bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of α‐tocopherol in heated bulk phase in the presence of methyl linoleate (13S)‐hydroperoxide or methyl linoleate
Authors: Yamauchi Ryo , Goto Kumiko , Kato Koji
Published: November 2006

α‐Tocopherol and methyl (9Z, 11E)‐(S)‐13‐hydroperoxy‐9, 11‐octadecadienoate (13‐MeLOOH) were allowed to stand at 100°C in bulk phase. The products were isolated and identified as methyl 13‐hydroxyoctadecadienoate (1), stereoisomers of methyl 9,11,13‐octadecatrienoate (2), methyl 13‐oxo‐9, 11‐octadecadienoate (3), epoxy dimers of methyl linoleate with an ether bond (4), a mixture of methyl (E)‐12, 13‐epoxy‐9‐(α‐tocopheroxy)‐10‐octadecenoates and methyl (E)‐12, 13‐epoxy‐9‐(α‐tocopheroxy)‐11‐(α‐tocopheroxy)‐9‐octadecenoates (5), a mixture of methyl 9‐(α‐tocopheroxy)‐10,12‐octadecadienoates and methyl 13‐(α‐tocopheroxy)‐9, 11‐octadecadienoates (6), α‐tocopherol spirodiene dimer (7), and α‐tocopherol trimer (8). α‐Tocopherol and 13‐MeLOOH were dissolved in methyl myristate, and the thermal decomposition rate and the distributions of reaction products formed from α‐tocopherol and 13‐MeLOOH were analyzed. α‐Tocopherol disappeared during the first 20 min, and the main products of α‐tocopherol were 5 and 6 with the accumulation of 1–4 which were the products of 13‐MeLOOH. The results indicate that the alkyl and alkoxyl radicals from the thermal decomposition of 13‐MeLOOH could be trapped by α‐tocopherol to produce 5 and 6. The reaction products of α‐tocopherol during the thermal oxidation of methyl linoleate were compounds 6 and 7. Since the radical flux during the autoxidation might be low, the excess α‐tocopheroxyl radical reacted with each other to form 7.
Penetration and distribution of α‐tocopherol, α‐ or γ‐tocotrienols applied individually onto murine skin
Authors: Traber Maret G. , Rallis Michalis , Podda Maurizio , Weber Christine , Maibach Howard I. , Packer Lester
Published: November 2006

To evaluate skin penetration of various vitamin E homologs, a 5% solution of either α‐tocopherol, α‐tocotrienol, or γ‐tocotrienol in polyethylene glycol was topically applied to SKH‐1 hairless mice. After 0.5, 1, 2, or 4 h (n=four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidlly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5‐μm sections—SC1 and SC2), epidermis (next two 10μm sections—E1 and E2), papillary dermis (next 100μ, PD), dermis (next 400 μm, D), and subcutaneous fat (next 100 μm, SF). SC1 contained the highest vitamin E concentrations per μ thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers—the lowest layers, PD (40±15%) and D (36±15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands—lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.
Structure‐retention correlation of isomeric bile acids in inclusion high‐performance liquid chromatography with methyl β‐cyclodextrin
Authors: Momose Toshiaki , Yamaguchi Yoshiya , Iida Takashi , Goto Junichi , Nambara Toshio
Published: November 2006

The structure‐retention correlation of various C24 bile acid isomers was studied by the addition of methyl β‐cyclodextrin (Me‐β‐CD) to mobile phases in reversed‐phase high‐performance liquid chromatography (HPLC). The compounds examined include a series of monosubstituted bile acids related to cholanoic acids differing from one another in the position and configuration of an oxygen‐containing function (hydroxyl or oxo group) at the position C‐3, C‐6, C‐7, or C‐12 and the stereochemistry of the A/B‐ring fusion (trans 5α‐H and cis 5β‐H) in the steroid nucleus. The inclusion HPLC with Me‐β‐CD was also applied to biologically important 4β‐ and 6‐hydroxylated bile acids substituted by three to four hydroxyl groups in the 5β‐steroid nucleus. These bile acid samples were converted into their fluorescence prelabeled 24‐pyrenacyl ester derivatives and chromatographed on a Capcell Pak C18 column eluted with methanol‐water mixtures in the presence or absence of 5 mM Me‐β‐CD. The effects of Me‐β‐CD on the retentions of each compound were correlated quantitatively to the decreasing rate of capacity factors and the relative strength of host‐guest inter‐actions. On the basis of the retention data, specific and nonspecific hydrogen‐bonding interactions between the bile acids and the Me‐β‐CD were discussed.
Seasonal changes in leaf lipid and fatty acid composition of nine plants consumed by two African herbivores
Authors: Davidson Bruce C.
Published: November 2006

In the wild, nutrients from plants provide for the requirements of all herbivores and ultimately all animals, yet little work has been published on how such nutrients change with environmental conditions. Plant lipids are nutritionally important for browsing mammals, initially with respect to taste and palability, but ultimately how they fulfill a variety of functions. This study reports on seasonal changes in fatty acid (FA) profiles of nine plants commonly consumed by two herbivore species (kudu and impala) in South Africa. The FA composition of the plants varied with both season and plant species but not with geographic location. The overall profile of FA provided a maximum of n−3‐essential FA during the transition and wet seasons, but there was no parallel increase in n−6‐essential FA.
Low‐fat, monounsaturate‐rich diets reduce susceptibility of low density lipoproteins to peroxidation ex vivo
Authors: O'Byrne Dawn J. , O'Keefe Sean F. , Shireman Rachel B.
Published: November 2006

