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1.
Milkfat is a complex mixture of many diverse FA, some of which have demonstrated health benefits including anticancer properties.
Attempts are under way to enrich milkfats with long-chain n−3 PUFA and CLA. It has been recommended that the analysis of these
milkfats requires gas chromatography (GC) equipped with long, highly polar capillary columns. However, many analyses have
been reported using CARBOWAXTM type (polyethylene glycol) capillary columns, such as SUPELCOWAX 10, even though the separation characteristics of many of
the FA and their isomers present in milkfats have not been described in detail. This includes the isomers of CLA, cis- and trans-octadecenoic acid (18∶1), linoleic acid (18∶2n−6), and linolenic acid (18∶3n−3), and the long-chain PUFA. On the other hand,
the resolution of these FA and their isomers has been more fully described using the highly polar capillary columns, such
as CP Sil 88 and SP2560 because of the improved resolution obtained using these polar columns. The present study was undertaken
to characterize the separation of these FA present in milkfats using a 60-m SUPELCOWAX 10 column, to compare the results to
those from a 100-m CP Sil 88 column, and to determine if these two columns could possibly serve to complement each other for
the analysis of total milkfat. The advantages of the SUPELCOWAX 10 column were a better resolution of the short-chain saturated
from their monounsaturated FA (MUFA) analogs, and a complete separation of the α-linolenic (18∶3n−3) and eicosadecenoic acid
(20∶1) isomers. It also provided an alternative elution order of the linoleic (18∶2n−6), 18∶3n−3 and γ-linolenic (18∶3n−6)
acid isomers. On the other hand, the CP Sil 88 column provided a better resolution of the CLA isomers, MUFA, the isolated
cis and trans MUFA fractions, the PUFA, and many the 18∶2n−6 and 18∶3n−3 isomers. A complete analysis of milk lipids using the CP Sil 88
column required the prior separation of total FAME using silver ion-TLC. The results of the present study confirm that the
100-m highly polar capillary GC columns are mandatory for the analysis of milk lipids, and at best, the 60 m SUPELCOWAX 10
capillary column serves as a complementary GC column to provide different separations in certain regions based on its intermediate
polarity. 相似文献
2.
A. Grandgirard J. M. Bourre F. Julliard P. Homayoun O. Dumont M. Piciotti J. L. Sebedio 《Lipids》1994,29(4):251-258
During heat treatment, polyunsaturated fatty acids and specifically 18∶3n−3 can undergo geometrical isomerization. In rat
tissues, 18∶3 Δ9c, 12c, 15t, one of thetrans isomers of linolenic acid, can be desaturated and elongated to givetrans isomers of eicosapentaenoic and docosahexaenoic acids. The present study was undertaken to determine whether such compounds
are incorporated into brain structures that are rich in n−3 long-chain polyunsaturated fatty acids. Two fractions enriched
intrans isomers of α-linolenic acid were prepared and fed to female adult rats during gestation and lactation. The pups were killed
at weaning. Synaptosomes, brain microvessees and retina were shown to contain the highest levels (about 0.5% of total fatty
acids) of thetrans isomer of docosahexaenoic acid (22∶6 Δ4c, 7c, 10c, 13c, 16c, 19t). This compound was also observed in myelin and sciatic nerve, but to a lesser extent (0.1% of total fatty acids). However,
the ratios of 22∶6trans to 22∶6cis were similar in all the tissues studied. When the diet was deficient in α-linolenic acid, the incorporation oftrans isomers was apparently doubled. However, comparison of the ratios oftrans 18∶3n−3 tocis 18∶3n−3 in the diet revealed that thecis n−3 fatty acids were more easily desaturated and elongated to 22∶6n−3 than the correspondingtrans n−3 fatty acids. An increase in 22∶5n−6 was thus observed, as has previously been described in n−3 fatty acid deficiency.
These results encourage further studies to determine whether or not incorporations of suchtrans isomers into tissues may have physiological implications.
Presented in part at the 32nd International Conference on the Biochemistry of Lipids, 1991, Granada, Spain.
