Fatty Acid Isomers Research Articles

The n-10 Fatty Acids Family in the Lipidome of Human Prostatic Adenocarcinoma Cell Membranes and Extracellular Vesicles.

A new pathway leading to the n-10 fatty acid series has been recently evidenced, starting from sapienic acid, a monounsaturated fatty acid (MUFA) resulting from the transformation of palmitic acid by delta-6 desaturase. Sapienic acid has attracted attention as a novel marker of cancer cell plasticity. Here, we analyzed fatty acids, including the n-10 fatty acid contents, and for the first time, compared cell membranes and the corresponding extracellular vesicles (EV) of two human prostatic adenocarcinoma cell lines of different aggressiveness (PC3 and LNCaP). The n-10 components were 9–13% of the total fatty acids in both cancer cell lines and EVs, with total MUFA levels significantly higher in EVs of the most aggressive cell type (PC3). High sapienic/palmitoleic ratios indicated the preference for delta-6 versus delta-9 desaturase enzymatic activity in these cell lines. The expressions analysis of enzymes involved in desaturation and elongation by qRT-PCR showed a higher desaturase activity in PC3 and a higher elongase activity toward polyunsaturated fatty acids than toward saturated fatty acids, compared to LNCaP cells. Our results improve the present knowledge in cancer fatty acid metabolism and lipid phenotypes, highlighting EV lipidomics to monitor positional fatty acid isomer profiles and MUFA levels in cancer.

An integrated electrocatalytic nESI-MS platform for quantification of fatty acid isomers directly from untreated biofluids.

Positional isomers of alkenes are frequently transparent to the mass spectrometer and it is difficult to provide convincing data to support their presence. This work focuses on the development of a new reactive nano-electrospray ionization (nESI) platform that utilizes non-inert metal electrodes (e.g., Ir and Ru) for rapid detection of fatty acids by mass spectrometry (MS), with concomitant localization of the C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C bond to differentiate fatty acid isomers. During the electrospray process, the electrical energy (direct current voltage) is harnessed for in situ oxide formation on the electrode surface via electro-oxidation. The as-formed surface oxides are found to facilitate in situ epoxide formation at the CC bond position and the products are analyzed by MS in real-time. This phenomenon has been applied to analyze isomers of unsaturated fatty acids from complex serum samples, without pre-treatment.

Routine Determination of Milk Fat Composition for Nutritional and Technological Purposes

78 individual milk samples (IS) were taken in the Czech Fleckvieh and Holstein dairy cow herds and 33 bulk milk samples (BS) were taken in 13 Holstein dairy cow herds to compare two methods for the determination of fatty acids (FAs) – routine/indirect (infrared (IR) spectroscopy, MIR-FT) and reference/direct (gas chromatography, GC). The IS results show that the fatty acids C16:0 and C18:1 and the group of saturated (SFA) and unsaturated (UFA) FAs can be determined using routine method with a relatively high reliability (correlations (r) 0.7543, 0.7607, 0.8424 and 0.9492; P < 0.001). In case of polyunsaturated FAs is the r lower (0.2891; P < 0.05). In BS the tightness of relations is stronger in the case of the SFA and UFA (r 0.7094; 0.9389; P < 0.001), while for the group of TFA (trans isomers of unsaturated FAs) and PUFA (polyunsaturated FAs) are lower r (0.5897 and 0.5931; P < 0.001 respectively). Routine method for fatty acids profile determination is efficient for selection of raw milk to guarantee the production of specific dairy products with increased content of healthful fatty acids.

Effect of 2-hydroxy-4-(methylthio) butanoate (HMTBa) supplementation on rumen bacterial populations in dairy cows when exposed to diets with risk for milk fat depression

