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PubMed1988

Abnormal 13C-fatty acid breath tests in patients treated with valproic acid.

Breath tests using fatty acids labeled with a stable isotope (carbon 13) were carried out on epileptic patients treated with valproic acid in order to detect abnormal fatty acid metabolism. The patients were given 13C-octanoic acid or 13C-palmitic acid orally, and expired air was collected at appropriate intervals for the analysis of 13CO2 content by a mass spectrometer. Eight patients were tested in the palmitic acid breath test and nine patients in the octanoic acid breath test. Controls for these tests were patients treated with antiepileptic drugs other than valproic acid and unmedicated cerebral palsy patients. In the valproic acid-treated group, 13C recovery was reduced by 56% in seven hours on the 13C-palmitic acid breath test, while the octanoic acid breath test showed a 52% reduction in one hour. This suppression of fatty acid oxidation was significantly correlated with dose of valproic acid in both tests. No influence of other drugs was detected, and the effect of administered carnitine was not conclusive. This study demonstrates the usefulness of 13C-labeled fatty acid breath tests in clinical practice.

Adolescent↗
PubMed1988

Long-chain fatty acyl-CoA synthetase of rat adrenal microsomes. Effect of ACTH and epinephrine.

Acyl-CoA synthetase activity with various long-chain fatty acid substrates and its kinetic properties were measured in rat adrenal microsomes. The apparent Michaelis constants (Km) for substrate fatty acids increased in the order eicosa-8,11,14-trienoic acid less than alpha-linolenic acid less than linoleic acid less than palmitic acid. The maximum velocities with these fatty acids decreased in the order linolenic greater than eicosa-8,11,14-trienoic acid greater than palmitic acid. The synthesis of radioactivity palmitoyl-CoA, linoleyl-CoA, alpha-linolenyl-CoA and eicosa-8,11,14-trienoyl-CoA from the respective radioactive substrates decreased in the presence of all the other fatty acids mentioned above. These effects were inversely correlated with their apparent Km values. These results support the idea of a single long-chain fatty acyl-CoA synthetase in the adrenal microsomal fraction for the acid tested. After testing the influence of different hormones, it was shown that the administration of epinephrine, ACTH and dexamethasone caused a significant decrease in the activity of the long-chain fatty acid-CoA synthetase. This inhibition is independent of the one produced by the same hormones on the desaturation of linoleic to gamma-linolenic acid.

Adrenal Glands↗
PubMed1987

Changes in the fatty acid composition of plasma and red blood cell membrane during the first hours of life in human neonates.

The objective of this work was to examine the changes in the fatty acid profiles of plasma lipid fractions and red blood cell membrane phospholipids in newborn infants during the first 6-8 h of life. Methyl esters of fatty acids from plasma free fatty acids and phospholipids and from membrane phosphatidylethanolamine, phosphatidylcholine and sphingomyelin for cord blood (n = 20) and venous blood (n = 19) were analyzed by GLC. Important changes were observed in plasma fatty acids. Palmitic and palmitoleic acid increased from birth to 6-8 h of age for both free fatty acids and phospholipids. Palmitic acid also increased in membrane phosphatidylcholine and phosphatidylethanolamine. In the former, stearic acid declined whereas oleic and docosatetraenoic acids increased. Phosphatidylethanolamine and sphingomyelin were less affected than phosphatidylcholine probably because the internal location of the two first fractions in erythrocyte membrane. Polyunsaturated fatty acids dropped slightly during the first hours of life in most lipid fractions. This may be a consequence of the interruption of placental fatty acid supply and the limited capacity of the newborn to desaturate their essential fatty acid tissue stores.

Erythrocyte Membrane↗
PubMed1996

The in vitro antioxidant activity of trilinolein and other lipid-related natural substances as measured by enhanced chemiluminescence.