Delta nomenclature (Δ) is used fortrans polyunsaturated fatty acids to specify the position and geometry of ethylenic bonds. Polyunsaturated fatty acids containingtrans double bonds are abbreviated giving the locations of thetrans double bonds only; e.g., 20∶5 Δ17t 20∶5 Δ5c,8c,11c,14c,17t; 22∶5 Δ19t, 22∶5 Δ7c,10c,13c,16c,19t; 22∶6 Δ19t 22∶6 Δ4c,7c,10c,13c,16c,19t. 相似文献
3.
Jean-Michel Chardigny Jean-Paul Blond Lionel Bretillon Estelle Mager Didier Poullain Lucy Martine Jean-Michel Vatèle Jean-Pierre Noël Jean-Louis Sébédio 《Lipids》1997,32(7):731-735
Several years ago, it was established that the Δ15 trans isomer of α-linolenic acid is converted in vivo into fatty acids containing 20 and 22 carbons (geometrical isomers of eicosapentaenoic and docosahexaenoic acids). The present
study focused on the in vitro Δ6 desaturation, the first step of the biosynthesis of the n-3 long-chain polyunsaturated fatty acids from 18:3n-3. For that
purpose, rat liver microsomes were prepared and incubated with radiolabeled 18∶3 Δ9cis, 12cis, 15cis (18∶3 c,c,c) or 18∶3 Δ9cis, 12cis, 15trans (18∶3c,c,t) under desaturation conditions. The data show that 18∶3c,c,t is converted at a lower rate compared with α-linolenic acid. The product of conversion of 18∶3 c,c,t may be 18∶4 Δ6cis, 9cis, 12cis, 15trans resulting from a Δ6 desaturation of the trans substrate. Moreover, the conversion of radiolabeled 18∶3c,c,t was strongly decreased by the presence of 18∶3c,c,c (up to 48%) while the 18∶3c,c,t only slightly decreased the conversion of radiolabeled 18∶3c,c,c. Thus, the desaturation enzyme presented a higher affinity for the native all-cis n-3 substrate. 相似文献
4.
Jean-Michel Chardigny Jean-Louis Sébédio André Grandgirard Lucy Martine Olivier Berdeaux Jean-Michel Vatèle 《Lipids》1996,31(2):165-168
Trans polyunsaturated n−3 fatty acids are formed as a result of the heat treatment of vegetable oils. It was demonstrated previously
that the 18∶3 Δ9cis, 12cis, 15trans containing acis Δ9 ethylenic bond was converted to a geometrical isomer of 20∶5n−3, the 20∶5 Δ5cis, 8cis, 11cis, 14cis, 17trans. In the present study, we have identified two new isomers of eicosapentaenoic acid, the Δ11 monotrans and the Δ11, 17 ditrans isomers in liver of rats fed a heated oil. These are formed as a result of the conversion of two of the main isomers of linolenic
acid which are present in refined and frying oils, the 18∶3 Δ9trans, 12cis, 15cis and the 18∶3 Δ9trans, 12cis, 15trans. 相似文献
5.
The fate of labeled linoleic, α-linolenic, and higher homologs of α-linolenic acid administered to the yellow clam,Mesodesma mactroides, was investigated. It was found that the clam incorporated the acids dissolved in sea water and converted 18∶2 (n−6) into
20∶2 (n−6) and 18∶3 (n−3) into 18∶4 (n−3) and 20∶3 (n−3). The addition of casein hydrolysate to the sea water increased the
desaturation capacity of the clam and allowed the conversion of 18∶2 (n−6) into 18∶3 (n−6) to be demonstrated. An enhanced
desaturation of 18∶3 (n−3) into 18∶4 (n−3) was also demonstrated. After 12 hr administration of the acid, no radioactivity
was found in arachidonic, 20∶5 (n−3), or 22∶6 (n−3). Feeding the clams a culture ofPhaeodactylum tricornutum previously incubated with 1-14C-α-linolenic acid demonstrated that all the homologs of the α-linolenic series were found in the clam without any important
changes. Six hour administration of labeled linolenic acid resulted in the incorporation of the acid into diglycerides and
phospholipids.
