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PubMed1991

Gas chromatographic analysis of malonaldehyde and 4-hydroxy-2-(E)-nonenal produced from arachidonic acid and linoleic acid in a lipid peroxidation model system.

Malonaldehyde (MA) and 4-hydroxynonenal (4-HN) formed upon oxidation with Fe2+/H2O2 from arachidonic acid and linoleic acid, and their ethyl esters were analyzed by gas chromatography (GC). The MA and 4-HN produced were reacted with N-methylhydrazine (NMH) to give 1-methylpyrazole and 5(1'-hydroxyhexyl)-1-methyl-2-pyrazoline, respectively. The derivatives were analyzed by GC on a fused silica capillary column using a nitrogen-phosphorus detector. With arachidonic acid, more MA and 4-HN were formed from the ester (88 nmol/mg and 23 nmol/mg, respectively) than from the free acid (25 nmol/mg and 9 nmol/mg, respectively). In contrast, with linoleic acid, more MA and 4-HN were produced from the free acid (53 nmol/mg and 13 nmol/mg, respectively) than from the ester (39 nm/mg and 8 nmol/mg, respectively).

Aldehydes↗

PubMed1991

The fate of arachidonic acid and linoleic acid in isolated working rat hearts containing normal or elevated levels of coenzyme A.

If myocardial levels of coenzyme A (CoA) are elevated, an increase in the rate of esterification of palmitate into myocardial triacylglycerols will occur. In this study, we determined the fate of linoleic acid and arachidonic acid in isolated working rat hearts containing normal or elevated levels of CoA. In hearts containing normal levels of CoA, oxidative rates (measured as 14CO2 production) of [14C]arachidonic acid were significantly lower than those of [14C]palmitic acid, whereas a significantly greater incorporation of [14C]arachidonic acid into myocardial neutral lipids (comprised predominantly of triacylglycerols) was seen when compared to hearts perfused with [14C]palmitic acid. In a second series of hearts, myocardial CoA levels were elevated by perfusing hearts with no carbon substrate, 15 microM pantothenate, 0.5 mM cysteine and 1 mM dithiothreitol, resulting in an increase in myocardial CoA levels from 553 +/- 2 to 918 +/- 63 nmol/g dry wt. Subsequent perfusion of hearts containing elevated CoA levels with 1.2 mM [3H]arachidonic acid or [14C]linoleic acid resulted in a significant increase in incorporation of both these fatty acids into myocardial neutral lipids compared to control hearts. Incorporation of these fatty acids into phospholipids was significantly lower than their incorporation into neutral lipids and was not affected by myocardial CoA levels. Linoleic acid oxidation was unaffected by increases in myocardial levels of CoA. If linoleic acid oxidation was inhibited by adding 5 mM pyruvate to the perfusate, no effect on the incorporation of [14C]linoleic acid into neutral lipids was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1990

Dietary n-9, n-6, and n-3 fatty acids modify linoleic acid more than arachidonic acid levels in plasma and platelet lipids and minimally affect platelet thromboxane formation in the rabbit.

We have studied the effects of semisynthetic diets containing 5% by weight (12% of the energy) of either olive oil (70% oleic acid, OA) or corn oil (58% linoleic acid), or fish oil (Max EPA, containing about 30% eicosapentaenoic, EPA C 20:5 n-3, plus docosahexaenoic, DHA C 22:6 n-3, acids, and less than 2% linoleic acid), fed to male rabbits for a period of five weeks, on plasma and platelet fatty acids and platelet thromboxane formation. Aim of the study was to quantitate the absolute changes of n-6 and n-3 fatty acid levels in plasma and platelet lipid pools after dietary manipulations and to correlate the effects on eicosanoid-precursor fatty acids with those on platelet thromboxane formation. The major differences were found when comparing the group fed fish oil and depleted linoleic acid vs the other groups. The accumulation of n-3 fatty acids in various lipid classes was associated with modifications in the distribution of linoleic acid and arachidonic acid in different lipid pools. In platelets maximal incorporation of n-3 fatty acids occurred in phosphatidyl ethanolamine, which also participated in most of the total arachidonic acid reduction occurring in platelets, and linoleic acid, more than archidonic acid, was replaced by n-3 fatty acids in various phospholipids. The archidonic acid content of phosphatidyl choline was unaffected and that of phosphatidyl inositol only marginally reduced. Thromboxane formation by thrombin stimulated platelets did not differ among the three groups, and this may be related to the minimal changes of arachidonic acid in phosphatidyl choline and phosphatidyl inositol.