Oxidative modification of low density lipoprotein (LDL) plays an important role in the process of atherosclerosis. The susceptibility of LDL to oxidation and the amount of peroxidation products formed are influenced by the lipoprotein content of 18∶1 n−9, 18∶2n−6, and the 18∶2n−6/18∶1n−9 ratio, which is dependent in part on dietary fatty acids. The purpose of this study was to determine if changing from a typical American diet to a low‐fat, monousaturate‐rich diet (LFMR) would result in favorable alterations in the fatty acid composition and oxidative profile of LDL in hypercholesterolemic individuals. Free‐living postmennopausal hypercholesterolemic women who routinely consumed a diet moderately high in total fat and total saturates (34 and 11%, respectively) followed an LFMR diet (26% fat, 6% saturated fat, and 14% monounsaturated fat) for 6 mon. Sixteen postmenopausal hypercholesterolemic women already following standard low‐fat (LF) diets acted as a control for seasonal variations in serum lipids. LDL from randomly selected subjects (LF n=6, LFMR n=5) was evaluated. LFMR diets resulted in LDL with increased concentrations and percentages of 18∶1n−9, reduced 18∶2n−6/18∶1n−9 ratio, and lower percentages of 18∶2n−6. No significant changes in LDL fatty acids occurred in the LF group. Conjugated diene lag time increased in both groups during copper‐induced in vitro oxidation. Only the LFMR group experienced an increase in lipid peroxide lag time and a decrease in lipid peroxide formation. The LFMR diet was well tolerated and may be of therapeutic value in the treatment of hypercholesterolemia.
A comparison of lycopene and canthaxanthin absorption: Using the rat to study the absorption of non‐provitamin a carotenoids
Authors: Clark Richard M. , Yao Lili , She Li , Furr Harold C.
Published: November 2006

The purpose of this study was to validate the use of the mesenteric lymph duct cannulated rat to study the absorption of carotenoids which do not have provitamin Activity. The absorption of two carotenoids, a hydrocarbon carotenoid (lycopene) and a xanthophyll carotenoid (canthaxanthin), were investigated. In the first experiment, lipid emulsions containing lycopene (LYC) or canthaxanthin (CTX) were continuously infused into the duodenum, and lymph was collected for analysis at 2‐h intervals. The time course for absorption of carotenoids and triacylglycerol (TAG) was similar. Carotenoids and TAG reached steady‐state concentrations in the lymph by 6 h. There was no evidence for a delayed release of either carotenoid from the intestine relative to TAG. During a second experiment, emulsions containing increasing concentrations of LYC or CTX (5, 10, 15, 20 μmol/L) were infused. The LYC and CTX in the lymph increased in a dose‐dependent manner. The average efficiency of CTX absorption was 16% while the efficiency of LYC absorption averaged only 6%. Efficiency of carotenoid absorption was not related to concentration infused. Finally, to test whether LYC and CTX interact during absorption both were added to a lipid emulsion at equal concentrations (20 μmol/L) and infused. The carotenoids did not significantly affect each other's absorption. These results demonstrate the usefulness of the rat as an animal model to study the absorption of non‐provitamin A carotenoids.
Hepatic cholesterol metabolism in experimental nephrotic syndrome
Authors: Al‐Shurbaji Ayman , Humble Elisabet , Rudling Mats , Lindenthal Bernhard , Berglund Lars
Published: November 2006

Hypercholesterolemia is a consistent feature of the nephrotic syndrome. However, the mechanisms underlying this perturbation are unclear. In the present work, we have investigated different factors that influence hepatic cholesterol metabolism using the nephrotic rat as a model. The induction of nephrosis resulted in a severe and sustained hypercholesterolemia. However, no effect on the rate‐limiting enzyme in cholesterol synthesis, 3‐hydroxy‐3‐methylglutaryl CoA reductase, could be detected. Further, plasma lathosterol/cholesterol ratio, a measure of cholesterol synthesis, was not altered. Also, plasma levels of mevalonate, both a substrate for cholesterogenesis beyond the rate‐limiting step and a marker for cholesterol synthesis, did not differ between control rats and those with established hypercholesterolemia. There was no detectable change in the expression of low density lipoprotein (LDL) receptor between the two experimental groups. We conclude that the early increase in cholesterol synthesis reported after the induction of nephrosis is not necessary for the maintenance of hypercholeserolemia. Established hypercholesterolemia of the nephrotic syndrome seems to represent a steady state in which neither enhanced hepatic cholesterol synthesis nor retarded LDL cholesterol clearance is of major importance.
Eicosapentaenoic and docosahexaenoic acids alter rat spleen leukocyte fatty acid composition and prostaglandin E2production but have different effects on lymphocyte functions and cell‐mediated immunity
Authors: Peterson L. D. , Jeffery N. M. , Thies F. , Sanderson P. , Newsholme E. A. , Calder P. C.
Published: November 2006

Weanling rats were fed on high‐fat (178 g/kg) diets which contained 4.4 g α‐linolenic (ALA), γ‐linolenic, arachidonic (ARA), eicosapentaenoic (EPA), or docosahexaenoic acid (DHA)/100 g total fatty acids. The proportions of all other fatty acids, apart from linoleic acid, and the proportion of total polyunsaturated fatty acids (PUFA) (approximately 35 g/100 g total fatty acids) were constant, and the n−6 to n−3 PUFA ratio was maintained as close to 7 as possible. The fatty acid compositions of the serum and of spleen leukocytes were markedly influenced by that of the diet. Prostaglandin E2production was enhanced from leukocytes from rats fed the ARA‐rich diet and was decreased from leukocytes from the EPA‐ or DHA‐fed rats. Replacing dietary ALA with EPA resulted in diminishedex vivolymphocyte proliferation and natural killer (NK) cell activity and a reduced cell‐mediated immune responsein vivo. In contrast, replacing ALA with DHA reducedex vivolymphocyte proliferation but did not affectex vivoNK cell activity or the cell‐mediated immune responsein vivo. Replacement of a proportion of linoleic acid with either γ‐linolenic acid or ARA did not affect lymphocyte proliferation, NK cell activity, or the cell‐mediated immune response. Thus, this study shows that different n−3 PUFA exert different immunomodulatory actions, that EPA exerts more widespread and/or stronger immunomodulatory effects than DHA, that a low level of EPA is sufficient to influence the immune response, and that the immunomodulatory effects of fish oil may be mainly due to EPA.
Catalytic properties of allene oxide synthase from flaxseed (Linum usitatissimum L.)
Authors: Schneider Claus , Schreier Peter
Published: November 2006