Member of the carrera del Investigador Cientifico of the Consejo Nacional de Investigaciones Cientificas y Tecnicas 相似文献
6.
Conjugated linoleic acid (CLA) is a collective term that describes different isomers of linoleic acid with conjugated double
bonds. Although the main dietary isomer is 9cis,11trans-18∶2, which is present in dairy products and ruminant fat, the biological effects of CLA generally have been studied using
mixtures in which the 9cis,11trans- and the 10trans,12cis-18∶2 were present at similar levels. In the present work, we have studied the impact of each isomer (9cis,11trans- and 10trans,12cis-18∶2) given separately in the diet of rats for 6 wk. The 10trans,12cis-18∶2 decreased the triacylglycerol content of the liver (−32%) and increased the 18∶0 content at the expense of 18∶1n−9,
suggesting an alteration of the Δ9 desaturase activity, as was already demonstrated in vitro. This was not observed when the 9cis,11trans-18∶2 was given in the diet. Moreover, the 10trans,12cis-18∶2 induced an increase in the C22 polyunsaturated fatty acids in the liver lipids. The 10trans,12cis-18∶2 was mainly metabolized into conjugated 16∶2 and 18∶3, which have been identified. The 9cis,11trans isomer was preferentially metabolized into a conjugated 20∶3 isomer. Thus, the 9cis,11trans- and the 10trans,12cis-CLA isomers are metabolized differently and have distinct effects on the metabolism of polyunsaturated fatty acids in rat
liver while altering liver triglyceride levels differentially. 相似文献
7.
The effect of very low levels of dietary long-chain n−3 fatty acids on Δ6 desaturation of linoleic acid (18∶2n−6) and α-linolenic
acid (18∶3n−3), and on Δ5 desaturation of dihomo-γ-linolenic acid (20∶3n−6), in liver microsomes and its influence on tissue
fatty acids were examined in obese and lean Zucker rats and in Wistar rats. Animals fed for 12 wk a balanced diet containing
ca. 200 mg of long-chain polyunsaturated n−3 fatty acids per 100 g of diet were compared to those fed the same amount of α-linoleic
acid. Low amounts of long-chain n−3 fatty acids greatly inhibited Δ6 desaturation of 18∶2n−6 and Δ5 desaturation of 20∶3n−6,
while Δ6 desaturation of 18∶3n−3 was not inhibited in Zucker rats and was even stimulated in Wistar rats. Inhibition of the
biosynthesis of long-chain n−6 fatty acids was reflected in a decrease in arachidonic acid (20∶4n−6) content of serum lipids
when fasting, and also in the phospholipid fatty acids of liver microsomes. On the contrary, heart and kidney phospholipids
did not develop any decrease in 20∶4n−6 during fish oil ingestion. Docosahexaenoic acid (22∶6n−3), present in the dietary
fish oil, was increased in serum lipids and in liver microsome, heart, and kidney phospholipids. 相似文献
8.
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
9.