There is abundant evidence for the premise that oxygen-derived free radicals (OFR) mediate ischemia/reperfusion injury to the myocardium. OFR scavengers such as superoxide dismutase can effectively reduce damage through lipid peroxidation during ischemia/reperfusion. Enhanced chemiluminescence, which has been used to measure OFR, was used to measure the antioxidant activity of fatty acids (palmitic and linoleic acid) and triglycerides (triolein, tristearin) and natural plant antioxidants (magnolol, catechin, trilinolein). Trilinolein, which has recently been isolated from natural products, as well as the well-known water soluble analogue of vitamin E-Trolox, were used as control. During pretreatment with chemicals, at concentrations of 10(-9) to 10(-7) M, enhanced chemiluminescence of linoleic acid (C 18:2) showed a dose-responsive reduction of OFR with a maximal mean reduction of -31.9% when compared to baseline. A saturated fatty acid such as palmitic acid (C 16:0) showed only relatively weak antioxidant activity at concentrations of 10(-7) to 10(-6) M with a maximum reduction of OFR of- 15.2% only. control chemicals such as trilinolein and Trolox showed significant antioxidant activity. At concentrations between 10(-10) and 10(-6) M and trilinolein has the most potent antioxidant activity with a maximal mean reduction of OFR of -48.0%, whereas Trolox showed only -39.2%. As for the natural plant antioxidants, only catechin showed potent antioxidant activity (-40%). Polyunsaturated triglycerides such as triolein (oleic acid, C 18:1) also possess significant OFR scavenging effect (-31.9%) whilst saturated triglycerides such as tristearin (stearic acid, C 18:0) had only relatively weak antioxidant activity (-15.2%). Generally, the antioxidant activity of unsaturated compounds is stronger than saturated compounds; double-bond existence may partially explain this phenomenon.

Antioxidants↗
PubMed2005

Non-esterified fatty acids in follicular fluid of dairy cows and their effect on developmental capacity of bovine oocytes in vitro.

In this study concentration and composition of non-esterified fatty acids (NEFA) in follicular fluid (FF) of high-yielding dairy cows were determined during the period of negative energy balance (NEB) early post partum. NEFA were then added during in vitro maturation at concentrations measured previously in FF to evaluate their effect on the oocyte's developmental competence. At 16 and 44 days post partum, FF of the dominant follicle and blood were collected from nine high-yielding dairy cows. Samples were analysed for NEFA concentration and composition. NEFA concentrations in FF (0.2-0.6 mmol/l) during NEB remained +/- 40% lower compared with serum (0.4-1.2 mmol/l). The NEFA composition differed significantly between serum and FF with oleic acid (OA), palmitic acid (PA) and stearic acid (SA) being the predominant fatty acids in FF. Based on these results, 5115 oocytes were matured for 24 h in serum-free media with or without (negative control) the addition of 0.200 mmol/l OA, 0.133 mmol/l PA or 0.067 mmol/l SA dissolved in ethanol or ethanol alone (positive control). Matured oocytes were fertilized and cultured for 7 days in SOF medium. Addition of PA or SA during oocyte maturation had negative effects on maturation, fertilization and cleavage rate and blastocyst yield. More (late) apoptotic cumulus cells were observed in cumulus-oocyte complexes matured in the presence of SA or PA. Ethanol or OA had no effect. These in vitro results suggest that NEB may hamper fertility of high-yielding dairy cows through increased NEFA concentrations in FF affecting oocyte quality.

Animals↗
PubMed1982

Selective changes in fatty acid composition of phosphatidylserine in rat erythrocyte membrane induced by nitrate.

