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At least 1,621 records · Page 90Linked to original sources
PubMed2000

Structured triacylglycerol containing medium-chain fatty acids in sn-1(3) facilitates the absorption of dietary long-chain fatty acids in rats.

A study was carried out to examine if the positional distribution of medium chain fatty acids (MCF) in triacylglycerol influences dietary fat absorption in rats. Two types of structure-specific fats, one predominantly composed of MCF in sn-1(3) and iinoleic acid in sn-2 [sn1(3)MCF-structured] and the others of MCF in sn-2 and linoleic acid in sn-1(3) [sn-2MCF-structured], were initially prepared, and the two structure-specific fats were interesterified and designated as sn-1(3)MCF-interesterified and sn-2MCF-interesterified. Synthetic fat was mixed with an equal amount of cocoa butter (103 g/kg of diet) and was supplemented to the AIN93G-based diet. Rats were fed on the diets for 4 wk. Long-chain saturated fatty acids were the predominant fatty acids excreted into the feces, and the positional distribution of MCF resulted in an altered fat absorption rate (%) of 81.8, 82.5, 84.2 and 86.3 for the rats fed on the diets containing sn-2MCF-structured, sn-1(3)MCF-interesterified, sn-2MCF-interesterified and sn-1(3)MCF-structured fats, respectively. The proportion of MCF in the serum, liver and adipose tissue triacylglycerols was not affected by the MCF distribution of the dietary fats. These results indicate that the distribution of MCF in dietary triacylglycerol is a determinant of intestinal fat absorption.

Absorption↗
PubMed1985

Fatty acid biosynthesis in Mycobacterium tuberculosis var. bovis Bacillus Calmette-Guérin. Purification and characterization of a novel fatty acid synthase, mycocerosic acid synthase, which elongates n-fatty acyl-CoA with methylmalonyl-CoA.

A crude extract from Mycobacterium tuberculosis var. bovis Bacillus Calmette-Guérin was previously shown to incorporate methylmalonyl-CoA into mycocerosic acids, exemplified by 2,4,6,8-tetramethyloctacosanoic acid, and malonyl-CoA into n-fatty acids (Rainwater D. L., and Kolattukudy, P. E. (1983) J. Biol. Chem. 258, 2979-2985). The presence of several fatty acid synthases with differences in substrate preference and product chain length was detected in the crude extract of M. tuberculosis var. bovis. Among them was a mycocerosic acid synthase which was purified to homogeneity using anion-exchange chromatography, gel filtration, affinity chromatography, and hydroxylapatite chromatography. This fatty acid synthase elongated long-chain fatty acyl-CoA primers using methylmalonyl-CoA and NADPH to produce multimethyl-branched mycocerosic acids. The enzyme was specific for methylmalonyl-CoA and would not incorporate malonyl-CoA into fatty acids. It elongated n-C6 to n-C20 CoA esters to generate primarily the corresponding tetramethyl-branched mycocerosic acids. Exogenous [1-14C]acyl-CoA and trideuteromethylmalonyl-CoA were incorporated into the multimethyl-branched fatty acids. Dodecyl sulfate electrophoresis showed that the enzyme had a molecular weight of 238,000, whereas gel filtration showed a native molecular weight of 490,000, indicating that the enzyme is composed of two monomers of identical molecular weight. The enzyme contained an acyl carrier protein-like segment as indicated by incorporation of [1-14C] pantothenate into the 238-kDa protein and production of 1 mol of taurine/mol of the monomer upon hydrolysis of performic acid-oxidized enzyme. It is concluded that the mycocerosic acid synthase is a multifunctional enzyme similar to the well-characterized multifunctional fatty acid synthases except for the substrate specificity.

Acyl Coenzyme A↗
PubMed1996

Chylomicron triacylglycerol fatty acids in suckling northern elephant seals (Mirounga angustirostris) resemble the composition and the distribution of fatty acids in milk fat.

