bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of low erucic acid turnip rapeseed oil (Brassica campestris) by negative ion chemical ionization tandem mass spectrometry. A method giving information on the fatty acid composition in positionssn‐2 andsn‐1/3 of triacylglycerols
Authors: Kallio Heikki , Currie Graeme
Published: November 2006

A tandem mass spectrometric method is described for the rapid analysis of fatty acid combinations in mixtures of triacylglycerols. Triacylglycerols were introduced into a triple quadrupole mass spectrometervia a direct exposure probe and deprotonated using ammonia negative ion chemical ionization. Collisionally activated spectra were obtained and the resulting fragments used to identify the fatty acid constituents, and the fatty acids preferentially located at thesn‐2 position of the triacylglycerols. Fourteen major molecular weight species of purified triacylglycerols of a supercritical fluid extract of low erucic acid turnip rapeseed oil (Brassica campestris) were analyzed. The five major combinations of fatty acids comprised two thrids of the total triacylglycerols and contained oleic, linoleic and α‐linolenic acids with linoleic acid favoring thesn‐2 position.
Triacylglycerols of human milk: Rapid analysis by ammonia negative ion tandem mass spectrometry
Authors: Currie Graeme J. , Kallio Heikki
Published: November 2006

Human milk traicylglycerols (TAG) were analyzed by ammonia negative ion chemical ionization tandem mass spectrometry. The deprotonated molecular ions of triacylglycerols were fractionated at the first mass spectrometry (MS) stage. Twenty‐nine of the deprotonated TAG ions were further analyzed based on their collisionally activated (CA) spectra. The tandem MS analysis covered eleven major acyl carbon number fractions, two of which contained odd carbon number fatty acids. Fatty acids of 28 different molecular weights were recorded from the daughter spectra. Hexadecanoic acid was present in all CA spectra, octadecenoic acid in the CA spectra of all mono‐ and higher unsaturated TAG, and octadecadienoic acid in the CA spectra of all di‐ and higher unsaturated TAG. The major fatty acid combinations in triacylglycerols were: with 0 double bonds (DB), 12∶0/12∶0/16∶0; with 1 DB, 12∶0/16∶0/18∶1; with 2 DB, 16∶0/18∶1/18∶1; with 3 DB, 16∶0/18∶2/18∶1; with 4 DB, 18∶2/18∶1/18∶1; and with 5 DB, 18∶2/18∶2/18∶1; hexadecanoic acid typically occupied thesn‐2 position. The most abundant TAG was shown to besn‐18∶1–16∶0–18∶1, comprising about 10% of all triacylglycerols.
Hypolipidemic activity of 6‐alkoxycarbonyl‐3‐aryl‐1,3,5‐triazabicyclo[3.1.0]hexane‐2,4‐diones and 2‐alkoxycarbonyl‐5‐aryl‐1,3,5‐triazine‐4,6(1H,5H)‐diones in rodents
Authors: Izydore Robert A. , Wong O. T. , Hall Iris H.
Published: November 2006

Significant hypolipidemic activity was demonstrated by 6‐ethoxycarbonyl‐3‐phenyl‐1,3,5‐triazabicyclo[3.1.0]hexane‐2,4‐dione, 2‐ethoxycarbonyl‐5‐phenyl‐1,3,5‐triazine‐4,6(1H,5H)‐dione and 2‐ethoxycarbonyl‐5‐(4‐chlorophenyl)‐1,3,5‐trizine‐4,6(1H,5H)‐dione in rodents at 20 mg/kg/day. These agents lowered serum cholesterol and triglyceride levels by approximately 40% in mice after 16 d. Tissue lipids in rat liver, small intestinal mucosa, aortic wall and feces were reduced by treatment with the agents. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol levels were reduced in the rat; high density lipoprotein (HDL) cholesterol levels were elevated after 14 d of treatment. The activities of regulatory enzymes,e.g., acetyl‐CoA synthetase, acyl‐CoA:cholesterol acyltransferase, cholesterol 7α‐hydroxylase,sn‐glycerol‐3‐phosphate acyltransferase, phosphatidylate phosphohydrolase and heparin‐induced lipoprotein lipase, involved inde novo synthesis of hepatic lipids were affected by the agents. The new compounds may represent another class of potentially useful hypolipidemic agents for the treatment of atherosclerosis since HDL cholesterol levels were increased and VLDL and LDL cholesterol levels were lowered by some of the agents.
Simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides obtained by lipoxygenase treatment
Authors: Therond Patrice , Couturier Martine , Demelier Jean‐François , Lemonnier Frédérique
Published: November 2006

A method for the simultaneous determination of the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their corresponding hydroperoxides is described. Hydroperoxides were formed by incubation of phospholipids with lipoxygenase at pH 9.2. Silicic acid column chromatography (silica Sep‐Pak column) was used to separate the phospholipids into phosphatidylcholine and phosphatidylethanolamine. A single C−18 reverse‐phase column was employed to separate the main molecular species of soybean phosphatidylcholine or phosphatidylethanolamine and their hydroperoxides by high‐performance liquid chromatography. The mobile phase consisted of 5% 10 mM ammonium acetate at pH 5 and 95% methanol. The molecular species of phosphatidylcholine and phosphatidylethanolamine were detected at 205 nm; the eluate was mixed with a chemiluminescence reagent (isoluminol and microperoxidase) and monitored by fluorometry. Under the experimental conditions used, three individual molecular species of both soybean phosphatidylethanolamine and phosphatidylcholine (18∶3/18∶2, 18∶2/18∶2 and 16∶0/18∶2), together with their corresponding hydroperoxides, were identified and quantitated.
Enantiomeric resolution of diacylglycerol derivatives by high‐performance liquid chromatography on a chiral stationary phase at low temperatures
Authors: Takagi Toru , Suzuki Toshiyuki
Published: November 2006