Journal Article↗

PubMed2005

Small differences in the effects of stearic acid, oleic acid, and linoleic acid on the serum lipoprotein profile of humans.

BACKGROUND: Studies have suggested that oleic and stearic acids, as well as oleic and linoleic acids, have comparable effects on the serum lipoprotein profile. If so, then substituting these three 18-carbon fatty acids for each other would result in similar effects on the serum lipoprotein profile. OBJECTIVE: The aim of this study was to compare simultaneously the effects of stearic, oleic, and linoleic acids on the serum lipoprotein profile of healthy subjects. DESIGN: Forty-five subjects (27 women and 18 men) consumed in random order 3 experimental diets, each for 5 wk. The diets provided 38% of energy from fat, of which 60% was supplied by the experimental fats. The dietary compositions of the diets were the same, except for 7% of energy, which was provided by stearic, oleic, or linoleic acid. At the end of each intervention period, serum lipid and lipoprotein concentrations were measured. In addition, LDL, HDL, and VLDL particle sizes and particle concentrations of lipoprotein subclasses were analyzed by nuclear magnetic resonance spectroscopy. RESULTS: No significant diet-induced changes in serum lipids and lipoproteins were found. Mean (+/-SD) serum LDL-cholesterol concentrations were 3.79 +/- 0.91, 3.71 +/- 0.79, and 3.65 +/- 0.91 mmol/L with the high-stearic acid, high-oleic acid, and high-linoleic acid diets, respectively (P = 0.137 for diet effects). Mean (+/-SD) HDL-cholesterol concentrations were 1.45 +/- 0.43, 1.46 +/- 0.45, and 1.46 +/- 0.44 mmol/L (P = 0.866). LDL, HDL, and VLDL particle sizes and lipoprotein subclass distributions also did not differ significantly between the 3 diets. CONCLUSIONS: With realistic intakes of stearic, oleic, and linoleic acids, differences between their effects on the serum lipoprotein profile are small.

Adult↗

PubMedDate not supplied

Modulation of MCF-7 breast cancer cell signal transduction by linoleic acid and conjugated linoleic acid in culture.

The effects of modifying membrane fatty acid composition on cell growth, phospholipase C (PLC) and protein kinase C (PKC) activities, and prostaglandin E2 (PGE2) secretion were investigated. Hormone responsive MCF-7 human breast cancer cells were incubated in a serum-free medium containing epidermal growth factor and supplemented with physiologic concentrations (0.18-1.78 x 10(-5) M) of linoleic acid (LA) or conjugated linoleic acid (CLA). Linoleic acid stimulated cancer cell growth, while CLA was inhibitory. Supplementation with LA or CLA altered cell membrane composition. Linoleic acid stimulated PLC activity with or without GTP gamma (S), and tended to increase membrane PKC activity. However, CLA supplementation did not modify membrane PLC or PKC activity. Prostaglandin E2 secretion was not influenced by LA or CLA. These data show that growth inhibition by CLA was not mediated through PLC-, PKC- or PGE2-dependent signal transduction pathways, suggesting that another inhibitory mechanism may be involved. Although biological differences appeared to be modest (5-20% of control), the fact that LA and CLA treatment resulted in significant biological effects at physiologic concentrations is relevant, since most human cancers require years to develop.

Anticarcinogenic Agents↗

PubMed1989

Formation of 9-hydroxyoctadecadienoic acid from linoleic acid in endothelial cells.

