共查询到20条相似文献,搜索用时 15 毫秒
1.
W. M. N. Ratnayake R. Hollywood E. O'Grady J. L. Beare-Rogers 《Journal of the American Oil Chemists' Society》1990,67(11):804-810
A combined capillary gas liquid chromatography (GLC) and infrared spectrophotometry (IR) method is described for the determination
ofcis andtrans-octadecenoic acids in margarines made from partially hydrogenated vegetable oils. The totaltrans-unsaturation of margarine fatty acid methyl esters determined by IR, with methyl elaidate as the external standard, was correlated
to the capillary GLC weight percentages of the componenttrans fatty acid methyl esters by the mathematical formula: IRtrans=%18∶1t+0.84×%18.2t+1.74×%18∶2tt+ 0.84×%18∶3t where 0.84, 1.74 and 0.84 are the correction factors which relate the GLC weight percentages to the IRtrans-equivalents for mono-trans-octadecadienoic (18∶2t),trans, trans-octadecadienoic (18∶2tt) and mono-trans-octadecatrienoic (18∶3t) acids, respectively. This formula forms the basis for the determination of totaltrans-andcis-octadecenoic acids in partially hydrogenated vegetable oils. From the weight percentages of 18∶2t, 18∶2tt and 18∶3t determined by capillary GLC on a cyanosilicone liquid phase and the totaltrans-unsaturation by IR, the percentage of the totaltrans-octadecenoic acids (18∶1t) is calculated using the formula. The difference between the total octadecenoic acids (18∶1), determined by capillary GLC,
and the 18∶1t gives the totalcis-octadecenoic acids.
Presented in part at the 81st Annual Meeting of the American Oil Chemists' Society, Baltimore, Maryland, April 22–25, 1990. 相似文献
2.
A. P. Tulloch 《Lipids》1982,17(8):544-550
13C Nuclear magnetic resonance spectroscopy has been used in a nondestructive investigation of conjugated unsaturated acids
in seed oil triacylglycerols. Spectra of seven seed oils, fromPunica granatum, Cucurbita palmata, Jacaranda mimosifolia, Centranthus ruber, Catalpa bignonioides, Chilopsis linearis andCalendula officinalis, containing among them six isomeric trienoic acids,cis,trans,cis- andtrans,trans,cis-8,10,12-,cis,trans,cis-, cis,trans,trans-, trans,trans,cis- andtrans,trans,trans-9,11,13-octadecatrienoic acids, and of the oil ofImpatiens balsamina containingcis,trans,trans,cis-9,11,13,15-octadecatetraenoic acid, have been examined. Structures of component acids were derived from shifts of double
bond carbons and of carbons close to the double bond systems. Compositions of the oils were obtained from signal intensities.
Results were similar to those obtained by older methods. Only oil ofCentranthus ruber contained more than one major conjugated acid; bothcis,trans,trans- andtrans,trans,trans-9,11,13-octadecatrienoic acids were found. The latter acid is now thought to occur naturally.
Presented in part at the International Society for Fat Research/American Oil Chemists' Society World Congress, New York, 1980.
NRCC no. 20405. 相似文献
3.
