bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of high‐resolution, two‐dimensional 1H and 13C nuclear magnetic resonance techniques to the characterization of lipid oxidation products in autoxidized linoleoyl/linolenoylglycerols
Authors: Silwood Christopher J. L. , Grootveld Martin
Published: November 2006

Subjection of polyunsaturated fatty acid (PUFA)‐rich culinary oils to standard frying episodes generates a range of lipid oxidation products (LOP), including saturated and α,β‐unsaturated aldehydes which arise from the thermally induced fragmentation of conjugated hydroperoxydiene precursors. Since such LOP are damaging to human health, we have employed high‐resolution, two‐dimensional 1H‐1H relayed coherence transfer, 1H‐1H total correlation, 1H‐13C heteronuclear multiple quantum correlation, and 1H‐1H J‐resolved nuclear magnetic resonance (NMR) spectroscopic techniques to further elucidate the molecular structures of these components present in (i) a model linoleoylglycerol compound (1,3‐dilinolein) allowed to autoxidize at ambient temperature and (ii) PUFA‐rich culinary oils subjected to repeated frying episodes. The above techniques readily facilitate the resolution of selected vinylic and aldehydic resonances of LOP which appear as complex overlapping patterns in conventional one‐dimensional spectra, particularly when employed in combination with solvent‐induced spectral shift modifications. Hence, much useful multi‐component information regarding the identity and/or classification of glycerol‐bound conjugated hydroperoxydiene and hydroxydiene adducts, and saturated and α,β‐unsaturated aldehydes, present in autoxidized PUFA matrices is provided by these NMR methods. Such molecular information is of much value to researchers investigating the deleterious health effects of LOP available in the diet.
Increased diaphragm expression of GLUT4 in control and streptozotocin‐diabetic rats by fish oil‐supplemented diets
Authors: Girón María D. , Salto Rafael , Hortelano Paloma , Periago José L. , Vargas Alberto M. , Suárez María D.
Published: November 2006

Dietary fat intake influences plasma glucose concentration through modifying glucose uptake and utilization by adipose and skeletal muscle tissues. In this paper, we studied the effects of a low‐fat diet on diaphragm GLUT4 expression and fatty acid composition in control and streptozotocin‐induced diabetic rats. Control as well as diabetic rats were divided into three different dietary groups each. Either 5% olive oil, 5% sunflower oil, or 5% fish oil was the only fat supplied by the diet. Feeding these low‐fat diets for 5 wk induced major changes in fatty acid composition, both in control and in diabetic rats. Arachidonic acid was higher in diabetic olive and sunflower oil‐fed rats with respect to fish oil‐fed, opposite to docosahexaenoic acid which was higher in diabetic fish oil‐fed rats with respect to the other two groups. Animals receiving a fish oil diet had the lowest plasma glucose concentration. GLUT4 expression in diaphragm, as indicated by GLUT4 protein and mRNA, is modulated both by diabetes and by diet fatty acid composition. Diabetes induced a decrease in expression in all dietary groups. Plasma glucose levels correlated well with the increased amount of GLUT4 protein and mRNA found in fish oil‐fed groups. Results are discussed in terms of the influence that arachidonic and n−3 polyunsaturated fatty acids may exert on the transcriptional and translational control of the GLUT4 gene.
Effects of cholestyramine on hepatic cholesterol 7α‐hydroxylase and serum 7α‐hydroxycholesterol in the hamster
Authors: Kuroki Syoji , Naito Tokio , Chijiiwa Kazuo , Tanaka Masao
Published: November 2006

Cholestyramine increases activities of hepatic cholesterol 7α‐hydroxylase and serum levels of 7α‐hydroxycholesterol. To examine if serum 7α‐hydroxycholesterol levels parallel with enzyme activity, 0, 0.5, 1, 2, 4, and 10% of cholestyramine was administered to female golden Syrian hamsters for 28 d in the dose‐dependent study, and 2% cholestyramine for 0, 1, 3, 7, 14, 21, and 28 d in the time‐dependent study. In the dose‐dependent study, hepatic and serum cholesterol levels were significantly decreased dose‐dependently when more than 0.5% of cholestyramine was fed for 28 d. Cholestyramine increased the cholesterol 7α‐hydroxylase activity in a dose‐dependent manner, while the serum 7α‐hydroxycholesterol level was essentially unchanged. No correlation was found between the serum level and the hepatic enzyme activity. In the time‐dependent study, hepatic and serum cholesterol levels markedly decreased when 2% cholestyramine was fed for longer than 3 d. The serum triglyceride level increased significantly for the first 7 d and then decreased. Cholesterol 7α‐hydroxylase activity increased significantly as early as day 1, reached maximum activity level on day 7, and then kept the significantly high values until day 28. The serum 7α‐hydroxycholesterol level significantly increased for the first 7 d and decreased to the pretreatment level thereafter. 7α‐Hydroxycholesterol levels significantly correlated with serum cholesterol and triglyceride levels. We conclude that the serum 7α‐hydroxycholesterol level does not always reflect the activity of hepatic cholesterol 7α‐hydroxylase, when cholesterol metabolism is severely disturbed by cholestyramine.
Incorporation of [1‐13C]oleate into cellular triglycerides in differentiating 3T3L1 cells
Authors: Guo Wen , Choi Ji‐Kyung , Kirkland James L. , Corkey Barbara E. , Hamilton James A.
Published: November 2006