Separation of 1,2‐diacylglycerol (DG) enantiomers as their 3,5‐dinitrophenylurethane derivatives by high‐performance liquid chromatography on a chiral column (Sumichiral OA‐4100) was significantly improved at low temperature,e.g., at −30°C. A linear relationship between logarithmic retention volumes and the number of carbons and olefinic bonds of the DG enantiomers was obtained. The effects of temperature on the separation are discussed.
On‐line straight‐phase liquid chromatography/plasmaspray tandem mass spectrometry of glycerolipids
Authors: Valeur Anders , Michelsen Peter , Odham Göran
Published: November 2006

Class separation of common glycerolipids on a diol‐phase liquid chromatography column with a gradient of the mixed solvents hexane/isopropanol/acetic acid/triethylamine is compatible with on‐line plasmaspray ionization mass spectrometry. The positive ion mass spectra exhibit prominent diacylglycerol and monoacylglycerol derived fragments, which can be utilized for quantification. In the selected‐ion monitoring mode, the detection limit for phospholipids is in the low nanogram range. The abundance of the diacylglycerol and monoacylglycerol fragments reflects the relative fatty acid composition of the phospholipid classes. Collision‐induced decomposition of diacylglycerol fragments with argon as collision gas unambiguously reveals the chain length and degree of unsaturation of the esterified fatty acids in the native lipid.
HDL3‐mediated cholesterol efflux from cultured enterocytes: The role of apoproteins A‐I and A‐II
Authors: Herold Gerhard , Hesse Uta , Wisst Frank , Fahr Carl , Fahr Milena , Rogler Gerhard , Geerling Irmlind , Stange Eduard F.
Published: November 2006

High density lipoproteins (HDL) were recently demonstrated in an enterocyte model (CaCo‐2 cells) to mediate reverse cholesterol transport by retroendocytosis. The present study was carried out to define the role of the major HDL apoproteins (apo) A‐I and apo A‐II in this pathway. HDL3 was fractionated by heparin affinity chromatography into the two main fractions containing either apo A‐I only (fraction A) or both apo A‐I and apo A‐II (fraction B). In addition, liposomes were reconstituted from purified apo A‐I or apo A‐II and dimyristoyl phosphatidylcholine. The cell binding properties and cholesterol efflux potential were studied in the lipoprotein fractions and the liposomes. Both fractions exhibited similar maximal binding capacities of 4427 (A) and 5041 (B) ng/mg cell protein, but their dissociation constants differed (40.5 and 167.7 μg/mL, respectively). Fraction A induced cholesterol efflux and stimulated cholesterol synthesis more than did fraction B. Fraction A mobilized both cellular free and esterified cholesterol, whereas fraction B preferentially mobilized cholesteryl esters. Liposomes, containing either apo A‐I or apo A‐II, showed specific binding, endocytosis and endosomal transport, and were released as intact particles. Apo A‐I liposomes also mediated cholesterol efflux. In conclusion, there is evidence that the HDL3 subfractions A and B, as well as reconstituted liposomes containing either apo A‐I or apo A‐II, were specifically bound and entered a retroendocytosis pathway which was directly linked to cholesterol efflux. Quantitatively, the apo A‐I subfraction appeared to play the dominant role in normal enterocytes. The apo A‐II content of fraction B was related to the mobilization of cholesteryl esters.
Liver, serum and adipose tissue fatty acid composition in suckling zucker rats
Authors: Cleary Margot P. , Phillips Frederick C. , Morton Ruth A.
Published: November 2006

Young adult obese Zucker rats have altered tissue fatty acid (FA) composition. The present study was aimed at determining whether such changes were seen in either liver, serum or adipose tissue obtained from 17‐day‐old obese (fafa) rats in comparison to both homozygous (FaFa) and heterozygous (Fafa) lean rats. Body weights of obese pups (30.3 g) were significantly greater than those of homozygous lean rats (25.2 g) (P<0.05). Liver weight and lipid content were similar in all groups. Inguinal fat pad weight and lipid content were greatest in obese pups (573 mg) followed by heterozygous lean pups (303 mg); homozygous lean pups (146 mg) had the lowest values. There were no differences among the groups in hepatic FA composition in either triacylglycerol (TG) or phospholipid fractions. Serum TG was similar among the groups, while serum phospholipid was greater (P< 0.05) in obese (269 mg/dL) than in homozygous lean pups (184 mg/dL); heterozygous lean pups had an intermediate value not significantly different from either homozygous group. On a percent basis, there were no differences in FA composition in either serum lipid fraction among the three groups. There were a number of significant differences in adipose tissue FA composition between the groups on a percent basis. The adipose tissue FA composition on a percent basis reflected that of maternal milk. The results indicate that suckling obese Zucker rats do not have tissue FA profiles that are characteristic of essential FA deficiency.
Composition and structure of triacylglycerols in brown adipose tissue of rats fed fish oil
Authors: Raclot Thierry , Groscolas René , Leray Claude
Published: November 2006

This study examines the incorporation of highly unsaturated n−3 fatty acids (HUFA) into triacylglycerols (TAG) of brown adipose tissue (BAT), and their effect on the positional distribution of saturated (SFA) and of unsaturated (UFA) 16‐ or 18‐carbon fatty acids. To this end, rats were fed a fish oil diet for up to four weeks. The stereospecific analysis of TAG was based on generation ofsn‐1,2‐ andsn‐2,3‐acylglycerols by Grignard degradation, followed by synthesis of phosphatidic acid and specific hydrolysis with phospholipase A2. From the end of the first week of fish oil feeding, a steady‐state in the fatty acid composition of TAG in BAT was reached. HUFA concentration increased 30‐fold, mainly at the expense of n−9 UFA and of SFA. The amount of SFA decreased selectively at position 3, where these fatty acids were progressively replaced by n−3 HUFA. By contrast, the amount of UFA decreased at all positions, and their positional distribution was not affected. About 60% of HUFA was incorporated at position 3. Nearly twice as much 22∶6n−3 was incorporated into TAG than had been previously observed in white adipose tissue (WAT) [Leray, C., Raclot, T., and Groscolas, R. (1993)Lipids 28, 279–284]. At the steady‐state, the distribution of HUFA was characterized by high proportions of 22∶6n−3 and 20∶5n−3 in position 3. Moreover, in each position of TAG, a steady level was reached rapidly (within 1 wk). It is concluded that, during fish‐oil feeding, fatty acids in TAG of BAT show characteristic time‐course changes that lead to a characteristic composition and a tissue‐specific positional distribution. This suggests that adipose tissue has its own specificity in controlling the build‐up of TAG stores, which is likely to be regulated by the specificity of acylating enzymes as well as molecular rearrangements.
n‐3 fatty acids inhibit defects and fatty acid changes caused by phenytoin in early gestation in mice
Authors: High Kim A. , Kubow Stan
Published: November 2006