Robert L. Wolff Laurent G. Deluc Anne M. Marpeau 《Journal of the American Oil Chemists' Society》1996,73(6):765-771
The seed oils from twenty-five Conifer species (from four families—Pinaceae, Cupressaceae, Taxodiaceae, and Taxaceae) have
been analyzed, and their fatty acid compositions were established by capillary gas-liquid chromatography on two columns with
different polarities. The oil content of the seeds varied from less than 1% up to 50%. Conifer seed oils were characterized
by the presence of several Δ5-unsaturated polymethylene-interrupted polyunsaturated fatty acids (Δ5-acids) with either 18
(cis-5,cis-9, 18∶2,cis-5,cis-9,cis-12 18∶3, andcis-5,cis-9,cis-12,cis-15 18∶4 acids) or 20 carbon atoms (cis-5,cis-11 20∶2,cis-5,cis-11,cis-14, 20∶3, andcis-5,cis-11,cis-14,cis-17 20∶4 acids). Pinaceae seed oils contained 17–31% of Δ5-acids, mainly with 18 carbon atoms. The 20-carbon acids present
were structurally derived from 20∶1n-9 and 20∶2n-6 acids. Pinaceae seed oils were practically devoid of 18∶3n-3 acid and did
not contain either Δ5-18∶4 or Δ5-20∶4 acids. Several Pinaceae seeds had a Δ5-acid content higher than 50 mg/g of seed. The
only Taxaceae seed oil studied (Taxus baccata) had a fatty acid composition related to those of Pinaceae seed oils. Cupressaceae seed oils differed from Pinaceae seed
oils by the absence of Δ5-acids with 18 carbon atoms and high concentrations in 18∶3n-3 acid and in Δ5-acids with 20 carbon
atoms (Δ5-20∶3 and Δ5-20∶4 acids). Δ5-18∶4 Acid was present in minute amounts. The highest level of Δ5-20∶4 acid was found
inJuniperus communis seed oil, but the best source of Δ5-acids among Cupressaceae wasThuja occidentalis. Taxodiaceae seed oils had more heterogeneous fatty acid compositions, but the distribution of Δ5-acids resembled that found
in Cupressaceae seed oils. Except forSciadopytis verticillata, other Taxodiaceae species are not interesting sources of Δ5-acids. The distribution profile of Δ5-acids among different
Conifer families appeared to be linked to the occurrence of 18∶3n-3 acid in the seed oils. 相似文献
4.
G. Gowrikumar V. V. S. Mani T. Chandrasekhara Rao T. N. B. Kaimal G. Lakshminarayana 《Lipids》1981,16(7):558-559
The seeds ofDiplocyclos palmatus L. (Cucurbitaceae) contained 23% oil and 15% protein. The UV, IR,1H-NMR and13C-NMR spectrometry of the oil, and oxidation, reduction and gas liquid chromatography (GLC) of the methyl ester of conjugated
fatty acid isolated by preparative thin layer chromatography (TLC) showed the presence of punicic (octadeca-cis-9,trans-11,cis-13-trienoic) acid. The fatty acid composition (wt %), as determined by GLC, is: punicic, 38.2; 18∶2, 43.9; 16∶0, 8.1; 18∶0,
4.9 and 18∶1, 4.9. 相似文献
5.
Robert L. Wolff 《Journal of the American Oil Chemists' Society》1994,71(8):907-909
Analysis of alpha-linolenic acid geometrical isomers in deodorized or heated oils by capillary gas-liquid chromatography (GLC)
on polar cyanoalkyl polysiloxane stationary phases requires some care to avoid interferences with other fatty acids. Depending
on the temperature of the column, thecis-11 20∶1 acid may elute before, with or after thecis-9,cis-12,cis-15 18∶3 acid during GLC. In some instances [temperature higher than 180°C with a CP Sil 88 column (Chrompack, Middelburg,
The Netherlands)], the 20∶1 acid coelutes with thetrans-9,cis-12,cis-15 18∶3 acid, leading to abnormally high levels of this last isomer. Consequently, the degree of isomerization of alpha-linolenic
acid will be over-estimated under such conditions. It is recommended that the behavior ofcis-11 20∶1 acid relative to temperature be checked carefully prior to the determination of alpha-linolenic acid geometrical
isomers by GLC. Temperatures lower than 160°C seem appropriate to separate all of these components from each other and fromcis-11 20∶1 acid in a 50 m×0.25 mm i.d. CP Sil 88 capillary column. 相似文献
6.
Conjugated α-linolenic acid (ClnA) was prepared from α-linolenic acid (9,12,15–18∶3n−3, LnA) by alkaline treatment; we fractionated
CLnA into three peaks by reversed-phase column-HPLC as evidenced by monitoring absorbance at 205, 235, and 268 nm. Peak I
was a conjugated dienoic FA derived from LnA, whereas Peaks II and III were conjugated trienoic LnA. Proton NMR analysis showed
that Peak III consisted of the all-trans isomer. The methylated Peak III was further divided into five peaks (Peaks IV–VIII) by silver ion column-HPLC. Peak V, a
major constituent in the Peak III fraction, was identified as conjugated 10t,12t,14t-LnA by GC-EIMS and 1H NMR analysis. Peaks III and V, which consisted of conjugated all-trans trienoic LnA, had stronger growth-inhibitory effects on human tumor cell lines than the other collected peaks and strongly
induced lipid peroxidation as compared with Peaks I, II, and LnA. We propose that conjugated all-trans trienoic FA have the strongest growth-inhibitory effect among the conjugated trienoic acids and conjugated dienoic acids
produced by alkaline treatment of α-LnA, and that this effect is mediated by lipid peroxidation. 相似文献
7.