Oleate is one of the most abundant dietary fatty acids, and much remains to be learned about its metabolism in fat cells. We studied the incorporation of exogenous [1‐13C]‐oleate into triglycerides (TG) in differentiating 3T3L1 preadipocytes using 13C NMR spectroscopy. The quantity of oleate incorporated into TG was found to increase as preadipocytes differentiated into fat cells. The ratio of unesterified [1‐13C]oleate to total stored fatty acids was higher in less differentiated cells, and declined at later stages of differentiation as cells accumulated fatty acids through de novo synthesis. When added as the only exogenous fatty acid, oleate was largely esterified at the sn‐2 position. When equimolar unlabeled linoleate was co‐provided at the same time, the ratio of [1‐13C]oleate esterified at the sn‐1,3 position increased, implying competition between linoleate and oleate for esterification, especially at the sn‐2 position. When cells pre‐enriched with [1‐13C]oleate (esterified to TG) were treated with isoproterenol, a lipolytic agent, most of the [1‐13C]oleate was still found in TG, despite a high rate of lipolysis determined by measuring glycerol release. This implies extensive re‐esterification of the oleate released by lipolysis.
The effect of conjugated linoleic acid on the antioxidant enzyme defense system in rat hepatocytes
Authors: Cantwell H. , Devery R. , O'Shea M. , Stanton C.
Published: November 2006

Short‐term effects of physiological concentrations of conjugated linoleic acid (CLA) on membrane integrity, metabolic function, cellular lipid composition, lipid peroxidation, and antioxidant enzymes were examined using rat hepatocyte suspension cultures. Incubation with CLA (5–20 ppm) for 3 h decreased the ability of hepatocyte plasma membranes to exclude trypan blue by approximately 25%, and caused leakage of cytosolic lactate dehydrogenase (LDH) into the medium. The significant decrease (P<0.02) in hepatocyte viability as measured by LDH leakage during cell incubation with 10 and 20 ppm CLA was not associated with significant changes in cellular ATP content. Protein synthesis in hepatocytes was elevated (P<0.05) in the presence of 5 and 10 ppm CLA, but at a higher concentration (20 ppm), protein synthesis was similar to that of control cells. Gluconeogenesis was maintained in cells incubated with lower concentrations of CLA (5 and 10 ppm) but was decreased (P<0.02) at the higher concentration. Incubation with 20 ppm CLA for 3 h did not affect the specific activity of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase, the rate‐limiting enzyme of cholesterol synthesis. Both cis‐9,trans‐11/trans‐9,cis‐11, and cis‐10,trans‐12/trans‐10,cis‐12 isomers of CLA were incorporated to a similar level into hepatocytes. Levels ranged from 3.9 to 4.1%, respectively, of total fatty acids in neutral lipids, and from 0.7 to 0.8%, respectively, of total fatty acids in phospholipids. Cellular lipid peroxidation remained unchanged in the presence of CLA (5–20 ppm), despite significant inhibition (P<0.05) of superoxide dismutase. Catalase activity was maintained near control levels in the presence of 5 and 10 ppm CLA but was significantly decreased in the presence of 20 ppm CLA. Glutathione peroxidase activity was significantly decreased in the presence of 10 ppm CLA. The apparent sensitivity of the antioxidant enzyme defense system of liver cells to CLA, coupled with the lack of effect of CLA on lipid peroxidation in cells, suggests that cytotoxic effects of CLA as described by LDH leakage and decreased gluconeogenesis were not mediated by a prooxidant action in hepatocytes.
Positional analysis of triglycerides and phospholipids rich in long‐chain polyunsaturated fatty acids
Authors: Amate L. , Ramírez M. , Gil A.
Published: November 2006

Four sources of long‐chain polyunsaturated fatty acids (LCP) differing in their chemical structure (triglycerides or phospholipids) and in their origin (tuna triglycerides, fungal triglycerides, egg phospholipids, and pig brain phospholipids) were analyzed to determine the distribution of the component fatty acids within the molecule. Lipase and phospholipase A2 hydrolysis was performed to obtain 2‐monoacylglycerols and lysophospholipids, respectively, which allowed us to determine the distribution of fatty acids between the sn‐2 and sn‐1,3 positions of triglycerides or between the sn‐1 and sn‐2 position of phospholipids. Fatty acids in the LCP sources analyzed were not randomly distributed. In tuna triglycerides, half of the total amount of 22∶6n−3 was located at the sn‐2 position (49.52%). In fungal triglycerides, 16∶0 and 18∶0 were esterified to the sn‐1,3 (92.22% and 91.91%, respectively) 18∶1 and 18∶2 to the sn‐2 position (59.77% and 62.62%, respectively), and 45% of 20∶3n−6 and only 21.64% of 20∶4n−6 were found at the sn‐2 position. In the lipid sources containing phospholipids, LCP were mainly esterified to the phosphatidylethanolamine fraction. In egg phospholipids, most of 20∶4n−6 (5.50%, sn‐2 vs. 0.91%, sn‐1) and 22∶6n−3 (2.89 vs. 0.28%) were located at the sn‐2 position. In pig brain phospholipids, 22∶6n−3 was also esterified to the sn‐2 (13.20 vs. 0.27%), whereas 20∶4n−6 was distributed between the two positions (12.35 vs. 5.86%). These results show a different fatty acid composition and distribution of dietary LCP sources, which may affect the absorption, distribution, and tissue uptake of LCP, and should be taken into account when supplementing infant formulas.
Synthesis of 9Z,11E‐octadecadienoic and 10E,12Z‐octadecadienoic acids, the major components of conjugated linoleic acid
Authors: Chen Chien‐An , Lu Wei , Sih Charles J.
Published: November 2006