The relationship between nitrate which is formed from inhaled nitrogen dioxide, a common air pollutant, and changes in fatty acid metabolism of phosphatidylserine in rat erythrocytes has been examined. When erythrocytes were incubated at 37 degrees C for 60 min with fatty acid, the incorporation rate of [1-14C]arachidonic acid and [9,10-3H]palmitic acid into phosphatidylserine was 15% (80 pmol/h per mumol lipid phosphorus) and 20% (12 pmol/h per mumol lipid phosphorus) of those into phosphatidylethanolamine, respectively. By the addition of 1.0 mM sodium nitrate or 0.5 microM ionophore A23187 to the incubation mixture, the rate of incorporation of both arachidonic acid and palmitic acid into phosphatidylethanolamine was stimulated 1.45-fold. On the other hand, the incorporation of palmitic acid into phosphatidylserine was little affected, while that of arachidonic acid was stimulated 1.35-fold. An increase in arachidonic acid of phosphatidylserine was also found by the addition of nitrate or ionophore A23187. This increase was dependent on the concentration of extracellular calcium and observed by the addition of other chaotropic anions in the order SCN- greater than ClO4- greater than NO3-. It seems likely, therefore, that nitrate causes changes in erythrocyte membranes to facilitate calcium uptake. Increasing the concentration of intracellular calcium may cause stimulation of acyl-CoA:lysophospholipid acyltransferase and/or endogenous phospholipase A2.

Animals↗
PubMed2005

The influence of bile salts and mixed micelles on the pharmacokinetics of quinine in rabbits.

The bioavailability of orally administered drugs can be influenced by interactions with food components and by physico-chemical conditions in the upper gastrointestinal tract. Normally, bile salts enhance the transport of lipophilic drugs across mucosal membranes. Bile salts are able to form stable mixed micelles consisting of fatty acids and phospholipids. Conventional micellar systems are known to solubilize lipophilic drugs having a low bioavailability. The influence of bile salts and mixed micelles on the pharmacokinetics of the lipophilic drug quinine was investigated in rabbits. Female rabbits were given intraduadenally quinine (5 mg/kg body weight) without and with incorporation into the micellar or mixed micellar systems. Blood was collected every 30 min for 6 h. In plasma, concentration of quinine was measured using HPLC. The plasma concentration-time profiles of quinine were significantly lower within the first 2 h after administration in presence of both the sodium salt of glycodeoxycholic acid (above the critical micellar concentration) as well as of mixed micellar systems consisting of glycodeoxycholic acid and palmitic acid and/or lecithin. The pharmacokinetic parameters AUC (relative bioavailability) and c(max) of quinine were significantly decreased by micellar systems in rabbits. These mixed micellar systems lower and not as expected, increase the absorption of quinine in vivo. Therefore, quinine should be orally administered at least 1h before food intake, particularly before fat intake.

Animals↗
PubMedDate not supplied

Chemical constituents from Mahkota dewa.

A new phenolic glycoside (1), mahkoside A, together with six known compounds including mangiferin (2), kaempferol-3-O-beta-D-glucoside (3), dodecanoic acid (4), palmitic acid (5) ethyl stearate (6) and sucrose (7), were isolated from the pit of Mahkota dewa. Their structures were identified on the basis of spectroscopic analysis. All the compounds were isolated from the title plant for the first time.

Glucosides↗
PubMed1977

Fatty acid synthesis in testes of fat-deficient and fat-supplemented rats.

Fatty acid synthesis was studied in testes of rats fed a fat-free or fat-supplemented diet. Testes of fat-deficient rats incorporated nearly twice as much intratesticularly injected [1-14C]acetate into total fatty acids (primarily into palmitic acid) as did supplemented rats. To determine the mechanism for the increased synthesis, the activities of the following enzymes were determined in the cytoplasmic fraction of testicular homogenates: fatty acid synthetase, acetyl CoA carboxylase [EC 6.4.1.2], citrate-cleavage [EC 4.1.3.8], malic [EC 1.1.1.38], and the glucose-l-phosphate dehydrogenase [EC 1.1.1.49]: 6-phosphogluconate dehydrogenase pair [EC 1.1.1.44]. Although the activity of fatty acid synthetase did increase in livers from fat-deficient rats, no change was observed in corresponding testes. No difference between the two groups could be demonstrated in testicular activity of citrate-cleavage enzyme, malic enzyme, or the glucose-6-phosphate dehydrogenase: 6-phosphogluconate dehydrogenase pair. However, the activity of cytoplasmic acetyl CoA carboxylase in testes of rats fed the fat-deficient diet was 1.4 times higher than the activity in testes of rats fed the supplemented diet. Fat deficiency did not affect the specific activity of the testicular microsomal elongation system, assayed by incubation with 14C-malonyl CoA. The concentration of unesterified fatty acids was lower in testes of the fat-deficient compared to supplemented rats, indicating that decreased inhibition of acetyl CoA carboxylase in the fat-deficient rats testes might have been responsible for the observed increased de novo synthesis of palmitic acid.

