Fatty Acid Isomers Research Articles

Effect of dietary vegetable oils on the fatty acid profile of plasma lipoproteins in dairy cows

ABSTRACTThe aim of this study was to elucidate the effect of dietary supplementation of soybean oil (SO) and hydrogenated palm oil (HPO) on the transport of fatty acids (FA) within plasma lipoproteins in lactating and non-lactating cows. Three lactating and three non-lactating Holstein cows were used in two different 3 × 3 Latin square experiments that included three periods of 21 d. Dietary treatments for lactating cows consisted of a basal diet (control; no fat supplement) and fat-supplemented diets containing SO (500 g/d per cow) or HPO (500 g/d per cow). For non-lactating cows, dietary treatments consisted of a basal diet (control; no fat supplement) and fat-supplemented diets containing SO (170 g/d per cow) or HPO (170 g/d per cow). Compared with the control and SO diet, HPO addition increased (p < 0.05) the concentration of C16:0, C18:0, C18:2cis-9,12, C18:3cis-9,12,15 and total saturated and polyunsaturated FA in the plasma of lactating cows. In non-lactating cows, the SO addition increased the plasma concentration of C18:1trans-11. In lactating cows, concentrations of C16:0, C18:0 and total saturated FA were increased (p < 0.05) by HPO addition in the high-density lipoprotein (HDL). Total saturated FA were increased (p < 0.05) by HPO in very-low-density lipoprotein (VLDL). In non-lactating cows, the concentration of C18:0 was increased (p < 0.05) by HPO in HDL, whereas C18:1trans-11 was increased (p < 0.05) by SO in the low-density lipoprotein. Overall, it was found that distribution and transport of FA within the bovine plasma lipoproteins may be influenced by chain length and degree of unsaturation of dietary lipids. Also, the distribution of individual FA isomers such as C18:1trans-11 and C18:2cis-9,trans-11 may vary depending on the physiological state of the cow (lactating or non-lactating), and are increased in plasma (lactating cows) and the HDL (non-lactating cows) when cows are fed SO.

Sources and Bioactive Properties of Conjugated Dietary Fatty Acids.

The group of conjugated fatty acids known as conjugated linoleic acid (CLA) isomers have been extensively studied with regard to their bioactive potential in treating some of the most prominent human health malignancies. However, CLA isomers are not the only group of potentially bioactive conjugated fatty acids currently undergoing study. In this regard, isomers of conjugated α-linolenic acid, conjugated nonadecadienoic acid and conjugated eicosapentaenoic acid, to name but a few, have undergone experimental assessment. These studies have indicated many of these conjugated fatty acid isomers commonly possess anti-carcinogenic, anti-adipogenic, anti-inflammatory and immune modulating properties, a number of which will be discussed in this review. The mechanisms through which these bioactivities are mediated have not yet been fully elucidated. However, existing evidence indicates that these fatty acids may play a role in modulating the expression of several oncogenes, cell cycle regulators, and genes associated with energy metabolism. Despite such bioactive potential, interest in these conjugated fatty acids has remained low relative to the CLA isomers. This may be partly attributed to the relatively recent emergence of these fatty acids as bioactives, but also due to a lack of awareness regarding sources from which they can be produced. In this review, we will also highlight the common sources of these conjugated fatty acids, including plants, algae, microbes and chemosynthesis.

Novel characterisation of minor α-linolenic acid isomers in linseed oil by gas chromatography and covalent adduct chemical ionisation tandem mass spectrometry

Discrimination between polyunsaturated fatty acid isomers with three double bonds is a great challenge, due to structural similarities and similar polarities. In this study, we report the identification of four minor geometrical isomers of α-linolenic acid (ALA) present in linseed oil samples: (9E,12Z,15E)-, (9Z,12Z,15E)-, (9Z,12E,15Z)- and (9E,12Z,15Z)-octadeca-9,12,15-trienoic acids, chromatographically resolved by gas chromatography (GC) using a new and highly polar ionic phase column (SLB-IL111). Gas chromatography–electron ionisation mass spectrometry (GC–EIMS) determined that the four unknown compounds were C18:3 n–3 isomers. The positional 9-12-15 C18:3 configuration was achieved by covalent adduct chemical ionisation tandem mass spectrometry (CACI-MS/MS) while geometrical configuration was established with analytical standards based on relative retention. We hypothesised that these isomers are formed during linseed oil deodorisation and postulate preferred and unfavoured isomerisation pathways of ALA.

