Individual Fatty Acid Methyl Esters Research Articles

Cell culture models demonstrate that CFTR dysfunction leads to defective fatty acid composition and metabolism

Cystic fibrosis (CF) is associated with fatty acid alterations characterized by low linoleic and docosahexaenoic acid. It is not clear whether these fatty acid alterations are directly linked to cystic fibrosis transmembrane conductance regulator (CFTR) dysfunction or result from nutrient malabsorption. We hypothesized that if fatty acid alterations are a result of CFTR dysfunction, those alterations should be demonstrable in CF cell culture models. Two CF airway epithelial cell lines were used: 16HBE, sense and antisense CFTR cells, and C38/IB3-1 cells. Wild-type (WT) and CF cells were cultured in 10% fetal bovine serum (FBS) or 10% horse serum. Fatty acid levels were analyzed by GC-MS. Culture of both WT and CF cells in FBS resulted in very low linoleic acid levels. When cells were cultured in horse serum containing concentrations of linoleic acid matching those found in human plasma, physiological levels of linoleic acid were obtained and fatty acid alterations characteristic of CF tissues were then evident in CF compared with WT cells. Kinetic studies with radiolabeled linoleic acid demonstrated in CF cells increased conversion to longer and more-desaturated fatty acids such as arachidonic acid. In conclusion, these data demonstrate that CFTR dysfunction is associated with altered fatty acid metabolism in cultured airway epithelial cells.

In-field variation in 2,4-D mineralization in relation to sorption and soil microbial communities

This study was undertaken to assess 2,4-D mineralization in an undulating cultivated field, along a sloping transect (458 m to 442 m above sea level), as a function of soil type, soil microbial communities and the sorption of 2,4-D to soil. The 2,4-D soil sorption coefficient (Kd) ranged from 1.81 to 4.28 L kg−1, the 2,4-D first-order mineralization rate constant (k) ranged from 0.04 to 0.13 day−1 and the total amount of 2,4-D mineralized at 130 days (M130) ranged from 24 to 39%. Both k and M130 were significantly negatively associated (or correlated) with soil organic carbon content (SOC) and Kd. Both k and M130 were significantly associated with two fatty-acid methyl esters (FAME), i17:1 and a18, but not with twenty-two other individual FAME. Imperfectly drained soils (Gleyed Dark Grey Chernozems) in lower-slopes showed significantly lesser 2,4-D mineralization relative to well-drained soils (Orthic Dark Grey Chernozems) in mid- and upper-slopes. Well-drained soils had a greater potential for 2,4-D mineralization because of greater abundance and diversity of the microbial community in these soils. However, the reduced 2,4-D mineralization in imperfectly drained soils was predominantly because of their greater SOC and increased 2,4-D sorption, limiting the bioavailability of 2,4-D for degradation. The wide range of 2,4-D sorption and mineralization in this undulating cultivated field is comparable in magnitude and extent to the variability of 2,4-D sorption and mineralization observed at a regional scale in Manitoba. As such, in-field variations in SOC and the abundance and diversity of microbial communities are determining factors that require greater attention in assessing the risk of movement of 2,4-D by runoff, eroded soil and leaching.

Phenotypic characterization of Escherichia coli through whole-cell fatty acid profiling to investigate host specificity

The objective of the study was to investigate whole-cell fatty acid methyl ester (FAME) profiles of 605 Escherichia coli isolates to determine their host specificity. The isolates were cultured from six possible sources of fecal pollution; 180 isolates from sewage, 85 from dairy cow, 98 from chicken, 76 from swine, 94 from deer, and 72 from waterfowl, mostly geese and ducks. The FAME profiles were presented as the relative masses of 12 FAMEs identified in the isolates and it was found that none of the six hosts carried a “signature” FAME, a FAME that is uniquely associated with a particular host category. However, two-sample t-test analyses indicated that the mean relative masses of seven FAMEs out of the 12 identified showed statistically significant differences (95% confidence interval) between isolates of human and non-human origins. In addition, a linear discriminant function based on mean relative mass variations in individual FAMEs classified the known-source isolates into their respective host categories with a 47.6% average rate of correct classification (ARCC) in a six-way discriminant analysis. The ARCC increased to 61.3% when the individual hosts were pooled into larger categories of human, livestock, and wildlife. The accuracy was 75.5% when isolates of human origin were discriminated against those of non-human origins. Random cluster formation analysis indicated that the library size was sufficient to prevent random grouping among the isolates.

