共查询到20条相似文献,搜索用时 31 毫秒
1.
Päivi Laakso 《Journal of the American Oil Chemists' Society》1997,74(10):1291-1300
Triacylglycerols of oils rich in α- and/or γ-linolenic acids were analyzed by reversed-phase high-performance liquid chromatography
(HPLC) coupled with atmospheric pressure chemical ionization mass spectrometry [(APCI)MS]. The (APCI)MS spectra of most triacylglycerols
exhibited [M + H]+ and [M - RCOO]+ ions, which defined the molecular weight and the molecular association of fatty acyl residues, respectively. Reversed-phase
HPLC resulted in, at least, partial separation of triacylglycerols containing α- and/or γ-linolenic acid moieties. Molecules
containing α-linolenic acid residues exhibited a relatively weaker retention by the stationary phase than the corresponding
molecules containing γ-linolenic acid residues. Good separation of triacylglycerols of cloudberry seed oil, evening primrose
oil, borage oil, and black-currant seed oil was achieved. The molecular species identification of separated components was
based on the (APCI)MS data as well as on the elution properties of triacylglycerols on reversed-phase HPLC. This study demonstrated
the efficiency of HPLC-(APCI)MS in determining the molecular species compositions of triacylglycerols in complex natural mixtures.
Good quality mass spectra could be extracted even from minor chromatographic peaks representing 0.2% or less of the total
triacylglycerols. 相似文献
2.
Huiling Mu Henrik Sillen Carl-Erik Hiy 《Journal of the American Oil Chemists' Society》2000,77(10):1049-1060
Atmospheric pressure chemical ionization liquid chromatography/mass spectrometry was used in the identification of diacylglycerol
and triacylglycerol (TAG) molecular species in a sample of a structured lipid. In the study of acylglycerol standards, the
most distinctive differences between the diacylglycerol and TAG molecules were found to be the molecular ion and the relative
intensity of monoacylglycerol fragment ions. All saturated TAG ranging from tricaproin to tristearin, and unsaturated TAG
including triolein, trilinolein, and trilinolenin, had ammonium adduct molecular ions [M+NH4]+. Protonated molecular ions were also produced for TAG containing unsaturated fatty acids and the intensity increased with
increasing unsaturation. Diacylglycerol fragment ions were also formed for TAG. The ammonium adduct molecular ion was the
base peak for TAG containing polyunsaturated fatty acids, whereas the diacylglycerol fragment ion was the base peak for TAG
containing saturated and monounsaturated medium- and long-chain fatty acids; the relative intensities of the ammonium adduct
molecular ions were between 14 and 58%. The most abundant ion for diacylglycerols, however, was the molecular ion [M−17]+, and the relative intensity of the monoacylglycerol fragment ion was also higher than that for TAG. These distinctive differences
between the diacylglycerol and TAG spectra were utilized for rapid identification of the acylglycerols in the sample of a
structured lipid. 相似文献
3.
A capillary supercritical fluid chromatograph (SFC), combined with a triple-quadrupole mass spectrometer (MS) via a liquid chromatography-atmospheric pressure chemical ionization (LC-APCI) interface, was utilized in the analysis of berry
oil triacylglycerols. No modification of the commercially available interface was required. Vapor of different solvents, such
as methanol, isopropanol, water, or ammonium hydroxide in methanol, was introduced in the sheath gas flow in the APCI source
to achieve adequate ionization of triacylglycerols. The separation of triacylglycerols according to acyl carbon number and
degree of unsaturation was accomplished on a 20 m × 50 μm i.d. SB-Cyanopropyl-25 column. The resolution of triacylglycerols
in the reconstructed ion chromatogram and the sensitivity of the SFC-(APCI)MS system was comparable to or slightly better
than that obtained with a flame ionization detector. No baseline drifting was observed during the SFC density programming.