Determination of trans -fatty acid isomers in human milk fat by gas chromatography-mass spectrometry

Determination of <i>trans</i> -fatty acid isomers in human milk fat by gas chromatography-mass spectrometry

Assessment of Lipid Quality and Composition of Commercial Infant Milk Formulas in Mexico: Emphasis on &amp;lt;i&amp;gt;Trans&amp;lt;/i&amp;gt; Fatty Acid Isomers

Objective: To assess the lipid quality focusing on trans fatty acids (TFA) content of standardized milk formulas marketed in Mexico for infants aged from 0 to 36 months. Material and Methods: A total of 27 infant formulas from eight different leading brands were analyzed. Nine of them belonged to stage 1 (age 12 months). Acquired products were treated by duplicate for extraction of total lipid content with the modified Folch method before their expiration date. Fatty acids were esterified in an alkaline medium followed by an acid-catalyzed esterification. Analysis was performed on a gas chromatograph (5890 Series II; Hewlett-Packard, USA) with a flame ionization detector. Results: Thirty-four fatty acids (C8 to C22) were identified. Most products complied with ESPHAGAN compositional requirements. Only one product exceeded the suggested limit (>3%) for TFA. Long chain polyunsaturated fatty acids (LC-PUFAs) content was consistently meager (≈78%), with low amounts of arachidonic (Conclusion: Most milk formulas complied with ESPHAGAN global recommendations. The content of TFA and LC-PUFAs was scarce in the majority of samples.

FATTY ACID COMPOSITION OF LIPIDS OF STRAIN BACILLUS SP. OЗ-5 ISOLATED FROM OIL-CONTAMINATED SOIL OF THE ZMIINY ISLAND

The aim. Determination of fatty acid composition of cell lipids and identification of a strain of microorganism selected in 2014 from a portion of the oil-contaminated soil of the Zmiiny island. Methods. Fatty acid analysis of the strains of genus Bacillus sp. ОЗ-5 was carried using the automatic identification system of microorganisms MIDI Sherlock (MIDI, USA) based on gas chromatograph Agilent 7890 (Agilent Technologies, USA). Results. Phenotypically characterized strain Bacillus sp. ОЗ-5 was identified as Bacillus megaterium ОЗ-5 – GC subgroup A by fatty acids composition. The analysis of obtained chromatograms revealed that dominant in the fatty-acid profile of strain Bacillus sp. ОЗ-5 there were branched structural isomers of long-chain saturated fatty acids with predominant content of 12-metyltetradecane (C15:0 anteiso, 39.6%) and 13-metyltetradecane (C15:0 iso, 32.93%) acids also С17:0 аnteiso (2.69%), С17:0 iso (1.88%), С14:0 iso (6.62%), С16:0 iso (1.76%), С13:0 аnteiso (0.25%) та С13:0 iso (0.5%) isomers were detected. Conclusion. By the fatty acid profile analysis with MIDI Sherlock system observable strain is identified as Bacillus megaterium-GC subgroup A with high level of similarity index 0.737. The peculiarities of the fatty acid profile of the investigated microorganism is systematized and can be used as an auxiliary key for distinguishing it as a genus and at the species level (based on the results of the study of the cellular fatty acid composition) from other bacteria of genus Bacillus.