Adebisi Mogeed Balogun Babatunde L. Fetuga 《Journal of the American Oil Chemists' Society》1985,62(3):529-531
Seed oils of some members of the Meliceae (six) and Combretaceae (three) were analyzed for their fatty acid composition. In
oils of members of both families palmitic acid was the most abundant saturated acid. Trace amounts of short chain (C12–C14)
and long chain (C20–C22) saturated acids were detected in some members of the two families. Oleic acid was the most abundant
unsaturated acids in the oils of four members of the Meliaceae. However, in the oils ofCedrella odorata andLovoa trichilloides, dienoic acid (C18:2) was the major unsaturated acid. Strikingly high levels of trienoic (C18:3) and monoenoic (C16:1) acids
were detected in the seed oils ofC. odorata andEnthandrophragma angolense, respectively. Oleic acid also was the most abundant unsaturated acid in the Combretaceae. The nutritional value and industrial
potentials of these oils are given. 相似文献
8.
Najibullah Sehat John K. G. Kramer Magdi M. Mossoba Martin P. Yurawecz John A. G. Roach Klaus Eulitz Kim M. Morehouse Youh Ku 《Lipids》1998,33(10):963-971
Commercial cheese products were analyzed for their composition and content of conjugated linoleic acid (CLA) isomers. The
total lipids were extracted from cheese using petroleum ether/diethyl ether and methylated using NaOCH3. The fatty acid methyl esters (FAME) were separated by gas chromatography (GC), using a 100-m polar capillary column, into
nine minor peaks besides that of the major rumenic acid, 9c, 11t-octadecadienoic acid (18∶2), and were attributed to 19 CLA isomers. By using silver ion-high performance liquid chromatography
(Ag+-HPLC), CLA isomers were resolved into seven trans, trans (5–9%), three cis/trans (10–13%), and five cis, cis (<1%) peaks, totaling 15, in addition to that of the 9c, 11t-18∶2 (78–84%). The FAME of total cheese lipids were fractionated by semipreparative Ag+-HPLC and converted to their 4,4-dimethyloxazoline derivatives after hydrolysis to free fatty acids. The geometrical configuration
of the CLA isomers was confirmed by GC-direct deposition-Fourier transform infrared, and their double bond positions were
established by GC-electron ionization mass spectrometry. Reconstructed mass spectral ion profiles of the m+2 allylic ion and the m+3 ion (where m is the position of the second double bond in the parent conjugated fatty acid) were used to identify the minor CLA isomers
in cheese. Cheese contained 7 t,9c-18∶2 and the previously unreported 11t, 13c-18∶2 and 12c, 14t-18∶2, and their trans,trans and cis,cis geometric isomers. Minor amounts of 8,10-, and 10, 12–18∶2 were also found. The predicted elution orders of the different
CLA isomers on long polar capillary GC and Ag*-HPLC columns are also presented. 相似文献
9.