Linoleic acid was efficiently converted into the two major components of conjugated linoleic acid, 9Z,11E‐octadecadienoic (1a) and 10E,12Z‐octadecadienoic acid (1b) using either the superbase (n‐butyllithium/potassium tert‐butoxide) or by simply refluxing with KOH in 1‐butanol. In turn, 1a and 1b were separated from each other using the lipase from Aspergillus niger via stereoselective esterification in 1‐butanol. This enzyme has a preference for the 9Z,11E isomer, 1a, and has excellent selectivity. This method has allowed the ready preparation of gram quantities of 1a and 1b in their highly purified forms, which are not readily accessible by current methods.
Lipidemic effects of an interesterified mixture of butter, medium‐chain triacylglycerol and safflower oils
Authors: Mascioli Edward A. , McLennan Christine E. , Schaefer Ernst J. , Lichtenstein Alice H. , Høy Carl‐Erik , Christensen Michael S. , Bistrian Bruce R.
Published: November 2006

The objective of this study was to determine if the positional structure of dietary triacylglycerol affected lipidemic responses. Thirty healthy adults (16 men and 14 postmenopausal women) with low‐density lipoprotein cholesterol (LDL‐C) concentrations >3.37 mM (130 mg/dl) enrolled in a prospective, single‐blind, cross‐over outpatient clinical trial that consisted of two 5‐wk dietary phases. After baseline screening, subjects were instructed to follow individualized meal plans (weight maintenance diets with 36% of total energy from fat, half of which was from a test oil) and randomized to receive either butter (B) or an interesterified mixture (IM) of butter, medium‐chain triacylglycerol (MCI), and safflower oils. Blood drawn during weeks 5 and 10 of feeding was analyzed for total cholesterol (TC), high density lipoprotein cholesterol (HDL‐C), LDL‐C, and triacylglycerols (TAG). Mean plasma levels of TC (B, 6.98±1.06 mM; IM, 7.09±1.20 mM), HDL‐C (B,1.30±0.35 mM; IM, 1.29±0.34 mM), and LDL‐C (B, 4.91±0.95 mM; IM, 492±1.10 mM) were not significantly different between the two dietary treatments. Mean TAG levels were higher for the interesterified B‐MCT mixture (B, 1.75±0.72 mM; IM, 1.96±0.86 mM, P<0.05). We conclude that an IM of B, MCT and safflower oils as compared to native B has no appreciable effect on plasma cholesterol concentrations but is associated with a modest rise in plasma TAG.
Hepatic zonation of the formation and hydrolysis of cholestery esters in periportal and perivenous parenchymal cells
Authors: Romero José Ramón , Fresnedo Olatz , Isusi Efrén , Barrionuevo Javier , Ochoa Begoña
Published: November 2006

The periportal (PP) and perivenous (PV) zones of the liver acinus differ in enzyme complements and capacities for cholesterol and bile acid synthesis and other metabolic processes. The aim of this investigation was to determine the acinar distribution of the catalytic activity of the enzymes governing the formation and hydrolysis of cholesteryl esters using PP and PV hepatocytes from normal or cholestyramine‐fed rats. The hepatocyte subpopulations were isolated by centrifugal elutriation, characterized according to the distribution pattern of a number of cell parameters and marker enzymes, and assayed for acyl‐CoA: cholesterol acyltransferase (ACAT) and lysosomal, cytosolic and microsomal cholesteryl ester hydrolase (CEH). In normally fed rats, no zonation was found in the activity of lysosomal CEH and ACAT, and the activity of both cytosolic and microsomal CEH zonated toward the PV zone of the acinus. Concentrations of free and esterified cholesterol in homogenates, cytosol, and microsomes of PP and PV cells were, however, similar. Cholestyramine raised significantly the PV/PP ratio of ACAT because of an exclusive PP reduction of activity and abolished the heterogeneity in microsomal CEH because of a greater inhibitory PV response, whereas the PV dominance of cytosolic CEH and the homogeneous distribution of lysosomal CEH were unaffected. These results demonstrated homogeneity within the liver acinus for the enzymatic degradation of endocyted lipoprotein‐derived cholesteryl esters, a structural zonation of the cytosolic CEH and a dynamic zonation of ACAT and the microsomal CEH, with a PV dominance of the enzymatic capacity for the degradation of stored cholesteryl esters in normal livers.
Acyltransferase activities in the yolk sac membrane of the chick embryo
Authors: Murray Alison M. B. , Denis Raphael , Speake Brian K.
Published: November 2006

The activities of some enzymes of glycerolipid synthesis and fatty acid oxidation were measured in subcellular fractions of the yolk sac membrane (YSM), an extra‐embryonic tissue that mediates the transfer of lipid from the yolk to the circulation of the chick embryo. The activities of monoacylglycerol acyltransferase and carnitine palmitoyl transferase‐1 in the YSM (respectively, 284.8±13.2 nmol/min/mg microsomal protein and 145.6±9.1 nmol/min/mg mitochondrial protein; mean ±SE; n=4) at day 12 of development appear to be the highest yet reported for any animal tissue. Also, the carnitine palmitoyl transferase‐1 of the YSM was very insensitive to inhibition by malonyl CoA. The maximal activities of glycerol‐3‐phosphate acyltransferase and diacylglycerol acyltransferase in the YSM (respectively, 26.7±2.2 and 36.1±2.1 nmol/min/mg microsomal protein) were also high compared with the reported values for various animal tissues. The very high enzymic capacity for glycerolipid synthesis supports the hypothesis that the yolk‐derived lipids are subjected to hydrolysis followed by reesterification during transit across the YSM. The monoacylglycerol pathway appears to be the main route for glycerolipid resynthesis in the YSM. The results also suggest that the YSM has the capacity to perform simultaneously β‐oxidation at a high rate in order to provide energy for the lipid transfer process.
Lipid composition of hepatocyte plasma membranes from geese overfed with corn
Authors: Cazeils J. L. , Bouillier‐Oudot M. , Auvergne A. , Candau M. , Babile R.
Published: November 2006