Diet-induced milk fat depression (MFD) is a condition marked by a reduction in milk fat yield experimentally achieved by increasing dietary unsaturated fatty acids and fermentable carbohydrates. 2-Hydroxy-4-(methylthio) butanoate (HMTBa) is a methionine analog observed to reduce diet-induced MFD in dairy cows. We hypothesize that the reduction in diet-induced MFD by HMTBa is due to changes in the rumen microbiota. To test this, 22 high-producing cannulated Holstein dairy cows were placed into 2 groups using a randomized block design and assigned to either control or HMTBa supplementation (0.1% of diet dry matter). All cows were then exposed to 3 different diets with a low risk (32% neutral detergent fiber, no added oil; fed d 1 to 7), a moderate risk (29% neutral detergent fiber and 0.75% soybean oil; fed d 8 to 24), or a high risk (29% neutral detergent fiber and 1.5% soybean oil; fed d 25 to 28) for diet-induced MFD. Rumen samples were collected on d 0, 14, 24, and 28, extracted for DNA, PCR-amplified for the V1-V2 region of the 16S rRNA gene, sequenced on an Illumina MiSeq (Illumina, San Diego, CA), and subjected to bacterial diversity analysis using the QIIME pipeline. The α diversity estimates (species richness and Shannon diversity) were decreased in the control group compared with the HMTBa group. Bacterial community composition also differed between control and HMTBa groups based on both weighted UniFrac (relative abundance of commonly detected bacteria) and unweighted UniFrac (presence/absence) distances. Within the HMTBa group, no differences were observed in bacterial community composition between d 0 and d 14, 24, and 28; however, in the control group, d 0 samples were different from d 14, 24, and 28. Certain bacterial genera including Dialister, Megasphaera, Lachnospira, and Sharpea were increased in the control group compared with the HMTBa group. Interestingly, these genera were positively correlated with milk fat trans-10,cis-12 conjugated linoleic acid and trans-10 C18:1, fatty acid isomers associated with biohydrogenation-induced MFD. It can be concluded that diet-induced MFD is accompanied by significant alterations in the rumen bacterial community and that HMTBa supplementation reduces these microbial perturbations.

Determination and quantification of fatty acid C=C isomers by epoxidation reaction and liquid chromatography-mass spectrometry

The location of double bond in unsaturated fatty acids (FAs) plays a critical role in their physiological properties. However, structural identification and quantification of unsaturated FAs by mass spectrometry are still challenging. In this work, we reported the coupling of epoxidation reaction of the C=C in unsaturated FAs and liquid chromatography-mass spectrometry (LC-MS) with multiple reaction monitoring (MRM) mode for accurate identification and quantification of C=C isomers of FAs. Epoxidation of the C=C in unsaturated FAs was induced by a dioxide of ketone, tetrahydrothiopyran-4-one 1,1-dioxide, as a catalyst and Oxone as an oxidant in less than 5 min with nearly 100% yield. All the C=C bonds were epoxidized to obtain a single product, simplifying the chromatographic separation of epoxidation products to enable more accurate quantification analysis. The epoxidation products were stable at room temperature and can produce highly abundant diagnostic ions indicative of C=C locations by tandem mass spectrometry using collision-induced association (CID). The application of this approach for the analysis of FAs isomers in human plasma demonstrated the potential of our method for the qualitative and quantitative analysis of unsaturated FAs in complex biological samples, which is valuable in biological and medical analysis.

The role of obesity and environmental factors such as diet and physical activity in the etiopathogenesis of fertility disorders

The most common causes affecting female reproductive potential in Poland are anovulatory cycles, diseases of the fallopian tubes and the peritoneum, male factor, and pathological changes of the uterus. It was observed that among couples originating from villages, there is a higher share of tubal infertility factor, while among couples originating from cities - of male factor. Environmental factors have been known to be part of infertility etiopathogenesis. However, despite the advances of recent years, the types of these factors and their mechanisms have not been sufficiently explained. Studies have demonstrated that there is a relation between diet and ovulatory infertility. The factors that reduce the risk of infertility include the presence of sufficient amounts of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) in the diet and reduced intake of isomers of trans fatty acids (TFA) and saturated fatty acids (SFA). Replacing animal proteins with plant proteins is also advantageous. Other important factors are low glycemic diet, high intake of fat-rich dairy products, and provision of the right amount of vitamins and non-haem iron in the form of plants and dietary supplements. Multiple studies have demonstrated that improper nutritional status, including weight deficiency or excessive weight, may have an adverse effect on female and male fertility. Physical activity is also an important factor influencing female reproductive functions. In conjunction with an appropriate diet, exercise reduces abdominal obesity and improves insulin sensitivity, thus directly decreasing the risk of infertility.

