Palmitic Acid Esters Research Articles

Palmitic Acid Esters of Hydroxy Stearic Acids Are Hepatic Insulin Sensitizers in Chow and High-Fat Diet (HFD)–Fed Mice

Palmitic Acid esters of Hydroxy Stearic Acids (PAHSAs), bioactive lipids with potent anti-inflammatory and antidiabetic effects, reduce ambient glycemia and improve glucose tolerance and insulin sensitivity in insulin resistant HFD-fed mice. We aimed to determine the mechanisms by which PAHSAs improve insulin sensitivity. We treated chow- and HFD-fed mice with 5-PAHSA (0.1 mg/day) and 9-PAHSA (0.4 mg/day) by SQ osmotic minipumps for 13 weeks. Serum 5-PAHSA levels increased 3.5 fold and 9-PAHSA 2.5 fold in chow-fed mice, while 5-PAHSA levels increased 17 fold and 9-PAHSA 6 fold in HFD-fed mice. PAHSAs had no effect on weight gain or fat mass. We performed hyperinsulinemic euglycemic clamps (2.5 mU/Kg/min insulin infusion rate). PAHSA treatment increased systemic insulin sensitivity in both chow- [glucose infusion rate (GIR): vehicle 13±2 vs. PAHSA 27±4 mg/kg/min] and HFD-fed mice (GIR: vehicle 2±0.5 vs. PAHSA 10±3 mg/kg/min). Endogenous glucose production (EGP) was suppressed 28% by insulin in vehicle-treated mice and 55% in PAHSA-treated mice on chow diet. Remarkably, while insulin failed to suppress EGP in vehicle-treated HFD-fed mice, PAHSA treatment led to a 37% reduction in EGP. PAHSAs also decreased glycemia during a pyruvate tolerance test, indicating that suppression of hepatic gluconeogenesis contributes to the EGP improvement. Mechanistic studies showed that PAHSAs inhibit basal and glucagon-stimulated EGP and reduce cAMP in isolated hepatocytes. This effect is blocked by pertussis toxin indicating it is mediated by Gα/i protein-coupled receptors. PAHSAs also reduce G6pase activity and phosphorylation of CREB in liver. Sum: PAHSAs are systemic insulin sensitizers and augment insulin action on EGP in vivo. In vitro, PAHSAs reduce EGP through a cAMP dependent pathway involving Gα/i protein-coupled receptors. Thus, PAHSAs could be effective antidiabetic agents and the pathways they engage could provide novel drug targets for type 2 diabetes. Disclosure A. Santoro: None. P. Zhou: None. O.D. Peroni: None. I. Syed: None. A.T. Nelson: None. D. Siegel: None. A. Saghatelian: None. B. Kahn: Advisory Panel; Self; Janssen Research & Development. Research Support; Self; Janssen Research & Development. Advisory Panel; Self; Alterna Biotech.

Analysis of Fatty Acid Composition of Crude Seed Oil of Lactuca sativa L. by GC-MS and GC Methods

Lactuca sativa L. (Garden Lettuce), is an edible herb cultivated in Iran and other parts of the world. In Traditional Iranian Pharmacy books, garden lettuce is named Kass Bostani and Hakim Aqili classified it as a Ghazā'ye Dawā'ee (Ghazā means Food; Dawā means Drug). It is said to be soporific, prescribed to cure insomnia and to be useful in thirst and feeling of hotness and burning in the stomach. Seeds of this herb reduce semen, suppress libido and are useful in cases of frequent nocturnal emissions. Fixed oil obtained from seeds of this plant is reputed to have hypnotic and brain moistening properties. In this study we aimed to analyze the fatty acid composition of the crude seed oil of Lactuca sativa L. Methyl esterification of the fatty acids was performed by the method of Ken'ichi Ichihara et al but with a slight modification. Components of the oil were then extracted by n-hexane and analyzed by Gas chromatography-Mass spectroscopy and Gas Chromatography methods. Identified constituents which represented 98.20% of the total elutes were the methyl esters of linoleic (52.38%), oleic (34.42%), palmitic (7.25%), stearic (2.66%), arachidic (1.32%) and myristic (0.17%) acids. Total percentages of methyl esters of the saturated and unsaturated fatty acids identified in our examined oil are 11.4 and 86.80% respectively. In conclusion, seed fat of Lactuca sativa L. like many other plant fats, is rich in unsaturated fatty acids.