Triacylglycerols formed diagnostic [M + H]+ and [M - RCOO]+ ions with all tested reactant ion solvents except with ammonium hydroxide in methanol, which formed abundant [M + 18]+ ions instead of [M + H]+ ions. The abundance of the [M + H]+ ion increased with increasing degree of unsaturation of a triacylglycerol, whereas the abundance of the [M - RCOO]+ ion depended on the regiospecific distribution of the fatty acid moiety between the sn-1/3 positions and the sn-2 position and on the number of double bonds. 相似文献
4.
Mass spectra of several triglycerides of specific structure or with specific deuterium labeling have been measured with a
low resolution mass spectrometer. With saturated triglycerides the abundances of ions characteristic of the component acids,
[M-RCO2]+, increase with increasing chain length, and [M-RCO2CH2]+ decrease with increasing chain length. Unsaturation in the acyl moiety causes the abundant formation of [RCO-1]+. Structures have been suggested for a number of the main peaks obtained from saturated triglycerides, and high resolution
spectra of one triglyceride agree with the postulated structures. The peaks, [RCO+74]+, [RCO+115]+ and [RCO+128+14n]+, represent structures which contain the glyceryl portion of the triglyceride, since in case of the replacement of its hydrogens
with deuteriums, these peaks are shifted accordingly. Evidence which indicates the possibility of determining the location
of unsaturation by the interruption of homology of the [RCO+128+14n]+ series, brought about by the addition of deuterium to the unsaturated linkages, is introduced. Further evidence is also presented,
which indicates that the [M-RCO2CH2]+ ions arise from the positions 1 and 3 and, in agreement with earlier studies from other laboratories, it is thus possible
to identify the acyl groups attached to the 1 and 2 positions of the glyceryl moiety.
Presented in part at the AOCS Meeting, New Orleans, April 1970. Part V of a series on Mass Spectrometry of Lipids. For IV
see Lipids 4:421–427 (1969). 相似文献
5.
Identification of milk fat triacylglycerols was accomplished by capillary supercritical fluid chromatography (SFC) combined
with atmospheric pressure chemical ionization mass spectrometry [(APCI)MS]. Supercritical carbon dioxide was the carrier fluid
in SFC. Ionization was achieved by introducing vapor of ammonia in methanol into the ionization chamber, which resulted in
the formation of abundant [M+18]+ and [M-RCOO]+ ions of triacylglycerols. These ions defined both the molecular weight and the fatty acid constituents of a triacylglycerol,
respectively. SFC on a nonpolar stationary phase provided an efficient separation of triacylglycerols according to the combined
number of carbon atoms in the acyl chains of a molecule. In addition to the identification of the major chromatographic peaks
representing molecules with 26–54 acyl carbons, minor peaks representing triacylglycerols with an odd number of acyl carbons
were separated and identified. Furthermore, compositional information on partially separated isobaric triacylglycerols, which
differed substantially in the chain length of the fatty acyl residues, was achieved within some of the peaks. A new finding
of the present study was the formation of abundant [M+18]+ ions of saturated triacylglycerols in addition to diagnostic fragment ions, being of primary importance in structure elucidation.
This extends the applicability of capillary SFC-(APCI)MS in the analysis of both saturated and unsaturated triacylglycerols. 相似文献
6.
Jinmao You Fang Zhu Wenchen Zhao Xian'en Zhao Yourui Suo Sujuan Liu 《European Journal of Lipid Science and Technology》2007,109(3):225-236
A sensitive method for the determination of free fatty acids using 2‐(2‐(anthracen‐10‐yl)‐1H‐naphtho[2,3‐d]imidazol‐1‐yl) ethyl‐p‐toluenesulfonate (ANITS) as tagging reagent with fluorescence detection has been developed. ANITS could easily and quickly label fatty acids in the presence of the K2CO3 catalyst at 90 °C for 40 min in N,N‐dimethylformamide solvent. From the extracts of rape bee pollen samples, 20 free fatty acids were sensitively determined. Fatty acid derivatives were separated on a reversed‐phase Eclipse XDB‐C8 column by HPLC in conjunction with gradient elution. The corresponding derivatives were identified by post‐column APCI/MS in positive‐ion detection mode. ANITS‐fatty acid derivatives gave an intense molecular ion peak at m/z [M+H]+; with MS/MS analysis, the collision‐induced dissociation spectra of m/z [M+H]+ produced the specific fragment ions at m/z [M–345]+ and m/z 345.0 (here, m/z 345 is the core structural moiety of the ANITS molecule). The fluorescence excitation and emission wavelengths of the derivatives were λex = 250 nm and λem = 512 nm, respectively. Linear correlation coefficients for all fatty acid derivatives are >0.9999. Detection limits, at a signal‐to‐noise ratio of 3 : 1, are 24.76–98.79 fmol for the labeled fatty acids. 相似文献
7.
