterization of components in the former oil established that the principal epoxy acid (4.0%) is the previously unknowncis-9, 10-epoxy-trans-3,cis-12-octadecadienoic acid. The conjugated dienols include two additional new acids with Δ3 unsaturation (2.5%): 9-hydroxy-trans-3,-trans-10,cis-12-octadecatrienoic and 13-hydroxy-trans-3,cis-9,trans-11-octadecatrienoic acoids. The nonoxygenated acids, except for the large amount (40%) oftrans-3,cis-9,cis-12-octadecatrienoic, are those that commonly occur in seed oils. Presented at the AOCS Meeting, San Francisco, April 1969. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Enzymatic enrichment of C20 cis-5 polyunsaturated fatty acids fromBiota orientalis seed oil

Enrichment ofcis-5 polyunsaturated fatty acids [20:3(5c,11c,14c), 4.3% and 20:4(5c,11c,14c,17c), 11.3%] fromBiota orientalis seed oil was carried out by lipase-catalyzed selective esterification and hydrolysis reactions. Lipases fromRhizomucor miehei (Lipozyme),Candida cylindracea and porcine pancreas were used. Lipozyme-catalyzed esterification ofBiota fatty acids withn-butanol inn-hexane allowed 20:3 and 20:4 (as fatty acids) to be enriched to a maximum level of 52.9%, and in the presence ofC. cylindracea lipase 61.5% enrichment was achieved. Esterification with pancreatic lipase was poor with low levels of enrichment of 20:3 and 20:4 (22%). A multigram scale esterification of the free fatty acids fromBiota seed oil by repeated treatment of the isolated fatty acid fraction withn-butanol inn-hexane in the presence ofC. cylindracea lipase furnished an enrichment yield of 72.5% of a mixture of 20:3 and 20:4 fatty acids. Urea fractionation of the free fatty acids ofBiota oil gave an initial enriched fraction of 20:3 (9.5%) and 20:4 (25.2%) which, upon treatment withC. cylindracea lipase inn-butanol andn-hexane, gave an enriched fraction of 85.3% of 20:3 and 20:4 fatty acids. Partial hydrolysis of the triglycerides ofBiota oil byC. cylindracea lipase in potassium phosphate buffer at 25°C resulted in a 2.8-fold enrichment ofcis-5 polyunsaturated fatty acids (40.8% of 20:3 and 20:4) as contained in the unhydrolyzed acylglycerol fractions.     

The fatty acid composition of gymnospermae seed and leaf oils

Of 12 Gymnospermae seed and leaf oils, only 2 contained cyclopropene fatty acids. All-cis 5, 11, 14, 17-eicosatetraenoic acid occurred in concentrations up to 11.9% in 6 seed oils, and up to 61% in 2 leaf oils. The structure of this acid, as its methyl ester, was established by the combination of physical (UV, IR,¹H- and¹³C-NMR and mass spectra) and chemical techniques. Arachidonic acid also occurred in 2 seed oils.     

Occurrence of unusual hexadecenoate fatty acids in hepatoma lipids

Cis-hexadecenoates isolated from rat liver and hepatoma 7288CTC lipids were analyzed for positional isomers by ozonolysis and capillary gas liquid chromatography. In addition to the Δ6, Δ7, Δ9 and Δ11 isomers found in both tissues, the hepatoma neutral and polar lipids contained relatively high percentages of Δ12 and Δ14 hexadecenoates that were virtually absent from liver. The occurrence of these unusual fatty acids may result from an error in lipid metabolism in the hepatoma.     

Determination of the positional distribution of fatty acids in butterfat triacylglycerols

Triacylglycerol (TAG) standards were separated by analytical high-performance liquid chromatography (HPLC) with laser light-scattering detection (LLSD). A high sensitivity for TAGs was observed with LLSD whereas poor sensitivity was observed with ultraviolet detection. The HPLC-LLSD analytical separation of butterfat TAGs showed that the TAGs were eluted according to increasing carbon number. Preparative HPLC-LLSD was used to characterize butterfat TAGs that contained hypercholesterolemic fatty acids (laurate, myristate, palmitate) with carbon chainlengths of 12 or greater. These TAG fractions accounted for 29.2% of the total butterfat TAGs. Analysis of the positional distribution of fatty acids of selected butterfat TAGs containing hypercholesterolemic fatty acids showed the presence of positional isomers in each of these fractions. These butterfat TAGs also showed the predominant presence of hypercholesterolemic fatty acids at thesn-2 position. The characterization of the positional distribution of hypercholesterolemic fatty acids in butterfat TAGs is the first step for the determination of the metabolic role of the positional distribution in the hypercholesterolemic effects of butter.     

Fatty acids and triacylglycerols of cherry seed oil

Cherry seed oil, from the Rosaceae family, prunoid subfamily, is characterized by the existence of about 10% α-eleostearic acid. The structure of the acid was proven by H and¹³C nuclear magnetic resonance. The triacylglycerols of this oil were identified and quantitated by highperformance liquid chromatography by means of several types of detectors. α-Eleostearic acid was not found in the seeds of previously studied prunoids (almond, peach, apricot and plum). The main fatty acids found in the seeds of cherry and other prunoids were linoleic (L), oleic (O) and palmitic acids, and the major triacylglycerols were LLO, LOO and OOO. These chemical data support the botanical relationship within the prunoid subfamily and show the proximity of cherry to the Chrysobalanaceae family.     

