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1.
David W. L. Ma Catherine J. Field M. T. Clandinin 《Journal of the American Oil Chemists' Society》2002,79(8):755-758
CLA refers to a group of geometrical and positional isomers of linoleic acid. CLA has been shown to have potentially beneficial
effects on cancer, atherosclerosis, and body metabolism in animals. Mixtures containing equal amounts of these isomers are
commonly used in many research studies because of their greater availability and lower cost relative to pure isomers. This
has hindered progress in elucidating the biological properties of specific isomers and their relevance in animal and human
biology. A method was developed that offers a compromise between cost and utility to make available enriched mixtures of either
the Δ9c,11t- or Δ10t,12c-18:2 isomers for use in a wide range of experimental applications. A countercurrent approach was developed to separate the
Δ9c,11t- and Δ10t,12c-18:2 isomers from an equal mixture of these two isomers by urea complexation. After three successive rounds of complexation
using an equal amount of CLA and urea, a fraction enriched in Δ9c,11t-18:2 containing 42.5 and 17.4% of Δ9c,11t-and Δ10t,12c-18:2, respectively, was recovered. After a single round of complexation using 2.5 g urea/g CLA, a fraction enriched in Δ10t,12c-18:2 was recovered containing 29.7 and 69.1% of Δ9c,11t- and Δ10t,12c-18:2, respectively. 相似文献
2.
Preparation of conjugated linoleic acid from safflower oil 总被引:5,自引:0,他引:5
David W. L. Ma Antoni A. Wierzbicki Catherine J. Field Michael T. Clandinin 《Journal of the American Oil Chemists' Society》1999,76(6):729-730
Synthetically prepared mixtures of conjugated linoleic acid (CLA) are widely used in animal and cell culture studies to investigate
the potential effects of the Δ9c, 11t-18:2 isomer found in food products from ruminant animals. Alkali isomerization of linoleic acid is a common method used in
the synthesis of a mixture of CLA isomers containing predominantly the Δ9c, 11t-18:2 and Δ10t, 12c-18:2 isomers. Some biological activity might also be mediated by the Δ10t, 12c-18:2 isomer. Currently few published methodologies exist describing procedures for the enrichment of these two isomers. A
method is described herein to take advantage of an inexpensive oil, safflower oil, for use in synthesis of CLA and a procedure
to enrich the Δ10t, 12c-18:2 isomer. 相似文献
3.
Conjugated linoleic acid (CLA; 9c, 11t-18∶2) and CLA isomers have been reported, in animals, to exhibit a variety of health-related benefits. Silver ion high-performance
liquid chromatography (Ag-HPLC) was found to provide better resolution of the isomes than gas chromatography. Most commercially
available samples of CLA, prepared by base-catalyzed isomerization of linoleic acid (9c, 12c-18∶2), are conposed of mixtures of four major isomers. While these isomers have been characterized, we found significant
changes in CLA isomer ratios within samples obtained from the same producer/commercial supplier over a period of 1.5 yr. In
the first sample, the four cis/trans isomers (8t, 10c-18∶2, 9c, 11t-18∶2, 10t, 12c-18∶2 and 11c, 13t-18∶2) were present in a ratio of approximately 1∶2∶2∶1, while in the second sample they were present in almost equal proportions.
If indeed certain daily levels of CLA intake are required to produce suggested health benefits in humans, changes in concentrations
of specific CLA isomers could significantly impact these effects. Care must be taken to analyze the CLA used in human and
animal studies. 相似文献
4.
Biosynthesis of conjugated linoleic acid in humans 总被引:7,自引:0,他引:7
This paper deals with the reanalysis of serum lipids from previous studies in which deuterated fatty acids were administered
to a single person. Samples were reanalyzed to determine if the deuterated fatty acids were converted to deuterium-labeled
conjugated linoleic acid (CLA, 9c, 11t-18∶2) or other CLA isomers. We found 11-trans-octadecenoate (fed as the triglyceride) was converted (Δ9 desaturase) to CLA, at a CLA enrichment ofca. 30%. The 11-cis-octadecenoate isomer was also converted to 9c, 11c-18∶2, but at <10% the concentration of the 11t-18∶1 isomer. No evidence (within our limits of detection) for conversion of 10-cis-or 10-trans-octadecenoate to the 10,12-CLA isomers (Δ12 desaturase) was found. No evidence for the conversion of 9-cis, 12-cis-octadecadienoate to CLA (via isomerase enzyme) was found. Although these data come from isomerase enzyme) was found. Although these data come from four
single human subject studies, data from some 30 similar human studies have convinced us that the existence of a metabolic
pathway in one subject may be extrapolated to the normal adult population. 相似文献
5.
