Polar Fatty Acids Research Articles

Characterization of a novel lipid A structure isolated from Azospirillum lipoferum lipopolysaccharide

The structure of lipid A from Azospirillum lipoferum, a plant-growth-promoting rhizobacterium, was investigated. It was determined by chemical analysis, mass spectrometric methods, as well as 1D and 2D NMR spectroscopy. Because of the presence of substituents, the investigated lipid A differs from typical enterobacterial lipid A molecules. Its backbone is composed of a β-(1,6)-linked d-glucosamine disaccharide but lacks phosphate residues. Moreover, the reducing end of the backbone (position C-1) is substituted with α-linked d-galacturonic acid. 3-hydroxypalmitoyl residues are exclusively connected to amino groups of the glucosamine disaccharide. Hydroxyls at positions C-3 and C-3′ are esterified with 3-hydroxymyristic acids. Primary polar fatty acids are partially substituted by nonpolar fatty acids (namely, 18:0, 18:1 or 16:0), forming acyloxyacyl moieties.

Inhibition of bacterial lipopolysaccharide-induced inflammatory effects by lipid peroxidation products

Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphatidylcholine (PAPC) was earlier shown to inhibit inflammatory effects of the bacterial endotoxin lipopolisacharide (LPS). We studied the antiendotoxin activity of other classes of oxidized phospholipids carrying different polar groups and fatty acids. Oxidized phosphatidylcholine, phosphatidylserine, phosphatidylethanolamine, and phosphatidic acid inhibited the LPS-induced expression of E-selectin on the surface of human endothelial cells. The type of esterified polyunsaturated fatty acid was not essential for inhibition of the LPS effects. Native unoxidized phospholipids did not influence the effects of LPS. Thus, the anti-endotoxin activity of oxidized phospholipids crucially depends on the presence of an oxidation-modified fatty acid residue.

Altered Fatty Acid Profile of Polar Lipids in Maize Seedlings in Response to Excess Copper

AbstractA wide range of cellular responses occur when plants are exposed to heavy metal stress, including changes in the membrane fatty acid composition. In this study, we examined the effect of excess copper (100 μm) on the degree of unsaturation [double bond index (DBI) of 18‐C fatty acids] and the polar lipid profiles in maize (Zea mays L.). The level of unsaturation of total fatty acids decreased from 1.42 to 1.28 in maize roots. However, copper‐induced compositional changes of polar fatty acid composition show a general trend of increasing DBI. These responses suggest that individual 18‐C fatty acid classes may have specific roles in maintaining optimal membrane function, enabling plant growth under copper stress. The results also reveal key changes including marked decrease in total root phospholipid levels and consistent increase in the steryl lipid/phospholipid (SL/PL) ratio, as well as a decrease in monogalactosyldiacylglycerol/digalactosyldiacylglycerol (MGDG/DGDG) ratio, reflecting alteration of membrane permeability and fluidity. In shoots, the DBI obtained from phosphatidylcholine (PC), sulphoquinovosyldiacylglycerol (SQDG) and monogalactosyldiacylglycerol (MGDG) was increased. In contrast, these indices were decreased in phosphatidylinositol (PI) and phosphatidylglycerol (PG). However, the PI, PC, PG, MGDG and DGDG contents in shoots were significantly decreased, suggesting alterations in the photosynthetic membranes.

Cold-induced alterations on proximate composition and fatty acid profiles of several tissues in gilthead sea bream ( Sparus aurata)