ATP Citrate (pro-S)-Lyase↗
PubMed2006

Free fatty acids inhibit insulin signaling-stimulated endothelial nitric oxide synthase activation through upregulating PTEN or inhibiting Akt kinase.

In metabolic syndrome, a systemic deregulation of the insulin pathway leads to a combined deregulation of insulin-regulated metabolism and cardiovascular functions. Free fatty acids (FFAs), which are increased in metabolic syndrome, inhibit insulin signaling and induce metabolic insulin resistance. This study was designed to examine FFAs' effects on vascular insulin signaling and endothelial nitric oxide (NO) synthase (eNOS) activation in endothelial cells. We showed that FFAs inhibited insulin signaling and eNOS activation through different mechanisms. While linoleic acid inhibited Akt-mediated eNOS phosphorylation, palmitic acid appeared to affect the upstream signaling. Upregulation of PTEN (phosphatase and tensin homolog deleted on chromosome 10) activity and transcription by palmitic acid mediated the inhibitory effects on insulin signaling. We further found that activated stress signaling p38, but not Jun NH(2)-terminal kinase, was involved in PTEN upregulation. The p38 target transcriptional factor activating transcription factor (ATF)-2 bound to the PTEN promoter, which was increased by palmitic acid treatment. In summary, both palmitic acid and linoleic acid exert inhibitory effect on insulin signaling and eNOS activation in endothelial cells. Palmitic acid inhibits insulin signaling by promoting PTEN activity and its transcription through p38 and its downstream transcription factor ATF-2. Our findings suggest that FFA-mediated inhibition of vascular insulin signaling and eNOS activation may contribute to cardiovascular diseases in metabolic syndrome.

Activating Transcription Factor 2↗
PubMed2006

The inhibitory effect of polyunsaturated fatty acids on human CYP enzymes.

The inhibitory effect of saturated fatty acids (SFAs): palmitic acid (PA), stearic acid (SA) and polyunsaturated fatty acids (PUFAs): linoleic acid (LA), linolenic acid (LN), arachidonic acid (AA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on six human drug-metabolizing enzymes (CYP1A2, 2C9, 2C19, 2D6, 2E1 and 3A4) was studied. Supersomes from baculovirus-expressing single isoforms were used as the enzyme source. Phenacetin O-deethylation (CYP1A2), diclofenac 4-hydroxylation (CYP2C9), mephenytoin 4-hydroxylation (CYP2C19), dextromethorphan O-demethylation (CYP2D6), chlorzoxazone 6-hydroxylation (CYP2E1) and midazolam 1-hydroxylation (CYP3A4) were used as the probes. Results show that all the five examined PUFAs competitively inhibited CYP2C9- and CYP2C19-catalyzed metabolic reactions, with Ki values ranging from 1.7 to 4.7 microM and 2.3 to 7.4 microM, respectively. Among these, AA, EPA and DHA tended to have greater inhibitory potencies (lower IC(50) and Ki values) than LA and LN. In addition, these five PUFAs also competitively inhibited the metabolic reactions catalyzed by CYP1A2, 2E1 and 3A4 to a lesser extent (Ki values>10 microM). On the other hand, palmitic and stearic acids, the saturated fatty acids, had no inhibitory effect on the activities of six human CYP isozymes at concentrations up to 200 microM. Incubation of PUFAs with CYP2C9 or CYP2C19 in the presence of NADPH resulted in the decrease of PUFA concentrations in the incubation mixtures. These results indicate that the PUFAs are potent inhibitors as well as the substrates of CYP2C9 and CYP2C19.