Human umbilical vein endothelial cells convert linoleic acid to two monohydroxyoctadecadienoic (HODE) acids, 9- and 13-HODE. More 9-HODE than 13-HODE is formed under most conditions. The production of these metabolites is reduced substantially by acetylsalicylic acid, ibuprofen, or arachidonic acid, suggesting that cyclooxygenase may be involved in endothelial HODE synthesis. Incubations lasting up to 4 h indicate that the endothelial cells can convert [U-14C] linoleic acid into at least four additional products, some of which may be derived from the HODE that is formed initially. Radioactive 9- and 13-HODE are produced when the endothelial cells are labeled with linoleic acid and then exposed to thrombin, suggesting that these metabolites also may be formed when the endothelium is activated. If endothelial monolayers grown on micropore filters are incubated with linoleic acid, a substantial amount of the HODE formed accumulates in the basolateral fluid. This suggests that HODE may have extracellular effects, especially within the vascular wall. Furthermore, when 9- or 13-HODE are added, endothelial cultures produce less prostaglandin I2 and convert less 12-hydroxyeicosatetraenoic acid to its main metabolite, 8-hydroxyhexadecatrienoic acid. Therefore, in addition to extracellular actions, HODE also may have functional effects within the endothelium.

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1977

Enzymatic oxydation of linoleic acid: formation of bittertasting fatty acids.

Linoleic acid was oxidized with a protein fraction from soya beans (25 degrees C; 2h), in which lipoxygenase and peroxydase activities occurred. The fatty acids formed were isolated and, after emulsification with a sugar ester, were evaluated for bitter taste. The main components of the bitter-tasting fractions was a mixture of 9.12.13-trihydroxyoctadec-10- and 9.10.13-trihydroxyoctadec-11-enoic acids. The taste threshold lies in the range 0.6-0.9 mumol/ml. Two further trihydroxy-acids and two oxodihydroxy-acids were also identified in the bitter-tasting fraction.

Fatty Acids↗

PubMedDate not supplied

A residential study comparing the effects of diets rich in stearic acid, oleic acid, and linoleic acid on fasting blood lipids, hemostatic variables and platelets in young healthy men.

Dietary fat is known to influence the variables of blood coagulation and fibrinolysis associated with vascular disease. However, the role of fat content and/or fat composition of the diet in this regard is still not well understood. In the present study, we investigated the effects of three isoenergic diets of differing fat composition in nine healthy young men in a strictly controlled residential study. Subjects consumed the three experimental diets for periods of 2 weeks each, separated by a washout period of at least 5 weeks in a randomized crossover design. The diets provided 38% of total energy intake as fat, 45% as carbohydrate, and 17% as protein, and differed only with respect to the fatty acid composition (stearic acid-rich diet: 34.1% stearic acid, 36.6% oleic acid; oleic acid-rich diet: 65.8% oleic acid; linoleic acid-rich diet: 36.5% linoleic acid, 38% oleic acid). Blood samples were collected at the beginning and at the end of each dietary period from fasted subjects for determination of factor VII coagulant activity (FVIIc), activated factor VII (FVIIa), factor VII antigen (FVIIag), tissue plasminogen activator (tPA) activity, plasminogen activator inhibitor type 1 (PAI-1) activity, fibrinogen, prothrombin fragment 1+2 (F(1+2)), and plasma lipids. There were no significant differences between diets in fasting plasma concentrations of FVIIc, FVIIa, FVIIag, fibrinogen, F(1+2), PAI-1 activity, and tPA activity. Plasma concentrations of lipids (high density lipoproteins, low density lipoproteins, triacylglycerols, and total cholesterol) were also unaffected. Although there were no changes in platelet aggregation response and membrane fluidity observed in any of the diets, increased anti-aggregatory prostaglandin E(1) binding to platelet membranes was observed only in the case of linoleic acid-rich diet. In conclusion, diets with very different fatty acid compositions, at 38% of energy as fat intake, did not significantly influence blood coagulation, fibrinolysis, or blood lipids in the fasting state in young healthy men.

Journal Article↗

PubMed1989

Synthesis of hydroxy fatty acids from linoleic acid by human blood platelets.