A new conjugated linoleic acid isomer, 7 trans, 9 cis-octadecadienoic acid, in cow milk, cheese, beef and human milk and adipose tissue 总被引:1,自引:0,他引:1
Martin P. Yurawecz John A. G. Roach Najibullah Sehat Magdi M. Mossoba John K. G. Kramer Jan Fritsche Hans Steinhart Youh Ku 《Lipids》1998,33(8):803-809
The identity of a previously unrecognized conjugated linoleic acid (CLA) isomer, 7 trans, 9 cis-octadecadienoic acid (18∶2) was confirmed in milk, cheese, beef, human milk, and human adipose tissue. The 7 trans, 9 cis-18∶2 isomer was resolved chromatographically as the methyl ester by silver ion-high-performance liquid chromatography (Ag+-HPLC); it eluted after the major 9 cis, 11 trans-18∶2 isomer (rumenic acid) in the natural products analyzed. In the biological matrices in-vestigated by Ag+-HPLC, the 7 trans, 9 cis-18∶2 peak was generally due to the most abundant minor CLA isomer, ranging in concentration from 3 to 16% of total CLA. By
gas chromatography (GC) with long polar capillary columns, the methyl ester of 7 trans, 9 cis-18∶2 was shown to elute near the leading edge of the major 9 cis, 11 trans-18∶2 peak, while the 4,4-dimethyloxazoline (DMOX) derivative permitted partial resolution of these two CLA isomers. The DMOX
derivative of this new CLA isomer was analyzed by gas chromatography-electron ionization mass spectrometry (GC-EIMS). The
double bond positions were at Δ7 and Δ9 as indicated by the characteristic mass spectral fragment ions at m/z 168, 180, 194, and 206, and their allylic cleavages at m/z 154 and 234. The cis/trans double-bond configuration was established by GC-direct deposition-Fourier transform infrared as evidenced from the doublet
at 988 and 949 cm−1 and absorptions at 3020 and 3002 cm−1. The 7 trans, 9 cis-18∶2 configuration was established by GC-EIMS for the DMOX derivative of the natural products examined, and by comparison
to a similar product obtained from treatment of a mixture of methyl 8-hydroxy-and 11-hydroxyoctadec-9 cis enoates with BF3, in methanol.
Contribution number S010 from the Food Research Center, Guelph, Ontario, Canada. 相似文献
10.
Sergiel JP Chardigny JM Sébédio JL Berdeaux O Juaneda P Loreau O Pasquis B Noel JP 《Lipids》2001,36(12):1327-1329
To assess the oxidative metabolism of conjugated linoleic acid (CLA) isomers, rats were force-fed 1.5–2.6 MBq of [1-14C]-linoleic acid (9c,12c-18∶2),-rumenic acid (9c,11t-18∶2), or-10trans, 12cis-18∶2 (10t, 12c-18∶2), and 14CO2 production was monitored for 24 h. The animals were then necropsied and the radioactivity determined in different tissues.
Both CLA isomers were oxidized significantly more than linoleic acid. Moreover, less radioactivity was recovered in most tissues
after CLA intake than after linoleic acid intake. The substantial oxidation of CLA isomers must be considered when assessing
the putative health benefits of CLA supplements. 相似文献
11.
Preparation, separation, and confirmation of the eight geometrical cis/trans conjugated linoleic acid isomers 8,10-through 11,13–18∶2 总被引:1,自引:0,他引:1
Klaus Eulitz Martin P. Yurawecz Najibullah Sehat Jan Fritsche John A. G. Roach Magdi M. Mossoba John K. G. Kramer Richard O. Adlof Yuoh Ku 《Lipids》1999,34(8):873-877
Conjugated linoleic acid (CLA) mixtures were isomerized with p-toluenesulfinic acid or I2 catalyst. The resultant mixtures of the eight cis/trans geometric isomers of 8,10-, 9,11-, 10,12-, and 11,13-octadecadienoic (18∶2) acid methyl esters were separated by silver ion-high-performance
liquid chromatography (Ag+-HPLC) and gas chromatography (GC). Ag+-HPLC allowed the separation of all positional CLA isomers and geometric cis/trans CLA isomers except 10,12–18∶2. However, one of the 8,10 isomers (8cis, 10trans-18∶2) coeluted with the 9trans,11cis18∶2 isomer. There were differences in the elution order of the pairs of geometric CLA isomers resolved by Ag+-HPLC. For the 8,10 and 9,11 CLA isomers, cis,trans eluted before trans,cis, whereas the opposite elution pattern was observed for the 11,13–18∶2 geometric isomers (trans,cis before cis,trans). All eight cis/trans CLA isomers were separated by GC on long polar capillary columns only when their relative concentrations were about equal.