Our previous work has shown that n‐3 fatty acids exert a protective effect against phenytoin‐induced cleft palate when phenytoin was administered midgestation [gestational days (GD) 12 and 13] to CD‐1 mice. The effects of dietary n‐3 fatty acids on phenytoin teratogenicity were investigated at an earlier gestational period (GD 9) to examine whether n‐3 fatty acids could exert protective action against other teratogenic effects of phenytoin apart from cleft palate. The effect of phenytoin exposure on maternal hepatic polyunsaturated fatty acid composition was also studied since Δ6 desaturase activity has been shown to be modified by pharmacological action. Female CD‐1 mice were fed a standard laboratory diet (SLD), safflower oil (SAFF) or a cod liver/linseed oil (CLO/LO)‐based diet for three weeks prior to impregnation and throughout pregnancy. Pregnant mice were administered a single i.p. dose of phenytoin on GD 9, and teratological assessments were performed on GD 19. Tissues were harvested on GD 10 for maternal hepatic phospholipid fatty acid analysis from another group of phenytoin‐treated mice. The CLO/LO and the SLD mice, as compared to the SAFF‐fed antimals, showed a reduction in total malformations and fetal growth retardation due to phenytoin. Open eye defect was the only anomaly induced by phenytoin in the CLO/LO fetuses while phenytoin produced a variety of malformations in the SAFF fetuses such as tail defects, cleft palate, open eye and absence or blockage of the ureter. Dietary n‐6/n‐3 fatty acid ratios were reflected in maternal hepatic phospholipids; however, phenytoin exposure appeared to inhibit the conversion of 18∶2n‐6 to 20∶4n‐6 in the SAFF dams only. These results indicate that the overall protective effects of dietary n‐3 fatty acids on phenytoin embryo‐toxicity are observed at an early gestational period.
Adipose monoacylglycerol: Acyl‐coenzyme a acyltransferase activity in the white‐throated sparrow (Zonotrichia albicollis): Characterization and function in a migratory bird
Authors: Mostafa Nadia , Ganesh Bhat B. , Coleman Rosalind A.
Published: November 2006

Although migrating birds use stored triacylglycerol as their primary fuel for flight, they must retain sufficient stores of ω6 and ω3 fatty acids to sustain reproduction after the spring migration. Hepatic monoacylglycerol:acyl‐coenzyme A acyltransferase (EC 2.3.1.22) (MGAT) activity is associated with physiological periods in which lipolysis and β‐oxidation are prominent, and it may also play a role in the selective retention of certain essential fatty acids. Therefore, we characterized MGAT activity in adipose tissue from the whitethroated sparrow (Zonotrichia albicollis), a migratory bird. MGAT specific activity from adipose tissue and liver, respectively, was 22.2±7.27 and 0.79±0.35 nmol/min/mg of total particulate protein. Activity did not vary seasonally or between male and female birds. Specific activity increased 4.3‐fold in the presence of 75 μg of phosphatidylcholine and phosphatidylserine (1∶1, w/w). MGAT acylatedsn‐1(3)‐monooleoyglycerol,sn‐2‐monoolyelglycerol ether andsn‐1(3)‐monooleylglycerol ether at 7.5, 5.7 and 1.7%, respectively, of the rate observed withsn‐2‐monooleoylglycerol. An initial lag phase observed at low concentrations of palmitoyl‐CoA was corrected by adding 2 mM MgCl2 Mg(NO2)2 or CaCl2, suggesting a requirement for divalent cations. MGAT acylatedsn‐2‐monolinolenoylglycerol andsn‐2‐monolinoleoylglycerol in preference tosn‐2‐monooleoylglycerol. Specificity of MGAT forsn‐2‐monoacylglycerols and the probable enhanced affinity forsn‐2‐monoacylglycerols of specific acyl chains may allow selected ω6 and ω3 fatty acids to be retained within the adipocyte, white nonessential fatty acids are released for β‐oxidation in flight muscles.
Inhibition of human neutrophil leukotriene B4 synthesis in essential fatty acid deficiency: Role of leukotriene a hydrolase
Authors: Cleland Leslie G. , James Michael J. , Proudman Susanna M. , Neumann Mark A. , Gibson Robert A.
Published: November 2006

A female subject dependent on long‐term total parenteral nutrition developed an aversion and noncompliance to a prescribed weekly lipid infusion designed to meet essential fatty acid (EFA) requirements. Fatty acids (FA) in the subject's plasma and isolated peripheral blood neurophils were analyzed in search of biochemical evidence of EFA deficiency. Neutrophil 5‐lipoxygenase metabolism was examined to assess the possible effects of EFA deficiency on neutrophil eicosanoid metabolism. EFA deficiency was confirmed by marked depletion of linoleic acid (18∶2n−6) and accumulation of eicosatrienoic acid (ETrA; 20∶3n−9) in plasma and neutrophil phospholipids. In the neutrophils, ETrA comprised 5.2% of phospholipid FA (normal reference values <0.1%), and arachidonic acid (AA; 20∶4n−6) comprised 8.6% of phospholipid FA (normal reference range 10–16%). When stimulated by A23187in vitro on three separate occasions, the subject's neutrophils displayed impaired synthesis of leukotriene B4 (LTB4), but produced normal amounts of 5‐hydroxyeicosatetraenoic acid andall‐trans isomers of LTB4 formed nonenzymatically from leukotriene A4 (LTA4). This pattern of synthesis suggested inhibition of LTA hydrolase and was also seen in neutrophils from healthy subjects by addition of exogenous ETrAin vitro. Comparative studies of the effects of ETrA and eico‐sapentaenoic acid (20∶5n−3) on neutrophilsin vitro suggested that ETrA is the more potent inhibitor. Accumulation of ETrA, rather than depletion of AA, appears principally responsible for the observed impairment of neutrophil LTB4 synthesis seen in this EFA‐deficient subject.
The effect of linoleic, arachidonic and eicosapentaenoic acid supplementation on prostacyclin production in rats
Authors: Mann Neil J. , Warrick Glenda E. , O'Dea Kerin , Knapp Howard R. , Sinclair Andrew J.
Published: November 2006