Following birth, the northern elephant seal (Mirounga angustirostris) pups rapidly gain weight by ingesting milk with a high fat content, as much as 50%. To better understand the metabolism of the pups during the suckling period, the positional distributions of triacylglycerol fatty acids in both the milk and chylomicra were determined. Extracts of enzymatically digested lipids were separated by thin layer chromatography and the constituent fatty acids were separated and quantified by gas liquid chromatography. Over 84% of the fatty acids were either monoenoic or saturated, with the ratio of monoenoic to saturated fatty acids ranging between 2.9-4.0. Positional distributional analyses revealed that the very long chain monoenoics (20:1 and 22:1) were located primarily at the sn-1,3 positions of milk triacylglycerols. In the interval between the onset of lactation to the time of weaning, the content of these very long chain monoenoic fatty acids at the sn-1,3 positions increased from 13-37%. At the sn-2 position, the percentage of 18:1 was 3-5-fold higher than 16:1. Analyses indicated that the triacylglycerols in both milk and suckling pup chylomicra were similar. This particularly was true for the distributions at the sn-2 position, indicating that milk fats are being absorbed primarily via the 2-monoacylglycerol pathway.

Animals↗
PubMed1991

Fatty acid and prostaglandin metabolism in children with diabetes mellitus. II. The effect of evening primrose oil supplementation on serum fatty acid and plasma prostaglandin levels.

Our previous study demonstrated that levels of dihomo-gamma-linolenic acid (DGLA) and arachidonic acid in serum total lipids decreased in association with increased plasma levels of prostaglandins E2 (PGE2) and F2 alpha (PGF2 alpha) in patients with insulin-dependent diabetes mellitus. In this study, 11 children with insulin-dependent diabetes mellitus completed a double-blind, placebo-controlled study to assess the effect of dietary supplementation with gamma-linolenic acid (GLA) on serum essential fatty acid and plasma PGE2 and PGF2 alpha levels. GLA was given as the seed oil from the evening primrose (EPO) and all patients received either EPO capsules (containing 45 mg of GLA and 360 mg of linoleic acid) or indistinguishable placebo capsules for 8 months. Initially patients took 2 capsules daily for 4 months then 4 capsules daily for a further 4 months. All patients were assessed at the start of the study, after 4 months and at the end of the study, by measuring serum essential fatty acid and plasma PGE2 and PGF2 alpha levels. After administration of 4 capsules daily the DGLA levels increased and PGE2 levels decreased significantly (p less than 0.01) in the EPO compared with the placebo group. Neither fatty acid nor PGE2 and PGF2 alpha levels were altered by administration of 2 EPO capsules daily. This suggests that the altered essential fatty acid and PG metabolism in diabetes may be reversed by direct GLA supplementation.

Adolescent↗
PubMed1988

Inhibition of 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestanoic acid oxidation and of bile acid secretion in rat liver by fatty acids.

In isolated rat hepatocytes, fatty acids inhibited the side chain oxidation, but not the uptake, of exogenously added 3 alpha,7 alpha,12 alpha-trihydroxy-5 beta-cholestan-26-oic acid (THCA). THCA did not inhibit fatty acid oxidation. In liver homogenates, fatty acids inhibited THCA activation to its CoA ester (THC-CoA) and THCA oxidation. THCA did not influence fatty acid activation or oxidation. Comparison of the THC-CoA concentrations present in the incubation mixtures during THCA oxidation, with substrate concentration curves determined for THC-CoA oxidation, indicated that the inhibition of THCA oxidation by fatty acids was at least partly exerted at the activation step. The inhibition of THCA activation by fatty acids was noncompetitive. Palmitoyl-CoA at concentrations found in the incubation mixtures during THCA oxidation in the presence of palmitate inhibited THC-CoA oxidation, but not sufficiently to fully explain the fatty acid-induced inhibition of THCA oxidation. The inhibition of THC-CoA oxidation by palmitoyl-CoA did not seem to be competitive. Acyl-CoA oxidase, the first enzyme of peroxisomal beta-oxidation (which catalyzes the side chain oxidation of THCA), was enhanced 15-fold in liver homogenates from clofibrate-treated rats when palmitoyl-CoA was the substrate, but the oxidase activity remained unaltered when THC-CoA was the substrate. In the perfused liver, oleate, infused after a wash-out period of 60 min, markedly inhibited bile acid secretion. The results 1) suggest that fatty acids inhibit THCA metabolism both at the activation step and at the peroxisomal beta-oxidation sequence and that separate enzymes may be involved in both the activation and peroxisomal beta-oxidation of fatty acids and THCA and 2) raise the question whether fatty acids might (indirectly?) affect overall bile acid synthesis via their inhibitory effect on THCA metabolism.