Cultured gilthead sea bream ( Sparus aurata L.) are exposed to a multifactorial disease termed “winter syndrome”, and low temperatures are the recurrent inducing factor. The effects of low temperatures on tissue composition and fatty acid profiles of polar and non-polar lipid fractions of sea bream were studied in two conditions: a gradual temperature drop (GD: from 18 °C to 8 °C at a rate of 1 °C·day − 1 ) or two sharp drops (SD: from 18 °C to 12 °C and then from 12 °C to 8 °C completed within a day, with a 1 week interval). No significant differences were detected between GD and SD in any of the variables studied. Animals stopped feeding when the temperature fell below 13 °C, and the resulting fast provoked body weight losses of 12% (GD) and 10% (SD) at the end of the experiment (15th day), and decreased non-polar lipids content in muscle. Unsaturation of polar fatty acids in muscle (SD) and in gills (SD and GD) rose, demonstrating a homeoviscous acclimation of membranes to cold. In contrast, unsaturation of liver polar fatty acids did not rise, but liver showed a great increase in total lipid content on day 15 (+ 35% SD, and + 43% GD), caused by the increase in non-polar lipids, especially n-3 fatty acids. The high deposition of these essential fatty acids, mainly 22:6n-3, in fasting sea bream implied mobilization from extra-hepatic stores and caused dramatic modifications in the physical properties of the liver (larger, more friable and yellowish), often associated with winter disease. Moreover, plasma aspartate aminotransferase (ASAT) levels rose three-fold in the two conditions. No fish succumbed to winter disease, but the incipient appearance of symptoms was evident. The relationships between the changes in muscle, gill, and, especially liver, at low temperature and the clinical signs of ‘winter disease’ are discussed.

Ultrasonic assessment of oil quality during frying.

In this paper, changes in ultrasonic properties during thermoxidation of virgin olive oil were studied. Samples of virgin olive oil were heated over different periods of time from 2 to 16 h at 200 degrees C. Oil degradation was characterized by means of physical and chemical changes, i.e., viscosity, color, polar compounds, polymers, and polar fatty acids. Ultrasonic measurements were carried out while the oil sample was cooled from 35 to 25 degrees C. It was found that velocity and attenuation measurements were related to viscosity measurements through a classical equation for viscous liquids. The ultrasonic measurements were also related to the percentages of polar compounds and polymers, which shows the feasibility of using ultrasonic properties to monitor oil quality. Nevertheless, as long as the ultrasonic measurements are temperature dependent, this variable must be controlled in order to obtain repetitive and reliable measurements.

Lipoprotein-associated phospholipase A(2), platelet-activating factor acetylhydrolase, is expressed by macrophages in human and rabbit atherosclerotic lesions.

We studied the expression of lipoprotein-associated phospholipase A(2) (Lp-PLA(2)), an enzyme capable of hydrolyzing platelet-activating factor (PAF), PAF-like phospholipids, and polar-modified phosphatidylcholines, in human and rabbit atherosclerotic lesions. Oxidative modification of low-density lipoprotein, which plays an important role in atherogenesis, generates biologically active PAF-like modified phospholipid derivatives with polar fatty acid chains. PAF is known to have a potent proinflammatory activity and is inactivated by its hydrolysis. On the other hand, lysophosphatidylcholine and oxidized fatty acids released from oxidized low-density lipoprotein as a result of Lp-PLA(2) activity are thought to be involved in the progression of atherosclerosis. Using combined in situ hybridization and immunocytochemistry, we detected Lp-PLA(2) mRNA and protein in macrophages in both human and rabbit atherosclerotic lesions. Reverse transcriptase-polymerase chain reaction analysis indicated an increased expression of Lp-PLA(2) mRNA in human atherosclerotic lesions. In addition, approximately 6-fold higher Lp-PLA(2) activity was detected in atherosclerotic aortas of Watanabe heritable hyperlipidemic rabbits compared with normal aortas from control rabbits. It is concluded that (1) macrophages in both human and rabbit atherosclerotic lesions express Lp-PLA(2), which could cleave any oxidatively modified phosphatidylcholine present in the lesion area, and (2) modulation of Lp-PLA(2) activity could lead to antiatherogenic effects in the vessel wall.

