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Metherel AH, Bazinet RP. Updates to the n-3 polyunsaturated fatty acid biosynthesis pathway: DHA synthesis rates, tetracosahexaenoic acid and (minimal) retroconversion. Prog Lipid Res 2019; 76:101008. [PMID: 31626820 DOI: 10.1016/j.plipres.2019.101008] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 09/26/2019] [Accepted: 10/02/2019] [Indexed: 12/14/2022]
Abstract
N-3 polyunsaturated fatty acids (PUFA) and the numerous families of lipid mediators derived from them collectively regulate numerous biological processes. The mechanisms by which n-3 PUFA regulate biological processes begins with an understanding of the n-3 biosynthetic pathway that starts with alpha-linolenic acid (18:3n-3) and is commonly thought to end with the production of docosahexaenoic acid (DHA, 22:6n-3). However, our understanding of this pathway is not as complete as previously believed. In the current review we provide a background of the evidence supporting the pathway as currently understood and provide updates from recent studies challenging three central dogma of n-3 PUFA metabolism. By building on nearly three decades of research primarily in cell culture and oral dosing studies, recent evidence presented focuses on in vivo kinetic modelling and compound-specific isotope abundance studies in rodents and humans that have been instrumental in expanding our knowledge of the pathway. Specifically, we highlight three main updates to the n-3 PUFA biosynthesis pathway: (1) DHA synthesis rates cannot be as low as previously believed, (2) DHA is both a product and a precursor to tetracosahexaenoic acid (24:6n-3) and (3) increases in EPA in response to DHA supplementation are not the result of increased retroconversion.
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Affiliation(s)
- Adam H Metherel
- Department of Nutritional Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada.
| | - Richard P Bazinet
- Department of Nutritional Sciences, University of Toronto, Toronto, ON M5S 1A8, Canada
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2
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Lin YH, Hibbeln JR, Domenichiello AF, Ramsden CE, Salem NM, Chen CT, Jin H, Courville AB, Majchrzak-Hong SF, Rapoport SI, Bazinet RP, Miller BV. Quantitation of Human Whole-Body Synthesis-Secretion Rates of Docosahexaenoic Acid and Eicosapentaenoate Acid from Circulating Unesterified α-Linolenic Acid at Steady State. Lipids 2018; 53:547-558. [PMID: 30074625 PMCID: PMC6105524 DOI: 10.1002/lipd.12055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Revised: 06/08/2018] [Accepted: 06/08/2018] [Indexed: 12/27/2022]
Abstract
The rate at which dietary α-linolenic acid (ALA) is desaturated and elongated to its longer-chain n-3 polyunsaturated fatty acid (PUFA) in humans is not agreed upon. In this study, we applied a methodology developed using rodents to investigate the whole-body, presumably hepatic, synthesis-secretion rates of esterified n-3 PUFA from circulating unesterified ALA in 2 healthy overweight women after 10 weeks of low-linoleate diet exposure. During continuous iv infusion of d5-ALA, 17 arterial blood samples were collected from each subject at -10, 0, 10, 20, 40, 60, 80, 100, 120, 150, 180, and 210 min, and at 4, 5, 6, 7, and 8 h after beginning infusion. Plasma esterified d5-n-3 PUFA concentrations were plotted against the infusion time and fit to a sigmoidal curve using nonlinear regression. These curves were used to estimate kinetic parameters using a kinetic analysis developed using rodents. Calculated synthesis-secretion rates of esterified eicosapentaenoate, n-3 docosapentaenoate, docosahexaenoic acid, tetracosapentaenate, and tetracosahexaenoate from circulating unesterified ALA were 2.1 and 2.7; 1.7 and 5.3; 0.47 and 0.27; 0.30 and 0.30; and 0.32 and 0.27 mg/day for subjects S01 and S02, respectively. This study provides new estimates of whole-body synthesis-secretion rates of esterified longer-chain n-3 PUFA from circulating unesterified ALA in human subjects. This method now can be extended to study factors that regulate human whole-body PUFA synthesis-secretion in health and disease.