Twelve‐week‐old Landes male geese were overfed with corn for 21 d in order to induce liver steatosis (fatty liver). Lipid composition of hepatocyte plasma membranes from fatty livers was compared to that of lean livers obtained from geese fed a normal diet. The ratio cholesterol/phospholipids was higher in fatty hepatocyte plasma membranes (0.63 vs. 0.47), whereas the phospholipid/protein ratio was less than half. Overfeeding induced changes in fatty acid composition of hepatocyte plasma membranes, including a greater than twofold increase in the percentage of oleic acid (29.7 vs. 13.8%) and a somewhat lesser increase in lauric, palmitic, and palmitoleic acid contents of plasma membrane lipids of fatty livers. A concomitant reduction in the proportion of stearic acid (18.4 vs. 25.1%) was also observed. In fatty livers, the increased ratio of saturated to polyunsaturated fatty acids (PUFA) (1.5 vs. 1.0) was related to a significant decrease in PUFA content. Among all the PUFA, only the eicosatrienoic acid (20∶3n−9) percentage was increased by liver steatosis. Overfeeding with corn appeared to induce competition between de novo synthesized and dietary fatty acids incorporated in hepatocyte plasma membranes. This resulted in an accumulation of de novo synthesized monounsaturated and derived fatty acids in plasma membranes from overfed birds. A defect in the incorporation of linoleic acid and linoleic‐ and linolenic‐derived PUFA was observed despite the high proportion of these essential fatty acids in the diet. It was conclued that in overfed palmipeds, de novo hepatic lipogenesis prevails over dietary lipid intake to modulate lipid composition of the fatty liver plasma membrane.
Metabolism of trideuterated iso‐lignoceric acid in rats in Vivo and in human fibroblasts in culture
Authors: Poulos Alfred , Stockham Peter C. , Johnson David W. , Paton Barbara C. , Beckman Kaye , Singh Harmeet
Published: November 2006

Saturated very long chain fatty acids (fatty acids with greater than 22 carbon atoms; VLCFA) accumulate in peroxisomal disorders, but there is little information on their turnover in patients. To determine the suitability of using stable isotope‐labeled VLCFA in patients with these disorders, the metabolism of 22‐methyl[23,23,23‐2H3]tricosanoic (iso‐lignoceric) acid was studied in rats in vivo and in human skin fibroblasts in culture. The deuterated iso‐VLCFA was degraded to the corresponding 16‐ and 18‐carbon iso‐fatty acids by rats in vivo and by normal human skin fibroblasts in culture, but there was little or no degradation in peroxisome‐deficient (Zellweger's syndrome) fibroblasts, indicating that its oxidation was peroxisomal. Neither the 14‐, 20‐, and 22‐carbon iso‐fatty acids nor the corresponding odd‐chain metabolites could be detected. In the rat, the organ containing most of the iso‐lignoceric acid, and its breakdown products, was the liver, whereas negligible amounts were detected in the brain, suggesting that little of the fatty acid crossed the blood‐brain barrier. Our data indicate that VLCFA labeled with deuterium at the ω‐position of the carbon chain are suitable derivatives for the in vivo investigation of patients with defects in peroxisomal β‐oxidation because they are metabolized by the same pathways as the corresponding n‐VLCFA. Moreover, as iso‐VLCFA and their β‐oxidation products are readily separated from the corresponding n‐fatty acids by normal chromatographic procedures, the turnover of VLCFA can be more precisely measured.
Δ9 desaturase activity in bovine subcutaneous adipose tissue of different fatty acid compositiondesaturase activity in bovine subcutaneous adipose tissue of different fatty acid composition
Authors: Yang A. , Larsen T. W. , Smith S. B. , Tume R. K.
Published: November 2006

Two experiments were conducted to investigate the relationship between Δ9 desaturase (stearoyl‐coenzyme A desaturase) activity and fatty acid composition in subcutaneous adipose tissue from cattle of different backgrounds. In Experiment 1, subcutaneous adipose tissue samples were taken from carcasses of pasture‐fed cattle and feedlot cattle fed for 100, 200, or 300 d. Adipose tissue from pasture‐fed cattle had significantly lower total saturated fatty acids and higher total unsaturated fatty acids than feedlot cattle. Desaturase activity correspondingly was 60–85% higher in pasture‐fed cattle than in feedlot cattle. There was no difference in the fatty acid composition or desaturase activity among samples from the 100‐, 200‐, and 300‐d feedlot cattle. In Experiment 2, adipose tissue samples were collected from carcasses of feedlot cattle fed for 180 d with either a standard feedlot ration (control group), or a ration containing rumen‐protected cottonseed oil (CSO) for the last 70–80 d. Adipose tissue from the CSO‐fed cattle was more saturated than that from the control group, having significantly more 18∶0 and less 16∶1 and 18∶1. Correspondingly, adipose tissue from the CSO group had significantly lower desaturase activity. The elevated 18∶2 in adipose tissue from the CSO group confirmed that unsaturated fatty acids (including cyclopropenoid fatty acids) were protected from biohydrogenation. Further studies are needed to determine whether the repression of desaturase activity results from direct inhibition by cyclopropenoic acids or by higher dietary contents of 18∶2.
Lipase‐catalyzed fractionation of conjugated linoleic acid isomers
Authors: Haas Michael J. , Kramer John K. G. , McNeill Gerald , Scott Karen , Foglia Thomas A. , Sehat Najibulla , Fritsche Jan , Mossoba Magdi M. , Yurawecz Martin P.
Published: November 2006