The use of coupled gas chromatography columns for the determination of individual isomers of trans fatty acids in the adipose tissue of vegans

The profile of fatty acids including detailed analysis of positional trans and cis isomers of octadecenoic acid in subcutaneous fat (adipose) tissue was determined on two polar 100-m SLB-IL111 and SP-2560 columns joined by a connector, with hydrogen carrier gas at a flow rate of 1.7 cm3/min and injection of the 1.0 mm3 of derivatised sample with split of 100:1. The separation time was 160 min, with determination of 62 fatty acids, 13 of which were trans isomers. An epidemiological study demonstrated a lower level of trans fatty acids in vegans; the sum of trans fatty acids in vegans equaled 4.6 mg/g of adipose tissue, while that for the control group of omnivores was 7.7 mg/g. In contrast, the level of beneficial polyunsaturated fatty acids in vegans was 201.8 mg/g, compared to 103.3 mg/g in omnivores.

Generating Fatty Acid Profiles in the Gas Phase: Fatty Acid Identification and Relative Quantitation Using Ion/Ion Charge Inversion Chemistry.

Representing the most fundamental lipid class, fatty acids (FA) play vital biological roles serving as energy sources, cellular signaling molecules, and key architectural components of complex lipids. Direct infusion electrospray ionization spectrometry, also known as shotgun lipidomics, has emerged as a rapid and powerful toolbox for lipid analysis. While shotgun lipidomics can be a sensitive approach to FA detection, the diverse molecular structure of FA presents challenges for unambiguous identification and the relative quantification of isomeric contributors. In particular, pinpointing double bond position(s) in unsaturated FA and determining the relative contribution of double bond isomers has limited the application of the shotgun approach. Recently, we reported the use of gas-phase ion/ion reactions to facilitate the identification of FA. Briefly, singly deprotonated FA anions undergo charge inversion when reacted in the gas phase with tris-phenanthroline magnesium dications by forming [FA - H + MgPhen]+ complex ions. These charge-inverted FA complex cations fragment upon ion-trap collision-induced dissociation (CID) to generate product ion spectra unique to individual FA isomers. Herein, we report the development of a mass spectral library comprised of [FA - H + MgPhen]+ product ion spectra. The developed FA library permits confident FA identification, including polyunsaturated FA isomers. Furthermore, we demonstrate the ability to determine relative contributions of isomeric FA using multiple linear regression analysis paired with gas-phase ion/ion reactions. We successfully applied the presented method to generate a FA profile for bovine liver phospholipidome based entirely on gas-phase chemistries.

Система «Светофор» в пищевой отрасли

The development and implementation of the ‘Traffic Light’ marking was a consequence of the concern of Rospotrebnadzor in connection with the increase in the growth of diseases related to nutrition. In particular, the development of cardiovascular diseases, obesity, hypertension, diabetes leads to increased consumption of sugar, saturated fatty acids, trans isomers of fatty acids, salts. This raised the issue of providing clear and reliable information to the consumer about these substances. The initiator of the project of color marking ‘Traffic Light’ was the CPS. He with the participation of Research Institute of Nutrition and Biotechnology was prepared, developed and published guidelines MR 2.3.0122-18 Color indication on the labelling of food products in order to inform consumers. The purpose of these recommendations is to provide more detailed and visual information about the content of individual substances in the product: salt added sugar and fat. Color indication includes the application of red, yellow and green — depending on the level of salt, sugar and fatty acids, taking into account the daily rate of consumption of these substances. For example, green mark bread products containing table salt less than 0.2 (0.5) g and red — if it contains more than 0.48 (1.2) g. For added sugar, in particular for dairy and cottage cheese products, green identification is put at less than 5 g and red identification — at more than 9 g per day. It should be noted that the system ‘Traffic Light’ does not indicate the harm or danger of the product to human health, and informs the buyer about the color of salt, sugar and fat in this product. Similar markings are used in the USA, Great Britain and Finland. In addition to the ‘Traffic Light’ marking and the indication of food and energy value, the European Union countries are also covered by the indication of allergens, vitamins and minerals on the product package.

Analysis of Conjugated Fatty Acid Isomers by the Paternò-Büchi Reaction and Trapped Ion Mobility Mass Spectrometry.