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
6.
Lu-Te Chuang Amanda E. Leonard Jim-Wen Liu Pradip Mukerji Tammy M. Bray Yung-Sheng Huang 《Lipids》2001,36(10):1099-1103
Conjugated linoleic acid (CLA; 18∶2) refers to a group of positional and geometric isomers derived from linoleic acid (LA;
Δ9, 12–18∶2). Using a growing baker's yeast (Saccharomyces cerevisiae) transformed with human elongase gene, we examined the inhibitory effect of CLA at various concentrations (10, 25, 50, and
100 μM) on elongation of LA (25 μM) to eicosadienoic acid (EDA; Δ11,14–20∶2). Among four available individual CLA isomers,
only c9,t11- and t10,c12-isomers inhibited elongation of LA to EDA. The extent of inhibition (ranging from 20 to 60%) was related to the concentration
of CLA added to the medium. In the meantime, only these two isomers, when added at 50 μM to the media, were elongated to conjugated
EDA (c11,t13- and t12,c14–20∶2) by the same recombinant elongase at the rate of 28 and 24%, respectively. The inhibitory effect of CLA on LA elongation
is possibly due to competition between CLA isomers and LA for the recombinant elongase. Thus, results from this study and
a previous study suggest that the biological effect of CLA is exerted through its inhibitory effect on Δ6-desaturation as
well as elongation of LA which results in a decrease in long-chain n−6 fatty acids and consequently the eicosanoid synthesis. 相似文献
7.
Rats were fed a fat-free diet for 2 wk. After this period, while maintaining the animals on the same diet, the rats were given
intragastrically 180 mg per day of a mixture of conjugated linoleic acids (CLA) as triacylglycerols. Gas chromatography-mass
spectrometry (GC-MS) analyses of this mixture, as well as hydrazine reduction and GC-MS and GC-Fourier transform infrared
analyses of the resulting monoenes, revealed the presence of two major isomers, the 9c, 11t-and the 10t, 12c-18∶2 accompanied by smaller amounts of the 8t, 10c and the 11c,13t−18∶2 isomers. Minor quantities of cis,cis and trans,trans conjugated isomers also were detected. The total fatty acid methyl esters from the liver lipids were fractionated by reversed-phase
high-performance liquid chromatography, and the fraction containing the 20∶4 isomers was further fractionated by silver nitrate
thin-layer chromatography. A band containing two 20∶4 conjugated isomers was submitted to hydrazine reduction and the resulting
monoenes analyzed by GC-MS as dimethyl-oxazoline derivatives. The two conjugated isomers were tentatively identified as 5c,8c,11c,13t–20∶4 and 5c,8c,12t,14c−20∶4. These could be formed by desaturation and elongation of the 9c,11t-and 10t,12c−18∶2 present in the commerical CLA mixture. 相似文献
8.
Hidetaka Uehara Tomomi Suganuma Satoshi Negishi Satoru Ueno Kiotaka Sato 《Journal of the American Oil Chemists' Society》2006,83(3):261-267
Conjugated linoleic acid (CLA) is commercially available as a mixture consisting of almost equal amounts of the cis-9,trans-11-CLA (c9, t11) and trans-10, cis-12-CLA (t10, c12) isomers. Separation of the two isomers is highly significant since each exhibits different biochemical properties. Highly
efficient separation could be accomplished by crystallization in acetone (solvent) of the two CLA isomers (solutes) in the
presence of medium-chain fatty-acid (MCFA) additives. The relative concentration ratios of the two CLA isomers in the solvent-crystallized
materials varied depending on which MCFA were added. Addition of lauric and decanoic acids resulted in the crystals predominantly
containing t10,c12, whereas octanoic acid yielded those predominantly containing c9,t11. We have confirmed that onetime solvent crystallization using decanoic acid and octanoic acid additives increased the t10,c12 and c9,t11 concentrations, and that repeated solvent crystallization resulted in the ratio of c9,t11 to t10,c12 of at least 4∶96 or 98∶2. 相似文献
9.