Jiann-Tsyh Lin Grace Q. Chen Ching T. Hou 《Journal of the American Oil Chemists' Society》2013,90(1):33-38
Castor oil can be used in industry. The molecular species of triacylglycerols containing hydroxy fatty acids (FA) in castor oil have been identified. We report here the identification of twelve diacylglycerols (DAG) containing hydroxy FA in castor oil using positive ion electrospray ionization mass spectrometry of the lithium adducts. They were RR (diricinolein, R is ricinoleate), RL, RS, R‐diOH18:0, R‐diOH18:1, R‐diOH18:2, R‐triOH18:0, R‐triOH18:1, R‐triOH18:2, diOH18:0‐diOH18:1, diOH18:1‐diOH18:1 and diOH18:1‐diOH18:2. The MS2 fragment ions, [M + Li ? FA]+ and [FA + Li]+, from the lithium adducts of DAG containing hydroxy FA (one or two hydroxy FA), were used for the identification. The additional fragment ions from the neutral losses of FA lithium salts [M + Li ? FALi]+ were used for the identification of eleven DAG containing two normal FA in a soybean oil bioconversion product. The MS2 fragment ions from the neutral losses of FA lithium salts [M + Li ? FALi]+ were not detected from the DAG containing hydroxy FA. The DAG containing FA with more hydroxyl groups than the other FA on the same DAG molecule tended to have a prominent fragment ion [FA + Li]+ and an undetectable fragment ion [M + Li ? FA]+ while the FA was the more hydroxylated FA. Also the less hydroxylated FA of a DAG tended to have a prominent fragment ion [M + Li ? FA]+ and an undetectable fragment ion [FA + Li]+ while the FA was the less hydroxylated FA. 相似文献
8.
Marco Roverso Roberta Seraglia Raghav Dogra Denis Badocco Silvia Pettenuzzo Luca Cappellin Paolo Pastore Sara Bogialli 《International journal of molecular sciences》2022,23(9)
Limits of Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry (MS) in the study of small molecules are due to matrix-related interfering species in the low m/z range. Single-walled carbon nanohorns (SWCNH) were here evaluated as a specific surface for the rapid analysis of amino acids and lipids by Surface-Assisted Laser Desorption Ionization (SALDI). The method was optimized for detecting twenty amino acids, mainly present as cationized species, with the [M+K]+ response generally 2-time larger than the [M+Na]+ one. The [M+Na]+/[M+K]+ signals ratio was tentatively correlated with the molecular weight, dipole moment and binding affinity, to describe the amino acids’ coordination ability. The SWCNH-based surface was also tested for analyzing triglycerides in olive oil samples, showing promising results in determining the percentage composition of fatty acids without any sample treatment. Results indicated that SWCNH is a promising substrate for the SALDI-MS analysis of low molecular weight compounds with different polarities, enlarging the analytical platforms for MALDI applications. 相似文献
9.
Methoxybromo derivatives of unsaturated fatty acids including conjugated acids yield simple mass spectra and can be used to
locate the position of double bonds in these acids. The derivatives are prepared under mild conditions by bromination of the
unsaturated fatty acids in methanol. The method is illustrated with the methoxybromo derivatives from methyl esters of oleic,
petroselenic, erucic, undecenoic, linoleic, linolenic, the conjugated diene acids from dehydrated castor oil, α-eleostearic,
punicic and parinaric acids. Unlike other methods using methoxy derivatives, the methoxybromo derivatives yield fewer ions,
the diagnostic peaks forming the most intense ions of the spectra. While unambiguous double bond location is possible with
monoenoic acids and conjugated fatty acids, only the end carbon atoms of the unsaturation system in nonconjugated polyenoic
acids is located. But the characteristic appearance of fragments corresponding to [CH3(CH2)nCH(OMe)CH(Br)CH2−2H]+ and fragments 24 mass units higher than those which locate the end carbons in such fatty acids indicate a methylene-interrupted
system of double bonds. 相似文献
10.