Fatty acids containing conjugated carbon-carbon double bonds (C═Cs), such as conjugated linoleic acids (CLAs), attract growing research interest due to their bioactivities against diabetes, cancer, and atherosclerosis. Analysis of conjugated fatty acid (CFA) is challenging for existing analytical techniques because it requires determination of geometry (cis ( Z) vs trans ( E)) and location of individual C═C. In this study, we developed a method to achieve confident, fast, and quantitative analysis of CFA isomers from mixtures. This method combines the strength of trapped ion mobility spectrometry (TIMS) for fast isomer separation and the Paternò-Büchi (PB) reaction followed by tandem mass spectrometry (MS/MS) for C═C location determination. Notably, the PB reaction of CFA is regioselective to terminal C═Cs, thus forming diagnostic fragment ions unique to conjugated C═Cs from PB-MS/MS. These fragment ions facilitate identification and quantitation of individual CLA isomers differing in C═C locations, affording limit of identification of 1 nM. Given that PB-MS/MS alone cannot identify the geometry of C═C, TIMS has been employed for characterizing C═C geometry. TIMS is capable to separate various C═C geometric isomers of CLAs, allowing visualization of C═C isomerization during the PB reaction. By coupling the PB-MS/MS with TIMS, two CLA isomers, CLA 18:2(9 Z,11 E) (46.9 ± 1.1%) and CLA 18:2(10 E,12 Z) (53.1 ± 1.1%), are quantified in a commercial CLA supplement.

Changes in fermentation and animal performance during recovery from classical diet-induced milk fat depression using corn with differing rates of starch degradability

Diet-induced milk fat depression (MFD) is a multifactorial disorder that can be triggered by a variety of conditions. Feeding high amounts of starch and unsaturated fatty acids has been shown to reduce milk fat yield and composition, as well as alter ruminal biohydrogenation patterns. However, little is known about how starch degradability in the rumen influences recovery from diet-induced MFD and if production of milk fat-inhibiting isomers will persist following an episode of MFD. The objective of this study was to evaluate production performance and ruminal fermentation in cows recovering from MFD when corn with a low or high starch degradability is fed. Six ruminally fistulated Holstein cows were used in a crossover design with 2 periods. During each period, MFD was induced for 10 d by feeding a diet with low fiber, high starch, and high unsaturated fatty acid. The polyunsaturated fatty acid concentration of the diet during the induction phase was modified primarily through inclusion of soybean oil. Following induction, cows were switched to either a high degradable starch recovery diet (HDS) or a low degradable starch recovery diet (LDS) for 18 d. The 7-h starch degradability was 66.5% for LDS and 87.8% for HDS. Milk was collected every 3 d for component and fatty acid analysis. On d 0, 4, 7, 10, 16, 22, and 28 of each period, ruminal pH and rumen fluid were collected every 2 h. Milk fat yield and composition was reduced during MFD induction and progressively increased by day in both HDS and LDS during recovery. Dry matter intake was similar among treatments and increased steadily over time during recovery. Preformed fatty acids were greater for HDS-fed animals, and de novo fatty acid in milk fat was greater for LDS-fed animals. Milk trans-10 C18:1 tended to be greater for HDS, and trans-10,cis-12 conjugated linoleic acid was significantly greater for HDS. cis-9,trans-11 conjugated linoleic acid was not affected by starch degradability during recovery. Total volatile fatty acids, butyrate, and valerate tended to differ or differed with recovery treatment, but ruminal pH and ammonia concentration were unaffected. The HDS diet responded similarly to the LDS diet during recovery with regard to milk fat percentage, but milk and fat yield tended to consistently be lower in HDS. When considering approaches to ameliorate diet-induced MFD, the degradability of the starch within rations should be evaluated. Although animal performance was similar, some trans fatty acid isomers were persistent in the milk through the recovery phase with HDS-fed animals, suggesting that milk fat synthesis might be potentially inhibited and biohydrogenation pathways modified in the rumen following an episode of MFD.