Large differences in the relative concentration of the CLA isomers found in natural products obscured the resolution and identification
of a number of minor CLA isomers. In such cases, GC-mass spectrometry of the dimethyloxazoline derivatives was used to identify
and confirm coeluting CLA isomers. For the same positional isomer, the cis,trans consistently eluted before the trans,cis CLA isomers by GC. High resolution mass spectrometry (MS) selected ion recording (SIR) of the molecular ions of the 18∶1
18∶2, and 18∶3 fatty acid methyl esters served as an independent and highly sensitive method to confirm CLA methyl ester peak
assignments in GC chromatograms obtained from food samples by flame-ionization detection. The high-resolution MS data were
used to correct for the nonselectivity of the flame-ionization detector. 相似文献
12.
Octadecapentaenoic acid (all-cis δ3,6,9,12,15–18∶5; 18∶5n−3) is an unusual fatty acid found in marine dinophytes, haptophytes, and prasinophytes. It is not
present at higher trophic levels in the marine food web, but its metabolism by animals ingesting algae is unknown. Here we
studied the metabolism of 18∶5n−3 in cell lines derived from turbot (Scophthalmus maximus), gilthead sea bream (Sparus aurata), and Atlantic salmon (Salmo salar). Cells were incubated in the presence of approximately 1 μM [U-14C] 18∶5n−3 methyl ester or [U-14C]18∶4n−3 (octadecatetraenoic acid; all-cis δ6,9,12,15–18∶4) methyl ester, both derived from the alga Isochrysis galbana grown in H14CO3
−, and also with 25 μM unlabeled 18∶5n−3 or 18∶4n−3. Cells were also incubated with 25 μM trans δ2, all-cis δ6,9,12,15–18∶5 (2-trans 18∶5n−3) produced by alkaline isomerization of 18∶5n−3 chemically synthesized from docosahexaenoic acid (all-cis δ4,7,10,13,16,19–22∶6). Radioisotope and mass analyses of total fatty acids extracted from cells incubated with 18∶5n−3 were
consistent with this fatty acid being rapidly metabolized to 18∶4n−3 which was then elongated and further desaturated to eicosatetraenoic
acid (all-cis δ8,11,14,17,19–20∶4) and eicosapentaenoic acid (all-cis δ5,8,11,14,17–20∶5). Similar mass increases of 18∶4n−3 and its elongation and further desaturation products occurred in cells
incubated with 18∶5n−3 or 2-trans 18∶5n−3. We conclude that 18∶5n−3 is readily converted biochemically to 18∶4n−3 via a 2-trans 18∶5n−3 intermediate generated by a Δ3, Δ2-enoyl-CoA-iso-merase acting on 18∶5n−3. Thus, 2-trans 18∶5n−3 is implicated as a common intermediate in the β-oxidation of both 18∶5n−3 and 18∶4n−3. 相似文献
13.
The effects of dietary cis and trans α-linolenic acid (18∶3n−3) on the FA composition of plasma, red blood cell, and liver phospholipids were studied in newborn
piglets. Animals were fed for 14 d with one of three diets: a control diet (group A) containing cis 18∶3n−3 at a level of 2.0% of total FA, a diet (group B) in which a part of the 18∶3n−3 acid was isomerized (1.3% of cis 18∶3n−3 and 0.7% of trans 18∶3n−3), or a diet (group C) with 2.0% cis 18∶3n−3 and 0.7% trans 18∶3n−3. Feeding animals with diets containing trans 18∶3n−3 resulted in the presence of trans isomers of 18∶3n−3, trans isomers of EPA, and trans isomers of DHA in phospholipids; however, the level of total trans n−3 PUFA in tissues was less than 0.3% of total tissue FA. In group B, the reduction of dietary amounts of cis 18∶3n−3 was associated with a decrease in individual and total cis n−3 PUFA. In contrast, in group C there was no decrease in tissue n−3 PUFA despite the increased dietary level of trans 18∶3n−3. These results suggest that the isomerization of a part of dietary n−3 PUFA, leading to the reduction of their levels
in the diet, could induce a decrease in n−3 PUFA in phospholipids. The physiological effects of trans PUFA are not known and should be considered in future studies. 相似文献
14.