Madeira laurel oil was fractionated by liquid extraction combined with TLC, and TAGs were analyzed by HPLC coupled with atmospheric
pressure chemical ionization-MS (APCI-MS). Eluted molecular species compositions of the eluted TAG in the complex natural
mixture were determined by GC identification of FAME and byLC-atmospheric pressure chemical ionization (APCI)-MS analysis
of the lipid. The APCI-MS spectra of most TAG exhibited [M+H]+ and [M−RCOO]+ ions, which defined the M.W. and the molecular association of fatty acyl residues, respectively. Despite the relatively high
degree of saturation, with a saturated/unsaturated ratio of 0.70, no totally saturated TAG nor mixed asymmetric TAG with two
saturated FA (SSM or SSU, where S is saturated, M is monounsaturated, and U is unsaturated) were found. This type of molecular
structure provides a possible explanation for the relatively low m.p. (12–15°C) and also the high oxidative resistance observed. 相似文献
11.
Ten diacylglycerols (DAG) and 74 triacylglycerols (TAG) in the seed oil of Physaria fendleri were recently identified by high‐performance liquid chromatography (HPLC) and mass spectrometry (MS). These acylglycerols (AG) were quantified by HPLC with evaporative light scattering detector and electrospray ionization mass spectrometry of the lithium adducts of the AG in the HPLC fractions of lesquerella oil. The MS1 ion signal intensities of molecular ions [M + Li]+ in HPLC fractions of an HPLC peak were used to estimate the ratios of AG in the HPLC peak. The ratios of TAG with the same mass in HPLC fractions were estimated by the ratios of the sums of MS2 ion signal intensities from the neutral loss of the three fatty acids [M + Li ? FA]+. The ratio of DAG with the same mass were estimated by the ratio of the sums of two MS2 ion signal intensities [M + Li ? FA]+ and [FA + Li]+ from the two different FA of a DAG. We have estimated the contents of ten molecular species of DAG and 74 molecular species of TAG in P. fendleri oil using this new method. The content of ten DAG combined was about 1 % and 74 TAG was about 98 %. The contents of DAG in decreasing order were: LsLs (0.25 %), LsLn (0.25 %), LsO (0.24 %), and LsL (0.11 %); and the contents of TAG in decreasing order were: LsLsO (31.3 %), LsLsLn (24.9 %), LsLsL (15.8 %), LsL‐OH20:2 (4.3 %), LsO‐OH20:2 (2.8 %), and LsLn‐OH20:2 (2.5 %). 相似文献
12.