Development of a design of experiments optimized method for quantification of polysorbate 80 based on oleic acid using UHPLC-MS

The aim was to develop a straightforward UHPLC-MS quantification method for polysorbate 80 using oleic acid as surrogate marker, which was the commonest substance within the emulsifier. However, hydrolysis of polysorbate 80 and subsequent analysis of fatty acids revealed a co-elution of oleic acid and an isomer while all the other fatty acids were successfully separated by varying retention times and mass-to-charge ratios. For identification and separation of the isomer a derivatization method was evaluated. Oxidation to the corresponding dihydroxystearic acids with potassium permanganate resulted in peak separation of cis/trans and structural isomers of the 18:1 fatty acids. Hydrolyzed and derivatized polysorbate 80 was quantified indirectly in the range of 0.046–5.83 μg/mL (R2 > 0.997) with a limit of detection of 11.4 ng/mL. Quantification of polysorbate 80 using oleic acid as a surrogate marker showed good reproducibility and linearity. As all isomers of the 18:1 fatty acids were successfully separated, the previously co-eluting peak was identified as elaidic acid and was found as a component in the mixture of the emulsifier polysorbate 80. Additionally, cis-vaccenic acid was separated as a second co-eluting isomer. Therefore, derivatization led to successful chromatographical separation of cis/trans and structural 18:1 fatty acid isomers.

GC‐MS Characterization of Cyclic Fatty Acid Monomers and Isomers of Unsaturated Fatty Acids Formed During the Soybean Oil Heating Process

In this work, the possibility of formation and isolation of cyclic fatty acid monomers (CFAM) from polyunsaturated fatty acids via prolonged heat treatment of soybean oil are studied. The structures of CFAM are determined using Gas chromatography‐Mass spectrometry (GC‐MS) of their 4, 4‐dimethyloxazoline (DMOX) derivatives, the yield of derivatization is 98%. Among CFAM, the cyclohexyl fatty acids with ring from C12 to C17 and the cyclohexneyl with ring from C10 to C15 formed acid are detected by GC‐MS. The new cyclopentyl with ring at C14 position or between C13 to C17 are detected from linoleic acid. Also, the variation of major fatty acids composition of soybean oil during heated treatment at 150, 180, 210, and 240 °C for 60 h are analyzed. The results indicate that after heating, soybean oil contains four isomers of conjugated linoleic acid (CLA), four isomers of C18:1 and four isomers of C18:3. The heating process, the enrichment steps, and CFAM concentration can modify the profile of CFAM and permit the emergence of new compounds, which can be useful to know the edible oil structural changes during the phases of extraction and analysis.Practical Applications: When heated at high temperature for a long time, soybean oil undergoes isomerization and cyclization reactions. In fact, CFAM structures with five and six membered carbon rings are identified from heated oil. A new mass spectrum of the CFAM derivative from the intramolecular C18:2 cyclization is also described. Although CFAM are present at very low concentrations in heated oils, these compounds are the most toxic metabolites produced in soybean oil heated at high temperature. In addition to the four isomers of conjugated linoleic acid, four isomers of C18:1 and four of C18:3 are detected during the heating process. The data clearly show that it is necessary to avoid heating the soybean oil to a temperature above 210 °C for a period of more than 60 h which can minimize the production of CFAM.The gap of 68 amu between the molecular ion (333) and m/z 265 indicate the location of cyclopentyl ring at C14, which is first determined in heated soybean oil.

Optimization of the composition of fat systems of new generation

Fats are an integral part of human nutrition. The increased content of trans-isomers in their composition causes a number of cardiovascular diseases and metabolic disorders. A promising approach to solving the problem of minimizing the content of trans- isomers of fatty acid in the composition of food products is the creation of a new generation of fat systems – the oleogel, which is the subject of the presented research. As the dispersion medium of the oleogel, high-oleic sunflower oil is used, in contrast to the oil of traditional varieties, it is possible to obtain systems with enhanced oxidation resistance. The dispersed phase of these fat systems is beeswax, tripalmitin and monoacylglycerols. The choice of a complex of these components is based on their properties to create in oleogels a three-dimensional structure with desired thermomechanical characteristics. At present, there is not enough information about the dependence of the main characteristics of the oleogel on the ratio of ingredients of dispersed phase. In particular, one of the most problematic places in the oleogel technology is its thermal stability, which significantly affects the parameters of production, transportation, as well as storage conditions and periods. To solve this problem, the methodology of the response surface is used in the work. The determination of the unknown values of the parameter vector is carried out by applying regression analysis algorithms. The minimization of the deviation functional is performed by finding the appropriate combinations of experimental predictor series. As a result of research, a mathematical model is developed, which allows, based on data on the component composition of the oleogel, to predict its thermal stability. Reasonably rational mass fractions of the components of the dispersed phase of the oleogel: the content of beeswax is 3.27 wt. %; content of tripalmitin is 3.07 wt. % and the content of monoacylglycerol is 4.70 wt. %, at which the maximum value of the response function is reached. The results will serve as a scientific basis for the development of technological parameters of the industrial production of fat systems of the new generation, the conditions and terms of their storage and transportation.

