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PubMed1990

Availability of linoleic acid from cereal-pulse diets.

Cereals and pulses alone provide nearly two-thirds of the daily linoleic acid requirement in habitual Indian diets. Two-thirds of the lipids present in cereals is in bound form. To investigate to what extent the essential fatty acids (EFA) present in cereals and pulses are biologically available, weanling rats were fed rice-pulse based diets either without supplementation or supplemented with one of three vegetable oils--coconut, palmolein or groundnut oil. Plasma phospholipid fatty acid composition was used to assess the EFA status, with ratios of eicosatrienoic/arachidonic acids (20:3n-9/20:4n-6) above 0.2, indicating linoleic acid deficiency. In the unsupplemented group, the levels of linoleic and arachidonic acids were low as compared to the groundnut oil fed group. However, the ratio of 20:3n-9/20:4n-6 was less than 0.2, indicating that there was no linoleic acid deficiency. This shows that the linoleic acid present in rice and pulse may be readily available.

Animals↗
PubMed1985

Absorption of 13C-labeled stearic, oleic, and linoleic acids in humans: application to breath tests.

Intestinal absorption of ingested [1-13C]stearic, [1-13C]oleic, and [1-13C]linoleic acid was compared in six healthy men. A bolus of each [1-13C]-labeled fatty acid was ingested in random order at 72-hour intervals with the breakfast meal. Subjects consumed fixed diets during a 9-day fecal collection period. Pooled 9-day fecal samples were homogenized and total fat extracted. Fat extracts were saponified and methylated, and individual fatty acids were quantitated by gas-liquid chromatography. Preparative high-performance liquid chromatography was used to obtain fractions containing stearic, oleic, and linoleic acid for combustion to CO2 and assay of 13C enrichment over background. Prelabel period 24-hour samples were treated similarly to measure background 13C abundance. Total fatty acid and stearic, oleic, and linoleic acid excretion (+/- SEM) in the six volunteers over the 9-day period was 41.5 +/- 7.3, 10.0 +/- 1.3, 8.8 +/- 2.9, and 0.8 +/- 0.1 mg/day/kg body weight, respectively. The absorption efficiency for [1-13C]stearic, [1-13C]oleic, and [1-13C]linoleic acid was 78.0% +/- 4.5%, 97.2% +/- 1.7%, and 99.9% +/- 0.1%, respectively. The reduced absorption of [1-13C]stearic acid observed emphasizes the importance of correcting breath test oxidation data for fecal loss of 13C substrate. The potential application of our method to other areas of intermediary metabolism is discussed.

Adult↗
PubMed1995

Hematopoietic toxicity of linoleic acid anilide: importance of aniline.

The purpose of this study was to investigate the role of hydrolysis products of linoleic acid anilide (LAA), i.e., aniline and linoleic acid (LA), in the toxicity to the hemopoietic system, especially to the spleen. To achieve this, the parent compound (LAA) and its putative hydrolysis products, i.e., aniline or linoleic acid (LA), were given to male SD rats at equimolar doses (0.7 mmol/kg) in 0.25 ml mineral oil by gavage, daily, for 14 days. The controls received equal volumes of vehicle only. Five animals from each group were euthanized at Days 1, 7, and 28 following the last dose. At all time points, spleen weights increased in the LAA- and aniline-treated rats, but spleen to body weight ratios were increased only at Days 1 and 7 in these groups. No changes were observed in the LA-treated rats at any time point. RBC counts were decreased in the LAA and aniline groups at Days 1 and 7, whereas hemoglobin content was decreased by 20 and 13% in the LAA- and aniline-treated rats, respectively, only at Day 1. Methemoglobin content in the LAA and aniline groups also increased by 76 and 101%, respectively, at Day 1. Serum transaminases (AST and ALT) decreased in the LAA, aniline, and LA groups but the decreases were more consistent in the LA group. Serum IgA increased in the LAA and aniline groups only at Day 1. Splenic iron content was increased 381, 486, and 51% in the LAA-treated rats and 474, 491, and 58% in the aniline-treated rats at Days 1, 7, and 28, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Anilides↗
PubMed1984

Experimental myocardial infarction: effects of a lipid peroxide, 13-hydroperoxy linoleic acid on coronary circulation in rats.