Characterization, quantitation and evolution of monoepoxy compounds formed in model systems of fatty acid methyl esters and monoacid triglycerides heated at high temperature

Monoepoxy compounds formed after heating methyl oleate and linoleate, triolein and trilinolein at 180°C for 5, 10 and 15 hours, were characterized and quantitated after derivatization to fatty acid methyl esters by using two base-catalyzed procedures. Structures were identified by GC-MS before and after hydrogenation. A complete recovery of the epoxy compounds was obtained by comparing results from methyl oleate and linoleate before and after transesterification, and good repeatability was also attained. Similar amounts of epoxides were found for methyl esters and triglycerides of the same degree of unsaturation, although formation was considerably greater for the less unsaturated substrates, methyl oleate and triolein, possibly due to the absence of remaining double bonds in the molecule which would involve a lower tendency to participate in further reactions. On other hand, independently of the degree of unsaturation of the model systems and of the period of heating, significantly higher amounts of trans isomers were formed. Finally from comparison between the amounts of epoxides and the level of polar fatty acids in samples, it was deduced that monoepoxy compounds were one of the major groups formed under the conditions used.

Lipid storage and composition in tropical surgeonfishes (Teleostei: Acanthuridae)

The lipid composition of tropical marine reef fishes is poorly known, despite their use as food by local human populations and recent interest in health-related benefits of fish lipids. We examined the composition of lipids from epaxial muscle, liver, and two storage sites [mesenteries surrounding the gut (intraperitoneal fat, IPFs) and retroperitoneal fat bodies (FBs) posterior to the peritoneal cavity] in three species of surgeonfishes from Ishigaki Island, Japan: Naso lituratus (Bloch and Schneider, 1801), Acanthurus lineatus (Linnaeus, 1758), and A. bariene (Lesson, 1830). Triacylglycerols dominated all samples of neutral lipid and constituted ≥ 99% of FBs and IPFs. Polar lipids generally contained large fractions of phosphatidylethanolamine and phosphatidylcholine. Quantified fatty acids ranged in length from C14 to C24. C16 fatty acids prevailed (>35% of neutral fatty acids, >23% of polar fatty acids), although C18 (>16 and >14%, respectively) and C20 acids (>8 and >19%, respectively) were also common. Saturated fatty acids, dominated by palmitic acid (16:0), comprised 38.7 to 50.7% of acids from neutral lipids and 30.8 to 41.1% from polar lipids. The most common monounsaturated acids were 18:1n9 and 20:1n9. Polyunsaturated acids were prevalent in polar lipids (especially 20:4n6, 20:5n3, 22:2n3, 22:5n3, 22:5n6 and 22:6n3). Common polyunsaturated acids of neutral lipids were 18:2n6, 18:4n3, several n-3 and n-6 C20 acids, 22:2n3 and 22:5n3. IPF and FB were almost identical across species, and lipids of fat bodies (IPFs, FBs) were more similar to those of muscle than those of liver for all three species. The FBs appear to constitute an accessory storage site, which overcomes constraints on lipid storage imposed by a small, inflexible abdominal cavity that contains both viscera and consistently voluminous gut contents. Fatty acid signatures indicate that largely overlooked epiphytic or epilithic diatoms contribute significantly to lipid acquisition. The combination of large quantities of both saturated and n-3 and other polyunsaturated fatty acids in surgeonfishes, in contrast to low saturates and high polyunsaturated acids in lipids of commercially important cool-water fishes, suggests that a study of dietary effects of fish lipids on human inhabitants of the tropics may be instructive insofar as human health and nutrition are concerned.

Linoleic acid peroxidation products are metabolized by hydrogenation in porcine liver tissue

Homogenization of mammalian tissue activates enzymes which cause degradation. This effect was used to elucidate the metabolism of 13-S-hydroxy-9,11-octadecadienoic acid (13-S-HODE) and 9-S-hydroxy-10,12-octadecadienoic acid (9-S-HODE), physiologically active products of lipid peroxidation (LPO) processes, by electron ionization GC/MS. 13-S-HODE was added to a porcine liver homogenate, samples withdrawn at timed intervals and extracts of polar fatty acids then subjected to GC/MS analysis, after methylation and trimethylsilylation, to give mass spectra of derivatised hydroxy acids that showed that degradation starts with the hydrogenation of one double bond. The position of the remaining double bond was determined by reacting the hydroxyoctadecenoic acid thus obtained with osmium tetroxide to give a trihydroxystearic acid. After appropriate derivatization (methylation, trimethylsilylation), the mass spectrum unambiguously demonstrated the presence of a 9,10,13-trihydroxystearic acid derivative and hence the double bond in the precursor molecule is located in position 9. Enzymatic hydrogenation of 13-S-HODE is enhanced by the addition of NADH and, to an even greater extent, by NADPH. Similarly, 9-S-HODE is metabolized to 9-S-hydroxy-12-octadecenoic acid.