Effect of dietary conjugated linoleic acid (CLA) on metabolism of isotope-labeled oleic,linoleic, and CLA isomers in women 总被引:1,自引:0,他引:1
The purpose of this study was to investigate the effect of dietary CLA on accretion of 9c-18∶1, 9c, 12c-18∶2, 10t, 12c-18∶2, and 9c, 11t-18∶2 and conversion of these FA to their desaturated, elongated, and chain-shortened metabolites. The subjects were six healthy
adult women who had consumed normal diets supplemented with 6 g/d of sunflower oil or 3.9 g/d of CLA for 63 d. A mixture of
10t, 12c-18∶2-d
4, 9c, 11t-18∶2-d
6, 9c-18∶1-d
8, and 9c, 12c-18∶2-d
2, as their ethyl esters, was fed to each subject, and nine blood samples were drawn over a 48-h period. The results show that
dietary CLA supplementation had no effect on the metabolism of the deuterium-labeled FA. These metabolic results were consistent
with the general lack of a CLA diet effect on a variety of physiological responses previously reported for these women. The
2H-CLA isomers were metabolically different. The relative percent differences between the accumulation of 9c, 11t-18∶2-d
6 and 10t, 12c-18∶2-d
4 in plasma lipid classes ranged from 9 to 73%. The largest differences were a fourfold higher incorporation of 10t, 12c-18∶2-d
4 than 9c, 11t-18∶2-d
6 in 1-acyl PC and a two- to threefold higher incorporation of 9c, 11t-18∶2-d
6 than 10t, 12c-18∶2-d
4 in cholesterol esters. Compared to 9c-18∶1-d
8 and 9c, 12c-18∶2-d
2, the 10t, 12c-18∶2-d
4 and 9c, 11t-18∶2-d
6 isomers were 20–25% less well absorbed. Relative to 9c-18∶1, incorporation of the CLA isomers into 2-acyl PC and cholesterol ester was 39–84% lower and incorporation of 10t, 12c-18∶2 was 50% higher in 1-acyl PC. This pattern of selective incorporation and discrimination is similar to the pattern generally
observed for trans and cis 18∶1 positional isomers. Elongated and desaturated CLA metabolites were detected. The concentration of 6c, 10t, 12c-18∶3-d
4 in plasma TG was equal to 6.8% of the 10t, 12c-18∶2-d
4 present, and TG was the only lipid fraction that contained a CLA metabolite present at concentrations sufficient for reliable
quantification. In conclusion, no effect of dietary CLA was observed, absorption of CLA was less than that of 9c-18∶1, CLA positional isomers were metabolically different, and conversion of CLA isomers to desaturated and elongated metabolites
was low. 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.
Endothelial cell function can be influenced by nutrition, especially dietary FA and antioxidants. One class of dietary FA
that is found in meat and dairy products derived from ruminant animals is conjugated linoleic acids (CLA). We have examined
the effects of several CLA isomers on endothelial cell proliferation. 9t,11t-CLA was the only isomer that inhibited bovine arotic endothelial cell (BAEC) [3H]methylthymidine incorporation (I50=35 μM), and this antiproliferative effect was time-dependent. A small decrease (20%) in cell number was observed only at
the highest concentration (60 μM) tested. The 9c,11t-, 9c,11c-, 10t 12c-, and 11c,13t-CLA isomers did not exhibit any antiproliferative effects over a 5–60 μM concentration range. α-Tocopherol and BHT decreased
BAEC proliferation, but pretreatment of cells with either of these antioxidants substantially attenuated the antiproliferative
effect of 9t,11t-CLA. No difference in lipid peroxidation, as measured by the thiobarbituric acid assay for malondialdehyde, was observed
on treatment of endothelial cells with either 9t,11t- or 9c,11t-CLA. However, a 43% increase in caspase-3 activity was observed after incubating BAEC with 9t,11t-CLA, suggesting that the antiproliferative effect of this isomer is partially due to an apoptotic pathway. In contrast to
the above results with normal endothelial cells, these five CLA isomers all inhibited proliferation of the human leukemic
cell line THP-1, with the 9t,11t isomer again being the most (I50=60 μM) effective. These results confirm that different CLA isomers have different inhibitory potencies on the proliferation
of normal and leukemic cells. 相似文献
12.