Dibutyroyl derivatives of monoacylglycerols (DBMAG) from conifer seed oil triacylglycerols (TAG) were prepared by partial
deacylation of TAG with ethylmagnesium bromide followed by diesterification with n-butyryl chloride. The resulting mixtures were analyzed by gas-liquid chromatography (GCL) with 65% phenylmethyl silicon open
tubular fused-silica capillary column operated under optimal conditions and separated according to both their fatty acid structures
and their regiospecific distribution. Seed oils of 18 species from 5 conifer families (Pinaceae, Taxaceae, Cupressaceae, Cephalotaxaceae,
and Podocarpaceae) were analyzed. The chromatograms showed a satisfactory resolution of DBMAG containing palmitic (16∶0) stearic
(18∶0), taxoleic (cis-5, cis-9 18∶2), oleic (cis-9 18∶1), cis-vaccenic (cis-11 18∶1), pinolenic (cis-5, cis-9, cis-12 18∶3), linoleic (cis-9, cis-12 18∶2), α-linolenic (cis-9 cis-12, cis-15 18∶3), and an almost baseline resolution of DBMAG containing gondoic (cis-11 20∶1), cis-5, cis-11 20∶2, sciadonic (cis-5, cis-11, cis-14 20∶3), dihomolinoleic (cis-11 cis-14 20∶2), juniperonic (cis-5, cis-11, cis-14, cis-17 20∶4), and dihomo-α-linolenic (cis-11, cis-14, cis-17 20∶3) acids. We have observed that results for Pinus pinaster and P. koraiensis seed oils obtained with this new simple method compared favorably with literature data established with other usual regiospecific
analytical techniques. Δ5-Olefinic acids are esterified mainly at the external positions of the glycerol backbone in all cases,
in agreement with data obtained by other methodologies allowing validation of the GLC regiospecific method. To date, 45 gymnosperm
species (mostly Coniferophytes) from 21 genera belonging to 9 families have been analyzed, all of them showing a definite
enrichment of Δ5-olefinic acids in the external positions of TAG. These fatty acids (FA), with one exception only, represent
between-2 and 8% of FA esterified to the internal positions. For some species, i.e., P. koraiensis and P. pinaster, this asymmetrical distribution was established by at least three analytical procedures and confirmed by stereospecific analysis
of their seed TAG. 相似文献
10.
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∶25,9 and 18∶35, 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. 相似文献
11.
The seed oil ofEuphoria longana, Sapindaceae, contains 17.4% of 9,10-methyleneoctadecanoic (dihydrosterculic) acid. This identification is based on information
from thin layer chromatography, infrared analysis, gas liquid chromatography, nuclear magnetic resonance and mass spectroscopy.
Since GLC of the oil showed components that emerged between the usual triglycerides, the cyclopropanoid acid is apparently
a triglyceride constituent. The presence of smaller amounts, less than 1%, of cyclopropanoid fatty acids of different chain
lengths is indicated by GLC and TLC analyses of the methyl esters. The other major fatty acids in this oil are: 16∶0 (19%),
18∶0 (7%), 18∶1 (36%), 18∶2 (6%), 18∶3 (5%) and 20∶0 (4%).Euphoria oil contains considerably larger amounts of cyclopropanoid fatty acids than previously reported in other seed oils.
Presented at the AOCS-AACC Joint Meeting, Washington, D.C., April 1968.
No. Utiliz. Res. Dev. Div.; ARS, USDA. 相似文献
12.
Improved separation of conjugated fatty acid methyl esters by silver ion-high-performance liquid chromatography 总被引:4,自引:7,他引:4
Najibullah Sehat Rainer Rickert Magdi M. Mossoba John K. G. Kramer Martin P. Yurawecz John A. G. Roach Richard O. Adlof Kim M. Morehouse Jan Fritsche Klaus D. Eulitz Hans Steinhart Yuoh Ku 《Lipids》1999,34(4):407-413
Operating from one to six silver ion-high-performance liquid chromatography (Ag+-HPLC) columns in series progressively improved the resolution of the methyl esters of conjugated linoleic acid (CLA) isomeric
mixtures from natural and commercial products. In natural products, the 8 trans, 10 cis-octadecadienoic (18∶2) acid was resolved from the more abundant 7 trans, 9 cis-18∶2, and the 10 trans, 12 cis-18∶2 was separated from the major 9 cis, 11 trans-18∶2 peak. In addition, both 11 trans, 13 cis-18∶2 and 11 cis, 13 trans-18∶2 isomers were found in natural products and were separated; the presence of the latter, 11 cis, 13 trans-18∶2, was established in commercial CLA preparations. Three Ag+-HPLC columns in series appeared to be the best compromise to obtain satisfactory resolution of most CLA isomers found in
natural products. A single Ag+-HPLC column in series with one of several normal-phase columns did not improve the resolution of CLA isomers as compared
to that of the former alone. The 20∶2 conjugated fatty acid isomers 11 cis, 13 trans-20∶2 and 12 trans, 14 cis-20∶2, which were synthesized by alkali isomerization from 11 cis, 14 cis-20∶2, eluted in the same region of the Ag+-HPLC chromatogram just before the corresponding geometric CLA isomers. Therefore, CLA isomers will require isolation based
on chain length prior to Ag+-HPLC separation. The positions of conjugated double bonds in 20∶2 and 18∶2 isomers were established by gas chromatography-electron
ionization mass spectrometry as their 4,4-dimethyloxazoline derivatives. The double-bond geometry was determined by gas chromatography-direct
deposition-Fourier transform infrared spectroscopy and by the Ag+-HPLC relative elution order. 相似文献
13.
