Double Bond Position Plays an Important Role in Delta-9 Desaturation and Lipogenic Properties of Trans 18:1 Isomers in Mouse Adipocytes

The objective of this research was to study the delta‐9 desaturation of individual trans (t) fatty acids that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on lipogenic gene expression in adipocytes. It was hypothesized that delta‐9 desaturation and lipogenic properties of t‐18:1 isomers depend on the position of double bond. Differentiated 3T3‐L1 adipocytes were treated with 200 µM of t6–18:1, t9–18:1, t11–18:1, t13–18:1 or t16–18:1, cis (c)‐9 18:1 or bovine serum albumin (BSA) vehicle control for 48 h. Cells were then harvested for fatty acid and gene expression analyses using gas chromatography and quantitative PCR respectively. Among t‐18:1 isomers, t13–18:1 and t11–8:1 had the greatest percent delta‐9 desaturation (44 and 41 % respectively) followed by t16–18:1 and t6–18:1 (32 and 17 % respectively), while c9–18:1 and t9–18:1 did not undergo delta‐9 desaturation. Trans9–18:1 up‐regulated (P < 0.05) the expression of lipogenic genes including fatty acid synthase and stearoyl‐CoA desaturase‐1 (P < 0.05), whereas the expression of these genes were not affected with other t‐18:1 isomers (P > 0.05). Consistent with gene expression results, t9–18:1 increased the de novo lipogenic index (16:0/18:2n‐6) compared with control cells and increased delta‐9 desaturation index (c9–16:1/18:0) compared to other t‐18:1 isomers (P < 0.05). The current study provides further evidence that the predominant trans fatty acid in PHVO (t9–18:1) has isomer specific lipogenic properties.     

Individual trans 18:1 Isomers are Metabolised Differently and Have Distinct Effects on Lipogenesis in 3T3‐L1 Adipocytes

The objective of this research was to study the metabolism of individual trans fatty acids (FAs) that can be found in ruminant fat or partially hydrogenated vegetable oils (PHVO) and determine their effects on FA composition and lipogenic gene expression in adipocytes. Differentiated 3T3‐L1 adipocytes were treated with 200 µM of either trans‐9‐18:1, trans‐11‐18:1, trans‐13‐18:1, cis‐9‐18:1 or BSA vehicle control for 120 h. Trans‐9‐18:1 increased total cell FA content (µmole/well) compared to other FA treatments, which was mainly related to the accumulation of trans‐9‐18:1 in the cells. Adipocytes were able to desaturate a significant proportion of absorbed trans‐11‐18:1 and trans‐13‐18:1 (~20 and 30 % respectively) to cis‐9,trans‐11‐18:2 and cis‐9,trans‐13‐18:2, whereas trans‐9‐18:1 was mostly incorporated intact resulting in a greater lipophilic index (i.e. decreased mean FA fluidity) of adipocytes. Trans‐9‐18:1 up‐regulated (P < 0.05) the expression of lipogenic genes including acetyl‐CoA carboxylase (1.65 fold), FA synthase (1.45 fold), FA elongase‐5 (1.52 fold) and stearoyl‐CoA desaturase‐1 (1.49 fold), compared to the control, whereas trans‐11‐18:1 and trans‐13‐18:1 did not affect the expression of these genes compared to control. Our results suggest that the metabolism and lipogenic properties of trans‐11‐18:1 and trans‐13‐18:1, typically the most abundant trans FA in beef from cattle fed forage‐based diets, are similar and are different from those of trans‐9‐18:1, the predominant trans FA in PHVO.     