The abilities of lipases produced by the fungus Geotrichum candidum to selectively fractionate mixtures of conjugated linoleic acid (CLA) isomers during esterification of mixed CLA free fatty acids and during hydrolysis of mixed CLA methyl esters were examined. The enzymes were highly selective for cis‐9,trans‐11–18∶2. A commercial CLA methyl ester preparation, containing at least 12 species representing four positional CLA isomers, was incubated in aqueous solution with either a commercial G. candidum lipase preparation (Amano GC‐4) or lipase produced from a cloned high‐selectivity G. candidum lipase B gene. In both instances selective hydrolysis of the cis‐9,trans‐11–18∶2 methyl ester occurred, with negligible hydrolysis of other CLA isomers. The content of cis‐9,trans‐11–18∶2 in the resulting free fatty acid fraction was between 94 (lipase B reaction) and 77% (GC‐4 reaction). The commercial CLA mixture contained only trace amounts of trans‐9,cis‐11–18∶2, and there was no evidence that this isomer was hydrolyzed by the enzyme. Analogous results were obtained with these enzymes in the esterification in organic solvent of a commercial preparation of CLA free fatty acids containing at least 12 CLA isomers. In this case, G. candidum lipase B generated a methyl ester fraction that contained >98% cis‐9,trans‐11–18∶2. Geotrichum candidum lipases B and GC‐4 also demonstrated high selectivity in the esterification of CLA with ethanol, generating ethyl ester fractions containing 96 and 80%, respectively, of the cis‐9,trans‐11 isomer. In a second set of experiments, CLA synthesized from pure linoleic acid, composed essentially of two isomers, cis‐9,trans‐11 and trans‐10,cis‐12, was utilized. This was subjected to esterification with octanol in an aqueous reaction system using Amano GC‐4 lipase as catalyst. The resulting ester fraction contained up to 97% of the cis‐9,trans‐11 isomer. After adjustment of the reaction conditions, a concentration of 85% trans‐10,cis‐12–18∶2 could be obtained in the unreacted free fatty acid fraction. These lipase‐catalyzed reactions provide a means for the preparative‐scale production of high‐purity cis‐9,trans‐11–18∶2, and a corresponding CLA fraction depleted of this isomer.
Enhancement of both reaction yield and rate of synthesis of structured triacylglycerol containing eicosapentaenoic acid under vacuum with water activity control
Authors: Han Jeong Jun , Yamane Tsuneo
Published: November 2006

Production of structured triacylglycerols (sTAG) containing eicosapentaenoic acid (EPA) at the sn‐1 (or 3) position using Lipozyme in a solvent‐free system was studied. Optimal water activity (aw) for the synthesis of the sTAG was investigated. Vacuum was applied to shift reaction equilibrium toward the synthesis reaction by removing by‐products. During vacuum application, the water level of the reaction system was controlled at the optimal level by addition of a suitable amount of water at a predetermined interval. Intermittent periodic addition of a suitable amount of water into the reaction mixture made the reaction rate faster than that without adding water. A molar yield of 89.7% of the targeted sTAG was obtained after 16 h reaction with aw control during the vacuum application as compared with the yield of 87.0% after 24 h of reaction without aw control during the vacuum application.
On the specificity of allene oxide cyclase
Authors: Ziegler Jörg , Wasternack Claus , Hamberg Mats
Published: November 2006

Jasmonic acid is a carbocyclic fatty acid that is biosynthesized from α‐linolenic acid in several steps. The formation of the ring structure of jasmonic acid is catalyzed by the enzyme allene oxide cyclase (EC 5.3.99.6) and involves the cyclization of an unstable allene oxide into the cyclopentenone 12‐oxo‐10,15(Z)‐phytodienoic acid. In this study, a number of allene oxides were generated, and their enzymatic and nonenzymatic cyclization into cyclopentenones was investigated. Nonenzymatic cyclization was observed with allene oxides having one pair of conjugated double bonds and an additional isolated double bond in the β,γ position relative to the epoxide group, i.e., the partial structure 4,5‐epoxy‐1,3,7‐octatriene. Enzymatic cyclization took place provided that this structural element was inserted in the fatty acid chain with its epoxide group in the n−6,7 position and the isolated double bond in the n−3 position. A number of oxygenated fatty acids having structural features in common with the natural allene oxides were tested as inhibitors of allene oxide cyclase. Fatty acids having an allene oxide structure in the n−6,7 position but lacking the double bond in the n−3 position, as well as fatty acids having a saturated epoxide group in the n−6,7 position, served as competitive inhibitors of the enzyme. Data on the substrate specificity of allene oxide synthase (EC 4.2.1.92) from corn seeds indicated that fatty acid hydroperoxides with a double bond at n−3 and with the hydroperoxide function at n−6 exhibit the highest affinity but the slowest reaction velocity.
Influence of diet on fatty acids of three subtropical fish, subfamily caesioninae (Caesio diagramma and C. tile) and family siganidae (Siganus canaliculatus)
Authors: Saito Hiroaki , Yamashiro Rieko , Alasalvar Cesarettin , Konno Toshiya
Published: November 2006