Tomohisa Kinami Naoto Horii Bhaskar Narayan Shingo Arato Masashi Hosokawa Kazuo Miyashita Hironori Negishi Junichi Ikuina Ryuji Noda Seiichi Shirasawa 《Journal of the American Oil Chemists' Society》2007,84(1):23-29
A high-performance liquid chromatographic (HPLC) method is described for the determination of conjugated linoleic acids (CLA)
and conjugated linolenic acids (CLN). Methyl esters prepared from purified lipid fractions of soybean oil were analyzed using
an HPLC system equipped with photodiode-array detector to detect peaks having maximum absorption around 233 and 275 nm. These
peaks were concentrated by AgNO3-silicic acid column chromatography and reversed-phase HPLC. The structural analysis, of dimethyloxazoline (DMOX) derivatized
methyl esters, using gas chromatography–mass spectrometry (GC–MS) showed the occurrence of 9,11- and 10,12-CLA and 8,10,13-,
8,10,12-, and 9,11,13-CLN. The comparison of these conjugated fatty acids with authentic isomers by HPLC revealed the presence
of isomeric mixtures of CLA [cis (c),trans(t) or t,c and t,t] and CLN (c,t,t or t,t,c and t,t,t). Traces of 9,11- and 10,12-CLA (c,t or t,c) were found in crude oil.
CLN isomers (8,10,12-18:3 and 9,11,13-18:3) were found to be forming during the bleaching phase of soybean oil processing.
8,10,13-CLN and 9,11- and 10,12-CLA (t,t) were only found in soybean oil after the deodorization step. CLN contents in commercial
soybean oil varied from 387 to 1,316 mg/kg oil. A decreased level of bleaching earth and temperature resulted in a reduced
CLN content. It is possible that CLN would be derived from the linoleate hydroperoxides formed during the processing and storage
of soybean oil. 相似文献
14.
This study reports a facile identification of the molecular species of enantiomeric diacylglycerols by combining chiral phase
high-performance liquid chromatography with positive chemical ionization mass spectrometry. For this purpose the 3,5-dinitrophenylurethane
(DNPU) derivatives ofsn-1,2(2,3)-diacylglycerols are separated on an (R+)-naphthylethylamine polymer column (25 cm × 0.46 cm ID) using an isocratic
solvent system made up of hexane/dichloroethane/acetonitrile (85∶10∶5, by vol) or isooctane/tert-butyl methyl ether/acetonitrile/isopropanol (80∶10∶5∶5, by vol). About 1% of the column effluent (1 mL/min) was admitted
to a quadrupole mass spectrometer (Hewlett-Packard, Palo Alto, CA)via direct liquid inlet interface, and positive chemical ionization spectra were recorded over the range of 200–900 mass units.
The DNPU derivatives of diacylglycerols yield characteristic [M-DNPU]+ and [RCO+74]+ ions for each diacylglycerol species from which the molecular weight and exact pairing of fatty acids can be unequivocally
obtained. The characteristic ions appear to be generated in nearly correct mass proportions as indicated by preliminary quantitative
comparisons.