We investigated the catalytic and kinetic properties of allene oxide synthase (AOS; E.C. 3.2.1.92) from flaxseed (Linum usitatissimum L.). Both Michaelis constant and maximal initial velocity for the conversion of 9(S)‐and 13(S)‐hydroper‐oxides of linoleic and linolenic acid were determined by a photometric assay, 13(S)‐Hydroperoxy‐9(Z), 11(E)‐octadecadienoic acid [13(S)‐HPOD] as the most effective substrate was converted at 116.9±5.8 nkat/mg protein by the flax enzyme extract. The enzyme was also incubated with a series of variable conjugated hydroperoxy dienyladipates. Substrates with a shape similar to the natural hydroperoxides showed the best reactivity. Monoenoic substrates as oleic acid hydroperoxides were not converted by the enzyme. In contrast, 12‐hydroperoxy‐9(Z), 13(E)‐octadecadienoic acid was a strong competitive inhibitor for AOS catalyzed degradation of 13(S)‐HPOD. The inhibitor constant was determined to be 0.09 μM. Based on these results, we concluded that allene oxide synthase requires conjugated diene hydroperoxides for successful catalysis. Studying the enantiomeric preference of the enzyme, we found that AOS was also able to metabolize (R)‐configurated fatty acid hydroperoxides. Conversion of these substrates into labile allene oxides was confirmed by steric analysis of the stable α‐ketol hydrolysis products.
Stereospecific analysis of soybean triacylglycerols
Authors: Harp Teresa K. , Hammond Earl G.
Published: November 2006

Thirty soybean germplasm lines representing a wide distribution of fatty acid compositions were analyzed stereospecifically by using a chiral column to resolve the sn‐1 and sn‐3 positions of glycerol. The amounts of each acyl group on each of the sn positions were plotted vs. the amount of that acyl group in the triacylglycerols (TAG), and the plots were fitted by linear regression. The deviation of individual data points from the linear regressions was much greater than observed in previous studies. This could be attributed to the inclusion of a number of germplasm lines with elevated or reduced percentages of saturates. The stereospecific distributions could not be fit with previously suggested mathematical models because the plots had intercepts that were not allowed by the models. Statistical tests of the analytical procedure indicated that slight oxidation of or bias against the polyunsaturates had occurred and that the Grignard deacylation method gave slightly less representative analyses of the sn‐2 position than pancreatic lipase deacylation on these TAG.
Phospholipase D hydrolyzes short‐chain analogs of phosphatidylcholine in the absence of detergent
Authors: Davis Leslee L. , Maglio Jeffrey J. , Horwitz Joel
Published: November 2006

Phospholipase D is an important enzyme in signal transduction in neuronal tissue. A variety of assays have been used to measure phospholipase D activity in vitro. The most typical measure of phospholipase D activity is the production of phosphatidylethanol in the presence of ethanol. Phosphatidylethanol is a product of transphosphatidylation activity that is considered a unique property of phospholipase D. To support transphosphatidylation activity, high concentrations of ethanol may be required. Furthermore, most assays in the literature utilize a detergent. These extreme conditions, detergent and ethanol, may alter phospholipase D and hinder the study of its regulation. In this manuscript we describe an assay that eliminates these potentially confounding conditions. It utilizes high specific activity [3H]butanol as a nucleophilic receptor. This eliminates the need for high concentrations of alcohol. The substrate is an analog of phosphatidylcholine that contains short‐chain fatty acids, 1,2‐dioctanoyl‐sn‐glycero‐3‐phosphocholine. Phospholipase D readily hydrolyzes this substrate in the absence of detergent. This novel assay should be useful in the further characterization of phospholipase D.
Dietary methionine level affects linoleic acid metabolism through phosphatidylethanolamine N‐methylation in rats
Authors: Sugiyama Kimio , Kumazawa Akemi , Zhou Hong , Saeki Shigeru
Published: November 2006

The effects of dietary methionine level on the profiles of fatty acids and phospholipids and on the plasma cholesterol concentration were investigated to confirm whether the methionine content of dietary proteins is one of the major factors that cause differential effects on lipid metabolism. The effect of dietary supplementation with eritadenine, which is shown to be a potent inhibitor of phosphatidylethanolamine (PE) N‐methylation, was also investigated. Rats were fed six diets containing casein (100 g/kg) and amino acid mixture (86.4 g/kg) differing in methionine content (2.5, 4.5, and 7.5 g/kg) and without or with eritadenine supplementation (30 mg/kg) for 14 d. The ratio of arachidonic to linoleic acid of liver microsomal and plasma phosphatidylcholine (PC) was significantly increased as the methionine level of diet was elevated, indicating that dietary methionine stimulates the metabolism of linoleic acid. The PC/PE ratio of liver microsomes and the plasma cholesterol concentration were also increased by dietary methionine. These effects of methionine were completely abolished by eritadenine supplementation The S‐adenosylmethionine concentration in the liver reflected the methionine level of diet. These results support the idea that the differential effects of dietary proteins on lipid metabolism might be ascribed, at least in part, to their different methionine contents, and that methionine might exert its effects through alteration of PE N‐methylation.
Interaction of n‐3 long‐chain polyunsaturated fatty acids with n‐6 fatty acids in suckled rat pups
Authors: Boyle Frances G. , Yuhas Rebecca J. , Goldberg Kenneth , Lien Eric L.
Published: November 2006