The previous studies showed that dietary 18∶2 c,t isomers could be chain-elongated and desaturated to produce unusual 20∶4 isomers. The present study was undertaken to determine
the minimal amount of 18∶2n−6 required to suppress the chain elongation and desaturation of 18∶2 c,t isomers in the lactating and neonatal rats when animals were fed 15% partially hydrogenated canola oil diet containing 1.72%
energy as 18∶2 c,t isomers and varying amounts of free 18∶2n−6. These diets induced marginal essential fatty acid (EFA) deficiency states (0.56%
energy 18∶2n−6) to EFA adequacy (2.56% energy 18∶2n−6). After feeding for 50 d, the female animals were mated with males by
overnight pairing. After conception, the lactating rats were killed, together with one pup from each dam, at term and day
26 of lactation. Two unusual 20∶4 isomers in both maternal and neonatal liver phospholipids were identified as 20∶4Δ5c,8c,11c,14t and 20∶4Δ5c,8c,11c,15t, which were derived from 18∶2Δ9c,12t, and 18∶2Δ9c,13t, respectively. The results showed that 18∶2n−6 at about 2.0% of total energy in maternal diet was required to block the production
of 20∶4Δ5c,8c,11c,14t and 20∶4Δ5c,8c,11c,15t in the maternal liver, whereas 18∶2n−6 at about 2.5% of total energy in maternal diet was required to suppress production
of these unusual 20∶4 isomers in the neonatal liver. 相似文献
15.
Jim-Wen Liu Stephen DeMichele Marti Bergana Emil Bobik Jr. Christine Hastilow Lu-Te Chuang Pradip Mukerji Yung-Sheng Huang 《Journal of the American Oil Chemists' Society》2001,78(5):489-493
The seed oil from a genetically transformed canola (Brassica napus) containing 43% (w/w) of γ-linolenic acid (G, 18∶3n−6), 22% linoleic acid (L, 18∶2n−6), and 16% oleic acid (O, 18∶1n−9) was
evaluated. In this high γ-linolenic acid canola oil (HGCO), the predominant 18∶3n−6-containing triacylglycerol (TG) molecular
species were GGL (23%), GLO (20%), and GGG (11%). In the total TG, approximately 75% of the 18∶3n−6 was located at the sn-1,3 positions, while only 34% of linoleic acid was at the sn-1,3 positions. The GGL molecular species of HGCO contained approximately equal amounts of GLG and GGL positional isomers,
while the GLO molecular species had 95% GOL and 5% GLO isomers. The general characteristics and the tocopherol and phytosterol
contents were mostly similar between HGCO and nontransformed canola oil. No detectable amounts of amino acids and nucleotides
were observed in the HGCO. 相似文献
16.
Klaus Eder 《Lipids》1999,34(7):717-725
This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly
the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either
fresh oil or thermally treated oil (150°C, 6d). The dietary fats used were markedly different for lipid peroxidation products
(peroxide value: 94.5 vs. 3.1 meq O2/kg; thiobarbituric acid-reactive substances: 230 vs. 7 μmol/kg) but were equalized for their fatty acid composition by using
different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with dl-α-tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study
the effect of the oxidized oil on the desaturation of α-linolenic acid. During the whole period, all the rats were fed identical
quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil.
Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats
fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced
food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total
lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were
calculated. Rats fed the oxidized oil had reduced ratios of 20∶4n−6/18∶2n−6, 20∶5n−3/18∶3n−3, 20∶4n−6/20∶3n−6, and 22∶6n−3/22∶5n−3
in liver phospholipids and reduced ratios of 20∶4n−6/18∶2n−6, 22∶5n−3/18∶3n−3, and 22∶6n−3/18∶3n−3 in heart phospholipids.
Those results suggest a reduced rate of desaturation of linoleic acid and α-linolenic acid by microsomal Δ4-, Δ5-, and Δ6-desaturases.
Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty
acids and total saturated fatty acids, suggesting a reduced Δ9-desaturation. Besides those effects, the study observed a slightly
increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma,
and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized
oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance. 相似文献
17.