Fatty Acid Content Of The Smoked, Fresh-Water Fish <i>Clairas Gariepinus</i> (<i>Wanka Harwada</i>, Hausa) In Northern Nigeria

Since the healthful n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are underrepresented in the diets of many people who live in the hot semi-arid regions of West Africa, we were interested in knowing the fatty acid content and composition of the oil of Clairas gariepinus ( wanka harwada , Hausa), a dried, fresh-water fish that is consumed widely in northern Nigeria. Dried C. gariepinus , purchased in the central market in Jos, Nigeria was divided into the head, mid-section, and tail sections, vacuum-dried to constant weight, and extracted with chloroform-methanol to provide the lipid fraction. After methylation of the lipid fraction, the individual fatty acid methyl esters were separated and quantified by gas-liquid chromatography. The fatty acid content and fatty acid composition of each of the three sections of the fish were very similar. Overall, fatty acids accounted for 9.43-11.5% of the true dry weight of C. gariepinus . The amounts of EPA and DHA were relatively low, 1.14 and 3.78 mg/g dry weight, respectively. The arachidonic acid, linoleic acid and α-linoleic acid contents were 4.52, 9.00, and 3.76 mg/g dry weight, respectively. Compared to marine fish such as salmon and herring that are rich sources of n-3 polyunsaturated fatty acids, C. gariepinus appears to be unsuitable as a source of healthful quantities of EPA or DHA. Highland Medical Research Journal Vol.2(1) 2004: 8-13

Optimization of a Supercritical Fluid Extraction/Reaction Methodology for the Analysis of Castor Oil Using Experimental Design

The aim of this work was to optimize a supercritical fluid extraction (SFE)/enzymatic reaction process for the determination of the fatty acid composition of castor seeds. A lipase from Candida antarctica (Novozyme 435) was used to catalyze the methanolysis reaction in supercritical carbon dioxide (SC-CO(2)). A Box-Behnken statistical design was used to evaluate effects of various values of pressure (200-400 bar), temperature (40-80 degrees C), methanol concentration (1-5 vol %), and water concentration (0.02-0.18 vol %) on the yield of methylated castor oil. Response surfaces were plotted, and these together with results from some additional experiments produced optimal extraction/reaction conditions for SC-CO(2) at 300 bar and 80 degrees C, with 7 vol % methanol and 0.02 vol % water. These conditions were used for the determination of the castor oil content expressed as fatty acid methyl esters (FAMEs) in castor seeds. The results obtained were similar to those obtained using conventional methodology based on solvent extraction followed by chemical transmethylation. It was concluded that the methodology developed could be used for the determination of castor oil content as well as composition of individual FAMEs in castor seeds.

Mathematical method for the prediction of retention times of fatty acid methyl esters in temperature-programmed capillary gas chromatography.

An accurate method for identification of fatty acids in complex mixtures analyzed by temperature-programmed capillary gas chromatography is described. The method is based on a mathematical approach using regression curves obtained by plotting the relative retention times of fatty acid methyl esters (FAMEs) analyzed in isothermal and gradient temperature conditions. The method was applied to a complex biological sample (human milk), and it was possible to identify 64 fatty acids, including branched-chain and other fatty acids for which reference standards were not readily available. The identities of the majority of the peaks were confirmed by mass spectrometry. The relative residuals and the relative differences between estimated and measured relative retention times of individual FAMEs varied from 0.03 to 3.15% and from 0.0 to 2.9%, respectively. The method is useful for identification of fatty acids in routine analysis.

A Biochemical GC-MS Application for the Organic Chemistry Laboratory: Determination of Fatty Acid Composition of Arabidopsis thaliana Lipids

A biochemical application of GC-MS in which students determine the qualitative and quantitative lipid composition of plant leaf samples is described. There are four facets of this project: (i) synthesis and characterization of individual fatty acid methyl esters (FAMEs) as standards for GC-MS analysis, (ii) isolation of the fatty acids of Arabidopsis thaliana leaves, both wild type and mutants, as FAMEs, (iii) GC-MS analysis of the Arabidopsis leaf extracts for fatty acid composition, and (iv) comparison of the class results with the literature data for both wild type and the four mutants and with a biochemical model of two pathways for lipid synthesis in Arabidopsis leaves. Because this experimental paradigm links organic synthesis and spectral characterization by IR and NMR, both 1H and 13C, with separation and identification via GC-MS analysis, all of the key areas of laboratory procedure are encompassed in this single project. The experimental design permits a myriad of hypothesis-testing variations. Plants can be grown at different temperatures and for different lengths of time to determine if and how fatty acid composition varies. Different types of plant leaves can be examined to ascertain if each has a unique fatty acid fingerprint.