The metabolism of linoleic acid by washed human platelets was investigated. [1.14C] linoleic acid was converted to [1.14C] hydroxy octadecadienoic acids (HODEs) at about the same rate with which [1.14C] 12-HETE was produced from [1.14C] arachidonic acid. The total radioactivity in HODEs was distributed among two isomers: 13-HODE (85%) and 9-HODE (15%) as defined by CG-MS. The production of HODEs by intact washed platelets was inhibited by indomethacin (IC50:5 x 10(-7) M) which suggest that hydroxy fatty acids were produced by PGH-synthase. By contrast, the production of HODEs by platelet cytosolic fractions was not modified under indomethacin treatment but completely abolished by NDGA (10(-3) M) and inhibited by the platelet lipoxygenase inhibitors 15-HETE (2.10(-5) M) and baicalein (10(-5) M). Platelets thus contain two different active systems which may convert linoleic acid to hydroxy fatty acids. Since these compounds remained essentially associated with the platelets, their presence may significantly participate in the mechanisms of platelet activation.

Arachidonate 15-Lipoxygenase↗

PubMed1993

Effects of stearic acid and trans fatty acids versus linoleic acid on blood pressure in normotensive women and men.

The objective of this study was to compare the effect of linoleic acid (cis,cis-C18:2) with that of its hydrogenation products stearic acid (C18:0) and elaidic acid (trans-C18:1) on blood pressure levels in normotensive humans. We therefore measured the effects of these fatty acids on systolic and diastolic blood pressure in 30 women and 25 men. Three strictly controlled experimental diets were supplied to every subject for 3 weeks each, in different order (multiple cross-over). The composition of the three diets was constant, except for 8% of daily energy, which was provided by either linoleic acid, stearic acid, or monounsaturated trans fatty acids. The statistical power for detecting a true difference between two diets of 3 mmHg in systolic and diastolic blood pressure was over 90%. Mean systolic/diastolic blood pressure at the end of the dietary periods was 114/69 mmHg on the linoleic acid diet, 113/70 on the stearic acid diet, and 113/69 on the trans fatty acid diet. No significant differences were observed in blood pressure levels after 3 weeks on each diet. We conclude that a major increase in the intake of linoleic acid at the expense of stearic acid or trans fatty acids has no effect on blood pressure in normotensive young women and men.

Adult↗

PubMed2000

Identification and enumeration of oleic acid and linoleic acid hydrating bacteria in the rumen of sheep and cows.

The diversity and population densities of facultative anaerobic bacteria with the capacity to hydrate oleic acid and linoleic acid in the rumen of sheep and dairy cows were determined. The screening of representative colonies, from rumen fluid plated aerobically on a range of agar media, revealed that sheep rumen fluid contained hydration-positive strains of Streptococcus, Staphylococcus, Enterococcus, Lactobacillus and Pediococcus, whereas cow rumen fluid contained hydration-positive strains of Streptococcus, Lactobacillus and Staphylococcus. Mean counts of facultative anaerobic bacteria in sheep and cattle rumen were log10 7.29 and log10 6.40, respectively, and were independent of diet. Approximately 56% of facultative anaerobic bacteria were able to hydrate oleic and/or linoleic acid in anaerobic broth culture. For both sheep and cows, the most numerous hydration-positive isolates were strains of Strep. bovis. The results, which are the first to show that pediococci have the capacity to hydrate unsaturated fatty acids, suggest that lactic acid bacteria are the major unsaturated fatty acid hydrating bacteria in the rumen.

Animals↗

PubMed2003

The effects of fish oil, olive oil, oleic acid and linoleic acid on colorectal neoplastic processes.

BACKGROUND AND AIMS: Several nutrients play a significant role in colorectal cancer development, and fats could be among the most determinant. While several studies have shown that the n-3 fatty acids eicosapentaenoic and docosahexaenoic and its main dietary source, fish oil could exert important antineoplastic effects, much less is known about the effects of olive oil and its main fatty acid, oleic acid, and linoleic acid. The aim of these studies is to assess the role of these nutrients in crucial processes involved in colorectal carcinogenesis. METHODS: Caco-2 and HT-29 colorectal cancer cells were supplemented with different fats and their role in apoptosis induction, cell proliferation, and differentiation was studied. COX-2 and Bcl-2 expressions were also assessed. RESULTS: Supplementation with fish oil or olive oil results in an induction of apoptosis and cell differentiation. The latest effect was also induced by oleic and linoleic acid. Fish oil diminishes significantly cell proliferation. Supplementation with fish oil and olive oil results in an early downregulation of COX-2 followed by a decrease in Bcl-2 expression. CONCLUSIONS: Fish oil and olive oil are capable of influencing crucial processes responsible for colorectal cancer development. COX-2 and Bcl-2 may be important mediators of some of these effects.