The total lipid and fatty acid compositions of tissues and the stomach contents of three subtropical marine fish species, subfamily Caesioninae, Caesio diagramma and C. tile, and family Siganidae Siganus canaliculatus, were investigated to clarify the differences between these species. Triacylglycerols (TAG) were the dominant depot lipids of the three species, whereas wax esters were found as a minor component. In particular, muscle lipids were found to contain mainly glycerol derivatives such as TAG and phospholipids. The major fatty acids identified in the three species were 16∶0, 18∶0, 18∶1n−9, and 22∶6n−3 (docosahexaenoic acid, DHA). In addition, noticeable levels of 16∶1n−7, 18∶1n−7, 20∶4n−6 (arachidonic acid, AA), and 20∶5n−3 (eicosapentaenoic acid) were found. DHA was the most abundant polyunsaturated fatty acid (PUFA) in the muscle and viscera lipids of the three species. The high DHA levels in the lipids of all the organs were found to be higher than those of the lipid extracted from the stomach contents of the three fishes. In addition, the specimens of S. canaliculatus contained significantly higher levels of AA in its tissues than did the other two species. A high AA content is unusual since such high levels of n−6 PUFA are rarely found in higher marine organisms. These levels may be due to its characteristic feeding pattern, because S. canaliculatus prefer and mainly feed on seaweed, which often contains high amounts of n−6 PUFA, such as linoleic acid (18∶2n−6) and AA.
An epoxy alcohol synthase pathway in higher plants: Biosynthesis of antifungal trihydroxy oxylipins in leaves of potato
Authors: Hamberg Mats
Published: November 2006

[1‐14C]Linoleic acid was incubated with a whole homogenate preparation of potato leaves (Solanum tuberosum 1., var. Bintje). The methyl‐esterified product was subjected to straight‐phase high‐performance liquid chromatography and was found to contain four major radioactive oxidation products, i.e., the epoxy alcohols methyl 10(S), 11(S)‐epoxy‐9(S)‐hydroxy‐12(Z)‐octadecenoate (14% of the recovered radioactivity) and methyl 12(R), 13(S)‐epoxy‐9(S)‐hydroxy‐10(E)‐octadecenoate (14%), and the trihydroxy derivatives methyl 9(S), 10(S), 11(R)‐trihydroxy‐12(Z)‐octadecenoate (18%) and methyl 9(S), 12(S), 13(S)‐trihydroxy‐10(E)‐octadecenoate (30%). The structures and stereochemical configurations of these oxylipins were determined by chemical and spectral methods using the authentic compounds as references. Incubations performed in the presence of glutathione peroxidase revealed that lipoxygenase activity of potato leaves generated the 9‐ and 13‐hydroperoxides of linoleic acid in a ratio of 95∶5. Separate incubations of these hydroperoxides showed that linoleic acid 9(S)‐hydroperoxide was metabolized into epoxy alcohols by particle‐bound epoxy alcohol synthase activity, whereas the 13‐hydroperoxide was metabolized into α‐ and γ‐ketols by a particle‐bound allene oxide synthase. It was concluded that the main pathway of linoleic acid metabolism in potato leaves involved 9‐lipoxygenase‐catalyzed oxygenation into linoleic acid 9(S)‐hydroperoxide followed by rapid conversion of this hydroperoxide into epoxy alcohols and a slower, epoxide hydrolase‐catalyzed conversion of the epoxy alcohols into trihydroxyoctadecenoates. Trihydroxy derivatives of linoleic and linolenic acids have previously been reported to be growth‐inhibitory to plant‐pathogenic fungi, and a role of the new pathway of linoleic acid oxidation in defense reactions against pathogens is conceivable.
Factors enhancing diacylglycerol acyltransferase activity in microsomes from cell‐suspension cultures of oilseed rape
Authors: Byers Susan D. , Laroche André , Smith Kevin C. , Weselake Randall J.
Published: November 2006

Several factors, including an unidentified endogenous component, were found to stimulate microsomal diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) from a microspore‐derived cell‐suspension culture of oilseed rape (Brassica napus L. cv. Jet Neuf). At a concentration of 25mM, MgSO4 and MgCl2 stimulated microsomal DGAT 25‐ and 10‐fold, respectively. AIP and CoA at concentrations of 2 and 1 mM stimulated the enzyme 2.4‐ and 12‐fold, respectively, although the effects were lessened in the presence of higher Mg2+ concentrations. Although microsomal DGAT activity was increased only slightly by the addition of exogenous sn‐1,2‐diacylglycerol to the reaction mixture, it was increased substantially by the addition of exogenous phosphatidate. sn‐Glycerol‐3‐phosphate and other phospholipids tested did not have this stimulatory effect. DGAT activity did not decrease when microsomes were incubated with ATP in the presence of the cytosolic fraction. This fraction, however, contained a small organic compound(s) that stimulated microsomal DGAT activity.
Effects of postnatal ethanol exposure on brain growth and lipid composition in n−3 fatty acid‐deficient and‐adequate rats
Authors: Ward G. R. , Xing H. ‐C. , Wainwright P. E.
Published: November 2006