Hepatocytes respond differently to major dietary trans fatty acid isomers, elaidic acid and trans-vaccenic acid

BackgroundIt has been discussed if the adverse health effect associated with the ingestion of trans fatty acids correlates with the food source, as the composition of the isomers varies in different foods. We have investigated the hepatocellular responses to the predominant trans fatty acid isomers in industrially produced partially hydrogenated vegetable oils (elaidic acid) and products of ruminant origin (trans-vaccenic acid).ResultsThe responses of HepG2-SF cells exposed to 100 μM fatty acids during 7 days were examined. Elaidic acid decreased the cellular proliferation rate while trans-vaccenic acid had no effect. Analysis of cellular triacylglycerol fractions showed, that both trans fatty acids were metabolized by HepG2-SF cells, although elaidic acid, to a higher degree than trans-vaccenic, accumulated in the triacylglycerol fraction. Proteome analysis revealed that the overlap of differentially regulated proteins only contained four proteins, suggesting that the two trans fatty acid isomers affect the cells in different ways. The data are available via ProteomeXchange with identifier PXD000760.ConclusionsOur investigations revealed that the hepatocellular response to the two most abundant dietary positional C18:1 trans fatty acid isomers differ substantially. In addition, the results suggest that trans-vaccenic acid does not affect cholesterol metabolism adversely compared to elaidic acid.Electronic supplementary materialThe online version of this article (doi:10.1186/s12953-015-0084-3) contains supplementary material, which is available to authorized users.

Vaccenic acid and trans fatty acid isomers from partially hydrogenated oil both adversely affect LDL cholesterol: a double-blind, randomized controlled trial

Adverse effects of industrially produced trans fatty acids (iTFAs) on the risk of coronary artery disease are well documented in the scientific literature; however, effects of naturally occurring trans fatty acids (TFAs) from ruminant animals (rTFA), such as vaccenic acid (VA) and cis-9,trans-11 conjugated linoleic acid (c9,t11-CLA), are less clear. Although animal and cell studies suggest that VA and c9,t11-CLA may be hypocholesterolemic and antiatherogenic, epidemiologic data comparing rTFAs and iTFAs are inconsistent, and human intervention studies have been limited, underpowered, and not well controlled. We determined the effects of VA, c9,t11-CLA, and iTFA, in the context of highly controlled diets (24 d each), on lipoprotein risk factors compared with a control diet. We conducted a double-blind, randomized, crossover feeding trial in 106 healthy adults [mean ± SD age: 47 ± 10.8 y; body mass index (in kg/m(2)): 28.5 ± 4.0; low-density lipoprotein (LDL) cholesterol: 3.24 ± 0.63 mmol/L]. Diets were designed to have stearic acid replaced with the following TFA isomers (percentage of energy): 0.1% mixed isomers of TFA (control), ∼3% VA, ∼3% iTFA, or 1% c9,t11-CLA. Total dietary fat (34% of energy) and other macronutrients were matched. Total cholesterol (TC), LDL cholesterol, triacylglycerol, lipoprotein(a), and apolipoprotein B were higher after VA than after iTFA; high-density lipoprotein (HDL) cholesterol and apolipoprotein AI also were higher after VA. Compared with control, VA and iTFA both increased TC, LDL cholesterol, ratio of TC to HDL cholesterol, and apolipoprotein B (2-6% change; P < 0.05); VA also increased HDL cholesterol, apolipoprotein AI, apolipoprotein B, and lipoprotein(a) (2-6% change; P < 0.05), whereas iTFA did not. c9,t11-CLA lowered triacylglycerol (P ≤ 0.01) and had no effect on other lipoprotein risk factors. With respect to risk of cardiovascular disease, these results are consistent with current nutrition labeling guidelines, with the requirement of VA, but not c9,t11-CLA, to be listed under TFA on the Nutrition Facts Panel. This trial was registered at clinicaltrials.gov as NCT00942656.

Deep sequencing shows microRNA involvement in bovine mammary gland adaptation to diets supplemented with linseed oil or safflower oil.