We examined the effect of dietary supplementation of linoleic acid (LA), arachidonic acid (AA) or eicosapentaenoic acid (EPA) to rats fed a diet low in linoleic acid onin vitro andin vivo production of prostacyclin. Male Sprague Dawley rats were fed a high‐fat diet (50% energy as fat, 1.5% linoleic acid) for two weeks. Three of the groups were then supplemented orally with either 90 mg/d of LA, AA or EPA, all as the ethyl esters, for a further two weeks while remaining on the high‐fat diet. Forty‐eight hour urine samples were collected at the end of the second and fourth weeks.In vivo prostacyclin production was determined by a stable isotope dilution, gas chromatography/mass spectrometry assay for the major urinary metabolite of prostacyclins (2,3‐dinor‐6‐keto‐PGF1α or PGI2‐M and Δ17‐2‐3‐dinor‐6‐keto‐PGF1α or PGI3‐M).In vitro prostacyclin production was determined by radioimmunoassay of the stable metabolite (6‐keto‐PGF1α) following incubation of arterial tissue. Oral supplementation with AA resulted in a rise in plasma and aorta 20∶4n−6, and increasedin vitro prostacyclin and urinary PGI2‐M production. EPA supplementation resulted in a rise in plasma and aorta 20∶5n−3 and 22∶5n−3, and a decline in plasma 20∶4n−6, but not in the aorta. In the EPA‐supplemented group, thein vitro prostacyclin and the urinary PGI3‐M increased, but urinary PGI2‐M decreased. The increase inin vitro prostacyclin production in the EPA‐supplemented rats was unexpected and without obvious explanation. Supplementation with LA had minimal effect on fatty acid composition of plasma or aorta and caused no change in prostacyclin production with either method. Thein vivo measure of prostacyclin production was positively correlated with aorta AA levels, and negatively correlated with aorta levels of EPA. There was a significant positive correlation between thein vitro production of prostacyclin and thein vivo production (as measured by the urinary prostacyclin metabolite level), despite the differences observed in the EPA‐fed group. There was a high inter‐animal variability in prostacyclin production using either method. These results indicate that dietary AA stimulates and dietary EPA reducesin vivo PGI2 production in the rat. An equivalent amount of dietary LA was without effect.
Characterization of calcium‐independent cytosolic phospholipase A2 activity in the submucosal regions of rat stomach and small intestine
Authors: Fukushima Takeshi , Serrero Ginette
Published: November 2006

This study was undertaken to compare the calcium‐independent phospholipase A2 (PLA2) activities in the cytosols of twelve rat tissues and to determine whether their activities were distinct. 1‐O‐Alk‐1′‐enyl‐2‐[14C]‐oleoyl‐sn‐glycero‐3‐phosphocho‐line (PlsC) and 1‐O‐Alk‐1′‐enyl‐2‐[14C]oleoyl‐sn‐glycero‐3‐phosphethanolamine (PlsE) were synthesized and used as substrates, instead of phosphatidyl compounds, to exclude hydrolysis by cytosolic PLA1 activity that could be present in some of the cytosolic preparations. For each tissue, we examined substrate specificity, pH optimum, and effect of adenosine triphosphate (ATP) and ATP analogues. PLA2 activity was detected in eleven out of the twelve issues examined. Based on substrate specificity and pH optimum, cytosolic calcium‐independent PLA2 were classified in three groups. The first group, which included PLA2 from small intestine, stomach and spleen, had the highest specific activity with PlsC as substrate (1253, 309 and 75 nmol/mg protein/hour, respectively) and an optimal pH at 6.5. Activity with PlsE as substrate was much lower (20–37%) than with PlsC. The second group of PLA2 activities included the cytosolic activities from thymus, lung, liver and pancreas that showed lower specific activities for both substrates (14–23 nmol/mg protein/hour with PlsC) and had a broader optimal pH range of 6.1 to 7.5. The cytosols from brain, kidney, heart and muscle comprised the third PLA2 group that was found to have a higher specific activity with PlsE (5–20 nmol/mg protein/hour) than PlsC and an optimal pH range from 7.4 to 7.9. Since the highest specific activity was found in the cytosol from small intestine, this PLA2 was examined further. PLA2 activity was found to be equally distributed in the cytosol of the submucosal portion of duodenum, jejunum and ileum with an optimal pH of 6.1 and a 5‐fold higher activity with PlsC than PlsE as substrate. Moreover, this PLA2 activity was inhibited by treatment with detergents. These results indicate the presence in the submucosal portion of the intestine of a calcium‐independent cytosolic PLA2 with a high specific activity toward PlsC and properties distinct from those described for the PLA2 found in the intestinal brush‐border.
Vitamin E isomers in grain amaranths (Amaranthus spp.)
Authors: Lehmann James W. , Putnam Daniel H. , Qureshi Asaf A.
Published: November 2006