Mammary Uptake of Fatty Acids Supplied by Intravenous Triacylglycerol Infusion to Lactating Dairy Cows

Supplementing dairy cows with n-3 fatty acid-rich feeds does not easily increase quantities in milk fat. Previous results demonstrated very long-chain n-3 fatty acids are primarily transported in the PL fraction of blood, making them largely unavailable to the mammary gland for enrichment of milk fat. Our objective was to compare mammary uptake of fatty acids of increasing chain length and unsaturation delivered intravenously as TAG emulsions. Late lactation dairy cows were assigned to a completely randomized block design. Treatments were intravenous TAG emulsions enriched with oleic acid (OLA), linoleic acid (LNA), alpha-linolenic acid (ALA), or docosahexaenoic acid (DHA) and were delivered continuously at 16 mL/h for 72 h. Each treatment supplied 30 g/day of the target fatty acid. Treatment did not affect feed intake, milk yield, or milk composition, but all treatments reduced intake and yield. The proportion of DHA increased in plasma FFA, TAG, and PL with infusion. Increases of n-3 fatty acids, ALA, EPA, and DHA, were evident in the plasma PL fraction, suggesting re-esterification in the liver. Transfer efficiencies were 37.8 ± 4.1, 27.6 ± 5.4, and 10.9 ± 4.1 %, and day 3 total milk fatty acyl yields were 37.0 ± 3.4, 10.8 ± 0.4, and 3.3 ± 0.3 g for LNA, ALA, and DHA. Variation in oleic acyl yield prevented calculation of OLA transfer efficiency. Mammary uptake of fatty acids was reduced with increased chain length and unsaturation. Both liver and mammary mechanisms may regulate transfer of long-chain polyunsaturates.     

Plasticity of Mouse Brain Docosahexaenoic Acid: Modulation by Diet and Age

Decreases in brain docosahexaenoic acid (DHA) have been associated with losses in brain function leading to an interest in the conditions which lead to such brain decreases, and such variables as age. Also of relevance would be the rate of repletion of DHA when the n-3 dietary deficiency is reversed. This experiment describes dietary deficiency in n-3 fatty acids induced in weanling (3 week) and young adult (7 week) mice. There was an immediate and continuous loss of brain DHA with similar rates in the two age groups. Serum DHA declined more rapidly in younger animals with respect to similarly treated adults. Brain and serum docosapentaenoic acid (DPAn-6) increased more rapidly and to higher levels in the younger animals. A second experiment determined the rates of normalization of brain fatty acid profiles when alpha-linolenic acid was added to the diets of n-3 deficient mice. Brain DHA recovery occurred at a faster rate (half-time, T _1/2 = 1.4 weeks) when begun at weaning relative to young adult mice (T _1/2 = 3.5 weeks). Correspondingly, brain DPAn-6 recovered faster in the younger animals; the adult group had a half-time of more than twice that of the 3-week old group. This study therefore demonstrates that the young adult mouse brain DHA is somewhat plastic and can be partially depleted via a low n-3 fatty acid diet and subsequently restored when dietary n-3 fatty acids are repleted. Relevance of these findings for human nutrition is discussed.     

Fish Oil Finishing Diet Maintains Optimal n-3 Long-Chain Fatty Acid Content in European Whitefish (<Emphasis Type="Italic">Coregonus lavaretus</Emphasis>)

This study examined the effect of substituting vegetable oil for fish oil in feed, with subsequent re-introduction of fish oil-rich feed (finishing feeding) in late stages of growth, on the fatty acids of cultivated European whitefish (Coregonus lavaretus). Restorative finishing feeding with fish oil-rich feed for 15 and 25 weeks was sufficient to change the total content of nutritionally valuable long-chain n-3 fatty acids, eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3), to correspond to that of fish fed the fish oil-rich feed throughout their lifespan. Under natural conditions, 15 and 25 weeks correspond to weight gains of 75% and 100% (i.e. doubling), respectively. Also, the fatty acid profile of the fish was restored after finishing periods of 15 and 25 weeks. Limiting the use of fish oil by lowering the overall fat content of the feed (no vegetable oil added) resulted in a decrease in the long-chain n-3 fatty acids. Based on the results, after receiving a vegetable oil-rich diet, restorative fish oil-rich feeding in the last stages of growth in European whitefish is nutritionally justified in order to balance nutritional gain for consumers with sustainable use of finite marine oils. The results encourage commercial efforts to further utilize and optimize finishing feeding practices.     