BackgroundBovine milk fat composition is responsive to dietary manipulation providing an avenue to modify the content of fatty acids and especially some specific unsaturated fatty acid (USFA) isomers of benefit to human health. MicroRNAs (miRNAs) regulate gene expression but their specific roles in bovine mammary gland lipogenesis are unclear. The objective of this study was to determine the expression pattern of miRNAs following mammary gland adaptation to dietary supplementation with 5 % linseed or safflower oil using next generation RNA-sequencing.MethodsTwenty-four Canadian Holstein dairy cows (twelve per treatment) in mid lactation were fed a control diet (total mixed ration of corn:grass silages) for 28 days followed by a treatment period (control diet supplemented with 5 % linseed or safflower oil) of 28 days. Milk samples were collected weekly for fat and individual fatty acid determination. RNA from mammary gland biopsies harvested on day-14 (control period) and on days +7 and +28 (treatment period) from six randomly selected cows per treatment was subjected to small RNA sequencing.ResultsMilk fat percentage decreased significantly (P < 0.001) during treatment with the two diets as compared to the control period. The individual saturated fatty acids C4:0, C6:0, C8:0, C14:0 and C16:0 decreased significantly (P < 0.05) while five USFAs (C14:1, C18:1n11t, C20:3n3, C20:5n3 and CLA:t10c12) increased remarkably (P < 0.05) in response to both treatments. Analysis of 361 million sequence reads generated 321 known bovine miRNAs and 176 novel miRNAs. The expression of fourteen and twenty-two miRNAs was affected (P < 0.05) by linseed and safflower oil treatments, respectively. Seven miRNAs including six up-regulated (bta-miR-199c, miR-199a-3p, miR-98, miR-378, miR-148b and miR-21-5p) and one down-regulated (bta-miR-200a) were found to be regulated (P < 0.05) by both treatments, and thus considered core differentially expressed (DE) miRNAs. The gene targets of core DE miRNAs have functions related to gene expression and general cellular metabolism (P < 0.05) and are enriched in four pathways of lipid metabolism (3-phosphoinositide biosynthesis, 3-phosphoinositide degradation, D-myo-inisitol-5-phosphate metabolism and the superpathway of inositol phosphate compounds).ConclusionOur results suggest that DE miRNAs in this study might be important regulators of bovine mammary lipogenesis and metabolism. The novel miRNAs identified in this study will further enrich the bovine miRNome repertoire and contribute to understanding mammary gland biology.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1965-7) contains supplementary material, which is available to authorized users.

An efficient and robust fatty acid profiling method for plasma metabolomic studies by gas chromatography–mass spectrometry

BackgroundTargeted metabolomic analysis of fatty acids has linked the dysregulation of fatty acids to many diseases. This study selected five frequently used fatty acid derivatization methods for comparison. MethodsWe compared the method precisions and derivatization efficiencies, the most economical and best performing method was subjected to method validation. Twenty-four fatty acid standards were used to validate the method, which was later applied to the investigation of potential fatty acid markers of breast cancer. ResultsThe acetyl chloride method was demonstrated to provide the best derivatization efficiency and lowest cost for plasma samples. The ionic liquid column successfully separated positional and geometric fatty acid isomers within 26min under the optimized conditions. Intra-day and inter-day CVs for most of the fatty acids were <10%. Over 90% of the results showed recoveries within 85%–115%. The validated method was applied to investigate potential fatty acid markers of breast cancer. The fatty acid profiling results revealed that 3 fatty acids (C22:0, C24:0, C18:2n6) were significantly lower in both pre- and post-menopausal breast cancer patients (P<0.05). ConclusionsWe demonstrated that the proposed method is an accurate, efficient and economical method for plasma metabolomic studies of fatty acids.

Determination of Fatty Acids in Beef by Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

A method was developed to separate, identify, and quantify 28 fatty acids of potential health relevance using liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS). Optimization of the experimental factors enabled baseline separation of the fatty acids including three pairs of closely related fatty acid isomers (C18:3n-3 and C18:3n-6; C18:1 and C18:1 t; and C20:3n-3 and C20:3n-6) that are challenging to separate. The limits of detection ranged from 0.01 to 0.26 mg L−1 for the 28 fatty acids, and average recovery (mean, n = 4) was found to be 102 ± 12 %. In addition, the proposed method was validated using a quality control standard mix of fatty acids which yielded acceptable precision and accuracy. Fatty acid concentrations in conventional grain-fed and organic grass-fed beef were determined, and the results show that grass-fed beef have a lower omega-6 to omega-3 ratio (1.6–2.8) compared to grain-fed beef (9.3–13.5). Principal component analysis (PCA) was applied on the resulting data to find correlations between significant fatty acid composition and the diet of beef samples.