The artificial rearing model was used to investigate the effects of short‐term exposure to ethanol on growth and fatty acid composition of forebrain (FB) and cerebellum (CB) during the brain growth spurt in either n−3 fatty acid‐adequate (AD) or n−3 deficient (DEF) rat pups. On postnatal day 5, offspring of female rats that had been fed AD or DEF diets from day 5 of life were assigned to three groups: members of two groups were gastrostomized and artificially fed formulas appropriate for their maternal history, and the third group (suckled control) was fostered to lactating dams of a similar dietary history. Half of the artificially reared pups in each dietary condition were fed ethanol in their formula (7% vol/vol) in one‐quarter of their daily feedings, while the others received maltose‐dextrin substituted isocalorically for ethanol. Blood alcohol concentrations did not differ betwen the dietary groups. FB weight on postnatal day 9 was lower in ethanol‐exposed offspring in both dietary conditions. Brain fatty acid composition reflected dietary history in that, compared with AD pups, DEF pups had lower percentages of docosahexaenoic acid, higher percentages of 22∶5n−6, and a higher n−6/n−3 fatty acid ratio. However, the effects of ethanol exposure were inconsistent, lowering the n−6/n−3 ratio in the phosphatidylethanolamine (PF) fraction in FB but not in CB, while increasing this ratio in the phosphatidylcholine (PC) fraction in FB of the DEF pups only. Thus, while ethanol had some effects on lipid composition, there was no difference between the dietary groups in their vulnerability to the effects of early short‐term ethanol exposure on brain growth.
Column and high‐performance size exclusion chromatography applications to the in vivo digestibility study of a thermoxidized and polymerized olive oil
Authors: Sánchez‐Muniz Francisco J. , Bastida Sara , González‐Muñoz M. José
Published: November 2006

This study aimed (i) to design an in vivo model to study fat digestibility, and (ii) to apply this design to test the in vivo digestibility of a highly thermoxidized olive oil. True digestibility of unheated olive oil was tested 2, 4, 6, and 7 h after administering 1 g of olive oil/100 g body weight to young adult Wistar rats by means of esophageal probes. Remaining gastrointestinal lumen fat showed an inversely linear relationship (t=−0.9932; P<0.001) with the length of the experiment. A 4‐h test was considered adequate because after this period, half of the oil administer still temains in the lumen, making it possible to accurately measure the different nondigested, nonabsorbed themoxidized compounds. In a second experiment, fresh olive oil (3.6 mg polar content/100 mg oil) was heated at 180°C for 50 h in the presence of air; the polar content in this oil rose to 46.0 mg/100 mg oil. After 4 h, the true digestibility coefficient of 50‐h heated olive oil did not significantly change, although it tended to decrease (24%) with respect to the unheated oil. Silica gel column chromatography and high‐performance size exclusion chromatography were used to quantify nonthermoxidized and thermoxidized products present in the oils and in the gastrointestinal lumen after these test periods. True digestibility of the different thermoxidized compounds from the heated oil was 30–40%, whereas that of thermoxidized compounds from the fresh oil was much higher (∼80%). Nonoxidized triacylglycerol hydrolysis was negatively affected by the presence of large amounts of thermoxidized compounds. The present proposed model seems to be a useful tool for the study of thermoxidized oils. Data also show that thermoxidized compounds from abused olive oil are poorly but actively hydrolyzed and absorbed in vivo.
Fullerene lipids: Synthesis of C60 fullerence derivatives bearing a long‐chain saturated or unsaturated triester system
Authors: Lie Ken Jie Marcel S. F. , Cheung Sunny Wai‐Hung
Published: November 2006

Tris(hydroxymethyl)aminomethane was successfully esterified with saturated and unsaturated long‐chain fatty acids. The resulting amino‐triester intermediates were successively reacted with chloroacetyl chloride, sodium azide, and C60 fullerene. Spectral evidence showed that the aziridine ring is joined to the junction of [6,6]‐fused rings of the fullerene. The structures of the various C60 fullerene derivatives bearing a long‐chain saturated or unsaturated triester system were characterized by spectroscopic and spectrometric methods.
Lipids in human milk
Authors: Jensen Robert G.
Published: November 2006

I have reviewed recent (March 1995–December 1997) papers on human milk lipids including many on fatty acid (FA) composition. The effects of maternal diets on the profiles are apparent. However, more data on the composition of milk lipids are needed. It is noteworthy that so few papers on milk FA composition have reported analyses using high‐resolution gas‐liquid chromatography columns. Two of these were on milk from women in North America. The diets in North America are varied and the number of analyses few. We do not have a reliable data base showing the ranges of biologically important acids. Except for the gangliosides, few new data on the other lipids appeared during this period.
Cerebrospinal fluid lipoproteins are more vulnerable to oxidation in Alzheimer's disease and are neurotoxic when oxidized ex vivo
Authors: Bassett Casey N. , Neely M. Diana , Sidell Kathrin R. , Markesbery William R. , Switt Larry L. , Montine Thomas J.
Published: November 2006

Brain regional oxidative damage is thought to be a central mechanism in the pathogenesis of Alzheimer's disease (AD). Recent studies of cerebrospinal fluid (CSF) have suggested that increased lipid peroxidation of CSF and CSF lipoproteins also may occur in AD patients. In the present study, we determined the susceptibility of human CSF to ex vivo lipid peroxidation and tested the hypothesis that oxidized CSF lipoproteins may be neurotoxic. Whole CSF or a CSF lipoprotein fraction (d<1.210 g/mL) was oxidized with 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH), a hydrophilic free‐radical generator. Kinetics of CSF lipid peroxidation were followed by a standard fluorescence product accumulation assay. Oxidation of AD CSF yielded significantly shorter fluorescent lag times than controls, indicating reduced antioxidant capacity. Electrophoretic mobilities of CSF apolipoproteins were specifically reduced upon oxidation of CSF with AAPH, suggesting that lipoproteins are primary targets of CSF lipid peroxidation. Cultured neuronal cells were exposed to physiological concentrations of isolated CSF lipoproteins oxidized with increasing concentrations of AAPH; the resulting neurotoxicity showed a significant linear AAPH concentration‐response relationship. These results suggest that oxidized CSF lipoproteins may contribute to the pathogenesis of neurodegeneration in AD.
Effect of eicosapentaenoic acid on the proliferation and incidence of apoptosis in the colorectal cell line HT29
Authors: Clarke Rosemary G. , Lund Elizabeth K. , Latham Peter , Pinder Andrew C. , Johnson Ian T.
Published: November 2006