Effects of 13-hydroperoxy linoleic acid on coronary circulation and vasculature were investigated using an electrocardiographic (ECG) and scanning electron microscopic (SEM) techniques. After the intra left ventricular injection of 13-hydroperoxy linoleic acid to rats the ischemic ECG changes, i.e., elevations of the ST segment and T wave, were observed with the reduction of systemic blood pressure and heart rate. By the SEM examination, the endothelial injuries were found with the platelet aggregation in the blood flow and the adherence of leukocytes. Thus it was clearly found that 13-hydroperoxy linoleic acid caused the various endothelial injuries and thrombus formation leading to coronary arterial occlusion. These results suggest that lipid peroxide may play an important role in the pathogenesis of vascular diseases especially in coronary vascular bed and take part in the generation of the severe myocardial ischemia.

Animals↗
PubMed2002

Suppressive effect of saturated acyl L-ascorbate on the oxidation of linoleic acid encapsulated with maltodextrin or gum arabic by spray-drying.

6-O-Palmitoyl L-ascorbate was added to linoleic acid at various molar ratios of the ascorbate to the acid, the mixtures were emulsified with a maltodextrin or gum arabic solution, and the emulsions were spray-dried to produce microcapsules. At higher molar ratios, the oil droplets in the emulsions were smaller, and the oxidative stabilities of the encapsulated linoleic acid were higher for both the maltodextrin- and gum arabic-based microcapsules. 6-O-Capryloyl, caproyl, and lauroyl L-ascorbates, which were synthesized through lipase-catalyzed condensation in acetone, were also used for the microencapsulation of linoleic acid. Except for capryloyl L-ascorbate, the addition of a saturated acyl ascorbate, especially caproyl ascorbate, to linoleic acid was effective for preparing oil droplets of small particle diameter and for suppressing the oxidation of the encapsulated linoleic acid.

Acylation↗
PubMed1994

The presence of linoleic acid in Escherichia coli cannot be confirmed.

Escherichia coli was recently reported to accumulate significant quantities of linoleic acid in stationary phase (H. Rabinowitch, D. D. Sklan, D. H. Chace, R. D. Stevens, and I. Fridovich, J. Bacteriol. 175:5324-5328, 1993). Since this finding would have considerable impact on the biochemical mechanisms of type II fatty acid synthases, we have attempted to confirm this observation. We found no evidence for the accumulation of linoleic acid in late-stationary-phase cultures of E. coli and conclude that the results of Rabinowitch et al. are artifactual.

Escherichia coli↗
PubMed1997

Identification and Characterization of Linoleic Acid as an Endogenous Modulator of in Vitro N-1-Naphthylphthalamic Acid Binding.

An endogenous inhibitor of the in vitro binding of the phytotropin N-1-naphthylphthalamic acid to microsomal membranes was detected in extracts prepared from etiolated pea (Pisum sativum L.) epicotyls. Following extensive purification, the inhibitor was identified as linoleic acid. Authentic linoleic acid inhibited N-1-naphthylphthalamic acid binding noncompetitively in a dose-dependent manner, exhibiting a 50% inhibitory concentration of approximately 24 ([mu]M. Using a variety of fatty acids and their derivatives, this inhibition was found to exhibit strict structural requirements, with both linoleic and linolenic acids being the most inhibitory. A variety of membrane-solubilizing detergents elicited no such inhibitory activity when tested at equivalent concentrations. The possible physiological significance of this interaction is discussed and it is proposed that linoleic acid serves as an intracellular modulator of phytotropin binding and therefore polar auxin transport.

Journal Article↗
PubMed2003

Relationship between the amount of linoleic acid in the diet and that in the adipose tissue of adult cats living freely in households.

The present study was carried out to ascertain whether linoleic acid intake and the content of this fatty acid in adipose tissue are correlated in cats. The linoleic acid intake, as estimated from a food intake questionnaire, was indeed correlated with the linoleic acid content of the abdominal body fat in 165 adult, female cats. A statistically significant linear correlation coefficient of 0.43 was found between the percentage of linoleic acid in the adipose tissue and that in the diet. It is plausible that the observed acid content of adipose tissue of free-living cats may be considered to be a valid biomarker of linoleic acid intake that might be used in studies on diet and chronic disease.