Influence of fatty acid composition on the formation of polar glycerides and polar fatty acids in sunflower oils heated at frying temperatures.

Conventional and high oleic sunflower oils as well as 50% mixture of both of them were heated at different temperatures under well-controlled conditions. Total polar compounds, the main groups of polar glycerides, total polar fatty acids, the main groups of polar fatty acids and the loss of initial fatty acids were quantitated. The most outstanding results demonstrated the primacy of the formation of glyceridic polymerization compounds during heating at high temperatures. After transesterification of the samples dimeric fatty acids was the most significant group of compounds obtained. As expected, linoleic acid was preferentially involved in the formation of polar fatty acids, although the participation of oleic acid became very important at low concentration of linoleic acid. Finally good statistical figures were obtained for the regression of polar fatty acids on polar compounds.

Biosynthesis of the algal pheromone hormosirene by the fresh-water diatom Gomphonema parvulum (Bacillariophyceae)

The fresh water diatom Gomphonema parvulum (Bacillariophyceae) produces the algal pheromones hormosirene 2 (C 11H 16) and dictyopterene A 16 (C 11H 18) from highly unsaturated eicosanoic acids like 20:5 ( ω−3) 21 and 20:4 ( ω−6) 14. The oxidative degradation is believed to proceed by cleavage of an intermediate 9-hydroperoxide like 6 by a hydroperoxide-lyase to yield 9-oxo-nona-(5 Z.7 E)-dienoic acid 8 and the corresponding C 11 hydrocarbon. The biosynthetic sequence is confirmed by identification and synthesis of the novel polar fatty acid fragment 8.

Short-Chain Fatty Acid Formation during Thermoxidation and Frying

Formation and evolution of the short-chain fatty acids originated by oxidation and remaining bound to the parent triglyceride, specifically heptanoate and octanoate, were studied during thermoxidation of palm olein, conventional sunflower oil and high-oleic sunflower oil at 180°C, as well as in real used frying oils of unknown history collected by Food Inspection Services. Fatty acids were quantified by gas-liquid chromatography following transesterification of samples and using methyl nonanoate and methyl heptadecanoate as internal standards. Alteration level was determined through analyses of polar compounds and polar fatty acids. Results showed high correlation coefficients between short-chain fatty acids and polar compounds or polar fatty acids, thus suggesting that quantification of short-chain fatty acids is a good indication of the total alteration level in used frying oils.

10% urea cream (Laceran) for atopic dermatitis: A clinical and laboratory evaluation

A clinical study was carried out on the effects of the application of a cream containing urea in 30 normal subjects and 40 patients with atopic dermatitis. In addition, in 20 treated atopic patients and 15 normal subjects, evaporimetry was carried out after 2 and 7 days. The subjective and objective clinical results and the evaporimetric data showed that twice daily applications of urea cream improved the dryness, the itching and the erythema of patients with atopic dermatitis. Furthermore, the patients considered the results to be correlated with the treatment and to be accompanied by a subjective feeling of greater skin plasticity. In the normal subjects there was also improvement in skin plasticity and a reduction in transepidermal water evaporation. In a laboratory study, the concentration of extractable epidermal lipids was also determined in eight treated atopic patients after 15 days of urea cream treatment. Polar fatty acids were much lower and the difference was due exclusively to reduced epiderm...