The addition of long‐chain polyunsaturated fatty acids (LCP: C20, and C22) to infant formula may permit fatty acid accretion rates similar to breast‐fed infants, and may have long‐term outcome benefits, such as improved visual acuity and cognitive development. Although fish oil may provide a source of n‐3 LCP, sources of n‐6 LCP have been more difficult to identify. The present study evaluates the effects of n‐3 and n‐6 LCP derived from single‐cell oils on liver, plasma, and brain fatty acid levels in a neonatal animal model. Newborn rat pups were suckled for 14 d by dams receiving diets containing n‐3 LCP alone or combinations of n‐3 LCP and increasing doses of linoleic acid (18∶2n−6) or arachidonic acid (20∶4n−6). Dietary groups received 2% n−3 LCP and 1, 2, or 5% of either 18∶2n−6 or 20∶4n−6. The 20∶4n−6 source also contained modest levels of 18∶2n−6. At the termination of the study, liver, plasma, and brain were obtained from the rat pups and the phospholipid fatty acid profiles determined. The results indicate complex interactions of n−3 and n−6 fatty acids. Groups receiving dietary 20∶4n−6 incorporated higher levels of n−6 LCP into tissues than did the groups receiving 18∶2n−6. The brain was relatively resistant to changes in fatty acid composition compared with the liver and plasma. As expected, tissue n−3 LCP levels were reciprocally related to n−6 levels. The present results document that single‐cell LCP oils are bioavailable in a neonatal animal model. The use of 20∶4n−6 is a more effective means of supporting n−6 status than the use of 18∶2n−6. These results may have implications for the addition of LCP to infant formula.
Absorption, excretion, and distribution of plant sterols after proximal gut resection and autotransplantation of porcine ileum
Authors: Pakarinen M. P. , Halttunen J. , Kuusanmäki P. , Lauronen J. , Miettinen T. A.
Published: November 2006

Contribution of different gut segments to plant sterol absorption, adaptation of plant sterol absorption after partial small bowel resection, and effects of gut transplantation (necessitates extrinsic autonomic denervation and lymphatic disruption) on plant sterol biodynamics are unclear. We studied the consequences of massive proximal small bowel resection and autotransplantation of the remaining ileum on the adaptive absorption and biodynamics of plant sterols. Dietary, fecal, biliary, hepatic and plasma plant sterols, fecal elimination and absorption of cholesterol, small bowel morphology, and intestinal transit were determined before (n=5) and at 4, 8, and 14 wk after resection of the proximal 75% of the jejunoileum (n=15) and autotransplantation of the remaining ileum (n=15) or transection (n=5). Proximal gut resection significantly reduced cholesterol absorption efficiency; percentage absorption and biliary secretion of plant sterols; plasma, biliary and hepatic campesterol‐to‐cholesterol proportions; and sitosterol proportions in plasma and bile. Autotransplantation of the remaining ileum further significantly decreased cholesterol absorption efficiency; percentage absorption and biliary secretion of campesterol; campesterol proportions in plasma, bile and liver; and plasma proportions of sitosterol while increasing fecal excretion of neutral and acidic steroids. Plasma proportions of the two plant sterols, but absorption of just campesterol, were gradually improved with increasing cholesterol absorption and villus height after proximal gut resection; the same result was observed to a lesser degree after ileal autotransplantation. In addition, significant positive correlations were found between percentage cholesterol and campesterol absorption and the plasma plant sterol proportions in both proximal resection groups, between campesterol absorption and ileal villus height in the resection group, and between campesterol absorption and intestinal transit time in the autotransplantation group. In conclusion, plasma campesterol and sitosterol closely reflect absorption of cholesterol and plant sterols from intact and autotransplanted ileum during adaptation to proximal gut resection. A loss of proximal gut absorptive surface impairs cholesterol and campesterol absorption more than sitosterol absorption, the later being apparently less dependent on available jejunal villus surface area.
The effect of dietary vitamin E supply and a moderately oxidized oil on activities of hepatic lipogenic enzymes in rats
Authors: Eder Klaus , Kirchgessner Manfred
Published: November 2006

Diets rich in polyunsaturated fatty acids (PUFA) are well known to suppress hepatic lipogenic enzymes compared to fat‐free diets or diets rich in saturated fatty acids. However, the mechanism underlying suppression of lipogenic enzymes is not quite clear. The present study was undertaken to investigate whether lipid peroxidation products are involved in suppression of lipogenic enzymes. Therefore, an experiment with growing male rats assigned to six groups over a period of 40 d was carried out. Rats received semisynthetic diets containing 9.5% coconut oil and 0.5% fresh soybean oil (coconut oil diet, peroxide value 5.1 meq O2/kg oil), 10% fresh soybean oil (fresh soybean oil diet, peroxide value 0.5 meq O2/kg oil), or 10% thermally treated soybean oil (oxidized soybean oil diet, peroxide value 74 meq O2/kg oil). To modify the antioxidant state of the rats, we varied the vitamin E supply (11 and 511 mg α‐tocopherol equivalents per kg of diet) according to a bi‐factorial design. Food intake and body weight gain were not influenced by dietary fat and vitamin E supply. Activities of hepatic lipogenic enzymes were markedly influenced by the dietary fat. Feeding either fresh or oxidized soybean oil diets markedly reduced activities of fatty acid synthase, (FAS), acetyl CoA‐carboxylase, (AcCX), glucose‐6‐phosphate dehydrogenase, (G6PDH), 6‐phosphogluconate dehydrogenase, and ATP citrate lyase (ACL) relative to feeding the coconut oil diet. Moreover, feeding oxidized soybean oil slightly, but significantly, lowered activities of FAS, AcCX, and ACL compared to feeding fresh soybean oil. Activities of hepatic lipogenic enzymes were reflected by concentrations of triglycerides in liver and plasma. Rats fed the coconut oil diet had markedly higher triglyceride concentrations in liver and plasma than rats consuming fresh or oxidized soybean oil diets, and rats fed oxidized soybean oil had lower concentrations than rats fed fresh soybean oil. The vitamin E supply of the rats markedly influenced concentrations of thiobarbituric acid‐reactive substances in liver, but it did not influence activities of hepatic lipogenic enzymes. Because the vitamin E supply had no effect, and ingestion of an oxidized oil had only a minor effect, on activities of hepatic lipogenic enzymes, it is strongly suggested that neither exogenous nor endogenous lipid peroxidation products play a significant role in the suppression of hepatic lipogenic enzymes by diets rich in PUFA. Therefore, we assumed that dietary PUFA themselves are involved in regulatio of hepatic lipogenic enzymes. Nevertheless, the study shows that ingestion of oxidized oils, regardless of the vitamin E supply, also affects hepatic lipogenesis, and hence influences triglyceride levels in liver and plasma.
Effects of polyunsaturated fatty acids and their n‐6 hydroperoxides on growth of five malignant cell lines and the significance of culture media
Authors: Nøding Randi , Schønberg Svanhild A. , Krokan Hans E. , Bjerve Kristian S.
Published: November 2006