Adipose Tissue↗
PubMed2005

Conjugated linoleic acid evokes de-lipidation through the regulation of genes controlling lipid metabolism in adipose and liver tissue.

Conjugated linoleic acid (CLA) is a unique lipid that elicits dramatic reductions in adiposity in several animal models when included at < or = 1% of the diet. Despite a flurry of investigations, the precise mechanisms by which conjugated linoleic acid elicits its dramatic effects in adipose tissue and liver are still largely unknown. In vivo and in vitro analyses of physiological modifications imparted by conjugated linoleic acid on protein and gene expression suggest that conjugated linoleic acid exerts its de-lipidating effects by modulating energy expenditure, apoptosis, fatty acid oxidation, lipolysis, stromal vascular cell differentiation and lipogenesis. The purpose of this review shall be to examine the recent advances and insights into conjugated linoleic acid's effects on obesity and lipid metabolism, specifically focused on changes in gene expression and physiology of liver and adipose tissue.

Adipose Tissue↗
PubMed1992

IL-1 increases phospholipase A2 activity, expression of phospholipase A2-activating protein, and release of linoleic acid from the murine T helper cell line EL-4.

The early events in IL-1-mediated activation of T cells were investigated in the murine T cell line, EL-4. Treatment of EL-4 cells with human rIL-1 beta resulted in a rapid increase in phospholipase A2 (PLA2) activity. PLA2 activity increased approximately fivefold within 4 min after exposure to IL-1. Synthesis of the phospholipase A2- activating protein (PLAP) and its mRNA were also increased within 4 min of IL-1 treatment and preceded the increase in PLA2 enzyme activity. The increases in PLA2 activity and PLAP protein and mRNA levels were all transient and declined to baseline within 10 min after the addition of IL-1. The changes in levels of PLAP as a function of time after IL-1 treatment were consistent with PLAP playing an important role in the regulation of PLA2 activity in this system. The consequence of the elevated PLA2 activity was examined by analysis of the fatty acids released from IL-1-treated cells. There was a 20-fold increase in the release of radioactivity from [14C]-linoleic acid labeled cells whereas there was very little change in the release of radioactivity from [14C]-arachidonic acid labeled cells in response to the addition of IL-1. The radioactivity released from [14C]-linoleic acid labeled cells was analyzed by HPLC; no conversion of radiolabeled linoleic into arachidonic acid was observed. In EL-4 cells, IL-1 potentiates PMA-mediated release of IL-2 at suboptimal concentrations of PMA. Linoleic acid also augmented PMA-induced IL-2 release from the EL-4 cells. This fatty acid was more than 10 times more effective than arachidonic acid in this regard. Furthermore, the addition of exogenous PLAP to EL-4 cells could substitute for IL-1 in the stimulation of IL-2 release. These results suggest that the IL-1 effects on T cells may be mediated at least in part through increased PLA2 activity due to increased synthesis of PLAP. Furthermore, the release of the unsaturated fatty acid linoleic acid or its metabolites may be of functional importance in IL-1-mediated IL-2 production by EL-4 cells.

Animals↗
PubMed2002

Linoleic acid, other fatty acids, and the risk of stroke.