Determination of Lipids in Infant Formula Powder by Direct Extraction Methylation of Lipids and Fatty Acid Methyl Esters (FAME) Analysis by Gas Chromatography

Fatty acid methyl esters (FAMEs) of pure triglyceride standards, oils, and fat from dry matrixes were formed by transesterification using sodium methoxide in methanol-hexane. FAMEs were produced by direct addition of sodium methoxide-hexane to samples and heating to simultaneously extract and transesterify acyl lipids. FAMEs were quantitated by capillary gas chromatography (GC) over a fatty acid concentration range of 0 to 1.7 mg/mL (r > or = 0.9997). Total fat was calculated as the sum of individual fatty acids expressed as triglyceride equivalents, in accordance with nutrition labeling guidelines. Saturated, polyunsaturated, and monounsaturated fats were calculated as sums of individual free fatty acids. Absolute recoveries determined from individual fatty acids in test samples ranged from 69.7 to 106%. Recoveries (relative to the C13:0 internal standard) for individual fatty acids in test samples ranged from 95 to 106%. Reproducibility was constant at each fatty acid level in the reaction mixture (n = 5, coefficient of variation [CV] < 2%). Absolute recovery determined from the sum of total fatty acids in standard reference material (SRM) 1846 (powdered infant formula) was 96.4%. Analysis of SRM 1846 gave results that agreed closely with the certified fat and fatty acid values. Analysis of commercial infant formula gave results that were comparable to those obtained with AOAC Method 996.01. The direct extraction methylation procedure is rapid, and the transesterification of acyl lipids to form FAMEs is complete within 15 min. Classical saponification and refluxing are not required. This method provides FAMEs free of interferences and easily quantitated by GC or confirmed by GC/mass spectrometry (MS). Unambiguous MS identification of individual FAMEs derived from pure standards, SRM 1846, and powdered infant formula product was obtained.

Influence of gas chromatographic parameters on measurement of 13C/ 12C isotope ratios by gas-liquid chromatography-combustion isotope ratio mass spectrometry. I

A potential influence of gas chromatographic parameters on measured 13C/ 12C-isotope ratios of saturated fatty acid methyl esters in gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) has been studied. A dependence of measured isotope ratios on temperature gradients was observed and differences in measured δ 13C-values for individual fatty acid methyl esters varied by 0.5 to 3‰. Possible reasons for this isotopic fractionation and its implications for 13C natural abundance work are discussed.

THE EFFECT OF DIETARY POULTRY OFFAL HYDROLYSATE ON THE FATTY ACID COMPOSITION AND MEAT QUALITY OF PORK

Seventy-two feeder pigs, with a mean weight of 24.6 kg, were randomly allotted in groups of three to four dietary treatments to determine the effect of feeding poultry offal hydrolysate (POH) on fatty acid composition and meat quality. The four dietary treatments were: 0% POH (control), 5% POH, 10% POH and 15% POH on a dry matter basis. At slaughter (96.8 kg), the right loins from 60 pigs were retained for fatty acid analysis and meat quality evaluation. The longissimus dorsi muscle was dissected from each loin; 200 g were stored in an atmosphere of nitrogen and frozen for fatty acid analysis and 500 g were frozen for meat quality evaluation. Fat was extracted and methylated for fatty acid analysis. Separation and identification of individual fatty acid methyl esters was performed using gas chromatography. Sensory meat evaluation (pork flavour, off-flavour, tenderness and juiciness) was performed by 10 trained panelists. Warner-Bratzler shear evaluation and free moisture analyses were performed. The fatty acids in pork appear to exhibit a sensitive response to changes in dietary fat. Linear trends for fatty acids in the pork were, for the most part, opposite to trends in the diets. Inclusion of POH resulted in an increase in the total polyunsaturates present in the pork. There was no effect (P &gt; 0.05) due to dietary treatment on flavour, tenderness or juiciness of the pork. No significant differences were found among the Warner-Bratzler shear measurements or free moisture determinations. Changes in fatty acid profile of pork do not appear to affect eating quality when POH is included in the diet at levels of up to 15% DM. Key words: Poultry offal, pork, fatty acid, meat quality

Gas liquid chromatography analysis of the fatty acid composition of fats and oils: A total system for high accuracy

AbstractThe generally accepted approach to the analysis of fatty acid methyl esters (FAME) by gas liquid chromatography (GLC) is to analyze a standard mixture of known composition and to determine empirical correction factors for individual FAME. These correction factors, which are a composite of the theoretical flame ionization detector (FID) relative response factors and an empirical factor to correct for any system errors that may be present, then are used to correct the raw peak areas of the individual FAME of the sample undergoing analysis. It is proposed that this approach is fundamentally unsound as a means of generating consistently accurate results. Rather, it has been proven that theoretically calculated FID relative response factors are valid, both for the saturated and unsaturated FAME commonly encountered in edible oils, and that these should be used as the only response factors for the correction of raw peak areas. Thus, the proper approach to the generation of highly accurate results is to optimize both equipment and operator technique so that a correct answer is obtained for a primary standard when these theoretical factors are used, rather than to introduce an empirical correction factor other than the theoretical response factor to take account of faulty practice. Eight facets of equipment operation or operator technique have been identified which must be addressed to optimize accuracy.

A simple method for estimation of cetane index of vegetable oil methyl esters

AbstractThis article illustrates a simple method for estimation of cetane indexes of vegetable oil methyl esters from their saponification and iodine numbers. The range of the calculated values covers all the cetane numbers of vegetable oil methyl esters determined experimentally. when it was applied to individual fatty acid methyl esters from C8 to C24, a straight line parallel to that of Klopfenstein was obtained.