We examined effects of polyunsaturated fatty acids (PUFA), their corresponding hydroperoxy fatty acids (hp‐PUFA), as well as various pro‐ and antioxidants on the growth of tumor cells in culture. When cultured in RPMI 1640 medium, A‐427 and WEHI clone 13 cells were both highly sensitive to hydroperoxy docosahexaenoic acid (hp‐DHA), but they were far less sensitive in minimum essential medium (MEM). In contrast, A‐427 cells were also sensitive to DHA in both culture media, while WEHI clone 13 cells, as well as other cell lines, tested in their respective media, were resistant. The lower sensitivity of the cell lines to hp‐DHA in MEM‐medium was apparently due to a more rapid reduction of hp‐DHA to the corre‐sponding hydroxy‐DHA in MEM‐medium. Addition of glutathione (GSH) to the culture medium abolished the effects of hp‐DHA, but not the effects of DHA, while depletion of intracellular GSH levels by L‐buthionine‐S,R‐sulfoximine strongly enhanced the cytotoxic effect of hp‐DHA, but not the cytotoxic effect of DHA. α‐Tocopherol protected A‐427 cells against the toxic effect of DHA and abolished the induced lipid peroxidation, while it did not protect against the toxic effects of hp‐DHA in A‐427 or WEHI clone 13 cells. Ascorbic acid reduced the cytotoxic effect of DHA, but potentiated the toxic effect of hp‐DHA while selenite essentially abolished the toxicity of both DHA and hp‐DHA. These results indicate that sensitivity of tumor cell lines to PUFA and their oxidation products depends on their antioxidant defense mechanisms, as well as culture conditions, and establishes hp‐DHA as a major, but probably not the sole, metabolite responsible for cytotoxicity of DHA.
Rapid hydrolysis of bile acid conjugates using microwaves: Retention of absolute stereochemistry in the hydrolysis of (25R) 3α,7α,12α‐trihydroxy‐5β‐cholestan‐26‐oyltaurine
Authors: Dayal Bishambar , Ertel Norman H.
Published: November 2006

In recent years, defects of bile acid synthesis caused by disorders of peroxisome biogenesis have led to increased interest in C27 bile acids. In humans, while the majority of bile acids are C24 carboxylic acids, the presence of increased concentrations of C27 bile acids and their metabolites in hereditary diseases associated with peroxisomal dysfunction can serve as a useful marker for the intensity of the metabolic disorder. Our present studies describe an efficient method for the rapid hydrolysis of C27 and C24 bile acid conjugates using a commercial microwave oven. The advantages of this method include freedom from racemization, minimal activation, mild reaction conditions, and the highly stereocontrolled nature of the reaction, thus allowing for free bile acid recovery in high yield. For example, when (25R) 3α,7α,12α‐trihydroxy‐5β‐cholestan‐26‐oyl taurine, a major compound present in the bile of Alligator mississippiensis, was deconjugated with 4% NaOH/diethylene glycol or 1 M LiOH/propylene glycol in the microwave oven for 4–6 min, 3α,7α,12α‐trihydroxy‐5β‐cholestan‐26‐oic acid (THCA) was obtained in 81% yield with retention of configuration at C‐25. It is suggested that present studies will be helpful in delineating the absolute stereochemistry of 3α,7α,12α‐trihydroxy‐5β‐cholestanoyl‐CoA oxidase, the peroxisomal enzyme that catalyzes the first step in the oxidation of THCA.
Gas chromatography‐mass spectrometry methods for structural analysis of fatty acids
Authors: Christie William W.
Published: November 2006

Procedures for structural analysis of fatty acids are reviewed. The emphasis is on methods that involve gas chromatography‐mass spectrometry and, in particular, the use of picolinyl ester and dimethyloxazoline derivatives. These should be considered as complementing each other, not simply as alternatives. However, additional derivatization procedures can be of value, including hydrogenation and deuteration, and preparation of dimethyl disulfide and 4‐methyl‐1,2,4‐triazoline‐3,5‐dione adducts. Sometimes complex mixtures must be separated into simpler fractions prior to analysis by gas chromatography‐mass spectrometry. Silver ion and reversed‐phase high‐performance liquid chromatography are then of special value. In particular, a novel application of the latter technique, involving a base‐deactivated stationary phase and acetonitrile as mobile phase, is described that is suited to the separation of fatty acids in the form of picolinyl ester and dimethyloxazoline derivatives, as well as methyl esters.
Effect of selenium and vitamin E supplements on tissue lipids, peroxides, and fatty acid distribution in experimental diabetes
Authors: Douillet C. , Bost M. , Accominotti M. , Borson‐Chazot F. , Ciavatti M.
Published: November 2006