Animals↗
PubMed2001

Enzymatic purification of polyunsaturated fatty acids.

Polyunsaturated fatty acids (PUFAs) have various physiological functions. Of these, ethyl eicosapentaenoate is industrially purified and used as a medicine. Other PUFAs, such as docosahexaenoic acid (DHA), gamma-linolenic acid (GLA), and arachidonic acid (AA), are also expected to be used as pharmaceutical agents; however, their industrial purification processes have not been established. Because PUFAs are highly unstable against heat and oxidation, we attempted to purify them by taking advantage of their enzymatic reactions. When free fatty acids (FFAs) originating from PUFA-containing oil were selectively esterified with lauryl alcohol (LauOH) using a lipase acting on a desired PUFA very weakly, the PUFA was efficiently enriched in the FFA fraction. In addition, when selective alcoholysis of ethyl esters originating from PUFA-containing oil with LauOH was carried out, the PUFA ethyl ester (EtPUFA) was enriched to a desired purity in the unreacted ethyl ester fraction. These reaction mixtures contain LauOH, PUFA (EtPUFA), and lauryl esters, and their molecular weights are different from one another. Hence, PUFA or EtPUFA can be easily separated by conventional distillation. Selective esterification increased the purity of DHA, GLA, and n-6 PUFAs rich in AA to 91, 98, and 96 wt%, respectively. Selective alcoholysis was also effective for increasing the purity of ethyl docosahexaenoate to 90 wt%.

Journal Article↗
PubMed2001

Kinetic parameters of hepatic oxidation of cyclic fatty acid monomers formed from linoleic and linolenic acids.

Cyclic fatty acid monomers (CFAM) occur from linoleic (CFAM-18:2) or linolenic (CFAM-18:3) acids present in some edible oils as a result of domestic frying or industrial refining. They present adverse effects in pups and weaning rats. In the present work, we studied the importance of hepatic oxidation in the metabolism of CFAM. For this purpose, kinetic parameters of Carnitine Palmitoyl Transferase I (key enzyme of the channeling of the fatty acids into the mitochondrial beta-oxidation pathway) and Acyl CoA Oxidase (key enzyme of the peroxisomal oxidation pathway) towards CFAM-18:2 and CFAM-18:3 were calculated on hepatic sub-cellular fractions of rats. For mitochondrial oxidation of CFAM, we observed a lower oxygen consumption and a lower activity of Carnitine Palmitoyl Transferase compared to 18:2w6 and 16:0. For peroxisomal oxidation, CFAM-18:2 showed the same kinetic parameters (Vm and K(0.5)) as 18:2w6 and 16:0, used for oxidative controls, whereas CFAM-18:3 presented a lower Vm (-50%). This difference should induce a lower catabolism of CFAM-18:3 in liver. This could contribute to their accumulation and probably to their toxic effect.

Journal Article↗
PubMed2006

Omega 6 to omega 3 fatty acid imbalance early in life leads to persistent reductions in DHA levels in glycerophospholipids in rat hypothalamus even after long-term omega 3 fatty acid repletion.