Dietary fish oil supplements depress milk fat yield and alter milk fatty acid composition in lactating cows fed grass silage-based diets

The potential of dietary fish oil (FO) supplements to increase milk 20:5n-3 and 22:6n-3 concentrations and the associated effects on milk fatty acid (FA) composition, intake, and milk production were examined. Four multiparous lactating cows offered a grass silage-based diet (forage:concentrate ratio 58:42, on a dry matter basis) supplemented with 0, 75, 150, or 300g of FO/d (FO0, FO75, FO150, and FO300, respectively) were used in a 4×4 Latin square with 28-d experimental periods. Milk FA composition was analyzed by complementary silver-ion thin-layer chromatography, gas chromatography-mass spectrometry, and silver-ion HPLC. Supplements of FO decreased linearly dry matter intake, yields of energy-corrected milk, milk fat and protein, and milk fat content. Compared with FO0, milk fat content and yield were decreased by 30.1 and 40.6%, respectively, on the FO300 treatment. Supplements of FO linearly increased milk 20:5n-3 and 22:6n-3 concentrations from 0.07 to 0.18 and 0.03 to 0.10g/100g of FA, respectively. Enrichment of 20:5n-3 and 22:6n-3 was accompanied by decreases in 4- to 18-carbon saturated FA and increases in total conjugated linoleic acid (CLA), trans FA, and polyunsaturated FA concentrations. Fish oil elevated milk fat cis-9,trans-11 CLA content in a quadratic manner, reaching a maximum on FO150 (from 0.61 to 2.15g/100g of FA), whereas further amounts of FO increased trans-10 18:1 with no change in trans-11 18:1 concentration. Supplements of FO also resulted in a dose-dependent appearance of 37 unique 20- and 22-carbon intermediates in milk fat. Concentrations of 16-, 18-, 20-, and 22-carbon trans FA were all increased by FO, with enrichment of trans 18:1 and trans 18:2 being quantitatively the most important. Decreases in milk fat yield to FO were not related to changes in milk trans-10,cis-12 CLA concentration or estimated milk fat melting point. Partial least square regression analysis indicated that FO-induced milk fat depression was associated with changes in the concentrations of multiple FA in milk. Even though a direct cause and effect could not be established, a decrease in 18:0 supply in combination with increased mammary uptake of cis-11 18:1, trans-10 18:1, and trans 20- and 22-carbon FA may contribute. In conclusion, dietary FO supplements enrich 20:5n-3 and 22:6n-3 in milk, but also elevate mono- and polyenoic trans FA concentrations, and in high amounts alter the distribution of individual trans FA isomers.

A Promising Raman Spectroscopy Technique for the Investigation of trans and cis Cholesteryl Ester Isomers in Biological Samples.

Lipid geometry is an important issue in biology and medicine. The cis-trans geometry conversion of double bonds in lipids is an endogenous process that can be mediated by sulfur-centered free radicals. Trans isomers of polyunsaturated fatty acids can be used as biological markers of free radical stress, and their presence in biological samples can be determined by synthesis and characterization of appropriate reference compounds. Fractions of plasma lipids, such as cholesteryl linoleate and arachidonate esters, are interesting targets because of their connection with membrane phospholipid turnover and their roles in cardiovascular health. In this context, Raman spectroscopy can provide a useful contribution, since Raman analysis can be performed directly on the lipid extracts without any derivatization reaction, is nondestructive, and can rapidly supply biochemical information. This study focused on the build up of Raman spectral libraries of different cis and trans isomers of cholesteryl esters to be used as references for the examination of complex biological samples and to facilitate isomer recognition. Unsaturated cholesteryl esters obtained by chemical synthesis and with different alkyl chain lengths, double bond numbers, or both, were analyzed. The potential of Raman analysis for trans isomer detection in biological samples was successfully tested on some cholesteryl ester lipid fractions from human serum. The data suggest promising applications of Raman spectroscopy in metabolomics and lipidomics.