The protective role of selenium (Se), given as a Se‐rich yeast, selenomethionine or selenomethionine+vitamin E supplement, toward changes in lipid, peroxide, and fatty acid distribution in tissues of streptozotocin‐induced diabetic rats, was investigated, after 24 wk of disease. Diabetes increased liver thiobarbituric acid‐reactive substances and conjugated dienes; Se supplement completely corrected these changes. In kidney, as in heart, the peroxide levels were not significantly changed by diabetes. In diabetic rat liver, a significant drop in triglycerides and phospholipids (P<0.05) was observed; this was modulated by Se+vitamin F supplementation. Se+vitamin E supplementation also inhibited the decrease in 18∶2n‐6 and the increase in 22∶6n‐3 observed in liver of diabetic rats, changes which reflect altered glycemic control. In kidney, heart, and aorta, diabetes produced some changes in lipid content and fatty acid distribution, especially an increase in heart triglycerides which was also corrected by the Se supplement. Se supplementation to diabetic rats also increased 18∶0 etherlinked alcohol, 20∶4 n‐6, and 22∶5 n‐3 in cardiac lipids. In aorta, Se + vitamin E significanlty increased 20∶5 n‐3. These polyunsaturated fatty acids are precursors, in situ, of prostaglandin l2 (PGl2) and PGl3 which may protect against cardiovascular dysfunction. In kidney, converrely, Se decreased 20∶4 n‐6, the precursor of thromboxane A1 implicated in diabetic glomerular injury. thus Se, and more efficiently Se + vitamin E supplementation, in experimental diabetes could play a role in controlling oxidative status and altered lipid metabolism in liver, thereby maintaining favorable fatty acid distribution in the major tissues affected by diabetic complications.
Chronic dietary n‐3 polyunsaturated fatty acids deficiency affects the fatty acid composition of plasmenylethanolamine and phosphatidylethanolamine differently in rat frontal cortex, striatum, and cerebellum
Authors: Favrelière S. , Barrier L. , Durand G. , Chalon S. , Tallineau C.
Published: November 2006

As chronic consumption of a diet devoid of n‐3 fatty acid induced modification of neurotransmission pathways in the frontal cortex of rats, plasmalogen alteration could occur in this area. Because of the propensity to facilitate membrane fusion, plasmenylethanolamine (PmE), a major plasmalogen of brain, may be involved in synaptic transmission. Female rats were fed diet containing peanut oil [(n‐3)‐deficient diet] through two generations. Two weeks before mating, half of the female rats of the second generation received a diet containing peanut oil and rapeseed oil (control group). The distribution and acyl composition of major phospholipids, phosphatidylethanolamine and PmE, were measured in the frontal cortex, striatum, and cerebellum of the male progeny of the two groups at 60 d of age. The n‐3 polyunsaturated fatty acid (PUFA) deficiency had no effect on the distribution of phospholipids in all brain regions but affected their acyl composition differently. The level of 22∶6n‐3 was significantly lower and compensated for by higher levels of n‐6 fatty acids in all regions and phospholipids studied. However, docosahexaenoic acid, being more concentrated in the PmE of frontal cortex, is also more decreased in the n‐3‐deficient rats compared to the striatum. By contrast, striatum PmE has retained more 22∶6n‐3 than PmE of the other regions. In addition, the increase of n‐6 PUFA was significantly lower in frontal cortex PmE compared to the striatum and cerebellum PmE. In association with altered neurotransmission observed in frontal cortex of n‐3‐deficient rats, our results suggest that frontal cortex PmE might be more affected in chronically α‐linolenic‐deficient rats. However, by retaining 22∶6n‐3, striatum PmE could be most resilient.
Inhibitory effect of linoleic acid on chain elongation and desaturation of 18∶2 c,t isomers in lactating and neonatal rats
Authors: Kwan Kwok Yiu , Wang Li‐Ya , Chan Kwok Pan , Chen Zhen Yu
Published: November 2006

The previous studies showed that dietary 18∶2 c,t isomers could be chain‐elongated and desaturated to produce unusual 20∶4 isomers. The present study was undertaken to determine the minimal amount of 18∶2n−6 required to suppress the chain elongation and desaturation of 18∶2 c,t isomers in the lactating and neonatal rats when animals were fed 15% partially hydrogenated canola oil diet containing 1.72% energy as 18∶2 c,t isomers and varying amounts of free 18∶2n−6. These diets induced marginal essential fatty acid (EFA) deficiency states (0.56% energy 18∶2n−6) to EFA adequacy (2.56% energy 18∶2n−6). After feeding for 50 d, the female animals were mated with males by overnight pairing. After conception, the lactating rats were killed, together with one pup from each dam, at term and day 26 of lactation. Two unusual 20∶4 isomers in both maternal and neonatal liver phospholipids were identified as 20∶4Δ5c,8c,11c,14t and 20∶4Δ5c,8c,11c,15t, which were derived from 18∶2Δ9c,12t, and 18∶2Δ9c,13t, respectively. The results showed that 18∶2n−6 at about 2.0% of total energy in maternal diet was required to block the production of 20∶4Δ5c,8c,11c,14t and 20∶4Δ5c,8c,11c,15t in the maternal liver, whereas 18∶2n−6 at about 2.5% of total energy in maternal diet was required to suppress production of these unusual 20∶4 isomers in the neonatal liver.
Effects of dietary marine oils and olive oil on fatty acid composition, platelet membrane fluidity, platelet responses, and serum lipids in healthy humans
Authors: Vognild Eva , Elvevoll Edel O. , Brox Jan , Olsen Ragnar L. , Barstad Harald , Aursand Marit , Østerud Bjarne
Published: November 2006