Evidence suggests that minor isomers of conjugated linoleic acid (CLA), such as trans8, cis10 CLA, can elicit unique biological effects of their own. In order to determine the effect of a mixture of t8, c10+c9, t11 CLA isomers on selected aspects of lipid metabolism, 3T3-L1 preadipocytes were differentiated for 8 days in the presence
of 100 μM linoleic acid (LA); t8, c10+c9, t11 CLA; t10, c12+c9, t11 CLA or purified c9, t11 CLA. Whereas supplementation with c9, t11 and t10, c12+c9, t11 CLA resulted in cellular triglyceride (TG) concentrations of 3.4 ± 0.26 and 1.3 ± 0.11 μg TG/μg protein, respectively (P < 0.05), TG accumulation following treatment with CLA mixture t8, c10+c9, t11 was significantly intermediate (2.5 ± 0.22 μg TG/μg protein, P < 0.05) between the two other CLA treatments. However, these effects were not attributable to an alteration of the Δ9 desaturation index. Adiponectin content of adipocytes treated with t8, c10+c9, t11 mixture was similar to the individual isomer c9, t11 CLA, and both the t8, c10+c9, t11 and c9, t11 CLA groups were greater (P < 0.05) than in the t10, c12+c9, t11 CLA group. Overall, these results suggest that t8, c10+c9, t11 CLA mixture affects TG accumulation in 3T3-L1 cells differently from the c9, t11 and t10, c12 isomers. Furthermore, the reductions in TG accumulation occur without adversely affecting the adiponectin content of these
cells. 相似文献
13.
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
14.
The effect of dietary conjugated linoleic acid (CLA) supplementation in combination with fat from vegetable versus animal
origin on the fatty acid deposition, including that of individual 18:1 and 18:2 (conjugated and non-conjugated) isomers, in
the liver and muscle of obese rats was investigated. For this purpose, 32 male Zucker rats were randomly assigned to one of
four diets containing palm oil or ovine fat, supplemented or not with 1% of 1:1 cis(c)9,trans(t)11 and t10,c12 CLA isomers mixture. Total fatty acid content decreased in the liver and muscle of CLA-fed rats. In the liver, CLA increased
saturated fatty acids (SFA) in 11.9% and decreased monounsaturated fatty acids (MUFA) in 6.5%. n-3 Polyunsaturated fatty acids
(PUFA) relative proportions were increased in 30.6% by CLA when supplemented to the ovine fat diet. In the muscle, CLA did
not affect SFA but decreased MUFA and PUFA percentages. The estimation of Δ9-indices 16 and 18 suggested that CLA inhibited
the stearoyl-CoA desaturase activity in the liver (a decrease of 13–38%), in particular when supplemented to the ovine fat
diet. Concerning CLA supplementation, the t10,c12 isomer percentage was 60–80% higher in the muscle than in the liver. It is of relevance that rats fed ovine fat, containing
bio-formed CLA, had more c9,t11 CLA isomer deposited in both tissues than rats fed palm oil plus synthetic CLA. These results highlight the importance
to further clarify the biological effects of consuming foods naturally enriched in CLA, alternatively to CLA dietary supplementation. 相似文献
15.