Vitamin E isomers are important antioxidants, but their variation is poorly documented in pseduocereal grains such as amaranths. Using normal‐phase, high‐performance liquid chromatography with fluorescence detection, seeds of thirteen amaranth (Amaranthus cruentus L.,A. hypochondriacus L.) accessions were surveyed for the composition of tocols. The most common tocols found were α‐tocopherol (2.97 to 15.65 mg/kg seed) and β‐tocotrienol (5.92 to 11.47 mg/kg seed) and γ‐tocotrienol (0.95 to 8.69 mg/kg seed), while someA. cruentus accessions contained δ‐tocotrienol (0.01 to 0.42 mg/kg seed). This is the first report of tocotrienols in amaranths.Amaranthus cruentus grain‐types of Mesoamerican origin had significantly (P≤0.01) greater levels of four tocols than didA. cruentus African vegetable‐types. Unlike many cereal grains, amaranths have significant amounts of both β‐ and γ‐tocotrienols; however, β‐tocopherol was not detected in any of the amaranths. Using multiple linear regressions, α‐tocopherol variation of both species and types was consistently explained by variation in tocols other than α‐tocopherol. On the whole, fresh amaranth samples of both species tended to have higher levels of tocotrienols than samples stored for two years. Storage effects on amaranth tocol composition are suspected.
Structure and biosynthesis of novel conjugated polyene fatty acids from the marine green algaAnadyomene stellata
Authors: Mikhailova Marina V. , Bemis Debra L. , Wise Mitchell L. , Gerwick William H. , Norris James N. , Jacobs Robert S.
Published: November 2006

Novel polyunsaturated fatty acids with four conjugated double bonds were found in extracts of the green macroalga,Anadyomene stellata. The isolation of five of these with different chain lengths and varying degrees of unsaturation −16∶5, 18∶4, 20∶5, 20∶6, and 22∶7—was accomplished by organic extraction followed by a combination of vaccum and high‐performarce liquid chromatography. One of these that was a novel substance (22∶7) was characterized as 4ZZ,7Z,9E,13Z,16Z,19Z‐docosaheptaenoic acid and assigned the trivial name stellaheptaenoic acid. The structure of this new compound, isolated as its methyl ester derivative, was deduced from detailed nuclear magnetic resonance, gas chromatography/mass spectrometry (GC/MS), and other spectroscopic methods. Incubation of a chloroplast preparation, isolated from a crude algal homogenate by differential centrifugation, with six unsaturated fatty acids (palmitoleic, 6Z,9Z,12Z,15Z‐octadecatetraenoic acid, arachidonic acid, eicosapentaenoic acid, 7Z,10Z,13Z,16Z‐docosatetraenoic acid, and 4Z,7Z,10Z,13Z,16Z,19Z‐docosahexaenoic acid) resulted in substantially increased synthesis of unique tetraene compouds as detected by ultraviolet spectrophotometry and tentatively identified by GC/MS.
Furan fatty acids determined as oxidation products of conjugated octadecadienoic acid
Authors: Yurawecz Martin P. , Hood Jennifer K. , Mossoba Magdi M. , Roach John A. G. , Ku Yuoh
Published: November 2006

The objective of this study was to identify oxidation products of conjugated linoleic acid (CLA), a series of octadecadienoic acids with conjugated double bonds, which have been reported to have antioxidant and anticarcinogenic properties. Reference materials of CLA were oxidized in different concentrations of water/methanol; for example, 0.5 g octadecadienoic acid was dissolved in 50 mL methanol, and 100 mL water was added; this suspension was heated at 50°C and continuously aerated. Aliquots of 5 mL were taken over time, extracted with ether, treated with diazomethane and examined by gas chromatography/mass spectrometry and/or gas chromatography with flame‐ionization detection. Products identified included the following furan fatty acids (FFAs): 8,11‐epoxy‐8,10‐octadecadienoic; 9,12‐epoxy‐9,11‐octadecadienoic; 10,13‐epoxy‐10,12‐octadecadienoic; and 11,14‐epoxy‐11,13‐octadecadienoic. Conjugated dienes should be considered as a possible source of FFAs, and CLA may have products common to furans in their overall oxidative scheme.
Reinvestigation of the antioxidant properties of conjugated linoleic acid
Authors: van den Berg Jeroen J. M. , Cook Nancy E. , Tribble Diane L.
Published: November 2006

Despite repeated suggestions that antioxidant activity of conjugated linoleic acid (CLA), a collective of conjugated dienoic isomers of linoleic acid, underlies its reported anticarcinogenic and antiatherosclerotic effects, the antioxidant properties of CLA remain ill‐defined. Therefore, this study was undertaken to gain more insight into the mechanism of potential CLA antioxidant activity. It was tested whether CLA could protect membranes composed of 1‐palmitoyl‐2‐linoleoyl phosphatidylcholine (PLPC) from oxidative modification under conditions of metal ion‐dependent or‐independent oxidative stress. Progress of oxidation was determined by direct spectrophotometric measurement of conjugated diene formation and by gas chromatographic/mass spectrometric analysis of fatty acids. The oxidative susceptibility of CLA was higher than that of linoleic acid, and comparable to arachidonic acid. When oxidation of PLPC (1.0 mM) was initiated using the lipid‐soluble 2,2′‐azobis(2,4‐dimethylvaleronitrile) or the water‐soluble 2,2′‐azobis(2‐amidinopropane) hydrochloride, the radical scavengers vitamin E and butylated hydroxytoluene (BHT) at 0.75 μM efficiently inhibited PLPC oxidation, as evident from a clear lagphase. In contrast, 0.75 μM CLA did not have any significant effect on PLPC oxidation. Inhibition of PLPC oxidation by higher concentrations of CLA appeared due to competition, not to an antioxidant effect. When oxidation of PLPC was initiated by hydrogen peroxide/Fe2+ (500 μM/0.05–20 μM), both vitamin E (1 μM) and ethylene glycol‐bis(aminoethyl ether) tetraacetic acid (50 μM) efficiently inhibited PLPC oxidation. However, CLA (1–50 μM) did not show a clear protective effect under any of the conditions tested. We conclude that CLA, under these test conditions, does not act as an efficient radical scavenger in any way comparable to vitamin E or BHT. CLA also does not appear to be converted into a metal chelator under metal‐ion dependent oxidative stress, as had previously been suggested. On the basis of our observations, a role for CLA as an antioxidant does not seem plausible.
Studies on the mechanism of the ursodeoxycholic acid‐induced increase in hepatic low‐density lipoprotein binding
Authors: Bouscarel Bernard , Caryak Susan , Robins Sander J. , Fromm Hans
Published: November 2006