Faster Protocol for Endogenous Fatty Acid Esters of Hydroxy Fatty Acid (FAHFA) Measurements.

Fatty acid esters of hydroxy fatty acids (FAHFAs) are a recently discovered class of endogenous lipids with antidiabetic and anti-inflammatory activities. Interest in these lipids is due to their unique biological activites and the observation that insulin-resistant people have lower palmitic acid esters of hydroxystearic acid (PAHSA) levels, suggesting that a FAHFA deficiency may contribute to metabolic disease. Rigorous testing of this hypothesis will require the measurement of many clinical samples; however, current analytical workflows are too slow to enable samples to be analyzed quickly. Here we describe the development of a significantly faster workflow to measure FAHFAs that optimizes the fractionation and chromatography of these lipids. We can measure FAHFAs in 30 min with this new protocol versus 90 min using the older protocol with comparable performance in regioisomer detection and quantitation. We also discovered through this optimization that oleic acid esters of hydroxystearic acids (OAHSAs), another family of FAHFAs, have a much lower background signal than PAHSAs, which makes them easier to measure. Our faster workflow was able to quantify changes in PAHSAs and OAHSAs in mouse tissues and human plasma, highlighting the potential of this protocol for basic and clinical applications.

Nrf2-Mediated Antioxidant Defense and Peroxiredoxin 6 Are Linked to Biosynthesis of Palmitic Acid Ester of 9-Hydroxystearic Acid.

Fatty acid esters of hydroxy fatty acids (FAHFAs) are lipid mediators with promising antidiabetic and anti-inflammatory properties that are formed in white adipose tissue (WAT) via de novo lipogenesis, but their biosynthetic enzymes are unknown. Using a combination of lipidomics in WAT, quantitative trait locus mapping, and correlation analyses in rat BXH/HXB recombinant inbred strains, as well as response to oxidative stress in murine models, we elucidated the potential pathway of biosynthesis of several FAHFAs. Comprehensive analysis of WAT samples identified ∼160 regioisomers, documenting the complexity of this lipid class. The linkage analysis highlighted several members of the nuclear factor, erythroid 2 like 2 (Nrf2)-mediated antioxidant defense system (Prdx6, Mgst1, Mgst3), lipid-handling proteins (Cd36, Scd6, Acnat1, Acnat2, Baat), and the family of flavin containing monooxygenases (Fmo) as the positional candidate genes. Transgenic expression of Nrf2 and deletion of Prdx6 genes resulted in reduction of palmitic acid ester of 9-hydroxystearic acid (9-PAHSA) and 11-PAHSA levels, while oxidative stress induced by an inhibitor of glutathione synthesis increased PAHSA levels nonspecifically. Our results indicate that the synthesis of FAHFAs via carbohydrate-responsive element-binding protein-driven de novo lipogenesis depends on the adaptive antioxidant system and suggest that FAHFAs may link activity of this system with insulin sensitivity in peripheral tissues.