Failure to provide omega 3 fatty acids in the perinatal period results in alterations in nerve growth factor levels, dopamine production and permanent elevations in blood pressure. The present study investigated whether changes in brain (i.e., hypothalamus) glycerophospholipid fatty acid profiles induced by a diet rich in omega 6 fatty acids and very low in alpha-linolenic acid (ALA) during pregnancy and the perinatal period could be reversed by subsequent feeding of a diet containing ALA. Female rats (6 per group) were mated and fed either a low ALA diet or a control diet containing ALA throughout pregnancy and until weaning of the pups at 3 weeks. At weaning, the pups (20 per group) remained on the diet of their mothers until 9 weeks, when half the pups were switched onto the other diet, thus generating four groups of animals. At 33 weeks, pups were killed, the hypothalamus dissected from the male rats and analysed for glycerophospholipid fatty acids. In the animals fed the diet with very little ALA and then re-fed the control diet containing high levels of ALA for 24 weeks, the DHA levels were still significantly less than the control values in PE, PS and PI fractions, by 9%, 18% and 34%, respectively. In this group, but not in the other dietary groups, ALA was detected in all glycerophospholipid classes at 0.2-1.7% of the total fatty acids. The results suggest that omega 6-3 PUFA imbalance early in life leads to irreversible changes in hypothalamic composition. The increased ALA and reduced DHA proportions in the animals re-fed ALA in later life are consistent with a dysfunction or down-regulation of the conversion of ALA to 18:4n-3 by the delta-6 desaturase.

Animals↗
PubMed1988

Alteration in fatty acid composition of adult rat brain capillaries and choroid plexus induced by a diet deficient in n-3 fatty acids: slow recovery after substitution with a nondeficient diet.

Wistar rats were fed for three generations with a semisynthetic diet containing either 1.5% sunflower oil (940 mg% of C18:2n-6, 6 mg% of C18:3n-3) or 1.9% soya oil (940 mg% of C18:2n-6, 130 mg% of C18:3n-3). At 60 days of age, the male offspring of the third generation were killed. The fatty acyl composition of isolated capillaries and choroid plexus was determined. The major changes noted in the fatty acid profile of isolated capillaries were a reduction (threefold) in the level of docosahexaenoic acid and, consequently, a fourfold increase in docosapentaenoic acid in sunflower oil-fed animals. The total percentage of polyunsaturated fatty acids was close to that in the soya oil-fed rats, but the ratio of n-3/n-6 fatty acids was reduced by threefold. In the choroid plexus, the C22:6n-3 content was also reduced, but by 2.6-fold, whereas the C22:5n-6 content was increased by 2.3-fold and the ratio of n-3/n-6 fatty acids was reduced by 2.4-fold. When the diet of sunflower oil-fed rats was replaced with a diet containing soya oil at 60 days of age, the recovery in content of n-6 and n-3 fatty acids started immediately after diet substitution; it progressed slowly to reach normal values after 2 months for C22:6n-5 and 2.5 months for C22:6n-3. The recovery in altered fatty acids of choroid plexus was also immediate and very fast. Recovery in content of C22:5n-6 and C22:6n-3 was complete by 46 days after diet substitution.

Animals↗
PubMed1989

[Tests evaluating the influence of plasma fatty acid composition on the dynamics of contractions of the left heart ventricle in children with simple obesity. Part I. Influence of plasma fatty acid composition in children with simple obesity].

Percent composition of the plasma fatty acids in 48 children with simple obesity was determined with gas-chromatography. Thirty seven healthy, normotensive children served as the control group. An increased content of the saturated fatty acids and decreased content of the unsaturated fatty acids together with the decrease in unsaturated fatty acids:multi-unsaturated fatty acids ratio were seen in children with simple obesity.

Adolescent↗
PubMed2000

Plants as 'chemical factories' for the production of polyunsaturated fatty acids.

Polyunsaturated fatty acids (PUFAs) are valuable products because of their involvement in several aspects of human health. Market demand for most PUFAs is growing continually and current sources are considered insufficient for satisfying this demand; alternative sources are actively sought after. Oilseed plants can be a potential source of PUFAs if they are appropriately gene engineered. Most of the basic tools for genetic engineering of oilseed plants for giving them the ability to produce PUFAs are already developed. Here we review the prospects of genetic engineering of oilseed plants for producing some valuable long-chain polyunsaturated fatty acids. Genetic transformation for GLA production seems to be a near-term possibility, but gene engineering seems considerably more difficult for the other long-chain PUFAs. Nevertheless, with the current rapid pace of biotechnological advancement, the remaining difficulties may be surmounted in the near future.

Journal Article↗