BACKGROUND AND PURPOSE: The role of serum fatty acids as a risk factor for stroke and stroke subtypes is largely unknown. METHODS: A prospective nested case-control study of Japanese 40 to 85 years of age was conducted through the use of frozen serum samples from 7450 participants in cardiovascular risk surveys collected from 1984 to 1989 for 1 community and 1989 to 1992 for the other 2 communities. By the end of 1998, we identified 197 incident strokes whose subtypes were confirmed by imaging studies. Three controls per case were selected by matching for sex, age, community, year of serum storage, and fasting status. RESULTS: Compared with controls, total (n=197), hemorrhagic (n=75), and ischemic (n=122) strokes had similar proportions of n3 polyunsaturated fatty acids, lower proportions of linoleic and arachidonic acids, and higher proportions of saturated and monosaturated acids, determined by gas chromatography. The multivariate odds ratios associated with a 1-SD increase in linoleic acid (5%) after adjustment for hypertension, diabetes, serum total cholesterol, and other cardiovascular risk factors were 0.72 [95% confidence interval (CI), 0.59 to 0.89] for total stroke, 0.66 (95% CI, 0.49 to 0.88) for ischemic stroke, 0.63 (95% CI, 0.46 to 0.88) for lacunar infarction, and 0.81 (95% CI, 0.59 to 1.12) for hemorrhagic stroke. The respective odds ratios for saturated fatty acids (4%) were 1.13 (95% CI, 1.05 to 1.65), 1.35 (95% CI, 1.01 to 1.79), 1.44 (95% CI, 1.03 to 2.01), and 1.21 (95% CI, 0.82 to 1.80). Further adjustment for other fatty acids attenuated these relations, but the relation between linoleic acid and risk of ischemic stroke remained statistically significant. CONCLUSIONS: A higher intake of linoleic acid may protect against ischemic stroke, possibly through potential mechanisms of decreased blood pressure, reduced platelet aggregation, and enhanced deformability of erythrocyte cells.

Adult↗
PubMed1999

Metabolic profile of linoleic acid in stored apples: formation of 13(R)-hydroxy-9(Z),11(E)-octadecadienoic acid.

During our ongoing project on the biosynthesis of R-(+)-octane-1,3-diol the metabolism of linoleic acid was investigated in stored apples after injection of [1-14C]-, [9,10,12,13-3H]-,13C18- and unlabeled substrates. After different incubation periods the products were analyzed by gas chromatography-mass spectroscopy (MS), high-performance liquid chromatography-MS/MS, and HPLC-radiodetection. Water-soluble compounds and CO2 were the major products whereas 13(R)-hydroxy- and 13-keto-9(Z),11(E)-octadecadienoic acid, 9(S)-hydroxy- and 9-keto-10(E),12(Z)-octadecadienoic acid, and the stereoisomers of the 9,10,13- and 9,12,13-trihydroxyoctadecenoic acids were identified as the major metabolites found in the diethyl ether extracts. Hydroperoxides were not detected. The ratio of 9/13-hydroxy- and 9/13-keto-octadecadienoic acid was 1:4 and 1:10, respectively. Chiral phase HPLC of the methyl ester derivatives showed enantiomeric excesses of 75% (R) and 65% (S) for 13-hydroxy-9(Z),11(E)-octadecadienoic acid and 9-hydroxy-10(E),12(Z)-octadecadienoic acid, respectively. Enzymatically active homogenates from apples were able to convert unlabeled linoleic acid into the metabolites. Radiotracer experiments showed that the transformation products of linoleic acid were converted into (R)-octane-1,3-diol. 13(R)-Hydroxy-9(Z),11(E)-octadecadienoic acid is probably formed in stored apples from 13-hydroperoxy-9(Z),11(E)-octadecadienoic acid. It is possible that the S-enantiomer of the hydroperoxide is primarily degraded by enzymatic side reactions, resulting in an enrichment of the R-enantiomer and thus leading to the formation of 13(R)-hydroxy-9(Z),11(E)-octadecadienoic acid.

Chromatography, High Pressure Liquid↗
PubMed2003

Dietary conjugated linoleic acid reduces PGE2 release and interstitial injury in rat polycystic kidney disease.