Oxidative stability of margarine enriched with different structures of β -sitosteryl esters during storage

Abstract Oxidations of margarine incorporated with β-sitosteryl esters of hexanoic (Sito-C6), lauric (Sito-C12), palmitic (Sito-C16) and oleic (Sito-C18:1) acids were evaluated during storage at ambient temperature (25 °C) and at 55 °C for 20 days in comparison with native β-sitosterol. All oxidative indices, including hydroperoxide value (HPV), thiobarbituric acid reactive substances (TBARS), p-Anisidine value (AnV) and 7-keto derivatives, tended to increase with increasing storage time. Overall, losses of sterol esters in margarine during storage at both temperatures fitted a first order kinetic model. Margarine with unsaturated ester oxidized faster (k = 0.0355 day−1, R2 = 0.8126) than those with saturated counterpart and native β-sitosterol, particularly at higher temperature (55 °C). As a consequence, sterol structure and storage temperature were the main factors influencing the oxidative stability of margarine enriched phytosterol esters during storage.

Levels of palmitic acid ester of hydroxystearic acid (PAHSA) are reduced in the breast milk of obese mothers

To achieve optimal development of a newborn, breastfeeding is extensively recommended, but little is known about the role of non-nutritive bioactive milk components. We aimed to characterize the fatty acid esters of hydroxy fatty acids (FAHFAs), namely palmitic acid hydroxystearic acids (PAHSAs)—endogenous lipids with anti-inflammatory and anti-diabetic properties, in human breast milk.Breast milk samples from 30 lean (BMI=19–23) and 23 obese (BMI>30) women were collected 72h postpartum. Adipose tissue and milk samples were harvested from C57BL/6J mice. FAHFA lipid profiles were measured using reverse phase and chiral liquid chromatography-mass spectrometry method.PAHSA regioisomers as well as other FAHFAs were present in both human and murine milk. Unexpectedly, the levels of 5-PAHSA were higher relative to other regioisomers. The separation of both regioisomers and enantiomers of PAHSAs revealed that both R- and S-enantiomers were present in the biological samples, and that the majority of the 5-PAHSA signal is of R configuration. Total PAHSA levels were positively associated with weight gain during pregnancy, and 5-PAHSA as well as total PAHSA levels were significantly lower in the milk of the obese compared to the lean mothers.Our results document for the first time the presence of lipid mediators from the FAHFA family in breast milk, while giving an insight into the stereochemistry of PAHSAs. They also indicate the negative effect of obesity on 5-PAHSA levels. Future studies will be needed to explore the role and mechanism of action of FAHFAs in breast milk.

Amylose-lipid complex as a measure of variations in physical, mechanical and barrier attributes of rice starch- ι -carrageenan biodegradable edible film

Abstract Improvements in the hygroscopic properties of starch based films are important to strengthen their mechanical properties. The effects of different hydrophobic components-butyric acid (BA, C4:0), lauric acid (LA, C12:0), palmitic acid (PA, C16:0), oleic acid (OA, C18:1), stearic acid (SA, C18:0) and sucrose fatty acid ester (FAEs) on the rice starch (RS)-ι-carrageenan (ι-car) composite films were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) in combination with amylose-lipid complexing index (CI) were used to characterise the changes in structure and properties of edible films. The SEM results showed that the surface of films became smoother after the incorporation of fatty acids. Carbon-chain length was a major determinant of CI formation which further influenced the attributes of RS-ι-car films. The addition of FAEs to RS-ι-car improved film thickness, permeability, transparency, tensile properties (TS) and could be used to tailor biodegradable edible films with enhanced properties and future fruit coating applications.

Absence of Carbohydrate Response Element Binding Protein in Adipocytes Causes Systemic Insulin Resistance and Impairs Glucose Transport

Lower adipose-ChREBP and de novo lipogenesis (DNL) are associated with insulin resistance in humans. Here, we generated adipose-specific ChREBP knockout (AdChREBP KO) mice with negligible sucrose-induced DNL in adipose tissue (AT). Chow-fed AdChREBP KO mice are insulin resistant with impaired insulin action in the liver, muscle, andAT and increased AT inflammation. HFD-fed AdChREBP KO mice are also more insulin resistantthan controls. Surprisingly, adipocytes lacking ChREBP display a cell-autonomous reduction in insulin-stimulated glucose transport that is mediated by impaired Glut4 translocation and exocytosis, not lower Glut4 levels. AdChREBP KO mice have lower levels of palmitic acid esters of hydroxy stearic acids (PAHSAs) in serum, and AT. 9-PAHSA supplementation completely rescues their insulin resistance and AT inflammation. 9-PAHSA also normalizes impaired glucose transport and Glut4 exocytosis in ChREBP KO adipocytes. Thus, lossof adipose-ChREBP is sufficient to cause insulin resistance, potentially by regulating AT glucose transport and flux through specific lipogenic pathways.