A quick method for routine analysis of C18 trans fatty acids in non-hydrogenated edible vegetable oils by gas chromatography–mass spectrometry

A quick routine analysis has been established for quantitative determination of thirteen individual C18 trans fatty acids in both pressed and solvent extracted non-hydrogenated edible vegetable oils, using gas chromatography-mass spectrometer (GC–MS) equipped with HP-88 capillary column following potassium hydroxide/methanol (KOH/MeOH) methylation. Based on optimization and appraisal of the characteristics of GC–MS, thirteen C18 trans fatty acid methyl ester (FAME) standards were separated and verified in 23 min, validation experiments were also conducted. The correlation coefficient was R2 ≥ 0.99 in the linear range of each FAME. At the low, medium and high fortification levels, recoveries fell within 90–119%. The relative standard deviations were below 9% for all 13 FAMEs. Low limits of detection (0.001–0.002 g/100 g) and quantification (0.002–0.007 g/100 g) were readily achieved. The content of C18 trans fatty acid isomers in pressed and solvent extracted oils were analyzed using this method.

Concerns about the use of 15:0, 17:0, and trans-16:1n–7 as biomarkers of dairy fat intake in recent observational studies that suggest beneficial effects of dairy food on incidence of diabetes and stroke

Concerns about the use of 15:0, 17:0, and trans-16:1n–7 as biomarkers of dairy fat intake in recent observational studies that suggest beneficial effects of dairy food on incidence of diabetes and stroke

The effects of feeding rations that differ in neutral detergent fiber and starch concentration within a day on rumen digesta nutrient concentration, pH, and fermentation products in dairy cows

There is a daily pattern of feed intake in the dairy cow, and feeding a single total mixed ration results in variation in the amount of fermentable substrate entering the rumen over the day. The object of this study was to determine if feeding multiple rations over the day that complement the pattern of feed intake would stabilize rumen pool sizes and fermentation. Nine ruminally cannulated cows were used in a 3×3 Latin square design with 23-d periods. Diets were a control diet [33.3% neutral detergent fiber (NDF)], a low-fiber diet (LF; 29.6% NDF), and a high-fiber diet (HF; 34.8% NDF). The LF and HF diets were balanced to provide the same nutrient composition as the control diet when cows were fed 3 parts of LF and 7 parts of HF. Cows on the control treatment (CON) were fed at 0900h, cows on the high/low treatment (H/L) were fed HF at 70% of daily offering at 0900h and LF at 30% of daily offering at 2200h, and cows on the low/high (L/H) treatment were fed LF at 30% of daily offering at 0900h and HF at 70% of daily offering at 1300h. All treatments were fed at 110% of daily intake. Preplanned contrasts compared CON with H/L and H/L with L/H. Feeding the LF diet in the evening resulted in a large increase in the amount of feed consumed immediately after feed delivery at that feeding. Rumen digesta starch concentration increased and NDF concentration decreased following feeding of the LF diet in both the L/H and H/L treatments. Starch pool size also increased following feeding of the LF diet in the evening and tended to increase after feeding the LF diet in the morning. Rumen ammonia concentration was increased following feeding of the HF diet in the morning and the LF diet in the evening in the H/L treatment. Additionally, cis-9 C18:1 and cis-9,cis-12 18:2 are higher in concentrate feeds and were increased after feeding the LF diet in both treatments. Trans fatty acid isomers of the normal and alternate biohydrogenation pathways followed a daily pattern, and the H/L treatment increased isomers of the alternate pathway during the overnight period following the evening feeding of the LF diet. Additionally, C17:0 decreased during the overnight period in the H/L treatment. Feeding multiple rations over the day changed feeding behavior, and the combined effect of diet composition and feeding pattern resulted in a change in rumen nutrient pool sizes and fermentation products. Feeding the low-fiber diet in the evening resulted in a large increase in feed intake after feed delivery and did not increase starch intake during the overnight period. The H/L treatment failed to stabilize rumen fermentation because of the shift in the feeding pattern. Feeding strategies that feed multiple diets over the day must integrate diet composition and feeding behavior to achieve the desired effect on rumen nutrient pools and fermentation.