Previously, we have shown, in golden Syrian hamsters, that chronic feeding of ursodeoxycholic acid (UDCA), in contrast to that of its 7α‐epimer, chenodeoxycholic acid (CDCA), produced a significant increment in hepatic low‐density lipoprotein (LDL) uptake, despite similar suppression of bile acid synthesis by both bile acids. Evidence for a direct effect of this bile acid on hepatic LDL metabolism was shownin vitro, with isolated hamster hepatocytes, suggesting that this effect was unique to UDCA and specific for receptor‐mediated LDL catabolism. The aim of the present study was to define the cellular mechanism(s) associated with this phenomenon, using male golden Syrian hamsters. Regardless of chronic exposure of the liver to either UDCA or CDCA, acute incubation with UDCA consistently resulted in an increase of LDL binding to isolated hepatocytes by 15 to 40%. Furthermore, chronic treatment with either UDCA or CDCA did not result in alterations in lipoprotein particle composition. Likewise, incubation of hepatocytes with UDCA was not associated with a change of the membrane lipid composition. In isolated liver membrane fractions, UDCA increased both the maximum number of LDL binding sites and the affinity constant for LDL by around 35% suggesting an interaction of UDCA with the LDL receptor, at the plasma membrane level, independent of an effect on receptor cycling. The results of the studies support a role for UDCA in the recruitment of cryptic LDL receptors from a cellular membrane pool, possibly due to the unique localization of UDCA in the plasma membrane lipid bilayer.
Carbohydrate type and amount alter intravascular processing and catabolism of plasma lipoproteins in guinea pigs
Authors: Fernandez Maria Luz , Conde A. Karin , Ruiz Laura R. , Montano Carlos , Ebner John , McNamara Donald J.
Published: November 2006

To test the effects of exchanging dietary complex and simple carbohydrate for fat calories on lipoprotein metabolism, guinea pigs were fed two different fat/carbohydrate ratios: 2.5∶58% (w/w) or 25∶29% (w/w) with either sucrose or starch as the carbohydrate source. Animals fed high‐fat had higher plasma low‐density lipoprotein (LDL) and hepatic cholesterol concentrations than animals fed low‐fat diets (P<0.01). The cholesteryl ester content per particle was higher, and the number of triacylglycerol (TAG) molecules was lower in very low density lipoprotein (VLDL) and LDL from animals fed high‐fat diets. Intake of high‐fat/sucrose resulted in higher plasma LDL concentrations than intake of high‐fat/starch, and animals fed low‐fat/starch had the highest plasma TAG concentrations associated with VLDL particles containing more TAG molecules, as well as a TAG‐enriched LDL. The activity of plasma lecithin cholesteryl:acyl transferase (LCAT) was highest in animals fed high‐fat/sucrose, and heart lipoprotein lipase (LPL) activity was higher in animals fed high‐fat diets. Hepatic apoprotein B/E (apo B/E) receptor number (Bmax) was increased 21% with low‐fat diets (P<0.01). These results suggest that the hypercholesterolemia induced by high‐fat and by sucrose intake are associated with a higher plasma LCAT activity which results in a cholesteryl ester‐enriched VLDL which, by the action of LPL, might be more readily converted to LDL through the delipidation cascade leading to downregulation of hepatic apo B/E receptors. The hypertriglyceridemia associated with low‐fat intake may result from increased production of VLDL TAG, which would explain the increased TAG content and the higher TAG/CE ratio of VLDL from animals fed the low‐fat/starch diet.
Dietary fatty acids, membrane transport, and oxidative sensitivity in human erythrocytes
Authors: Mills David E. , Murthy Mahadev , Galey William R.
Published: November 2006

This study examined effects of dietary n−3 fatty acids on age‐related changes in erythrocyte anion transport and susceptibility to oxidation. Blood was drawn from healthy adult volunteers before and after six weeks' supplementation (nine/group) with 4.0 g/day of safflower oil (containing 2.9 g n−6 fatty acids) or fish oil (containing 1.2 g long‐chain n−3 fatty acids). Following density separation of young and old erythrocytes, membrane anion transport and cell membrane lipid composition were measured. Oxidative damage was measured in erythrocyte ghosts exposed to a free radical generator. Fish oil significantly increased 16∶0 and 20∶5n−3 in ghosts of both young and old cells, and 22∶5n−3 and 22∶6n−3 in old cells alone. Safflower oil increased 16∶0, 18∶0, 18∶1n−9, and 22∶5n−6 in ghosts of young cells only. The age‐dependent increase in membrane anion transport (P<0.01) was decreased by dietary fish oil supplementation, but not by safflower oil supplementation. Safflower oil and fish oil increased the susceptibility of both young and old erythrocytes to oxidative damage by free radical generation (P<0.001).
Separation of γ‐ and α‐linolenic acid containing triacylglycerols by capillary supercritical fluid chromatography
Authors: Manninen Pekka , Laakso Päivi , Kallio Heikki
Published: November 2006

The separation of γ‐ and α‐linolenic acid containing triacylglycerols with an identical acyl carbon number and degree of unsaturation was obtained on capillary supercritical fluid chromatography using a 25% cyanopropyl−75% methylpolysiloxane stationary phase. The resolution of 1,3‐dioleoyl‐2‐γ‐linolenoyl‐sn‐glycerol and 1,3‐dioleoyl‐2α‐linolenoyl‐sn‐glycerol was 1.35 on a 10 m×50 μm i.d. column, whereas the resolution was enhanced to 1.66 by combining two 10‐meter columns in series. The difference in the position of double bonds in one linolenic acid residue of triacylglycerols resulted in two series of peaks in the separation of alpine currant (Ribes alpinum) and black currant (R. nigrum) seed oils. The use of the 10‐meter column was found to be appropriate for the screening of the triacylglycerol profile in both seed oils studied.
Lymphatic fatty acids from rats fed human milk and formula supplemented with fish oil
Authors: Clark Richard M. , She Li
Published: November 2006