Formation, characterization and theoretical evaluation of combustion of biodiesel obtained from wax esters of A. Mellifera

The search for alternate and sustainable fuel for internal combustion engines which fulfils around 25% of energy needs has lead the researchers towards biodiesel which can be easily extracted from vegetable oils. Biodiesels can also be extracted from waxes, oligenius species of algae and pyrolysis oils. In the above mentioned materials waxes can be used predominantly because, they are entirely composed of esters of higher chain aliphatic alcohols. In the current study biodiesel from beeswax has been studied for its characteristics with the aid of analytical techniques such as GC-MS and FTIR spectrum. And also the properties of fuel and combustion chemistry of biodiesels have been discussed. The spectrum results have clearly shown the presence of five methyl esters of palmitic acid and oleic acid. Further the biodiesel is found to have density of 880kg/m3 and calorific value of 38.5MJ/kg with the Cetane number of 48. The analysis of the combustion of the fuel gives compromising results proving biodiesels from wax esters will be an excellent alternative to mineral diesel and will find a valuable position in list of materials that can be used for biodiesel formulation.

Stereochemistry of Endogenous Palmitic Acid Ester of 9-Hydroxystearic Acid and Relevance of Absolute Configuration to Regulation.

Lipids have fundamental roles in the structure, energetics, and signaling of cells and organisms. The recent discovery of fatty acid esters of hydroxy fatty acids (FAHFAs), lipids with potent antidiabetic and anti-inflammatory activities, indicates that our understanding of the composition of lipidome and the function of lipids is incomplete. The ability to synthesize and test FAHFAs was critical in elucidating the roles of these lipids, but these studies were performed with racemic mixtures, and the role of stereochemistry remains unexplored. Here, we synthesized the R- and S- palmitic acid ester of 9-hydroxystearic acid (R-9-PAHSA, S-9-PAHSA). Access to highly enantioenriched PAHSAs enabled the development of a liquid chromatography-mass spectrometry (LC-MS) method to separate and quantify R- and S-9-PAHSA, and this approach identified R-9-PAHSA as the predominant stereoisomer that accumulates in adipose tissues from transgenic mice where FAHFAs were first discovered. Furthermore, biochemical analysis of 9-PAHSA biosynthesis and degradation indicate that the enzymes and pathways for PAHSA production are stereospecific, with cell lines favoring the production of R-9-PAHSA and carboxyl ester lipase (CEL), a PAHSA degradative enzyme, selectively hydrolyzing S-9-PAHSA. These studies highlight the role of stereochemistry in the production and degradation of PAHSAs and define the endogenous stereochemistry of 9-PAHSA in adipose tissue. This information will be useful in the identification and characterization of the pathway responsible for PAHSA biosynthesis, and access to enantiopure PAHSAs will elucidate the role of stereochemistry in PAHSA activity and metabolism in vivo.

Vitamin Fortification of Fluid Milk.

Vitamin concentrates with vitamins A and D are used for fortification of fluid milk. Although many of the degradation components of vitamins A and D have an important role in flavor/fragrance applications, they may also be source(s) of off-flavor(s) in vitamin fortified milk due to their heat, oxygen, and the light sensitivity. It is very important for the dairy industry to understand how vitamin concentrates can impact flavor and flavor stability of fluid milk. Currently, little research on vitamin degradation products can be found with respect to flavor contributions. In this review, the history, regulations, processing, and storage stability of vitamins in fluid milk are addressed along with some hypotheses for the role of vitamin A and D fortification on flavor and stability of fluid milk.