Geometrical effects of phospholipid olefinic bonds on the structure and dynamics of membranes: A molecular dynamics study

The trans isomers of fatty acids are found in human adipose tissue. These isomers have been linked with deleterious health effects (e.g., coronary artery disease). In this study, we performed molecular dynamics simulations to investigate the structures and dynamic properties of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) and 1-palmitoyl-2-elaidoyl sn-glycero-3-phosphatidylcholine (PEPC) lipid bilayers. The geometry of the olefinic bond and membrane packing effects significantly influenced the conformations and dynamics of the two CC single bonds adjacent to the olefinic bond. For the PEPC lipid, the two CC single bonds adjacent to the olefinic bond adopted mainly nonplanar skew–trans and planar cis–trans motifs; although the cis conformation featured relatively strong steric repulsion, it was stabilized through membrane packing because its planar structure is more suitable for membrane packing. Moreover, membrane packing effects stabilized the planar transition state for conformational conversion to a greater extent than they did with the nonplanar transition state, thereby affecting the dynamics of conformational conversion. The rotational motions of the first neighboring CC single bonds were much faster than those of typical saturated CC single bonds; in contrast, the rotational motions of the second neighboring CC single bonds were significantly slower than those of typical saturated torsion angles. The packing of PEPC lipids is superior to that of POPC lipids, leading to a smaller area per lipid, a higher order parameter and a smaller diffusion coefficient. The distinct properties of POPC and PEPC lipids result in PEPC lipids forming microdomains within a POPC matrix.

MiRNA expression in human intestinal Caco-2 cells is comparably regulated by cis- and trans-fatty acids.

Trans-fatty acids are unsaturated fatty acids with at least one double bond in trans configuration. While their role in the development of coronary heart disease is broadly accepted, a potential impact of these fatty acids on colon carcinogenesis is still under discussion. MiRNAs are small non-coding RNAs that regulate the gene expression at a post-transcriptional level by inhibiting the translation of target mRNAs. We investigated the effect of 16 different C 18 fatty acid isomers on the expression of 84 cancer-related miRNAs in the human colorectal adenocarcinoma cell line Caco-2 by using a qRT-PCR array. 66 of these 84 miRNAs were deregulated by at least one fatty acid, however, there was no trans-specific impact on miRNA expression as the corresponding cis isomer of a given fatty acid generally had comparable effects on the miRNA expression profile. The most pronounced effects were observed for hsa-miR-146a-5p, which was upregulated by four of the 16 investigated fatty acids, and hsa-miR-32-5p, which was strongly downregulated by five fatty acids. As hsa-miR-32-5p was described to target genes being involved in the regulation of apoptosis, the effect of α-eleostearic acid on the expression of the apoptosis-associated genes BCL2L11, BCL-2, and BCL-XL was examined. The qPCR results indicate that fatty acid-mediated downregulation of hsa-miR-32-5p is accompanied by a downregulation of BCL-2 and BCL2L11 mRNA whereas BCL-XL was shown to be simultaneously upregulated. In conclusion, our data indicate that several fatty acids are able to regulate miRNA expression of human colon cancer cells. However, no trans-specific regulation was observed.

Isolation of α-linolenic acid biohydrogenation products by combined silver ion solid phase extraction and semi-preparative high performance liquid chromatography.