Apoptosis↗

PubMed1995

Palmitic acid and linoleic acid metabolism in Caco-2 cells: different triglyceride synthesis and lipoprotein secretion.

Polarized monolayers of intestinal Caco-2 cells were used to study the effects of saturated palmitic acid (16:0) and polyunsaturated linoleic acid (18:2) on triglyceride synthesis and lipoprotein secretion. Monolayers were incubated for 24 h, at the apical or lumenal side, with palmitic acid (16:0) or linoleic acid (18:2) in physiological concentrations. Incubation with 1.0 mM 16:0 or 18:2 resulted in differences in the composition and amount of secreted lipoproteins. Radiolabeled lipids in the lipoproteins secreted during incubation with 18:2 were found in the chylomicron/VLDL (very low density lipoprotein) density whereas with 16:0 the secreted lipoproteins were in the intermediate density/low density lipoprotein (IDL/LDL) density range. More triglyceride was secreted into the (basolateral) medium during incubation with 1.0 mM 18:2 (41 +/- 12% of total triglyceride synthesized) than with 1.0 mM 16:0 (18 +/- 3% of total). The biochemical findings correlate with conspicuous morphological changes in the cells in the presence of 16:0, but not 18:2. Increasing concentrations of 16:0 (0.1-1.0 mM) caused gradual accumulation of intracellular membrane. Microvilli became strongly reduced in number. With 1.0 mM palmitic acid we found an increased incorporation of [1-14C]palmitic acid into phosphatidic acid (14.8% of total incorporation into phospholipid with 16:0 vs. < 0.5% with 18:2) and diacylglycerol (12.5% with 16:0 vs. < 0.5% with 18:2) and diacylglycerol (12.5% with 16:0 vs. 0.5% with 18:2) and the amount of intracellular phospholipid doubled. The morphological changes were completely reversed after 24 h with 1.0 mM 18:2. We conclude from our results that, compared to 18:2, 16:0 is not efficiently incorporated into triglycerides. 16:0 is incorporated into cellular phospholipids in a greater proportion than 18:2, causing accumulation of intracellular phospholipid and the precursors phosphatidic acid and diacylglycerol. Different processing of 18:2 and 16:0 by Caco-2 cells resulted in profound differences in triglyceride synthesis and lipoprotein composition and secretion.

Carbon Radioisotopes↗

PubMed2001

Beta-oxidation of conjugated linoleic acid isomers and linoleic acid in rats.

To assess the oxidative metabolism of conjugated linoleic acid (CLA) isomers, rats were force-fed 1.5-2.6 MBq of [1-14C]-linoleic acid (9c,12c-18:2), -rumenic acid (9c,11t-18:2), or-10trans,12cis-18:2 (10t,12c-18:2), and 14CO2 production was monitored for 24 h. The animals were then necropsied and the radioactivity determined in different tissues. Both CLA isomers were oxidized significantly more than linoleic acid. Moreover, less radioactivity was recovered in most tissues after CLA intake than after linoleic acid intake. The substantial oxidation of CLA isomers must be considered when assessing the putative health benefits of CLA supplements.

Administration, Oral↗

PubMed2001

Effect of diets rich in oleic acid, stearic acid and linoleic acid on postprandial haemostatic factors in young healthy men.