Process conditions for separating fatty acid esters by supercritical CO2

The solubilities of ethyl palmitate, ethyl oleate, ethyl eicosapentaenoate (EPA) and ethyl docosahexaenoate (DHA) in supercritical carbon dioxide were determined by a continuous flow method. The solubilities of fatty acid ethyl esters increased with pressure and decreased as the temperature was increased. An empirical equation, similar to Chrastil's equation, was used to describe the relationship between solute solubility and the density of carbon dioxide. The empirical equation was further used to qualitatively estimate the separation efficiency of isolating EPA and DHA ethyl esters from fatty acid esters. The operating conditions yielding high solubility gave fast extraction rate but resulted in low separation efficiency. Experiments were conducted to separate ethyl EPA and ethyl DHA from a model mixture containing four fatty acid ethyl esters and from esterified squid visceral oil. The experimental data compared closely with the calculated values.     

Reduced Maternal Erythrocyte Long Chain Polyunsaturated Fatty Acids Exist in Early Pregnancy in Preeclampsia

The present prospective study examines proportions of maternal erythrocyte fatty acids across gestation and their association with cord erythrocyte fatty acids in normotensive control (NC) and preeclamptic pregnancies. We hypothesize that maternal fatty acid status in early pregnancy influences fetal fatty acid stores in preeclampsia. 137 NC women and 58 women with preeclampsia were included in this study. Maternal blood was collected at 3 time points during pregnancy (16–20th weeks, 26–30th weeks and at delivery). Cord blood was collected at delivery. Fatty acids were analyzed using gas chromatography. The proportions of maternal erythrocyte α‐linolenic acid, docosahexaenoic acid, nervonic acid, and monounsaturated fatty acids (MUFA) (p < 0.05 for all) were lower while total n‐6 fatty acids were higher (p < 0.05) at 16–20th weeks of gestation in preeclampsia as compared with NC. Cord 18:3n‐3, 22:6n‐3, 24:1n‐9, MUFA, and total n‐3 fatty acids (p < 0.05 for all) were also lower in preeclampsia as compared with NC. A positive association was observed between maternal erythrocyte 22:6n‐3 and 24:1n‐9 at 16–20th weeks with the same fatty acids in cord erythrocytes (p < 0.05 for both) in preeclampsia. Our study for the first time indicates alteration in maternal erythrocyte fatty acids at 16th weeks of gestation which is further reflected in cord erythrocytes at delivery in preeclampsia.     

From Aquatic to Terrestrial Food Webs: Decrease of the Docosahexaenoic Acid/Linoleic Acid Ratio

Fatty acid composition of the adipose tissue of six carnivorous mammalian species (European otter Lutra lutra, American mink Mustela vison, European Mink Mustela lutreola, European polecat Mustela putorius, stone marten Martes foina and European wild cat Felis silvestris) was studied. These species forage to differing degrees in aquatic and terrestrial food webs. Fatty acid analysis revealed significant differences in polyunsaturated fatty acid composition between species. More specifically, our results underline a gradual significant decrease in the docosahexaenoic acid (DHA)/linoleic acid (LNA) ratio of carnivore species as their dependence on aquatic food webs decreases. In conclusion, the use of the DHA/LNA ratio in long-term studies is proposed as a potential proxy of changes in foraging behaviour of semi-aquatic mammals.     

An Empirical Equation for Estimation of Kinematic Viscosity of Fatty Acid Methyl Esters and Biodiesel

Kinematic viscosity (µ) is an important physical property of fatty acid methyl esters (FAME) and biodiesel. In this work, the Martin's rule of free energy additivity is extended to cover the kinematic viscosity of saturated and unsaturated FAME commonly found in nature. The proposed model can also be extended to estimate kinematic viscosity of biodiesel. The kinematic viscosity of a FAME or a biodiesel can be easily estimated from its carbon number (z), number of double bonds (n_d) at different temperatures (T) without a prior knowledge of the viscosity of individual FAME. Both z_ave and n_d(ave) can be derived from its fatty acid composition. Thus, kinematic viscosity of biodiesel at temperatures between 20 and 100 °C and at atmospheric pressure can be estimated. The average absolute deviation (AAD) estimated at 20–100 °C for saturated, unsaturated FAME, biodiesels and biodiesel blends are 4.15, 3.25, 6.95 and 2.79 %, respectively. The biodiesels collected in this study (191 data points) have the z_ave and n_d(ave) between 14.10 and 17.96 and 0.21–1.54, respectively. The standard deviation was 0.249. The proposed model would be good for estimation of viscosity of biodiesel containing normal fatty acids, generally found in biodiesel feed stocks.     