Immune-modulating effects of CLA have been reported in animals, but results are inconsistent. In humans, CLA has shown no
effects or only minor effects on immune function. The objective of this study was to evaluate the immune-modulating effects
of 3 g cis-9,trans-11 (c9,t11) vs. trans-10,cis-12 (t10,c12) CLA isomers in a population with a high risk of coronary heart disease characterized by moderate overweight (body-mass
index, 25–32.5 kg/m2) in combination with LDL-phenotype B (≥35% small LDL cholesterol, density≥1.040 g/mL). After a run-in period of 1 wk, 42
men and women were randomly allocated to the c9,t11 CLA group, the t10,c12 CLA group, or the placebo group. Effects of 13 wk of consumption of 3 g of CLA isomers on cytokine production by ex vivo lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells (PBMC) and whole blood, and on plasma C-remononuclear
protein (CRP) concentrations were evaluated. To generate hypotheses for future studies, protein expression patterns of 42
cytokines, chemokines, and growth factors were evaluated with an antibody array in pooled, nonstimulated, fasting plasma samples.
LPS induced interleukin (IL)-6, IL-8, and tumor necrosis factor-α production by PBMC, and whole blood as well as plasma CRP
concentrations were not significantly changed by the c9,t11, and the t10,c12 CLA isomers. The cytokine expression profile in nonstimulated plasma suggested that both CLA isomers induced a specific
inflammatory signature, in which the c9,t11 CLA group showed more activity in terms of numbers of proteins regulated. We conclude that daily consumption of 3 g of
c9,t11 or t10,c12 CLA isomer did not affect LPS-stimulated cytokine production by PBMC or whole blood and plasma CRP levels. Inflammatory
signatures in fasting, nonstimulated plasma as determined by an antibody array may indicate enhanced immune function by both
CLA isomers. 相似文献
16.
The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand,
the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors
for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius
equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA
or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested
that the autoxidation mechanisms for the CLA and PUFA were essentially the same. 相似文献
17.
The amounts of Δ9,Δ11-conjugated linoleic acid (CLA) isomers were determined in loin-associated fat samples of bulls (n=6) and steers (n=7) by capillary gas chromatography of fatty acid methyl ester (FAME) derivatives. The main CLA-isomer—18:2 c9,t11—provided approximately 0.76 ± 0.15% and 0.86 ± 0.15% of total FAME in bulls and steers, respectively. No differences (P>0.05) were observed between the CLA isomer distribution of bulls (t9,c11, 0.026 ± 0.014%; c9,c11, 0.015 ± 0.008%; and t9,t11, 0.029 ± 0.003%) and steers (t9,c11, 0.027 ± 0.014%; c9,c11, 0.015 ± 0.005%; and t9,t11, 0.030 ± 0.007%). 相似文献
18.
Effects of conjugated linoleic acid isomers on the hepatic microsomal desaturation activities in vitro 总被引:4,自引:0,他引:4
The influence of individual conjugated linoleic acid (CLA) isomers on the Δ6 desaturation of linoleic and α-linolenic acids
and on the Δ9 desaturation of stearic acid was investigated in vitro, using rat liver microsomes. The Δ6 desaturation of 18∶2n−6 was decreased from 23 to 38% when the ratio of 9cis,11trans-18∶2 to 18∶2n−6 increased from 0.5 to 2. The compound 10trans,12cis-18∶2 exhibited a similar effect only at the highest concentration. The Δ6 desaturation of α-linolenic acid was slightly affected
by the presence of CLA isomers. The sole isomer to induce an inhibitory effect on the Δ9 desaturation of stearic acid was
10trans,12cis-18∶2. 相似文献
19.