Animals↗
PubMed1993

Palmitoylation of bovine opsin and its cysteine mutants in COS cells.

Previously, bovine rhodopsin has been shown to be palmitoylated at cysteine residues 322 and 323. Here we report on palmitoylation of bovine opsin in COS-1 cells following expression of the synthetic wild-type opsin gene and several of its cysteine mutants in the presence of [3H]palmitic acid. Two moles of palmitic acid are introduced per wild-type opsin molecule in thioester linkages. Palmitoylation is abolished when both Cys-322 and Cys-323 are replaced by serine residues. Replacement of Cys-322 by serine prevents palmitoylation at Cys-323, whereas replacement of the latter with serine allows palmitoylation at Cys-322. Opsin mutants that evidently do not contain a Cys-110/Cys-187 disulfide bond and presumably remain in the endoplasmic reticulum are not palmitoylated. Replacement of Cys-140 or Cys-185 reduces the extent of palmitoylation of the opsin. Lack of palmitoylation at Cys-322 and/or Cys-323 does not affect 11-cis-retinal binding, absorption maximum or extinction coefficient of the chromophore, the bleaching behavior of the chromophore, or the light-dependent binding and activation of transducin. Mutants containing serine substitutions at Cys-140 or Cys-323 showed reduced light-dependent phosphorylation by rhodopsin kinase.

Amino Acid Sequence↗
PubMed1983

Mouse submaxillary gland renin contains a noncovalently attached fatty acid.

Renin A from the submaxillary gland of male mice has been shown by a gas chromatography/mass spectrometry method to contain near stoichiometric amounts of a fatty acid mixture. The fatty acids on mouse renin were partially exchangeable with free tridecanoic acid in solution, with the tridecanoic acid truly exchanged and not just adsorbed in addition to the fatty acids already present. A gas chromatography/mass spectrometry analysis of the composition of the free fatty acids of the submaxillary gland of male mice showed that the mixture of fatty acids extracted from the gland was significantly different from the mixture of free fatty acids extracted from renin A. The renin-extracted fatty acids were relatively richer in saturated fatty acids, like myristic and palmitic acids, and poorer in polyunsaturated fatty acids, like linoleic and arachidonic acid, than the free fatty acids of the gland. The enzymatic activity of mouse renin was markedly stimulated by saturated fatty acids in 50 mM sodium acetate, pH 5.38, in a concentration-dependent, saturable manner. Palmitic acid stimulated renin activity versus synthetic tetradecapeptide renin substrate about 7-fold in this buffer, with half-maximal stimulation at 14 microM. Stearic and myristic acids also showed good stimulation but linoleic acid and ethyl myristate were much less effective at the stimulation. A possible physiological role for the loss of renin activity at acid pH due to loss of bound fatty acids would be to protect the mouse against internalized renin.

Animals↗
PubMed2002

Do lithium and anticonvulsants target the brain arachidonic acid cascade in bipolar disorder?

BACKGROUND: Lithium and certain anticonvulsants, including carbamazepine and valproic acid, are effective antimanic drugs for treating bipolar disorder, but their mechanisms of action remain uncertain. EXPERIMENTAL OBSERVATIONS: Feeding rats lithium chloride for 6 weeks, to produce a brain lithium concentration of 0.7mM, reduced arachidonic acid turnover within brain phospholipids by 75%. The effect was highly specific, as turnover rates of docosahexaenoic acid and palmitic acid were unaffected. Arachidonate turnover in rat brain also was reduced by long-term valproic acid administration. Lithium's reduction of arachidonate turnover corresponded to its down-regulating gene expression and enzyme activity of cytosolic phospholipase A(2), an enzyme that selectively liberates arachidonic but not docosahexaenoic acid from phospholipids. Lithium also reduced the brain protein level and activity of cyclooxygenase 2, as well as the brain concentration of prostaglandin E(2), an arachidonate metabolite produced via cyclooxygenase 2. CONCLUSIONS: These results give rise to the hypothesis that lithium and antimanic anticonvulsants act by targeting parts of the "arachidonic acid cascade," which may be functionally hyperactive in mania. Thus, drugs that target enzymes in the cascade, such as cyclooxygenase 2 inhibitors, might be candidate treatments for mania. Also, in view of competition between arachidonic and docosahexaenoic acids in a number of functional processes, docosahexaenoic acid or its precursors would be expected to be therapeutic. Neither of these predictions is evident from other current hypotheses for the antimanic action of lithium and anticonvulsant drugs.