Synthesis of Biodiesel via Deoxygenation of Stearic Acid over Supported Pd/C Catalyst

High catalytic activity was achieved in the deoxygenation of stearic acid in dodecane in a temperature range of 270–300 °C under 17 bar helium over palladium on nanocomposite carbon Sibunit. Besides n-heptadecane, which was obtained previously in this reaction with palladium on activated carbon, n-pentadecane was also formed in significant amounts.     

Genetic Background and Diet Impact Beef Fatty Acid Composition and Stearoyl-CoA Desaturase mRNA Expression

The intramuscular fat composition of ruminant meats influences the quality of the final product, which explains the increasing interest in assessing the fatty acid profile of meat from different production systems. In this study, it was hypothesized that there are breed- and diet-induced variations on lipid metabolism in the muscle, which may be, at least partially, modulated by the stearoyl-CoA desaturase (SCD) gene expression levels. Forty purebred young bulls from two phylogenetically distant autochthonous cattle breeds, Alentejana and Barrosã (n = 20 for each breed), were assigned to two different diets (low vs. high silage) and slaughtered at 18 months of age. Meat fatty acid composition, including the detailed conjugated linoleic acid (CLA) isomeric profile, was determined along with the SCD mRNA levels. Meat from Barrosã bulls fed the low silage diet was richer in monounsaturated fatty acids, CLA and trans fatty acids, when compared to that from Alentejana bulls. The meat content in polyunsaturated fatty acids was similar across experimental groups. Moderate positive correlations between the SCD mRNA levels and the products of this enzyme activity were found, although they were not reflected on the calculated desaturase indices. Overall, these findings highlight the importance of taking into account the genetic background while devising feeding strategies to manipulate beef fatty acid composition.     

藻类花生四烯酸的提取工艺

花生四烯酸作为一种重要的保健、营养品,越来越受到人们的重视。从鱼油、真菌丝、微藻中都可以提取花生四烯酸,但这些工艺都有着明显的缺点。设计了一种从藻类提取花生四烯酸的新工艺过程。     

脂肪酸三乙醇胺单酯琥珀酸磺酸盐的制备及表面活性

以三乙醇胺、长链脂肪酸为原料,先经酯化、柱色谱提纯得到脂肪酸三乙醇胺单酯(FTME),再经磺化反应合成了4种脂肪酸三乙醇胺单酯琥珀酸酯磺酸盐(FTMS)两性表面活性剂,以月桂酸、棕榈酸、硬脂酸、油酸为脂肪酸合成的FTMS分别命名为FTMS-1、FTMS-2、FTMS-3、FTMS-4,通过FTIR与1HNMR表征了其结构,分别用碱性亚甲基蓝法和酸性溴酚蓝法验证了产物的离子性,并考察了FTMS结构中的烷基链长度及其不饱和度对表面张力、Krafft点、样品液粒径及粒径分布、乳化能力的影响。实验结果表明：产物显示出两性离子的特征;在系列FTMS中,随着脂肪链碳数增加,其Krafft点升高,平均粒径逐渐增大,但脂肪链中的不饱和双键有助于Krafft点的降低和粒径的减小。FTMS-1和FTMS-4具有优异的表面活性,其中FTMS-1的临界胶束质量浓度(CMC)为52.97mg/L,表面张力γCMC为36.1mN/m,其乳化能力（分离时间为148.8s）与AEO-9（分离时间为139.0s）相当且优于十二烷基磺酸钠(分离时间为113.8s)。