BACKGROUND: Conjugated linoleic acid (CLA) describes positional isomers of linoleic acid (LA). Experimental health benefits of CLA include amelioration of malignancy and inflammatory disease and reduction of adiposity. The Han:SPRD-cy rat model of polycystic kidney disease (PKD) features prominent renal interstitial inflammation and fibrosis that is amenable to dietary modification. We studied CLA supplementation in the modification of inflammatory outcomes in the Han:SPRD-cy rat. METHODS: Male offspring of Han:SPRD-cy heterozygotes were fed diets, using corn oil or corn oil with a CLA enriched oil (1% of diet by weight as CLA). After 8 weeks, measurements included renal function and morphometry, ex vivo release of renal prostaglandin E2 (PGE2), and renal and hepatic tissue fatty acid profiles. RESULTS: Urine creatinine was significantly higher in PKD animals fed CLA (P = 0.004), but differences in serum creatinine and creatinine clearance did not quite reach significance in PKD animals. CLA feeding reduced interstitial inflammation (P < 0.001), fibrosis (P = 0.03), and renal PGE2 release (P = 0.02). Cystic change and oxidized low-density lipoprotein (LDL) staining did not change significantly. CLA feeding produced increased renal and hepatic CLA isomers. Hepatic, but not renal, LA proportion was reduced on the CLA diet. The renal proportion of the PGE2 precursor, arachidonic acid (AA), was not changed by diet, but hepatic AA proportion increased significantly with CLA feeding (P= 0.009). CONCLUSION: CLA reduces renal production of PGE2, without reduced availability of the precursor fatty acid, AA. Short-term feeding of CLA to Han:SPRD-cy rats also has significant renal anti-inflammatory and antifibrotic effects. As inflammation and fibrosis are important components of the progression of chronic renal injury, CLA may be a useful agent in dietary amelioration of renal disease.

Animals↗
PubMed1987

Linoleic acid levels in white blood cells, platelets, and serum of multiple sclerosis patients.

We found a small but statistically significant reduction in the linoleic acid concentration of white blood cells and platelets in MS patients. The percent linoleic acid concentration (mean +/- S.D.) in the white blood cells if 24 MS patients was 8.8 +/- 1.8% as compared with 11.4 +/- 4.9 in 24 age and sex-matched controls (p less than 0.05). Platelet levels were 8.5 +/- 2.4% and 10.6 +/- 3.8% respectively (P less than 0.05). Serum linoleic acid levels were not significantly different in the two groups. The possible role of linoleic acid in the pathogenesis of MS has yet to be defined.

Adult↗
PubMed1996

Zinc deficiency and the desaturation of linoleic acid in rats force-fed fat-free diets.

Recent studies with rats force-fed zinc-deficient diets containing various types of fat failed to demonstrate a role of zinc in desaturation of linoleic acid. The present study was conducted to investigate the effect of zinc deficiency on desaturation of linoleic acid in rats that were initially force-fed fat-free diets to stimulate activity of desaturases. Therefore, rats were fed zinc-adequate and zinc-deficient fat-free diets for 6 d. After that period, the groups were divided and half of the rats continued feeding the fat-free diet for another 3.5 d whereas the other half was switched to a fat diet by supplementing the fat-free diet with 5% safflower oil. In order to assess desaturation of linoleic acid, fatty acid compositions of liver phosphatidylcholine, -ethanolamine, and -serine were considered, particularly levels of individual (n-6) polyunsaturated fatty acids (PUFA). Levels of total and individual (n-6) PUFA were similar in zinc-adequate and zinc-deficient rats fed the fat-free diet throughout the experiment. Addition of 5% safflower oil increased levels of total and individual (n-6) PUFA in both zinc-adequate and zinc-deficient rats. However, total (n-6) PUFA in all types of phospholipids were higher in zinc-adequate rats than in zinc-deficient rats. Additionally, in zinc-deficient rats there were changes of (n-6) PUFA levels typical for impaired delta 5 and delta 6 desaturation: linoleic acid and dihomo-gamma-linolenic acid were elevated; arachidonic acid, docosatetraenoic acid, and docosapentaenoic were lowered by zinc deficiency. Therefore, the study shows that zinc deficiency impairs desaturation of linoleic acid in rats force-fed fat-free diets and therefore supports results from former convential zinc deficiency experiments suggesting a role of zinc for desaturation of linoleic acid.

Analysis of Variance↗
PubMed2004

The trans-10,cis-12 isomer of conjugated linoleic acid reduces hepatic triacylglycerol content without affecting lipogenic enzymes in hamsters.