Polyunsaturated fatty acids typically found in cattle feed include linoleic (LA) and α-linolenic acid (ALA). In the rumen, microbes metabolize these resulting in the formation of biohydrogenation products (BHP), which can be incorporated into meat and milk. Bioactivities of LA-BHP, including conjugated linoleic acid (cis (c) 9,trans (t) 11-18:2 and t10,c12-18:2) and trans fatty acid isomers (t9-, t10- and t11-18:1) have been investigated, but effects of several BHP unique to ALA have not been extensively studied, and most ALA-BHP are not commercially available. The objective of the present research was to develop methods to purify and collect ALA-BHP using silver ion (Ag(+)) chromatography in sufficient quantities to allow for convenient bioactivity testing in cell culture. Fatty acid methyl esters (FAME) were prepared from perirenal adipose tissue from a cow enriched with ALA-BHP by feeding flaxseed. These were applied to Ag(+)-solid phase extraction, and eluted with hexane with increasing quantities of acetone (1, 2, 10, 20%) or acetonitrile (2%) to pre-fractionate FAME based on degree of unsaturation and double bond configuration. Fractions were collected, concentrated and applied to semi-preparative Ag(+)-high performance liquid chromatography (HPLC) for the isolation and collection of purified isomers, which was accomplished using isocratic elutions with hexane containing differing amounts of acetonitrile (from 0.015 to 0.075%). Purified trans-18:1 isomers collected ranged in purity from 88 to 99%. Purity of the ALA-BHP dienes collected, including c9,t13-18:2, t11,c15-18:2 and t10,c15-18:2, exceeded 90%, while purification of other dienes may require the use of other complementary procedures (e.g. reverse phase HPLC).

Rapeseed or linseed in dairy cow diets over 2 consecutive lactations: Effects on adipose fatty acid profile and carry-over effects on milk fat composition in subsequent early lactation

During early lactation, milk fatty acid (FA) composition is influenced by diet, animal genetics, and the high availability of preformed FA from body-fat mobilization. Long-term prepartum dietary oilseed supplementation could, therefore, modify milk FA composition postpartum in the subsequent lactation through changes in adipose tissue (AT) FA profile. To test this hypothesis, measurements were made in 19 Holstein cows fed grass-based diets containing no additional lipid (control, CTL; n=4) or supplemented with extruded linseeds (EL; n=4), cold-pressed fat-rich rapeseed meal (FRM; n=6), or whole unprocessed rapeseeds (WR; n=5) over 2 consecutive lactations (yr 1 and 2) and 2 dry periods. Oilseed supplements were withdrawn from the diets 23 d before the calving of yr 3, following the end of the previous experimental periods in yr 1 to 2. Thereafter, all cows received a total mixed ration composed of grass silage, grass hay, and concentrates (forage:concentrate ratio of 70:30 on a dry-matter basis). Cows previously fed EL and WR had a lower milk fat content (6.32% for CTL and FRM vs. 5.46% for EL and WR) and yield (1.90kg/d for CTL and FRM vs. 1.61kg/d for EL and WR) during the first week of lactation. Treatment effects on milk fat content and yield did not persist into lactation wk 3 and 7. Whatever the week, EL and WR increased concentration of FA in milk synthesized de novo (i.e., carbon number ≤15; 17.1g/100g of FA for CTL and FRM vs. 22.2g/100g of FA for EL and WR) and decreased concentration and secretion of preformed FA (i.e., carbon number ≥17; 56.1g/100g of FA for CTL and FRM vs. 49.9g/100g of FA for EL and WR). Alterations in milk FA composition may be explained by the lower availability of mobilized FA for uptake by the mammary gland, as indicated by the lower plasma nonesterified FA concentrations for EL and WR compared with CTL and FRM. Prepartum EL feeding increased AT and milk concentration of 18:3n-3 (0.96 vs. 0.79g/100g of milk FA for EL and the other groups, respectively) and intermediates of ruminal 18:3n-3 biohydrogenation. In contrast, FRM increased AT and milk concentration of ruminal cis-9 18:1 biohydrogenation intermediates. However, EL and FRM supplements resulted in a similar profile of 18-carbon FA isomers in AT (yr 2) and milk (yr 3, 4–10 wk after removing oilseeds from the diet). In conclusion, results confirm that long-term feeding of oilseed supplements alter AT FA composition and may influence milk FA composition during periods of extensive body-fat mobilization such as early lactation.