Lipid Content and Composition of Wagyu and Domestic Breeds of Beef

The influence of beef source and cooking method on neutral (NL) and polar (PL) lipid contents, fatty acid profiles, and cholesterol contents of Wagyu and domestic sources of beef was determined. Longissimus dorsi muscle from Japanese Wagyu, American Wagyu, Longhorn, Angus, and U.S. Choice was boiled or roasted. Beef from Wagyu breeds had a significantly higher (P < 0.05) NL content than that of domestic sources. The NL from Japanese Wagyu samples was lower in saturated fatty acid content and higher in monounsaturated fatty acid content than samples from other beef sources. The PL from the Japanese Wagyu had the lowest content of saturated fatty acids, while the PL from the American Wagyu had the highest content of monounsaturated fatty acids and the lowest content of polyunsaturated fatty acids. Cholesterol content was highest for the Wagyu breeds. The contents of total NL and individual fatty acids were significantly (P < 0.05) higher in the roasted beef than boiled beef. Cooking method did not have a significant effect on the PL content, PL fatty acid profiles, and cholesterol content.

Growth and Liver Polar Fatty Acid Composition of Year-1 Channel Catfish Fed Various Lipid Sources at Two Water Temperatures

Abstract Young channel catfish (Ictalurus punctatus) with an initial weight of 0.9 ± 0.03 g were fed semipurified diets containing 7% lipids as beef tallow, corn oil, linseed oil, menhaden oil, or a mixture (1:1:1) of menhaden oil, beef tallow, and corn oil at two water temperatures, 17 ± 1°C and 28 ± 0.5°C, for 9 weeks. At the higher temperature, fish fed the menhaden oil and the mixed-oil diets had greater weight gains (P < 0.05) than fish fed the other diets. Weight gains for fish fed beef tallow, corn oil, or linseed oil did not significantly differ (P > 0.05). At the lower water temperature, weight gain was much less, and the only significant difference among treatments was between the fish fed menhaden oil or mixed oil and those fed beef tallow, which gained no weight. The concentration of polyene fatty acids in liver phospholipids was higher at the low temperature than at the high temperature (P < 0.05). The primary n-3 highly unsaturated fatty acid (HUFA) in liver phospholipids of fish fed menhaden oil or the mixed oils was 22:6 n-3, docosahexaenoic acid (DHA). Fish fed corn oil had primarily 20:4 n-6, arachidonic acid (AA), in their phospholipids, and those fed linseed oil had a small amount of 20:5 n-3, eicosapentaeonic acid (EPA), but no DHA in their liver phospholipids. This study indicates that the presence of fish oil, a source of n-3 HUFA, in the diet enhances growth of young channel catfish at optimum and suboptimum temperatures.

Reducing frictional constraint in compression testing through lubrication

J. F. LABUZ~ J. M. BRIDELL~ INTRODUCTION A basic assumption in material testing is the existence of a uniform stress state, where the loading surfaces are usually the principal planes. During compressive load- ing, however, this condition becomes untenable because a frictional constraint develops at the interface between the material and loading system [1-4]. A cylindrical geometry, for example, takes on a barrel shape and a nonuniform stress state develops throughout the cylin- der. This is especially important in studying failure of rock-like materials, as the observed response may be due to the unknown boundary conditions [5, 6]. Homogeneous deformation can be achieved by finding an appropriate friction reducer [7]. In compression test- ing of high-strength materials such as hard rock, this means using a lubricant that performs well at normal stresses up to several hundred MPa, at displacements on the order of hundreds of microns, and at displacement rates of a few microns per second. The objective of this research was to find such a lubricant. LUBRICANTS Boyd and Robertson [8] used a torsional shear appar- atus to measure the coefficient of friction (COF) of various substances subjected to large (up to 1.4GPa) normal stresses. They evaluated solid lubricants, greases, mineral oils, animal and vegetable oils and fatty acids. The COF for graphite measured 0.036, while the COF for both tungsten disulfide and molybdenum disulfide was 0.032. Stearic acid, a fatty acid, showed remarkable friction behavior, with the lowest COF (0.022) of all substances tested. Tarrant [9] measured a low COF, 0.040, for grease containing a slight excess of highly polar fatty acid molecules. For some polar hydrocarbons, friction seems to decrease with increasing chain length [10]. Stearic acid, a polar hydrocarbon with a chain length of 16 [stearic acid