Conjugated linoleic acids (CLAs) consist of a series of positional and geometrical isomers of linoleic acid. CLA have been
reported to beneficially affect cardiovascular risk factors in animal models. In order to assess the role of individual CLA
isomers on lipoprotein cholesterol concentration, 30 hamsters were fed for 12 weeks an hyperlipidic diet containing pure cis-9,trans-11 CLA (c9,t11) or pure trans-10, cis-12 CLA (t10,c12) isomers given alone or as a mixture. Plasma total cholesterol, LDL and HDL cholesterol concentrations were significantly
lower in the c9,t11 CLA isomer fed hamsters relative to the Control group, with the most substantially effect on LDL cholesterol (−56%; P < 0.05). Plasma triacylglycerol concentrations did not differ significantly regarding those two groups. Plasma cholesterol
parameters showed a tendency to decrease in the t10,c12 CLA isomer and CLA mixture fed hamsters compared with the Control group, but differences were not significant. For the
first time, the atherogenic fraction of small dense LDL was investigated. Plasma small dense LDL cholesterol concentration
was lower in the c9,t11 CLA relative to Control, while the t10,c12 and CLA mixture groups showed only a non significant tendency to decrease. Taken together, these data indicate that feeding
rumenic acid (c9,t11 CLA) may beneficially affect lipoprotein profile in hamster fed a cholesterol- and lipid-enriched semi-purified diet, when
t10,c12 CLA isomer or CLA mixture would be less active. 相似文献
20.
The aim of the present study was to characterize plasma lipids and lipoprotein cholesterol and glucose concentrations in hamsters
fed either cis-9, trans-11 CLA (9c, 11t CLA); trans-10, cis-12 CLA (10t, 12c CLA); or linoleic acid (LA) on the accumulation of aortic cholesterol in hypercholesterolemic hamsters. One hundred male
F1B strain Syrian Golden Hamsters (Mesocricetus auratus) (BioBreeders Inc., Watertown, MA) approximately 9 wk of age were housed in individual stainless stel hanging cages at room
temperature with a 12-h light/dark cycle. Hamsters were given food and water ad libitum. Following a 1-wk period of acclimation, the hamsters were fed a chow-based (nonpurified) hypercholesterolemic diet (HCD)
contaning 10% coconut oil (92% saturated fat) and 0.1% cholesterol for 2 wk. After an overnight fast, the hamsters were bled
and plasma cholesterol concentrations were measured. The hamsters were then divided into 4 groups of 25 based on similar mean
plasma VLDL and LDL cholesterol (non HDL-C) concentrations. Group 1 remained on the HCD (control). Group 2 was fed the HCD plus 0.5% 9c, 11t CLA isomer. Group 3 was fed the HCD plus 0.5% 10t, 12c CLA isomer. Group 4 was fed the HCD plus 0.5% LA. Compared with the control, both CLA isomers and LA had significantly lower
plasma total cholesterol and HDL cholesterol concentrations (P<0.001) after 12 but not 8 wk of treatment and were not significantly different from each other. Also, both CLA isomers had
significantly lower plasma non HDL-C concentrations (P<0.01) compared with the control after 12 but not 8 wk of treatment and were not significantly different from each other or
the LA-fed hamsters. Plasma TG concentrations were significantly higher (P<0.004) with the 10t, 12c CLA isomer compared with the other treatments at 8 but not at 12 wk of treatment. Plasma TG concentrations were also significantly
lower (P<0.03) with the 9c, 11t CLA isomer compared with the control at 12 wk of treatment. Also, the 10t, 12c CLA isomer and LA had significantly higher plasma glucose concentrations compared with the control and 9c, 11t CLA isomer (P<0.008) at 12 wk of treatment whereas at 8 wk, only the LA treatment had significantly higher plasma glucose concentrations
(P<0.001) compared with the 9c, 11t CLA isomer. Although liver weights were significantly higher in 10t, 12c CLA isomer-fed hamsters, liver total cholesterol, free cholesterol, cholesterol ester, and TG concentrations were significantly
lower in these hamsters compared with hamsters fed the control, 9c, 11t CLA isomer, and LA diets (P<0.05). The 9c, 11t CLA isomer and LA diets tended to reduce cholesterol accumulation in the aortic arch, whereas the 10t, 12c CLA isomer diet tended to raise cholesterol accumulation compared with the control diet; however, neither was significant.
In summary, no differences were observed between the CLA isomers for changes in plasma lipids or lipoprotein cholesterol concentrations.
However, the 9c, 11t CLA isomer did appear to lower plasma TG and glucose concentrations compared with the 10t, 12c CLA isomer. Such differences may increase the risk of insulin resistance and type 2 diabetes in humans when the 10t, 12c CLA isomer is fed separately. 相似文献