Absorption of long‐chain polyunsaturated fatty acids from human milk and formula supplemented with fish oil was studied to determine if the distribution route into lymphatic triacylglycerol (TAG) and phospholipid (PL) varies with the dietary source. Rats were intraduodenally infused with human milk or formula containing graded amounts of fish oil (0, 0.5, or 1.0 g/100 mL), and the mesenteric lymph was collected. Arachidonic acid (20∶4n−6) levels in lymphatic TAG and PL were highest from animals fed human milk. In the animals infused with formula containing fish oil, as the amount of eicosapentaenoic acid (EPA, 20∶5n−3) infused increased, there was essentially an equal increase of EPA associated with both lymphatic TAG and PL. Animals intraduodenally infused with human milk or formula without fish oil had only minor levels (less than 1%) of EPA in the lymph. In the fish oil‐treated animals, as the amount of docosahexaenoic acid (DHA, 22∶6n−3) infused increased, there was a 16‐fold increase in DHA associated with lymphatic TAG, but only a 3‐fold increase in DHA associated with lymphatic PL. The highest level of DHA in rats infused with human milk was observed in lymphatic PL. Hence, fish oil can be added to formula as a source of long‐chain polyunsaturated fatty acids, but the distribution of fatty acids into lymphatic TAG and PL is not the same as that observed with human milk.
9‐cis β‐carotene in human plasma and blood cells after ingestion of β‐carotene
Authors: Tamai Hiroshi , Morinobu Takao , Murata Takuji , Manago Mitsuhiro , Mino Makoto
Published: November 2006

For 44 wk, thirty male volunteers were given daily either 60 mg of synthesized all‐trans β‐carotene, a naturally‐occurring β‐carotene derived fromDunaliella bardawil, or a placebo. Basal levels of 9‐cis β‐carotene in plasma, platelets, and mononuclear cells were 10, 20 and 25% of those of the all‐trans form, respectively. The plasma levels reached a maximum after two weeks of administration and plateaued thereafter in the subjects who took the β‐carotene preparations. The all‐trans β‐carotene level in the subjects given the synthesized all‐trans form was almost twice that for theDunaliella preparation. The plasma 9‐cis level was found to be higher in the all‐trans β‐carotene group than in theDunaliella group, despite no intake of the 9‐cis form in the all‐trans group and the higher intake of the 9‐cis form in theDunaliella group. This finding suggests that isomerization of the all‐trans form to the 9‐cis form may occur in the body either during or after absorption.
Sesamin (a compound from sesame oil) increases tocopherol levels in rats fedad libitum
Authors: Kamal‐Eldin Afaf , Pettersson Dan , Appelqvist Lars‐Åke
Published: November 2006

Six groups of rats were fed diets low, but adequate, in α‐tocopherol but high in γ‐tocopherol. The six diets differed only in their contents (0, 0.25, 0.5, 1.0, 2.0, and 4.0 g/kg, respectively) of sesamin, a lignan from sesame oil. After four weeks ofad libitum feeding, the rats were sacrificed and the concentrations of α‐ and γ‐tocopherols were measured in the plasma, livers, and lungs. Sesamin‐feeding increased γ‐tocopherol and γ‐/α‐tocopherol ratios in the plasma (P<0.05), liver (P<0.001), and lungs (P<0.001). The increase was non‐significant for α‐tocopherol. Thus, sesamin appears to spare γ‐tocopherol in rat plasma and tissues, and this effect persists in the presence of α‐tocopherol, a known competitor to γ‐tocopherol. This suggests that the bioavailability of γ‐tocopherol is enhanced in phenol‐containing diets as compared with purified diets.
Inhibition of cardiolipin biosynthesis in the hypoxic rat heart
Authors: Cheng Philip , Hatch Grant M.
Published: November 2006

Cardiolipin is the principal polyglycerophospholipid in the heart. The effect of hypoxia on cardiolipin biosynthesis was investigated in isolated rat hearts perfused in the Langendorff mode. Hearts were pulsed‐labeled for 60 min with 0.1 mM [1,(3)‐3H]glycerol in Krebs Henseleit buffer saturated with either 95% O2/5% CO2 (control) or 95% N2/5% CO2 (hypoxic). Radioactivity incorporated into phosphatidylglycerol and cardiolipin were reduced 88% (P<.05) and 79% (P<.05), respectively, in hypoxic hearts compared to controls. In other experiments, hearts were pulse‐labeled for 15 min with 1.4 mM [32P]Pi in Krebs Henseleit buffer saturated with 95% O2/5% CO2 and subsequently perfused for 60 min under control or hypoxic conditions. The radioactivity incorporated into CDP‐1,2‐diacyl‐sn‐glycerol, phosphatidylglycerol, and cardiolipin were reduced 61% (P<.05), 71% (P<.05), and 70% (P<.05), respectively, in the hypoxic hearts compared to controls, indicating a decreased formation of CDP‐1,2‐diacyl‐sn‐glycerol in the hypoxic heart. The activities of the enzymes involved in cardiolipin biosynthesis and the cardiac pool sizes of cardiolipin, phosphatidylglycerol, and CDP‐1,2‐diacyl‐1,2‐diacyl‐sn‐glycerol were unaltered between hypoxic and control hearts. In contrast, cardiac adenosine‐5′‐triphosphate and CPT levels were decreased 94% (P<.05) and 92% (P<.05), respectively, in hypoxic hearts compared to controls. We postulate that the biosynthesis of the cardiac polyglycerophospholipid cardiolipin may be inhibited by a decreased adenosine‐5′‐triphosphate and cytidine‐5′‐triphosphate level in the heart.
Absorption of triglycerides with defined or random structure by rats with biliary and pancreatic diversion
Authors: Christensen Michael Søberg , Müllertz Anette , Høy Carl‐Erik
Published: November 2006