Positional distribution of fatty acids in the triacylglycerols of developing oil palm fruit

The pattern of accumulation of triacylglycerols, their fatty acid compositions and the positional distribution of the fatty acids at thesn-2- andsn-1,3-positions of the triacylglycerol molecules at progressive stages of oil palm fruit development were determined. There was an exponential rate of increase of triacylglycerols and their fatty acids toward the end of fruit development. The fatty acid composition of the triacylglycerols in the early stages of development, prior to active accumulation, was more or less similar, but differed appreciably from the later stages, and the transition of fatty acid composition toward that of normal palm oil occurred at around 16 wk after anthesis (WAA) and stabilized at 20 WAA. All fatty acids increased in terms of absolute quantity. There was an overall consistency in fatty acid positional distribution, irrespective of development stage. More saturated fatty acids were found to be esterified at thesn-1,3-positions and more unsaturated fatty acids at thesn-2-position of triacylglycerol. Higher rate of incorporation of 16:0 at the 1,3-positions during the active phase of triacylglycerol synthesis was observed, while 18:1 acid exhibited a reverse trend.     

Monoenoic fatty acids in human brain lipids: Isomer identification and distribution

The carbon chain length distribution and the double bond positional isomer composition of the monoenoic fatty acids of the lipids of total human brain tissue have been determined using gas chromatography and gas chromatography/mass spectrometry of the fatty acid methyl and picolinyl esters. The even chain length monoenoic C₁₆ to C₂₈ fatty acids contain predominantly two positional isomer series, the n−7 and n−9cis homologues, whose relative proportion varies significantly with chain length. The odd chain length long-chain fatty acids consist of n−8 and n−10 isomers, whereas the odd chain length very long-chain (more than 22 carbon) fatty acids are n−7 and n−9 isomers.     

Stereospecific analysis of triacylglycerols rich in long-chain polyunsaturated fatty acids

Six oils of marine, algal, and microbial origin were analyzed for stereospecific distribution of component fatty acids. The general procedure involved preparation ofsn-1,2-(2,3)-diacylglycerols by partial deacylation with ethylmagnesium bromide or pancreatic lipase, separation of X-1,3- andsn-1,2(2,3)-diacylglycerols by borate thin-layer chromatography, resolution of thesn-1,2- andsn-2,3-enantiomers by chiral phase high-performance liquid chromatography following preparation of dinitrophenylurethane derivatives, and determination of the fatty acid composition by gas chromatography. Unexpected complications arose during a stereospecific analysis of triacylglycerols containing over 33% of either 20∶4 or 22∶6 fatty acids. Thesn-1,2(2,3)-diacylglycerols made up of two long-chain polyunsaturated acids migrated with the X-1,3-diacylglycerols and required separate chiral phase resolution. Furthermore, the enzymatic method yieldedsn-1,2(2,3)-diacylglycerols, overrepresenting the polyenoic species due to their relative resistance to lipolysis, but prolonged digestion yielded correct composition for the 2-monoacylglycerols. The final positional distribution of the fatty acids was established by pooling and normalizing the data from subfractions obtained by norman- and chiral-phase separation of diacylglycerols. The molecular species of X-1,3-,sn-1,2- andsn-2,3-diacylglycerol dinitrophenylurethanes were identified by chiral-phase liquid chromatography/mass spectrometry with electrospray ionization, which demonstrated a preferential association of the paired long-chain acids with thesn-1,2- andsn-2,3-diacylglycerol isomers.     

Occurrence of n−5 monounsaturated fatty acids in jujube pulp lipids

The pulp lipids of jujube (Zizyphus jujuba var.inermis) fruit have been shown by chromatographic, spectrometric and chemical analyses to contain a series ofcis-monoenoic fatty acids with n−5 unsaturation as major acyl moieties. The total concentration of these n−5 fatty acids, such as 14∶1n−5, 16∶1n−5 and 18∶1n−5, ranged from 22 to 54% of total fatty acids in the pulp lipids of 11 different sources. The main component of the n−5 homologues was 16∶1n−5 in all cases. Other monoenoic acids with n−7 unsaturation, namely palmitoleic (cis-9-hexadecenoic) acid andcis-vaccenic (cis-11-octadecenoic) acid, as well as with n−9 unsaturation, namely oleic acid, were also identified. In the seed lipids of jujube fruit, none of the n−5 monoenoic acids could be detected. Thus the jujube pulp lipids are characterized by the predominance of n−5 monoenoic acid isomers.     

On the syntheses of triacylglycerols from branched saturated fatty acids

A number of triacylglycerols with branched acyl groups were prepared via 1,2-isopropylidene glycerol for the purpose of studying three different physical properties: gel point, refractive index, and density. The monoacid triacylglycerols were prepared either via the corresponding acids or the acyl chlorides.     

Cis-5-monoenoic fatty acids ofCarlina (Compositae) seed oils

Seed oils ofCarlina corymbosa L. andC. acaulis L. containcis-5-octadecenoic acid as a major fatty acid (21–24%). This acid has not been previously reported as a constituent of Compositate seed oils. The predominant fatty acid in theCarlina oils is linoleic (50–52%); lesser amounts (≦10% each) of palmitic, stearic and oleic acids are also present. The oil ofC. acaulis has almost 2% ofcis-5-hexadecenoic acid;C. corymbosa oil includes minor amounts of some oxygenated fatty acids. Presented at the AOCS Meeting, New York, October 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.