The abbreviations 14∶0, 16∶1, 18∶2, etc. represent normal chain fatty acids of 14, 16, 18, etc. acyl carbons and 0, 1, 2,
etc. double bonds, respectively; 16∶0–18∶1, etc. represent diacylglycerols containing 16∶0 and 18∶1 fatty acids of unspecified
positional distribution;sn indicates stereospecific numbering of glycerol carbons;sn-1,2-diacylglycerols andsn-2,3-diacylglycerols are enantiomeric diacylglycerols of unspecified fatty acid composition;rac-1,2-diacylglycerols are racemic diacylglycerols representing equal amounts ofsn-1,2-andsn-2,3-enantiomers;sn-1,2(2,3)-diacylglycerols are a mixture ofsn-1,2-andsn-2,3-diacylglycerols of unspecified proportion of enantiomers and unspecified fatty acid compisition and positional distribution;
X-1,3-diacylglycerols are diacylglycerols of unspecified fatty acid composition and reverse isomer content. 相似文献
15.
Positional and geometrical isomers of monounsaturated long chain fatty acids were analyzed by the combination of high performance
liquid chromatography (HPLC) and glass capillary gas chromatography (GC). A preparative group separation ofcis andtrans isomers of the monounsaturated fatty acid methyl esters was achieved according to chain length by reversed-phase HPLC, and
using a highly sensitive interference refractive index detector. After collection of the different fractions containingcis andtrans forms of the monounsaturated fatty acid methyl esters, the fractions were analyzed for their content of positional isomers
using glass capillary GC with Silar-5 CP as stationary phase. The preparative step in the HPLC was also used analytically
for the determination of the ratio between thecis andtrans monounsaturated fatty acids. A comparison was made between the results obtained with the HPLC technique and the results of
a GLC technique with a packed OV-275 column. There was a good correlation between the 2 techniques with a tendency to highertrans values with the HPLC technique (4%). It was shown with reference substances that 18∶1ω6-cis to ω11-cis and 18∶1ω5-trans to ω12-trans, the most common monounsaturated fatty acid isomers in partially hydrogenated vegetable oils, could be almost quantitatively
recovered in the HPLC step. Most of the individual positional isomers of monounsaturated fatty acids of varying chain length
could be separated and determined in the glass capillary GC step with the exception of those isomers containing the double
bond in a relatively high ω-position. The relative standard deviation of the technique as determined with reference substances
was better than 4%. The described technique was applied to the analysis of the isomeric monounsaturated fatty acid content
in partially hydrogenated vegetable and marine oils, and about 5 samples a day could be executed.
Part of this work has been presented at the ISF/AOCS World Congress, New York (1980)JAOCS 58, (4), 1981, abstr. no. 184. 相似文献
16.
Open tubular gas liquid chromatographic (GLC) analyses of fatty acids from total lipids of 12 species of Echinoidea collected
at several locations along the Pacific coast of Japan showed the same unusualcis-5-olefinic acids in all species, i.e.,cis-5-octadecenoic acid (5–18∶1),cis-5-eicosenoic acid (5–20∶1), all-cis-5,11- and 5,13-eicosadienoic acids (5,11- and 5,13–20∶2), allcis-5,11,14-eicosatrienoic acid (5,11,14–20∶3) and all-cis-5,11,14,17-eicosatetraenoic acid (5,11,14,17–20∶4). The structural analysis of partially purified 5,11,14,17–20∶4 was undertaken
by reductive ozonolysis with GLC and gas chromatographic-mass spectrometric analyses of the products.13C-Nuclear magnetic resonance analyses of the totals and fractions of fatty acid methyl esters from the sea urchin lipids did
not show any occurrence of fatty acids having an isolated olefinic bond in the 2, 3 or 4 positions. The 5-olefinic acids were
concentrated on the polar lipids rather than neutral lipids. The branched and odd chain fatty acid contents of mud-feeding
sea urchins were found to be relatively greater proportions of total fatty acids than in algae feeders. 相似文献
17.