Esterification of Mixed Carboxylic-fatty Anhydrides Using Amberlyst-15 as Heterogeneous Catalyst.

The article deals with the use of mixed anhydrides for the synthesis of fatty esters. Both aliphatic and aromatic acids are involved, indicating different behaviors according to the chain length of the aliphatic acid. We describe a novel and efficient method for the synthesis of fatty esters by the esterification reaction of primary, secondary and tertiary alcohols with mixed carboxylic-palmitic anhydrides using resin Amberlyst-15 as heterogeneous acid catalyst. Influence of various reaction parameters such as molar ratio (anhydride/alcohol), catalyst amount, type of alcohol and type of mixed anhydride were studied to optimize the conditions for maximum yield. Among tested anhydrides we quote mainly the 4-chlorobenzoic palmitic anhydride because it was both reactive and selective for the preparation of palmitic acid ester. This anhydride gave a good yield of palmitic ester.

Chemometric profile & antimicrobial activities of leaf extract of Calotropis procera and Calotropis gigantea

Calotropis procera and Calotropis gigantea are medicinal plant having therapeutic value. The leaf extracts of C. procera have been investigated, its pharmacological actions in detail and leaf extracts of C. gigantea were not studied till date. The objective of present work was to find the bioactive constituents present in the ethanolic leaf extract of C. procera and C. gigantea to evaluate their antibacterial and anifungal activities. The major phytochemical groups in C. procera ethanolic leaf extracts were fatty acid ethyl ester (21.36%), palmitic acid ester (10.24%), linoleic acid (7.43%) and amino acid (8.10%) respectively, whereas ethanolic leaf extracts of C. gigantea contain palmitic acid (46.01%), diterpene (26.53%), triterpene (17.39%), linoleic acid (5.13%) as the major phytochemical groups. Ethanol extract of C. procera leaves showed the highest inhibition (11 mm) against Escherichia coli, while ethanolic extract of C. gigantea leaves inhibited Klebsiella (20 mm). These findings will use in new directions in pharmacological investigations.

Physiological and biochemical responses of the green alga Pachycladella chodatii (SAG 2087) to sodicity stress

The effects of various concentrations of different carbon sources (Na2CO3 and NaHCO3) as sodicity stress on growth parameters, CO2 consumption rate, enzyme activity, intracellular lipid content, and fatty acid profiles of Pachycladella chodatii were studied. Generally, the total chlorophyll was increased by increasing the concentrations of Na2CO3 and NaHCO3. The biomass productivity as well consumption rate of carbon dioxide of P. chodatii reached the highest values with increasing concentrations of Na2CO3 and NaHCO3. The soluble protein content of P. chodatii was highest at the lowest Na2CO3 and NaHCO3 concentrations. The addition of different concentrations of Na2CO3 and NaHCO3 in the growth media induces lipoxygenase and superoxide dismutase specific activity. Catalase and total antioxidant enzymes were increased by supplementing the growth media with 60 and 45mgl−1 of Na2CO3 and NaHCO3, respectively. Hydrogenase uptake activity in P. chodatii increased gradually in all treated cultures with the time elapsed recording the maximum activity after 11days of growth especially at 60, 45mgl−1 of Na2CO3 and NaHCO3 respectively. Lipids content was increased at low concentration of Na2CO3 (40 and 15mgl−1) and NaHCO3 (60, 45mgl−1) respectively. Subsequent to algal cultivation in different concentrations of Na2CO3, the cultures were filtered and biodiesel was prepared by direct esterification of dry algal biomass. Methyl esters of palmitic, elaidic and stearic acids represented the major components while myristic, pentadecanoic and 9,12-octadecenoic acids represented a minor component of biodiesel produced from P. chodatii treated with different concentrations of Na2CO3 and NaHCO3.