The influence of various dietary marine oils and olive oil on fatty acid composition of serum and platelets and effects on platelets and serum lipids were investigated as part of an extensive study of the effects of these oils on parameters associated with cardiovascular/thrombotic diseases. Healthy volunteers (266) consumed 15 mL/d of cod liver oil (CLO); whale blubber oil (refined or unrefined); mixtures of seal blubber oil and CLO; or olive oil/CLO for 12 wk. In the CLO, seal oil/CLO, and whale oil groups, serum levels of eicosapentaenoic acid (EPA) were increased. In platelets, EPA was increased in the CLO, seal/CLO, and olive oil/CLO groups. The localization of n‐3 polyunsaturated fatty acids in the triacylglycerols did not seem to influence their absorption. Intake of oleic acid is poorly reflected in serum and platelets. No significant differences in triacylglycerols (IG), total cholesterol, or high density lipoprotein cholesterol were observed, even though TG were reduced in the CLO, CLO/seal oil, and whale oil groups. Mean platelet volume increased significantly in both whale oil groups and the CLO/olive oil group. Platelet count was significantly reduced in the refined whale oil group only. Lipopolysaccharide‐stimulated blood tended to generate less thromboxane B2 in CLO, CLO/seal, and CLO/olive groups. The whale oils tended to reduce in vivo release of β‐thromboglobulin. In conclusion, intake of various marine oils causes changes in platelet membranes that are favorably antithrombotic. The combination of CLO and olive oil may produce better effects than these oils given separately. The changes in platelet function are directly associated with alterations of fatty acid composition in platelet membranes.
Contribution of meat fat to dietary arachidonic acid
Authors: Li Duo , Ng Alice , Mann Neil J. , Sinclair Andrew J.
Published: November 2006

Arachidonic acid (AA) in the diet can be efficiently absorbed and incorporated into tissue membranes, resulting in an increased production of thromboxane A2 by platelets and increased ex vivo platelet aggregability. Results from previous studies have shown that AA is concentrated in the membrane phospholipids of lean meats. However, the concentration of AA in the visible fat portion of meats also may be significant despite being ignored in most studies. The aim of this study was to accurately quantitate the AA content of visible fat and the lean portion of beef, lamb, pork, chicken, duck, and turkey. The visible fat of meat contained a significant quantity of AA, ranging from 20 to 180 mg/100 g fat, whereas the AA content of the lean portion of meat was lower, ranging from 30 to 99 mg/100 g lean meat. Beef and lamb meats contained lower levels of AA in both the visible fat and lean portion than that from the other species. The highest level of AA in lean meat was in duck (99 mg/100 g), whereas pork fat had the highest concentration for the visible fats (180 mg/100 g). The lean portions of beef and lamb contained the higher levels of n‐3 polyunsaturated fatty acids (PUFA) compared with white meats which were high in AA and low in n‐3 PUFA. The present data indicate that the visible meat fat can make a contribution to dietary intake of AA, particularly for consumers with high intakes of fat from pork or poultry meat.
Effects of caffeine on lipoprotein lipase gene expression during the adipocyte differentiation process
Authors: Couturier Cyril , Janyier Brigitte , Girlich Delphine , Béréziat Gilbert , Andréani‐Mangeney Marise
Published: November 2006

In this study, the effects of caffeine on lipoprotein lipase (LPL) gene expression were investigated in the 3T3‐F442A preadipocyte cell line during the adipocyte differentiation process by determining LPL enzymatic activity and its messenger RNA (mRNA) level. The results demonstrate that caffeine acts on the gene expression of LPL, an early marker of adipocyte differentiation. It has a biphasic action: it increases gene expression in terms of mRNA when it is added to preadipocytes during the early stage of differentiation, but this is accompanied by a reduction of enzymatic activity. On the other hand, when caffeine is added for long periods during differentiation and/or when it is added to mature adipocytes, it induces marked inhibition of mRNA levels, correlated with a marked reduction of secreted enzymatic activity. The inhibitory effect of caffeine on LPL mRNA level can be reproduced by theophylline, a phosphodiesterase inhibitor, and by dibutyryl cyclic AMP, a non‐metabolizable analog of cyclic AMP. However, the effect of caffeine and theophylline lasts longer than that of cyclic AMP, suggesting that a mechanism other than inhibition of cyclic AMP hydrolysis may be involved in the action of caffeine.
Effect of dietary arachidonic acid on metabolism of deuterated linoleic acid by adult male subjects
Authors: Emken E. A. , Adlof R. O. , Duval S. M. , Nelson G. J.
Published: November 2006