The microsomal desaturation of positional isomers oftrans-octadecenoic acids is effected by the Δ9-desaturase and, with concomitant geometric isomerization,cis,trans- andcis,cis-octadecadienoic acids of unusual structure are formed. Incorporation of the substrates and their products into lipids varied
from 50.5% for incubations with 14–18∶1 to 81.0% for 6–18∶1. A detailed study of the composition of each of the major lipid
classes, i.e., phospholipids, triacylglycerol and cholesteryl esters, as well as the composition of the free fatty acid fraction,
revealed a complex picture. Generally, thec,c-18∶2 products were enriched in the phospholipid fraction, whereas thec,t-18∶2 appeared preferentially in cholesteryl esters. The 18∶1 substrates themselves did not show marked preferences for any
of the lipid classes. Phospholipase A2 action on phosphatidylcholine and phosphatidylethanolamine demonstrated enrichment of thec,c- and thec,t-18∶2 products in the 2-position, whereas the 18∶1 substrates were preferentially inserted into the 1-positions. Thec,c- andc,t-18∶2 formed by desaturation oft11–18∶1 varied from this pattern, probably due to their conjugated double bond structures. Linoleic acid,c9,c12–18∶2, formed during desaturation oft12–18∶1, surprisingly showed enrichment in the 1-position of phosphatidylcholine. Incubation experiments witht5- andt6-isomers using liver microsomes from rats fed a corn-oil-supplemented diet showed conversion and incorporation rates similar
to the rates obtained with microsomes from EFA-deficient rats. The fatty acid composition of lipid classes and the distributions
of products and substrate between the 1- and 2-positions of phosphatidylcholine also agreed with results obtained using microsomes
from EFA-deficient rats. 相似文献
18.
Oil ofFevillea trilobata has the composition palmitic acid 31%, stearic acid 12%, oleic acid 11%, linoleic acid 7%,cis,trans,cis 9,11,13-octadecatrienoic acid 30% andcis,trans,trans-9,11,13-octadecatrienoic acid 9%. The oil was analyzed and components identified by13C NMR spectroscopy; the composition was also confirmed by conventional methods. Assignment of13C NMR signals of conjugated trienoic acids is discussed and it is shown that mixtures of isomeric conjugated acids can be
analyzed by this method.
NRCC No. 17797. 相似文献
19.
A previously undescribed fatty acid, all-cis 7, 11–20∶2 (dihomotaxoleic acid, DHT), has been characterized by gas chromatography-mass spectrometry as being present (approximately
0.1%) in seed oils of two Taxaceae containing high levels (11–16%) of taxoleic acid (all-cis 5,9–18∶2). This compound was absent from oils of 10 other conifer genera, as well as from one member of Taxaceae containing
very low amounts of taxoleic acid, suggesting that DHT is a taxoleic acid elongation product. 相似文献
20.
Olivier Berdeaux Robert L. Wolff 《Journal of the American Oil Chemists' Society》1996,73(10):1323-1326
The fatty acids from the seed oils of three Conifer species (one Pinaceae,Pinus pinaster, and two Cupressaceae,Chamaecyparis lawsoniana andBiota orientalis) have been analyzed as their 4,4-dimethyloxazoline (DMOX) derivatives by gas-liquid chromatography coupled with mass spectrometry.
The structures of six Δ5-unsaturated polymethylene-interrupted fatty acids (Δ5-UPIFA) were established, confirming previous
studies in which they were identified by their equivalent chainlengths (ECL) and by comparison with related authentic standards.
These acids were:cis-5,cis-9 18∶2,cis-5,cis-9,cis-12 18∶3 (P. pinaster),cis-5,cis-9,cis-12,cis-15 18∶4 (C.lawsoniana),cis-5,cis-11 20∶2,cis-5,cis-11,cis-14 20∶3 (all species),cis-5,cis-11,cis-14,cis-17 20∶4 (B. orientalis) acids. In addition,cis-9 18∶1,cis-9,cis-12 18∶2 (all species) andcis-9,cis-12,cis-15 18∶3 (Cupressaceae) acids, together with their elongation products [cis-11 20∶1,cis-11,cis-14 20∶2 (all species) andcis-11,cis-14,cis-17 20∶3 (B. orientalis) acids] were also identified. In the mass spectra, DMOX derivatives of all Δ5-UPIFA showed an intense peak atm/z 153, which is a diagnostic ion of fatty acid derivatives with a Δ5-ethylenic bond. Other double bonds were localized by ion
pairs that differed by 12 atomic mass units. The present study fully justifies the use of ECL to identify Δ5-UPIFA in Conifer
seed oils, in which they are ordinary components. 相似文献