Measurement of Hydroxy and Hydroperoxy Fatty Acids by a High Pressure Liquid Chromatography with a Column-switching System

Hydroxy and hydroperoxy fatty acids were labeled with 9-bromomethylacridine at room temperature. They were separated from the degradation products and less polar fatty acid derivatives on an octyl silicagel column, and put on an octadecyl silicagel column by on-line column switching. By this method, picomolar levels of the derivatives were measured with good reproducibility. The detection limit of 16-hydroxy-hexadecanoic acid as a representative was 0.9 pmol (S/N =3) and the relative standard deviation of its peak areas was 2.5% (18.5 pmol, n = 7). The method was used for the measurement of hydroxy fatty acids derived from hydroperoxy fatty acids and phosphatidylcholine (PC) hydroperoxides spiked in human plasma. By incubation at 37°C for 4h with human plasma, the hydroperoxy fatty acid was reduced to the corresponding hydroxy fatty acid. In this condition, the PC hydroperoxides showed a considerable decrease, however, a small portion (2.5–3%) of PC hydroperoxides decomposed gave the corresponding hydroxy...

Absorción de grasas termoxidadas. I. Reproducibilidad y exactitud de las técnicas analíticas previas a la evaluación de los lípidos no absorbidos

Reproducibility of the techniques used for isolation and separation of non-absorbed lipids present in feces from rats fed with diets containing heated oils are defined. Highly reproducible results have been found for total lipids, nonpolar fatty acid compositions. Results obtaines from extracted diets demonstrate both the absence of significant alteration and the complete extraction of the fat when compared to those obtained directly from the oils. Non-absorbed lipids from diets containing thermoxidized oils are characterized by high proportions of unsaponifiable compounds and polar fatty acids.

Combination of adsorption and size-exclusion chromatography for the determination of fatty acid monomers, dimers and polymers

A procedure based on adsorption and size-exclusion chromatography is proposed for evaluating fatty acid monomers, dimers and polymers in fats subjected to thermal oxidation. Starting from fatty acid methyl esters, two fractions of different polarity are obtained by silica column chromatography and submitted to a second separation by high-performance size-exclusion chromatography. The procedure allows the determination of unaltered fatty acids in addition to four groups of degradation compounds: non-polar fatty acid dimers, oxidized fatty acid monomers, polar fatty acid dimers and fatty acid polymers.

Ornithine-containing lipids of some Pseudomonas species.

Ornithine-containing lipids purified by thin-layer chromatography were found to represent 2-15% of the total extractable cellular lipids in two or three strains each of four Pseudomonas species: P. aeruginosa, P. fluorescens, P. stutzeri and P. cepacia. The structures of the ornithine-containing lipids were elucidated by chemical analysis, thin-layer chromatography, gas-liquid chromatography, gas-liquid chromatography/mass spectrometry (electron impact or secondary ion) and infrared absorption spectroscopy. At least six molecular species of ornithine-containing lipids were present in common in all of the preparations of the four Pseudomonas species. The structure which was the most abundantly in P. fluorescens (about 60% of the total amount of the ornithine-containing lipid) was 3-hydroxyhexadecanoic acid amide-linked to ornithine and esterified to hexadecanoic acid. In addition to this structure, 3-hydroxyoctadecenoic acid amide-linked to ornithine and esterified to hexadecanoic acid was a dominant structure in the ornithine-containing lipids of P. aeruginosa, P. stutzeri or P. cepacia. In P. cepacia, another ornithine-containing lipids with a terminal polar fatty acid, 3-hydroxyhexadecanoic acid amide-linked to ornithine and esterified to 2-hydroxynonadecacyclopropanoic acid or 2-hydroxyoctadecenoic acid, was found; its content, which represented 8-11% of the total extractable cellular lipids, was higher than that of the ornithine-containing lipids with a terminal nonpolar fatty acid. These ornithine-containing lipids exhibited hemagglutinating activity. Additionally, it was very interesting that hydroxy fatty acids included in the ornithine-containing lipids were not found in the phospholipids which represented more than 80% of the total extractable cellular lipids.