Fat absorption may be compromised by pancreatic or bile insufficiency, resulting in low uptake of essential fatty acid and energy. Using a rat model of malabsorption, we examined the absorption of defined triglycerides with medium‐chain fatty acids (MCFA) in thesn‐1,3 positions and essential fatty acids in thesn‐2 position (MLM) compared to other fats. The thoracic duct was cannulated for collection of lymph, and the common bile and pancreatic duct was cannulated to divert both the pancreatic juice and bile. The rats were given a single bolus of triglyceride as a taurocholate emulsion. Fat absorption was measured from collected lymph samples. The triglycerides administered were a defined triglyceride, MLM [mainly (8∶0/10∶0)‐(18∶2n−6)‐(8∶0/10∶0)], a similar triglyceride subjected to chemical randomization, a mixture of medium‐chain triglycerides and soybean oil, and soybean oil, respectively. The first three triglycerides had approximately 36 wt% linoleic acid (18∶2n−6) content. Administration of defined triglyceride was followed by significantly higher lymphatic level (wt%) of 18∶2n−6 (P<0.01) as well as a relative enhancement in mol% of 18∶2n−6 (P<0.05) compared to the other triglycerides. Lymphatic absorption of MCFA was similar in the three first groups but not as efficient as for long‐chain fatty acids. Our results indicate that defined triglycerides thus may provide a means to increase absorption of essential fatty acids in fat malabsorption, such as that seen in cystic fibrosis, or for pre‐term infants.
Sources of triacylglycerol accumulation in livers of rats fed a cholesterol‐supplemented diet
Authors: Liu Chuan‐Hsiu , Huang Ming‐ta , Huang Po‐Chao
Published: November 2006

The source of free fatty acids (FFA) and the pathways contributing to the accumulation of neutral fats in livers of rats fed a cholesterol‐enriched diet were investigated in this report. Supplementation with 1% cholesterol in the diet for four weeks resulted in hepatomegaly in the rats. The contents of cholesterol and triacylglycerols (TG) per gram liver measured in rats fasted overnight increased by 48 mg (∼tenfold) and 66 mg (∼fourfold), respectively. The activities of glycerophosphate acyltransferase and diacylglycerol acyltransferase, the two key enzymes for TG synthesis in liver microsomes, were found to increase by 23 and 19%, respectively, in the cholesterol‐fed rats. The secretion of plasma TG present predominantly in very low density lipoprotein was found to decrease by ∼30%. The incorporation of tritium from tritiated water in liver FFA increased by twofold in rats fed the cholesterol‐supplemented diet, whereas the activity of CPT I in liver mitochondria decreased by 23%. The uptake of plasma FFAin vivo in livers of fasted rats maintained on the cholesterol‐supplemented diet decreased by 60%. Our data thus indicate that the excess TG accumulated in livers of rats fed the cholesterol‐enriched diet resulted from increased synthesis and decreased secretion of TG. To meet the demand of fatty acids for this purpose,de novo lipogenesis increased, whereas β‐oxidation decreased. Although difference in the uptake of extrahepatic FFA may be discounted, a difference in the uptake of chylomicron remnants between the control and cholesterol‐fed rats may not be ruled out.
Effects of highly hydrogenated soybean oil and cholesterol on plasma, liver cholesterol, and fecal steroids in rats
Authors: Kamei Masaharu , Ohgaki Sumiko , Kanbe Tamotsu , Niiya Isao , Mizutani Haruo , Matsui‐Yuasa Isao , Otani Shuzo , Morita Shigeru
Published: November 2006

We investigated the relationship between dietary highly hydrogenated soybean oil (HSO) and cholesterol transport in rats. In the first study, to examine the effects of cholesterol transport of different concentrations of HSO in dietary oil, rats were given one of the three diets containing 0, 25, or 50% HSO in dietary oil with cholesterol (5 g/kg diet) or a diet without HSO and cholesterol for 22 d. Feeding the high concentration of HSO prevented the increase in plasma total cholesterol, hepatic total lipids, and cholesterol and the decrease in high‐density lipoprotein‐cholesterol, which were caused by dietary cholesterol. Moreover, HSO increased the fecal excretion, fecal lipids, and steroids in a dose‐dependent manner. In the second study, to examine the effects on cholesterol transport of redistribution of stearic acid in the triacylglycerol species contained in HSO, rats were given one of the six diets containing HSO (distearoylmonoacylglycerol and tristearoylglycerol)‐rich, monostearoylglycerol‐rich, or palmitic acid‐rich oil with/without cholesterol (5 g/kg diet), for 30 d. Whereas the accumulation of cholesterol in the body was reduced, cholesterol excretion was enhanced effectively in rats given the HSO‐rich diet compared with rats given the monostearoylglycerol‐rich diet. These results suggested that not only the high concentration of stearic acid but also its uneven distribution in HSO‐triacylglycerol contributed to the reduction in intestinal cholesterol absorption in rats.
Inhibition of gonadotropin‐stimulated ovarian steroid production by polyunsaturated fatty acids in teleost fish
Authors: Mercure François , Van Der Kraak Glen
Published: November 2006

The effects of the polyynsaturated fatty acids (PUFAs)—eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA)—onin vitro steroid production by full‐grown prematurational ovarian follicles from goldfish and rainbow trout were investigated. EPA and DHA inhibited gonadotropin‐stimulated testosterone production in a dose‐related manner, but AA was inhibitory only at the highest dose tested (400 μM). AA alone stimulated testosterone production by increasing cAMP production, but the effects of other PUFAs alone were marginal. The inhibitory actions by PUFAs were not restricted to long‐chain PUFAs, as linoleic and linolenic acids had similar actions in the goldfish. The inhibitory action of EPA on testosterone production was reversible upon removal of the PUFA from medium. Testosterone production stimulated by the addition of the cAMP analogues, dibutyryl cAMP, and 8‐bromo cAMP, was attenuated by PUFAs, suggesting that they act at a site distal to cAMP formation. A post‐cAMP site regulating cholesterol availability may be involved as testosterone production induced by addition of 25OH‐cholesterol was not affected by the PUFAs in either fish species. Together, these findings underscore the importance of lipids in ovarian physiology and suggest that PUFAs may participate in the regulation of ovarian steroidogenesis in teleost fish.