The bottom-up solution to the triacylglycerol lipidome using atmospheric pressure chemical ionization mass spectrometry 总被引:1,自引:0,他引:1
Byrdwell WC 《Lipids》2005,40(4):383-417
Presented here is an approach to representing the data from atmospheric pressure chemical ionization (APCI) mass spectrometry
(MS) of triacylglycerols (TAG) using a set of one, two, or three Critical Ratios. These Critical Rations may be used directly
to provide structural information concerning the regioisomeric composition of the triacylglycerols (TAG), and about the degree
of unsaturation in the TAG. An AAA-type, or Typel, TAG has only one Critical Ratio, the ratio of the protonated molecule,
[M+H]+, to the DAG fragment ion, [AA]+. The Critical Ratio for a Type I TAG is [MH]+/Σ[DAG]+, and the mass spectrum of a Type I TAG can be reproduced from only this one ratio. An ABA/AAB/BAA, or Type II, TAG has two
Critical Ratios, the [MH]+/Σ[DAG]+ ratio and the [AA]+/[AB]+ ratio. The [AA]+/[AB]+ ratio for a single TAG or TAG mixture can be compared with the [AA]+/[AB]+ ratios of pure regioisomeric standards, and the percentage of each regioisomer can be estimated. The abundance of the protonated
molecule and the abundances of the two [DAG]+ fragment ions can be calculated from the two Critical Ratios for a Type II TAG. To calculate the abundances, the Critical
Ratios are processed through the Bottom-Up Solution to the TAG lipidome. First, Critical Limits are calculated from the Critical
Ratios, and then the Critical Ratios are classified into Cases by comparison with the Critical Limits. Once the Case classification
is known, the equation for the abundance of each ion in the mass spectrum is given by the Bottom-Up Solution. A Type III TAG
has three different FA and three Critical Ratios. The [MH]+/Σ/[DAG]+ ratio is the first Critical Ratio, the [AC]+/([AB]++[BC]+) ratio is the second Critical Ratio, and the [BC]+/[AB]+ ratio is the third Critical Ratio. The second critical ratio for a Type III TAG can be compared with regioisomeric standards
to provide an estimate of the percentage composition of the regioisomers. The three Critical Ratios for a Type III TAG can
be processed through the Bottom-Up Solution to calculate the four ion abundances that make up the APCI-MS mass spectrum. The
Critical Ratios constitute a reduced data set that provides more information in fewer values than the raw abundances. 相似文献
13.
Faouzi Sakouhi Christelle Absalon Habib Kallel Sadok Boukhchina 《European Journal of Lipid Science and Technology》2010,112(5):574-579
MALDI‐TOFMS and HPLC are two analytical methods that were used to characterize triacylglycerols (TAG) of the Meski, Sayali, and Picholine Tunisian olive varieties. The HPLC chromatograms of the oils showed the presence of 15 TAG species, among which triolein (OOO) was the most abundant (21–48%). In the Sayali cultivar, OOO was the predominant TAG species followed by POO and LOO. However, the minor TAG molecules were represented by LnLO and LnLP. MALDI mass spectra produced sodiated ([M + Na]+) and potassiated ([M + K]+) TAG molecules; only the major TAG were potassiated [OOO + K] ([OOO + K]+, [POO + K]+, and [LOO + K]+). In contrast to the HPLC chromatograms, the MALDI mass spectra showed 13 peaks of TAG. The major peak was detected at m/z 907, which corresponds to OOO with an Na+ adduct. The results from both HPLC and MALDI techniques predict the fatty acid composition and their percentages for each olive variety. Practical applications: TAG are the main components in vegetable oils. These biomolecules determine the physical, chemical, and nutritional properties of the oils. The nutritional benefits of TAG are related to DAG (moderate plasma lipid level) and esterified FA, which are intermediate biosynthetic molecules of TAG. TAG analysis is necessary to discriminate between oils of different origin, since some oils have similar FA profiles. Olive products, oils, and table olives, are the main diet sources of TAG in the Mediterranean countries. In this work, chromatographic and spectrometric methods were used for TAG analysis and characterization of Tunisian olive varieties. 相似文献
14.