The aim of the present study was to investigate the effects of stearic acid-, oleic acid- and linoleic acid-rich meals on postprandial haemostasis in young healthy volunteers whose background diets had been controlled for 14 d in a residential study. Six healthy male volunteers were assigned randomly to consume diets rich in stearic acid, oleic acid or linoleic acid for 14 d. On day 15, plasma lipids and haematological variables were measured in the fasted state, and 3 and 7 h (factor VII and prothrombin activation peptide fragments, 1 and 2 only) after consumption of a test meal. Test meals provided 40 % of the subjects' daily energy requirement, with 41 % of the energy provided as fat, 17 % energy as protein and 42 % energy as carbohydrate. The mean fat content of the meal was 45 (sd 5) g. Significant alterations from fasted values were observed for activated factor VII after 7 h), factor VII antigen after 7 h), prothrombin activation peptide fragments 1 and 2 after 7 h) and plasminogen activator inhibitor type 1 activity after 3 h) after consumption of each of the three meals. No significant differences were observed in haemostatic values (factor VII coagulant activity, factor VII antigen, tissue plasminogen activator activity prothrombin activation peptide fragment and plasminogen activator inhibitor type-1) with regard to diet except for activated factor VII at 3 h; values were higher after the oleic acid- and linoleic acid-rich meals than after the stearic acid-rich meal After consumption of each of the three meals, chylomicrons contained proportionately more palmitic acid than the lipids ingested. The present study shows that there are demonstrable changes in postprandial haemostasis when young healthy volunteers with controlled dietary backgrounds are challenged with a physiological fat load. These changes are independent of the fatty acid composition of the test meals.

Adult↗

PubMed1992

Effects of cytochalasin, colchicine, and ethylenediaminetetraacetic acid on linoleic acid transport across rat jejunal enterocytes.

The involvement and the site of interference of the cytoskeleton in the transport of linoleic acid across the rat jejunum was investigated by administration of microfilamentous and microtubular altering agents such as cytochalasin, colchicine, and ethylenediaminetetraacetic acid (EDTA). An isolated jejunal segment was perfused with a buffer containing labeled linoleic acid, and portal blood and perfusate samples were collected concomitantly at 5-min intervals and assayed for their radioactivity. At the end of the perfusion, the amount of radioactivity retained in the intestine was also determined. The results were analyzed by using a three-compartment physical model that allows the determination of mucosal and serosal permeability coefficients, from which changes in the permeability of the mucosal and serosal membranes were assessed. Cytochalasin decreased the permeability of the mucosal membrane to linoleic acid, but not that of the serosal membrane. The administration of colchicine, EDTA, or cytochalasin + colchicine increased the permeability of the serosal membrane but did not affect the mucosal membrane.

Animals↗

PubMed1981

The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia.

Three long-stay, hospitalised schizophrenics who had failed to respond adequately to conventional drug therapy were treated with gamma-linolenic acid and linoleic acid in the form of evening primrose oil. They became substantially worse and electroencephalographic features of temporal lobe epilepsy became apparent. In all three the clinical state dramatically improved when carbamazepine, the conventional therapy for temporal lobe epilepsy was introduced. It can be extremely difficult to distinguish on clinical grounds between schizophrenia and temporal lobe epilepsy, and electroencephalographic studies do not always reveal an abnormality in the temporal lobe syndrome, unless additional procedure such as sphenoidal electroencephalography is undertaken. A trial of therapy with gamma-linolenic acid may prove of considerable value in distinguishing between these two states, so allowing specific therapy to be introduced.

Adult↗

PubMedDate not supplied

Differential stimulatory and inhibitory responses of human MCF-7 breast cancer cells to linoleic acid and conjugated linoleic acid in culture.

Consumption of dietary fat has been linked to the high incidence of certain cancers. However, recent research has stimulated interest in conjugated linoleic acid (CLA), a newly recognized anticarcinogenic fatty acid. Human MCF-7 breast cancer cells were incubated for 12 d in culture medium supplemented with various concentrations (1.78-7.14 x 10(-5) M) of linoleic acid (LA) or CLA. Linoleic acid initially stimulated MCF-7 cell growth with an optimal effect at concentrations of 3.57-7.14 x 10(-5) M, but was inhibitory at similar concentrations after 8 and 12 d of incubation. In contrast, CLA was inhibitory to cancer cell growth at all concentrations and times tested. Cell growth inhibition by CLA was dose- and time-dependent. Growth retardation at the prescribed LA and CLA concentrations ranged, respectively, from 4 to 33% and 54 to 100% following 8 to 12 d of treatment. At similar LA and CLA concentrations, cytostatic and cytotoxic effects of CLA were more pronounced (8-81%) than LA. These in vitro results suggest that CLA is cytotoxic to MCF-7 cells.

Breast Neoplasms↗