Fish oil has been shown to reduce the induction of colorectal cancer in animal models by a mechanism which may involve suppression of mitosis, increased apoptosis, or both. We used the human colonic adenocarcinoma cell line HT29 to explore the effects of the long‐chain n‐3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) on cell proliferation and death in vitro. Cells were cultured in media containing EPA at 5, 10, and 15 μg/mL. Cell number and thymidine incorporation were used to quantify proliferation, and cell cycle effects were studied using flow cytometry. Gel electrophoresis, annexin‐V binding, and morphological criteria were used to characterize apoptosis. Adherent cells and freely floating detached cells were treated as two distinct populations. In the presence of EPA at 10 and 15 μg/mL there was a marked reduction in the growth rate of adherent HT29 colonies, owing to an increased detachment of adherent cells. After treatment with 10 or 15 μg/mL EPA the proportion of adherent cells in S‐phase increased, indicating either a block in late S‐phase or early G2. Floating cells showed evidence of extensive DNA cleavage, but the proportion of floating cells with sub G0 DNA content declined on treatment with 10 or 15 μg/mL EPA even though the number of floating cells increased. We conclude that EPA does not inhibit mitosis of adherent cells, but increases the rate at which they become detached from the substrate, probably at an early stage in the initiation of apoptosis. This mechanism may be analogous to “anoikis”, or induction of apoptosis in response to loss of cell contact, and may contribute to the anticarcinogenic effects of fish oil in vivo.
Effect of peanut oil and randomized peanut oil on cholesterol and oleic acid absorption, transport, and distribution in the lymph of the rat
Authors: Satchithanandam Subramaniam , Flynn Thomas J. , Calvert Richard J. , Kritchevsky David
Published: November 2006

Peanut oil was shown to be atherogenic in cholesterol‐fed rats, rabbits, and monkeys. However, after randomization, a process in which the fatty acids in peanut oil are randomly rearranged, its atherogenicity was significantly reduced in cholesterol‐fed rabbits and monkeys. The mechanism for this effect remains unknown. This study was designed to investigate whether the absorption, transport and distribution of dietary cholesterol and oleic acid in the lymph were altered in the presence of peanut oil or randomized peanut oil. Previous investigators collected lymph through the mesenteric duct for 6 h and analyzed lymph for cholesterol. In the present study, lymph fluids were collected at timed intervals for up to 8 h and then at 24 h via the thoracic duct. Cholesterol and oleic acid (fatty acid) were estimated not only in the whole lymph but also in lymph lipoprotein fractions and in major lipid fractions. A 24‐h lymph collection will enhance accuracy as short‐term fluctuations in lipid absorption will not affect the results. Thoracic duct lymph collection is quantitative compared to mesenteric duct lymph collection, which provides only a fraction of the total lymph. Rats were given a lipid emulsion containing either peanut oil or randomized peanut oil. The emulsion also contained cholesterol, oleic acid, and sodium taurocholate in saline and was given through a duodenal catheter. Results show that absorption, transport, and distribution of cholesterol and oleic acid in the lymph fluids were similar in both dietary groups. These results suggest that the atherogenicity of peanut oil may be due to other events taking place subsequent to the release of cholesterol‐containing chylomicrons and very low density lipoprotein by the small intestinal epithelial cells into the blood or may be due to the triglyceride structure itself.
Dietary phospholipid alters biliary lipid composition in formula‐fed piglets
Authors: Devlin Angela M. , Innis Sheila M.
Published: November 2006

Plasma cholesterol, arachidonic acid (AA, 20∶4n−6), and docosahexaenoic acid (DHA, 22∶6n−3) are higher in breast‐fed infants than in infants fed formula without cholesterol, AA, or DHA. This study investigated differences in plasma, hepatic, and bile lipids and phospholipid fatty acids, and expression of hepatic proteins involved in sterol metabolism that result from feeding formula with cholesterol with egg phospholipid to provide AA and DHA. For this study, three groups of piglets were evaluated: piglets fed formula with 0.65 mmol/L cholesterol, the same formula with 0.8% AA and 0.2% DHA from egg phospholipid, and piglets fed sow milk. Piglets fed the formula with phospholipid AA and DHA had higher plasma high density lipoprotein, but not apoprotein (apo) B cholesterol or triglyceride; higher bile acid and phospholipid concentrations in bile; and higher liver and bile phospholipid AA and DHA than piglets fed formula without AA and DHA (P<0.05). Hydroxy methylglutaryl (HMG)‐CoA reductase and 7‐α‐hydroxylase, the rate‐limiting enzymes of cholesterol and bile acid synthesis, respectively, and low density lipoprotein receptor mRNA levels were not different between piglets fed formula without and with phospholipid AA and DHA, but HMG‐CoA reductase and 7α‐hydroxylase mRNA were higher, and plasma apo B containing lipoprotein cholesterol was lower in all piglets fed formula than in piglets fed milk. These studies show that supplementing formula with AA and DHA from egg phospholipid alters bile metabolism by increasing the bile AA and DHA, and bile acid and phospholipid.
Geometry of conjugated double bonds of CLA isomers in a commercial mixture and in their hepatic 20∶4 metabolites
Authors: Sébédio J. L. , Juanéda P. , Grégoire S. , Chardigny J. M. , Martin J. C. , Ginies C.
Published: November 2006

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.