The Updated Bottom Up Solution Applied to Atmospheric Pressure Photoionization and Electrospray Ionization Mass Spectrometry
下载免费PDF全文
![点击此处可从《Journal of the American Oil Chemists](/ch/ext_images/free.gif)
William Craig Byrdwell 《Journal of the American Oil Chemists' Society》2015,92(11-12):1533-1547
The Updated Bottom Up Solution (UBUS) was recently applied to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) of triacylglycerols (TAG). This report demonstrates that the UBUS applies equally well to atmospheric pressure photoionization (APPI) MS and to electrospray ionization (ESI) MS. Critical Ratio 1 (CR1), the [MH]+/Σ[DAG]+ or [MNH4]+/Σ[DAG]+ ratio, does not exhibit the same strongly sigmoidal shape as it does by APCI‐MS. CR1 varies more widely for APPI‐MS than by APCI‐MS, having a maximum value of 11.8, indicating a much greater effect of unsaturation on ion ratios in APPI‐MS than APCI‐MS. Critical Ratio 2, the [AA]+/[AB]+ ratio for Type II TAG or [AC]+/([AB]++[BC]+) ratio for Type III TAG, allows quantification of regioisomers of TAG, and shows good agreement for APPI‐MS to regioisomer quantification determined by APCI‐MS. Critical Ratio 3, the [BC]+/[AB]+ ratio for Type III TAG, reveals new trends relating the degree of unsaturation by APPI‐MS, and shows that structural assignments made by ESI‐MS are in good agreement to APCI‐MS data. In addition to providing valuable structural information, the Critical Ratios also constitute a reduced data set that allows APPI‐MS or ESI‐MS mass spectra to be reconstructed when processed through the UBUS. Quantification by APPI‐MS of vitamin D in the gelcaps gave values of 42.90 ± 0.83 μg, or 1716 ± 33 international units, in good agreement with APCI‐MS. 相似文献
15.
Mikołaj A. Pyziak Łukasz Popenda Stefan Jurga Grzegorz Schroeder 《Designed Monomers and Polymers》2017,20(1):144-156
Organic compounds designed to serve as stable dendrimer cores were developed. A series of aminosugar and amino polyol containing G0 dendrimers were synthesized. The reaction mixture composition was checked by MALDI TOF mass spectrometry, while that of purified products – by 1H and 13C NMR combined with 2D NMR spectroscopy as well as MALDI TOF MSMS mass spectra. Mass spectrometric fragmentation experiments were performed in positive ion mode in order to determine common fragmentation patterns of [M+H]+ ions. 相似文献
16.
In this study, Chinese gallotannins were characterized by MALDI‐TOF MS, and effects of cationization reagents on the quality of spectra were investigated. The trideca‐ and tetradeca‐galloyl glucoses were observed in Chinese gallotannins, which could not be detected in earlier studies. When Cs+ was used as the cationization reagent, Chinese gallotannins gave a relatively simple MALDI‐TOF spectrum, three series of quasimolecular ions [M + Cs]+, [M + 2Cs–H]+, and [M + 3Cs–2H]+ and a series of metastable ion peaks with minimum abundance were detected. Selection of Na+ as the cationization reagent, additional three series of ion peaks including two patterns from the fragmentation and complex 2M adducts [2M + Na]+ can be distinguished. In the case of no deionization or addition of cationization reagent to the analyte/matrix, naturally abundant Na+ and K+ as the cationization reagent, [M + Na]+ and [M + K]+ molecular ions both appeared in the complicated spectrum. Therefore, we conclude that cationization reagents affect the MALDI‐TOF MS spectrum of Chinese gallotannins significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
17.
Synthetic mixtures of C40 to C47 sterol esters in groups of 7 esters were effectively separated and analyzed by capillary gas chromatography-mass spectrometry.
Ammonia chemical ionization of all 20 sterol esters analyzed at a source block temperature of 120 C yielded (M+NH4)+ and (M+H-RCO2H)+ ions of high abundance or as base peak, thereby indirectly indicating the molecular weights of the ester and the sterol and
acid moieties. Ammonia CI spectra of all esters containing a Δ5-sterol moiety exhibited in addition to the above 2 ions an M+NH4-RCO2 H fragment. At a source block temperature of 150 C, M+H-RCO2 H fragment was the base peak for all esters, and there was little or no indication of an (M+NH4)+ adduct ion. Protonated molecules were not observed for any esters analyzed by methane or isobutane CI. Molecular ions of
3–14% intensity were obtained for only 3 of the esters analyzed by electron impact; they contained a Δ7-bond in the sterol nucleus, and the acid moiety was either saturated normal or branched chain or contained a single double
bond. The base peak was a function of both the acid and sterol moieties of the sterol ester. The esters containing both saturated
straight chain acid and saturated sterol moieties exhibited a base peak at m/z 215. The Δ5-sterol esters with saturated branched or straight chain acid moieties exhibited base peaks at M-RCO2 H. Other ions also were of diagnostic value. 相似文献
18.