The influence of dietary supplementation with 20:4n−6 on uptake and turnover of deuterium‐labeled linoleic acid (18:2n−6[d2]) in human plasma lipids and the synthesis of desaturated and elongated n−6 fatty acids from 18:2n−6[d2] were investigated in six adult male subjects. The subjects were fed either a high‐arachidonic acid (HIAA) diet containing 1.7 g/d or a low‐AA (LOAA) diet containing 0.21 g/d of AA for 50 d. Each subject was then dosed with about 3.5 g of 18:2n−6[d2] as the triglyceride (TG) at 8:00 a.m., 12:00, and 5:00 p.m. The total 18:2n−6[d2] fed to each subject was about 10.4 g and is approximately equal to one‐half of the daily intake of 18:2n−6 in a typical U.S. male diet. Nine blood samples were drawn over a 96‐h period. Methyl esters of plasma total lipid (TL), TG, phospholipid, and cholesterol ester were analyzed by gas chromatography‐mass spectroscopy. Dietary 20:4n−6 supplementation did not affect uptake of 18:2n−6[d2] in plasma lipid classes over the 4‐d study period nor the estimated half‐life of 24–36 h for 18:2n−6[d2]. The percentages of major deuterium‐labeled desaturation and elongation products in plasma TL, as a percentage of total deuterated fatty acids, were 1.35 and 1.34% 18:3n−6[d2]; 0.53 and 0.50% 20:2n−6[d2]; 1.80 and 0.92% 20:3n−6[d2] and 3.13 and 1.51% 20:4n−6[d2] for the LOAA and HIAA diet groups, respectively. Trace amounts (<0.1%) of the TL concentration data for both 20:3n−6[d2] and 20:4n−6[d2] were 48% lower (P<0.05) in samples from the HIAA diet group than in samples from the LOAA diet group. For a normal adult male consuming a typical U.S. diet, the estiamted accumulation in plasma TL of 20:4n−6 synthesized from 20 g/d (68 mmole) of 18:2n−6 is 677 mg/d (2.13 mmole). Dietary supplementation with 1.5 g/d of 20:4n−6 reduced accumulation of 20:4n−6 synthesized from 20 g/d of 18:2n−6 to about 326 mg/d (1.03 mmole).
Suppression of hypercholesterolemia in hepatoma‐bearing rats by cabbage extract and its component, S‐methyl‐l‐cysteine sulfoxide
Authors: Komatsu Wataru , Miura Yutaka , Yagasaki Kazumi
Published: November 2006

The effect of cabbage extract on cholesterol metabolism was studied in Donryu rats subcutaneously implanted with an ascites hepatoma cell line (AH109A). The hepatoma‐bearing rats exhibited hypercholesterolemia induced by increasing cholesterogenesis in the host liver and decreasing steroid excretion into feces. The cabbage extract intake or administration reduced serum cholesterol level and enhanced fecal bile acid excretion and cholesterol 7α‐hydroxylase activity, the rate‐limiting enzyme of bile acid biosynthesis, in the microsomal fraction of the liver. Furthermore, S‐methyl‐l‐cysteine sulfoxide, a component of cabbage, could mimic the effect of cabbage extract when orally administered. These results suggest that cabbage suppresses hypercholesterolemia responding to hepatoma growth by upregulating cholesterol catabolism and that S‐methyl‐l‐cysteine sulfoxide in cabbage is one of the factors suppressing hypercholesterolemia in the hepatoma‐bearing rats.
Conjugated linoleic acid modulates tissue levels of chemical mediators and immunoglobulins in rats
Authors: Sugano Michihiro , Tsujita Akira , Yamasaki Masao , Noguchi Miwa , Yamada Koji
Published: November 2006

The effects of conjugated linoleic acid (CLA) on the levels of chemical mediators in peritoneal exudate cells, spleen and lung, and the concentration of immunoglobulins in mesenteric lymph node and splenic lymphocytes and in serum were examined in rats. After feeding diets containing either 0 (control), 0.5 or 1.0% CLA for 3 wk, there was a trend toward a reduction in the release of leukotriene B4 (LTB4) from the exudate cells in response to the dietary CLA levels. However, CLA did not appear to affect the release of histamine. A similar dose‐response pattern also was observed in splenic LTB4, lung LTC4 and serum prostaglandin E2 levels, and the differences in these indices between the control and 1.0% CLA groups were all statistically significant. The reduction by CLA of the proportions of n−6 polyunsaturated fatty acids in peritoneal exudate cells and splenic lymphocyte total lipids seems to be responsible at least in part for the reduced eicosanoid levels. Splenic levels of immunoglobulin A (IgA), IgG, and IgM increased while those of IgE decreased significantly in animals fed the 1.0% CLA diet. This was reflected in the serum levels of immunoglobulins. The levels of IgA, IgG, and IgM in mesenteric lymph node lymphocytes increased in a dose‐dependent manner, while IgE was reduced in those fed the higher CLA intake. However, no differences were seen in the proportion of T‐lymphocyte subsets of mesenteric lymph node. These results support the view that CLA mitigates the food‐induced allergic reaction.
Dietary docosahexaenoic acid and immunocompetence in young healthy men
Authors: Kelley D. S. , Taylor P. C. , Nelson G. J. , Mackey B. E.
Published: November 2006

The purpose of this study was to examine the effect of dietary docosahexaenoic acid (DHA), in the absence of eicosapentaenoic acid, on human immune response (IR). A 120‐d study with 11 healthy men was conducted at the Metabolic Research Unit of the Western Human Nutrition Research Center. Four subjects (control group) were fed the stabilization or basal diet (15, 30, and 55% energy from protein, fat, and carbohydrate, respectively) throughout the study; the remaining seven subjects (DHA group) were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg d‐α‐tocopherol acetate per day. Indices of IR were examined on study day 22, 30, 78, 85, 106, and 113. Addition of DHA at moderately high levels did not alter the proliferation of peripheral blood mononuclear cells cultured with phytohemag‐glutinin or concanavalin A, or the delayed hypersensitivity skin response. Also, additional DHA did not alter the number of T cells producing interleukin 2 (IL2), the ratio between the helper/suppressor T cells in circulation, or the serum concentrations of immunoglobulin G, C3, and interleukin 2 receptor (IL2R). DHA supplementation, however, caused a significant (P=0.0001) decrease in the number of circulating white blood cells which was mainly due to a decrease in the number of circulating granulocytes. The number of lymphocytes in peripheral circulation was not affected by Dietary DHA enrichment, but the percentage of lymphocytes in white blood cells increased because of a reduction in granulocyte numbers. None of these indices was changed in the control group. Our results show that when total fat intake is low and held constant, DHA consumption does not inhibit many of the lymphocyte functions which have been reported to be inhibited by fish oil consumption.