Optimization of process variables in acid catalysed in situ transesterification of Hevea brasiliensis (rubber tree) seed oil into biodiesel

ABSTRACTIn situ transesterification of Hevea brasiliensis seed oil was done using sulphuric acid as catalyst with the aim of optimizing the process variables for higher yields. Response surface methodology based on Box-Behnken design was used to model the factors-yield relationship. The empirical model obtained shows that reaction time and amount of methanol are the most important variables that influence the process. Irrespective of the reaction temperature and concentration of the acid catalyst employed, biodiesel yields in excess of 80% are obtained only when the in situ transesterification is performed for >200 minutes when the volume of methanol is >9 cm3 per gram of the oilseed. The optimal process condition was discovered to be when the temperature, reaction time, amount of methanol and catalyst concentration are 55.91 °C, 240 minutes, 50.0 cm3, and 0.87 M, respectively. Validation results (93.15 ± 0.25%) are generally in agreement with the predicted value of 93.04%. Results from GC/MS analysis of the biodiesel revealed that the dominant components are methyl esters of linoleic and oleic acids (91%) while methyl esters of palmitic and stearic acids (9%) are the minor components of the biodiesel. Properties of the biodiesel showed that it was in conformity with ASTM D6751 requirement.

Branched Fatty Acid Esters of Hydroxy Fatty Acids (FAHFAs) Protect against Colitis by Regulating Gut Innate and Adaptive Immune Responses

We recently discovered a structurally novel class of endogenous lipids, branched palmitic acid esters of hydroxy stearic acids (PAHSAs), with beneficial metabolic and anti-inflammatory effects. We tested whether PAHSAs protect against colitis, which is a chronic inflammatory disease driven predominantly by defects in the innate mucosal barrier and adaptive immune system. There is an unmet clinical need for safe and well tolerated oral therapeutics with direct anti-inflammatory effects. Wild-type mice were pretreated orally with vehicle or 5-PAHSA (10 mg/kg) and 9-PAHSA (5 mg/kg) once daily for 3 days, followed by 10 days of either 0% or 2% dextran sulfate sodium water with continued vehicle or PAHSA treatment. The colon was collected for histopathology, gene expression, and flow cytometry. Intestinal crypt fractions were prepared for ex vivo bactericidal assays. Bone marrow-derived dendritic cells pretreated with vehicle or PAHSA and splenic CD4+ T cells from syngeneic mice were co-cultured to assess antigen presentation and T cell activation in response to LPS. PAHSA treatment prevented weight loss, improved colitis scores (stool consistency, hematochezia, and mouse appearance), and augmented intestinal crypt Paneth cell bactericidal potency via a mechanism that may involve GPR120. In vitro, PAHSAs attenuated dendritic cell activation and subsequent T cell proliferation and Th1 polarization. The anti-inflammatory effects of PAHSAs in vivo resulted in reduced colonic T cell activation and pro-inflammatory cytokine and chemokine expression. These anti-inflammatory effects appear to be partially GPR120-dependent. We conclude that PAHSA treatment regulates innate and adaptive immune responses to prevent mucosal damage and protect against colitis. Thus, PAHSAs may be a novel treatment for colitis and related inflammation-driven diseases.