The structures of two unusual fatty acids, the knownrans-3-hexadecenoic acid and a noveltrans-3-tetradecenoic acid, both isolated from the Nova Scotian sea-weedsPalmaria palmata andChondrus crispus, were positively identified. After the extraction of the total fatty acids by saponification, followed by methylation, the
monoenoictrans fractions were isolated by thin-layer chromatography on silica gel impregnated with silver nitrate. The monoenoictrans fractions were derivatized with 2-amino-2-methyl-propanol prior to analysis by gas chromatography/mass spectrometry. The
mass spectra showed prominent [M+1]+ ions but lacked the 12 amu interval useful for identifying the double bond position. Hence, alternative diagnostic peaks
were used to confirm the position of the double bond in these two fatty acids. As thetrans-3-hexadecenoic acid is found in the photosynthetic tissue of all plants, it may also be present in ruminant fats and, presumably,
in human adipose tissue. 相似文献
19.
The suppression of plasma very low density lipoprotein (VLDL) triglyceride levels by dietary fish oils rich in polyunsaturated
n−3 fatty acids has been attributed to decreased hepatic VLDL secretion. To investigate the effect of n−3 fatty acids on lipid
metabolism and VLDL secretion in a tissue culture system, we incubated rabbit hepatocytes with oleic acid and eicosapentaenoic
acid (EPA) and examined [3H]glycerol and [14C]fatty acid incorporation into hepatocyte triglyceride and phospholipid and into media VLDL. Glycerol incorporation studies
showed that EPA failed to stimulate VLDL triglyceride secretion from hepatocytes as occurred with oleic acid (P<0.05). Oleic
acid preferentially enhanced hepatocyte triglyceride synthesis while EPA stimulated significantly phospholipid synthesis (P<0.01).
Varying the relative concentrations of oleic acid and EPA at a constant total fatty acid concentration corroborated preferential
triglyceride synthesis from oleic acid. Synthesis shifted predominantly to phospholipids with increasing concentrations of
EPA and lower levels of oleic acid. Incorporation of the [14C]fatty acids (800 μM) followed similar patterns: 87% of [14C]oleic acid was incorporated into hepatocyte triglyceride and 44% of [14C]EPA was assimilated in hepatocyte phospholipid (p<0.001). Fatty acids at trace concentrations (53 nM) showed a more divergent
pattern of lipid incorporation: 60% of [14C]oleic acid was incorporated into triglyceride while 91% of [14CEPA was incorporated into phospholipid (p<0.001). We conclude that in primary rabbit hepatocyte culture, which appears to
be a useful model to study lipid metabolism and VLDL secretion, EPA is avidly incorporated into phospholipid while oleic acid
predominantly becomes esterified in triglyceride. In addition, EPA, unlike oleic acid, fails to stimulate hepatocyte VLDL
secretion. These divergent effects on hepatocyte lipid metabolism are, at least in part, likely to be responsible for fish
oil induced suppression of plasma triglycerides. 相似文献
20.
A simple, fast and reproducible reversed‐phase high performance liquid chromatography (HPLC) method coupled to electrospray ionization mass spectrometry (ESI‐MS) for the analysis of triacylglycerols (TAGs) species in the commercial edible oils has been developed. The TAGs species were separated using isocratic 18% isopropanol in methanol and a Phenomenex C18 column. The ESI‐MS conditions were optimized using flow injection analysis of standard TAG. Fifteen, fourteen, and sixteen TAGs were separated and identified in corn oil, rapeseed oil, and sunflower oil, respectively. The presence of intense protonated molecular (M + H+), ammonium (M + ${\rm NH}_{4}^{ + } $ ), and sodium (M + Na+) adducts ions and their respective diacylglycerols ions in the ESI‐MS spectra showed correct identification of TAGs. Some minor potassium adducts (M + K+) were also found. In addition, the identity of the fatty acid, position of each fatty acid, and the location of the double bond in the fatty acid moiety were explained. It was found that this isocratic method is useful for fast screening and identification of triacylglycerols in lipids. 相似文献