Hexadecenoic Fatty Acid Positional Isomers and De Novo PUFA Synthesis in Colon Cancer Cells.

Palmitic acid metabolism involves delta-9 and delta-6 desaturase enzymes forming palmitoleic acid (9cis-16:1; n-7 series) and sapienic acid (6cis-16:1; n-10 series), respectively. The corresponding biological consequences and lipidomic research on these positional monounsaturated fatty acid (MUFA) isomers are under development. Furthermore, sapienic acid can bring to the de novo synthesis of the n-10 polyunsaturated fatty acid (PUFA) sebaleic acid (5cis,8cis-18:2), but such transformations in cancer cells are not known. The model of Caco-2 cell line was used to monitor sapienic acid supplementation (150 and 300 μM) and provide evidence of the formation of n-10 fatty acids as well as their incorporation at levels of membrane phospholipids and triglycerides. Comparison with palmitoleic and palmitic acids evidenced that lipid remodelling was influenced by the type of fatty acid and positional isomer, with an increase of 8cis-18:1, n-10 PUFA and a decrease of saturated fats in case of sapienic acid. Cholesteryl esters were formed only in cases with sapienic acid. Sapienic acid was the less toxic among the tested fatty acids, showing the highest EC50s and inducing death only in 75% of cells at the highest concentration tested. Two-photon fluorescent microscopy with Laurdan as a fluorescent dye provided information on membrane fluidity, highlighting that sapienic acid increases the distribution of fluid regions, probably connected with the formation of 8cis-18:1 and the n-10 PUFA in cell lipidome. Our results bring evidence for MUFA positional isomers and de novo PUFA synthesis for developing lipidomic analysis and cancer research.

Evaluating the Content and Distribution of Trans Fatty Acid Isomers in Foods Consumed in Japan.

Trans fatty acids (TFA) are considered risk factors for cardiovascular disease. However, detailed information on total content of TFA and TFA isomers and distribution of trans-octadecenoic acid positional isomers in foods consumed in Japan is not available till date. In this study, 250 foods, 169 processed foods and 81 foods derived from ruminant meat or milk, were analyzed. According to the results, most foods contained less than 1.0 g TFA / 100 g food. However, almost all foods containing butter had more than 1.0 g TFA / 100 g food. TFA isomers in foods were classified into two categories, monoene-rich type and polyenerich type. We hypothesized that these differences were attributed to diverse TFA formation mechanisms. Furthermore, we observed that trans-10-18:1 was also the dominant trans-18:1 positional isomer in foods consumed in Japan. These results are valuable for future analysis of the role of TFA in epidemiological studies in Japan.

Basic eluent for rapid and comprehensive analysis of fatty acid isomers using reversed-phase high performance liquid chromatography/Fourier transform mass spectrometry

Comprehensive separation of fatty acids, including various isomers, is very important for chemical analyses associated with detailed physiological function investigations. We found that a basic eluent is effective for realizing clear separation of double-bond regioisomers by reversed-phase high-performance liquid chromatography. We carried out a comprehensive analysis of fatty acids, including double-bond positional isomers, trans-fatty acids, and iso-fatty acids using reversed-phase high-performance liquid chromatography coupled with Fourier transform mass spectrometry (LC/FTMS). Clear separation of these fatty acids was achieved using a C18 column and a basic eluent. A three-pump gradient system using acetone provided rapid elution within 22 min. In a single run, 184 fatty acid molecular species contained in a dietary fish oil supplement were detected by the FTMS full scan. A previously unreported peak was also detected, which was assigned as tetratriacontadecaenoic acid by comparison with the MS2 profiles of fatty acids with known chemical structures. This result demonstrates that the developed method is useful for clarifying the composition of fatty acid molecular species in target samples, providing a promising approach to discover unreported fatty acids.