Preparation of biodiesel in subcritical methanol catalyzed by acidic dication ionic liquid

The acidic dication ionic liquid C3MS was prepared and then was applied in the preparation of biodiesel from soybean oil or waste cooking oil in subcritical methanol. The effects of the reaction temperature and reaction time on the biodiesel yield were investigated and the chemical components of products were analyzed with GC‐MS. The results showed that the catalyst had exhibited a highly effective catalytic activity and strong stability. The yield of biodiesel from soybean oil under optimum conditions was up to 98% and it could be maintained at 93.7% even if the catalyst had been reused for seven times. Under the same condition, the yields of biodiesel from four kinds of waste cooking oil were more than 92%, and the highest yield could reach up to 97.2%. The results of GC‐MS showed that the main components of products were methyl ester of palmitic acid, oleic acid, linoleic acid, stearic acid and ricinoleic acid, and the total content of fatty acid methyl esters (FAME) was more than 99% (except from LRO). In addition, the content of water, free fatty acid and the degree of unsaturation would slightly lower the yield of biodiesel. In a word, the dication ionic liquids could be regarded as a potential catalyst for the biodiesel preparation. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 571–576, 2017

GLUT4 Expression in Adipocytes Regulates De Novo Lipogenesis and Levels of a Novel Class of Lipids With Antidiabetic and Anti-inflammatory Effects.

Adipose tissue (AT) regulates systemic insulin sensitivity through multiple mechanisms, and alterations in de novo lipogenesis appear to contribute. Mice overexpressing GLUT4 in adipocytes (AG4OX) have elevated AT lipogenesis and enhanced glucose tolerance despite being obese and having elevated circulating fatty acids. Lipidomic analysis of AT identified a structurally unique class of lipids, branched fatty acid esters of hydroxy–fatty acids (FAHFAs), which were elevated in AT and serum of AG4OX mice. Palmitic acid esters of hydroxy–stearic acids (PAHSAs) are among the most upregulated FAHFA families in AG4OX mice. Eight PAHSA isomers are present in mouse and human tissues. PAHSA levels are reduced in insulin resistant people, and levels correlate highly with insulin sensitivity. PAHSAs have beneficial metabolic effects. Treatment of obese mice with PAHSAs lowers glycemia and improves glucose tolerance while stimulating glucagon-like peptide 1 and insulin secretion. PAHSAs also reduce inflammatory cytokine production from immune cells and ameliorate adipose inflammation in obesity. PAHSA isomer concentrations are altered in physiological and pathophysiological conditions in a tissue- and isomer-specific manner. The mechanisms most likely involve changes in PAHSA biosynthesis, degradation, and secretion. The discovery of PAHSAs reveals the existence of previously unknown endogenous lipids and biochemical pathways involved in metabolism and inflammation, two fundamental physiological processes.

A LC-MS-based workflow for measurement of branched fatty acid esters of hydroxy fatty acids.

Branched fatty acid esters of hydroxy fatty acids (FAHFAs) are a recently discovered class of endogenous mammalian lipids with antidiabetic and anti-inflammatory effects. We previously identified 16 different FAHFA families, such as branched palmitic acid esters of hydroxy stearic acids (PAHSAs); each family consists of multiple isomers in which the branched ester is at different positions (e.g., 5- and 9-PAHSA). We anticipate increased need for PAHSA measurements as markers of metabolic and inflammatory health. In this protocol, we provide a detailed description of the extraction of FAHFAs from human or mouse tissues, their enrichment by solid-phase extraction and subsequent analysis by LC-MS. For a sample size of 6-12, the time frame is 2-3 d.

The effect of frying on glycidyl esters content in palm oil

The changes in palm oil, as affected by frying temperature, and content of the glycidyl esters (GEs) were studied. Potato chips were fried intermittently in palm oil, which was heated for 8h daily over five consecutive days. Frying was conducted at three frying temperatures: 150, 165 and 180°C. Thermo-oxidative alterations of the oil were measured by acid and anisidine values, changes in fatty acid composition, total polar components, polar fraction composition and colour components formation. Content of GE was measured by liquid chromatography–mass spectrometry. Results showed that amount of products of hydrolysis, oxidation and polymerization (excluding decrease of degree of unsaturation) increased significantly as a function of frying temperature and time. Between GEs of fatty acids the most abundant were esters of palmitic and oleic acids. With increasing temperature and frying time, the content of GE decreased. The extent of GE decrease was correlated with degree of oil degradation.