Robert L. Wolff 《Lipids》1995,30(10):893-898
When rats were fed elaidic (trans-9 18∶1) acid at a high load in diets that were otherwise marginally or almost completely deficient in linoleic (cis-9,cis-12 18∶2) acid, elaidic acid was desaturated tocis-5,trans-9 18∶2 acid. This polymethylene-interrupted acid was then incorporated into most phospholipids from rat mitochondria, cardiolipin
being an exception. Its level of esterification in phospholipids followed the increasing order: phosphatidylethanolamine <phosphatidylcholine
< phosphatidylinositol (PI). The content ofci-5,trans-9 18∶2 acid decreased in organs in the order liver > kidney > heart. The levels ofcis-5,trans-9 18∶2 acid increased in mitochondria phospholipids as the level of linoleic acid was lowered in the diet. In liver mitochondria
PI, it reached 16% of total fatty acids. After hydrolysis of liver mitochondria PI withNaja naja phospholipase A2, we observed that elaidic acid was essentially esterified to position 1 at the expense of saturated acids, whereascis-5,trans-9 18∶2 acid was exclusively esterified to position 2, along with 20∶3n−9 and 20∶4n−6 acids. As a consequence, the sums of
saturated andtrans-9 18∶1 acids on the one hand, and of 20∶3n−9, 20∶4n−6, andcis-5,trans-9 18⩺2 acids on the other hand, remained fairly constant in liver mitochondria PI (ca. 55 and 30%, respectively). Becausetrans-9 18∶1 andcis-5,trans-9 18∶2 acids differ only by thecis-5 ethylenic bond, which is also present in 20∶3n−9 and 20∶4n−6 acids, this distribution pattern indicates that thecis-5 double bond, rather than any other ethylenic bond, may be of major structural importance for channeling fatty acids to
position 2 of PI. 相似文献
18.
The inhibitory effects of the positional isomers oftrans-18∶1 acids on the desaturation of palmitic acid to palmitoleic (Δ9-desaturase), linoleic to γ-linolenic (Δ6-desaturase) and
eicosa-8,11,14-trienoic to arachidonic acid (Δ5-desaturase) were investigated. Thesetrans-18∶1 acids were found to be inhibitory for the microsomal Δ6-, Δ9- and Δ5-desaturases of rat liver. The position of the double
bond in thetrans-18∶1 acids seems to be important in determining the degree of inhibition. At inhibitor/substrate ratio of 3∶1, the Δ6-desaturase
was most strongly inhibited bytrans-Δ3,-Δ4,-Δ7 and-Δ15-18∶1 isomers, whereas the Δ9-desaturase was most strongly inhibited bytrans-Δ3,-Δ5,-Δ7,-Δ10,-Δ12,-Δ13 and-Δ16 isomers. At inhibitor/substrate ratio of 6∶1, the Δ5-desaturase was most strongly inhibited
by Δ3-, Δ9-, Δ13- and Δ15-isomers. When 18∶0 was added to the incubations of 16∶0, 18∶2 and 20∶3 at the same I/S ratios used
for thetrans-18∶1 acids, weak inhibition for Δ9-desaturase and no inhibition for Δ5-and Δ6-desaturases was observed. 相似文献
19.