Animals↗
PubMed1972

Synthesis of fatty acids from (1- 14 C)acetyl-coenzyme A in subcellular particles of rat epididymal adipose tissue.

1. Mitochondrial and microsomal fractions of rat epididymal adipose tissue incorporated [1-(14)C]acetyl-CoA equally well into various fatty acids by a chain-elongation mechanism. C(18) and C(20) fatty acids were the two major products, and comprised about 80% of the total fatty acids synthesized in both particles. 2. When incubated in air, mitochondria synthesized stearic acid, octadecenoic acid and eicosamonoenoic acid in almost equal amounts (about 20% each), whereas in microsomal fractions, the synthesis of octadecenoic acid was more than fivefold the stearic acid formation. In both fractions, major components of synthesized monoenoic fatty acids were the Delta(11:12) isomers. Hexadecenoic acid and octadecenoic acid from whole adipose tissue contained approx. 11 and 14% of the Delta(11:12) isomer respectively. 3. When mitochondria or microsomal fractions were incubated in nitrogen, there was increased synthesis of stearic acid and palmitic acid and less of C(16) and C(18) monoenoic acids; synthesis of C(20) acids remained predominantly of the monoenoic acids. Determination of the position of the double bond in the monoenoic acids supported the view that the synthesis of hexadecenoic acid and octadecenoic acid involves a desaturase activity, whereas eicosamonoenoic acid and eicosadienoic acid are formed only by elongation of endogenous fatty acids. 4. Most of the radioactivity was found in free fatty acids (63%) and the phospholipid (26%) fraction. In phospholipids, phosphatidylcholine and phosphatidylethanolamine were the two major components. 5. Most of the fatty acids synthesized, including those not normally found in particle lipids (arachidic acid, eicosamonoenoic acid and eicosadienoic acid) were distributed fairly evenly in the phospholipid and free fatty acid fractions. However, stearic acid was found predominantly in the phospholipid fraction.

Adipose Tissue↗
PubMed2002

Cloning and expression of two novel pig liver and kidney fatty acid hydroxylases [cytochrome P450 (CYP)4A24 and CYP4A25].

A new member of the cytochrome P450 (CYP) 4A subfamily (CYP4A21) was recently cloned by PCR from pig liver [Lundell, Hansson, and Wikvall (2001) J. Biol. Chem. 276, 9606-9612]. This enzyme does not catalyse omega- or (omega-1)-hydroxylation of lauric acid, the model substrate for CYP4A enzymes. Instead, CYP4A21 participates in bile acid biosynthesis in the pig. Extensive studies, primarily conducted to verify the aberrant amino acids found in CYP4A21 within a normally conserved CYP4A motif, revealed that besides CYP4A21 two additional sequences were co-amplified by PCR. These two sequences (designated CYP4A24 and CYP4A25), generated from both pig liver and kidney, were characterized by restriction-enzyme analysis and were subsequently cloned. The deduced amino acid sequences of CYP4A24 and CYP4A25 share extensive sequence identity (97%). Both enzymes, expressed in yeast cells, exhibit omega-and (omega-1)-hydroxylase activities towards lauric acid and palmitic acid. The positions of the variable regions between CYP4A24 and CYP4A25, which are confined to beta-sheets 1 and 4, indicate a possible difference in substrate specificity or regioselectivity. The porcine CYP4A21, CYP4A24 and CYP4A25 enzymes, with an overall identity of 94%, have probably evolved from a common ancestral gene, perhaps in conjunction with species-specific habits.

Amino Acid Sequence↗