Screening method for simultaneous detection of elaidic and vaccenic trans fatty acid isomers by capillary zone electrophoresis

A novel screening method for the simultaneous detection of elaidic and vaccenic trans fatty acid isomers by CZE-UV was proposed and applied to brazilian spreadable cheese analysis. Optimized background electrolyte was composed by 10 mmol L−1 heptakis (2, 3, 6-tri-o-methyl)-beta cyclodextrin, 24 mmol L−1 sodium tetraborate buffer solution, 45% methanol and 15% acetonitrile. Sample preparation comprised only a saponification reaction and dilution of sample solution before analysis. The method proved to be simple, environmental friendly and sensitive (LOD calculated for elaidic and vaccenic acid were 0.0163 mmol L−1 and 0.0169 mmol L−1, respectively) and may be used to detect adulteration in dairy products, where the addition of hydrogenated vegetable fat to food is prohibited.

Diverse Odd-Chain Monoenoic Fatty Acids and Novel Non-Methylene-Interrupted Heptadecadienoic Acids in Ovaries of the Limpet Cellana toreuma.

Highly diverse dienoic fatty acids (FA), especially non-methylene-interrupted (NMI) FA, have been recognized in triacylglycerols (TAG) and polar lipids of ovaries of the limpet Cellana toreuma. To gain additional insights into the structural diversity of FA in ovaries, this study aimed to clarify previously undescribed minor monoenoic FA isomers and unidentified minor NMI FA by combined argentation thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) of their 3-pyridylcarbinol derivatives. A total 66 monoenoic FA from C14 to C22, including 12 branched-chain FA, were identified. A surprising finding was a series of 13 heptadecenoic acids with double bonds at either Δ5, Δ6, Δ7, Δ8, Δ9, Δ10, Δ11, Δ12, Δ13, Δ15, or Δ16 positions. Besides previously identified NMI FA, 7,18-nonadecadienoic (19:2Δ7,18), 9,18-nonadecadienoic (19:2Δ9,18), 11,18-nonadecadienoic (19:2Δ11,18), 7,20-heneicosadienoic (21:2Δ7,20), and 11,20-heneicosadienoic (21:2Δ11,20) acids, two novel related NMI FA, 5,16-heptadecadienoic (17:2Δ5,16) and 7,16-heptadecadienoic (17:2Δ7,16) acids, were found in TAG. These findings could provide new insights into clarifying the biological characteristics of marine NMI FA.

Constraints on the Metabolic Activity of Microorganisms in Atacama Surface Soils Inferred from Refractory Biomarkers: Implications for Martian Habitability and Biomarker Detection.

Dryness is one of the main environmental challenges to microbial survival. Understanding the threshold of microbial tolerance to extreme dryness is relevant to better constrain the environmental limits of life on Earth and critically evaluate long-term habitability models of Mars. Biomolecular proxies for microbial adaptation and growth were measured in Mars-like hyperarid surface soils in the Atacama Desert that experience only a few millimeters of precipitation per decade, and in biologically active soils a few hundred kilometers away that experience two- to fivefold more precipitation. Diversity and abundance of lipids and other biomolecules decreased with increasing dryness. Cyclopropane fatty acids (CFAs), which are indicative of adaptive response to environmental stress and growth in bacteria, were only detected in the wetter surface soils. The ratio of trans to cis isomers of an unsaturated fatty acid, another bacterial stress indicator, decreased with increasingly dry conditions. Aspartic acid racemization ratios increased from 0.01 in the wetter soils to 0.1 in the driest soils, which is indicative of racemization rates comparable to de novo biosynthesis over long timescales (∼10,000 years). The content and integrity of stress proteins profiled by immunoassays were additional indicators that biomass in the driest soils is not recycled at significant levels. Together, our results point to minimal or no in situ microbial growth in the driest surface soils of the Atacama, and any metabolic activity is likely to be basal for cellular repair and maintenance only. Our data add to a growing body of evidence that the driest Atacama surface soils represent a threshold for long-term habitability (i.e., growth and reproduction). These results place constraints on the potential for extant life on the surface of Mars, which is 100-1000 times drier than the driest regions in the Atacama. Key Words: Atacama Desert-Dryness-Growth-Habitability-Biomarker-Mars. Astrobiology 18, 955-966.