John K. G. Kramer Najibullah Sehat Michael E. R. Dugan Magdi M. Mossoba Martin P. Yurawecz John A. G. Roach Klaus Eulitz Jennifer L. Aalhus Allan L. Schaefer Youh Ku 《Lipids》1998,33(6):549-558
Pigs were fed a commercial conjugated linoleic acid (CLA) mixture, prepared by alkali isomerization of sunflower oil, at 2%
of the basal diet, from 61.5 to 106 kg live weight, and were compared to pigs fed the same basal diet with 2% added sunflower
oil. The total lipids from liver, heart, inner back fat, and omental fat of pigs fed the CLA diet were analyzed for the incorporation
of CLA isomers into all the tissue lipid classes. A total of 10 lipid classes were isolated by three-directional thin-layer
chromatography and analyzed by gas chromatography (GC) on long capillary columns and by silver-ion high-performance liquid
chromatography (Ag+-HPLC); cholesterol was determined spectrophotometrically. Only trace amounts (<0.1%; by GC) of the 9,11–18∶2 cis/trans and trans, trans isomers were observed in pigs fed the control diet. Ten and twelve CLA isomers in the diet and in pig tissue lipids were
sepatated by GC and Ag+-HPLC, respectively. The relative concentration of all the CLA isomers in the different lipid classes ranged from 1 to 6%
of the total fatty acids. The four major cis/trans isomers (18.9% 11 cis, 13 trans-18∶2; 26.3% 10 trans, 12 cis-18∶2; 20.4% 9 cis, 11 trans-18∶2; and 16.1% 8 trans, 10 cis-18∶2) constituted 82% of the total CLA isomers in the dietary CLA mixture, and smaller amounts of the corresponding cis,cis (7.4%) and trans,trans (10.1%) isomers were present. The distribution of CLA isomers in inner back fat and in omental fat of the pigs was similar
to that found in the diet. The liver triacylglycerols (TAG), free fatty acids (FFA), and cholesteryl esters showed a similar
patterns to that found in the diet. The major liver phospholipids showed a marked increase of 9 cis,11 trans-18∶2, ranging from 36 to 54%, compared to that present in the diet. However, liver diphosphatidylglycerol (DPG) showed a
high incorporation of the 11 cis,13 trans-18∶2 isomer (43%). All heart lipid classes, except TAG, showed a high content of 11 cis,13 trans-18∶2, which was in marked contrast to results in the liver. The relative proportion of 11 cis,13 trans-18∶2 ranged from 30% in the FFA to 77% in DPG. The second major isomer in all heart lipids was 9 cis,11 trans-18∶2. In both liver and heart lipids the relative proportions of both 10 trans,12 cis-18∶2 and 8 trans,10 cis-18∶2 were significantly lower compared to that found in the diet. The FFA in liver and heart showed the highest content of
trans,trans isomers (31 to 36%) among all the lipid classes. The preferential accumulation of the 11 cis,13 trans-18∶2 into cardiac lipids, and in particular the major phospholipid in the inner mitochondrial membrane, DPG, in both heart
and liver, appears unique and may be of concern. The levels of 11 cis,13 trans-18∶2 naturally found in foods have not been established. 相似文献
20.
Akinori Ando Jun Ogawa Shigenobu Kishino Taiyo Ito Norifumi Shirasaka Eiji Sakuradani Kenzo Yokozeki Sakayu Shimizu 《Journal of the American Oil Chemists' Society》2009,86(3):227-233
The fatty acid desaturation and elongation reactions catalyzed by Trichoderma sp. 1-OH-2-3 were investigated. This strain converted palmitic acid (16:0) mainly to stearic acid (18:0), and further to
oleic acid (c9-18:1), linoleic acid (c9,c12-18:2), and α-linolenic acid (c9,c12,c15-18:3) through elongation, and Δ9, Δ12, and Δ15 desaturation reactions, respectively. Palmitoleic acid (c9-16:1) and cis-9,cis-12-hexadecadienoic acid were also produced from 16:0 by the strain. This strain converted n-tridecanoic acid (13:0) to cis-9-heptadecenoic acid and further to cis-9,cis-12-heptadecadienoic acid through elongation, and Δ9 and Δ12 desaturation reactions, respectively. trans-Vaccenic acid (t11-18:1) and trans-12-octadecenoic acid (t12-18:1) were desaturated by the strain through Δ9 desaturation. The products derived from t11-18:1 were identified as the conjugated linoleic acids (CLAs) of cis-9,trans-11-octadecadienoic acid and trans-9,trans-11-octadecadienoic acid. The product derived from t12-18:1 was identified as cis-9,trans-12-octadecadienoic acid. cis-6,cis-9-Octadecadienoic acid was desaturated to cis-6,cis-9,cis-12-octadecatrienoic acid by this strain through Δ12 desaturation. The broad substrate specificity of the elongation, and
Δ9 and Δ12 desaturation reactions of the strain is useful for fatty acid biotransformation. 相似文献