Conjugated linoleic acid (CLA) refers to the positional and geometric dienoic isomers of linoleic acid. The dietary intake of CLA has been associated with changes in lipid metabolism. The aim of the present work was to assess the effects of the two main isomers of CLA on sterol regulatory element binding protein (SREBP)-1a and SREBP-1c mRNA levels, as well as on mRNA levels and the activities of several lipogenic enzymes in liver. For this purpose hamsters were fed an atherogenic diet supplemented with 5 g linoleic acid, cis-9,trans-11 or trans-10,cis-12 CLA/kg diet for 6 weeks. The trans-10,cis-12 isomer intake produced significantly greater liver weight, but also significantly decreased liver fat accumulation. No changes in mRNA levels of SREBP-1a, SREBP-1c and lipogenic enzymes, or in the activities of these enzymes, were observed. There was no effect of feeding cis-9,trans-11 CLA. These results suggest that increased fat accumulation in liver does not occur on the basis of liver enlargement produced by feeding the trans-10,cis-12 isomer of CLA in hamsters. The reduction in hepatic triacylglycerol content induced by this isomer was not attributable to changes in lipogenesis.

Acetyl-CoA Carboxylase↗
PubMed2006

Linoleic acid induces proinflammatory events in vascular endothelial cells via activation of PI3K/Akt and ERK1/2 signaling.

Linoleic acid (18:2n-6), is a major unsaturated fatty acid in the American diet. Linoleic acid is considered to be atherogenic because of its pro-oxidative and proinflammatory properties. There is substantial evidence that linoleic acid (LA) can activate vascular endothelial cells and contribute to an inflammatory response. To explore the mechanisms of LA-induced proinflammatory signaling pathways, the present study addresses the role of the phosphatidylinositol 3-kinase/amino kinase terminal (PI3K/Akt), extracellular signal regulated kinase 1/2 (ERK1/2) and p38 mitogen-activated protein kinase (MAPK) pathways during vascular endothelial cell activation. After a 3- to 6-h exposure, LA significantly activated both Akt and ERK in endothelial cells, as assessed by western blot and immunofluorescence. In contrast, LA activated p38 MAPK already at 10 min, suggesting that p38 MAPK signaling occurred upstream of the ERK1/2 pathway. Furthermore, inhibition of ERK activity by PD98059 and PI3K/Akt activity by LY294002 or wortmannin significantly reduced the LA-induced activation of nuclear factor kappa B (NF-kappaB). These results suggest a contribution of both the ERK1/2 and PI3K/Akt pathways to the effect of LA on NF-kappaB-dependent transcription. Indeed, LA-mediated gene expression of the vascular cell adhesion molecule 1 was suppressed by PD98059, wortmannin and LY294002. These data indicate that both PI3K/Akt- and ERK1/2-mediated proinflammatory signaling events are critical in LA-induced endothelial cell activation and vascular inflammation.

Animals↗
PubMed2001

Transgenic expression of a delta 12-epoxygenase gene in Arabidopsis seeds inhibits accumulation of linoleic acid.

The Crepis palaestina cDNA Cpal2 encodes a delta 12-epoxygenase that can catalyse the synthesis of 12,13-epoxy-cis-9-octadecenoic acid (18:1E) from linoleic acid (18:2). When the Cpal2 gene was expressed under the control of the napin seed-specific promoter in Arabidopsis thaliana (L.) Heynh., the seed lipids accumulated only low levels of 18:1E and also 12,13-epoxy-cis-9,15-octadec-2-enoic acid (18:2E). Despite the fact that the levels of these epoxy fatty acids comprised only up to 6.2% of the total fatty acids, there was a very marked increase in oleic acid (18:1) and decrease in linoleic (18:2) and alpha-linolenic (18:3) acids in these plants, indicating that endogenous delta 12-desaturation was greatly reduced in these plants. Significant between-line differences in the levels of Cpal2 mRNA were observed during seed development, but were not associated with any major variation in mRNA levels for the endogenous Arabidopsis delta 12-desaturase (Fad2). This suggests that if an unfavourable interaction occurs between the transgenic delta 12-epoxygenase and the endogenous delta 12-desaturase, which decreases the level of desaturation, it occurs at either the translational or post-translational level. We further show that the co-expression of a delta 12-desaturase gene from C. palaestina in Cpal2 transgenic Arabidopsis returns the relative proportions of the C18 seed fatty acids to normal levels and results in an almost twofold increase in total epoxy fatty acids.

2S Albumins, Plant↗