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Affiliation(s)
- Yu-Hong Lin
- Section of Nutritional Neuroscience, LMBB, DICBR, NIAAA, NIH, U.S.A
| | | | | | - Christopher E. Ramsden
- Lipid Mediator, Inflammation and Pain Unit, Laboratory of Clinical Investigation, NIA, NIH
- DICBR, NIAAA, NIH
- School of Agriculture, Food and Wine, University of Adelaide, Australia
| | | | - Chuck T Chen
- Section of Nutritional Neuroscience, LMBB, DICBR, NIAAA, NIH, U.S.A
| | - Haksong Jin
- Pharmacy Department, NIH Clinical Center, NIH
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Metherel AH, Domenichiello AF, Kitson AP, Lin YH, Bazinet RP. Serum n-3 Tetracosapentaenoic Acid and Tetracosahexaenoic Acid Increase Following Higher Dietary α-Linolenic Acid but not Docosahexaenoic Acid. Lipids 2016; 52:167-172. [DOI: 10.1007/s11745-016-4223-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/09/2016] [Indexed: 12/13/2022]
Affiliation(s)
- Adam H. Metherel
- ; Department of Nutritional Sciences, Faculty of Medicine; University of Toronto; 150 College St., Room 307, Fitzgerald Building Toronto ON M5S 3E2 Canada
| | - Anthony F. Domenichiello
- ; Department of Nutritional Sciences, Faculty of Medicine; University of Toronto; 150 College St., Room 307, Fitzgerald Building Toronto ON M5S 3E2 Canada
| | - Alex P. Kitson
- ; Department of Nutritional Sciences, Faculty of Medicine; University of Toronto; 150 College St., Room 307, Fitzgerald Building Toronto ON M5S 3E2 Canada
| | - Yu-Hong Lin
- ; Section of Nutritional Neurosciences, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism; National Institutes of Health; Bethesda MD USA
| | - Richard P. Bazinet
- ; Department of Nutritional Sciences, Faculty of Medicine; University of Toronto; 150 College St., Room 307, Fitzgerald Building Toronto ON M5S 3E2 Canada
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A Simple Method for Measuring Carbon-13 Fatty Acid Enrichment in the Major Lipid Classes of Microalgae Using GC-MS. Metabolites 2016; 6:metabo6040042. [PMID: 27845718 PMCID: PMC5192448 DOI: 10.3390/metabo6040042] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Revised: 10/29/2016] [Accepted: 11/07/2016] [Indexed: 12/14/2022] Open
Abstract
A simple method for tracing carbon fixation and lipid synthesis in microalgae was developed using a combination of solid-phase extraction (SPE) and negative ion chemical ionisation gas chromatography mass spectrometry (NCI-GC-MS). NCI-GC-MS is an extremely sensitive technique that can produce an unfragmented molecular ion making this technique particularly useful for stable isotope enrichment studies. Derivatisation of fatty acids using pentafluorobenzyl bromide (PFBBr) allows the coupling of the high separation efficiency of GC and the measurement of unfragmented molecular ions for each of the fatty acids by single quadrupole MS. The key is that isotope spectra can be measured without interference from co-eluting fatty acids or other molecules. Pre-fractionation of lipid extracts by SPE allows the measurement of 13C isotope incorporation into the three main lipid classes (phospholipids, glycolipids, neutral lipids) in microalgae thus allowing the study of complex lipid biochemistry using relatively straightforward analytical technology. The high selectivity of GC is necessary as it allows the collection of mass spectra for individual fatty acids, including cis/trans isomers, of the PFB-derivatised fatty acids. The combination of solid-phase extraction and GC-MS enables the accurate determination of 13C incorporation into each lipid pool. Three solvent extraction protocols that are commonly used in lipidomics were also evaluated and are described here with regard to extraction efficiencies for lipid analysis in microalgae.
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Lin YH, Brown JA, DiMartino C, Dahms I, Salem N, Hibbeln JR. Differences in long chain polyunsaturates composition and metabolism in male and female rats. Prostaglandins Leukot Essent Fatty Acids 2016; 113:19-27. [PMID: 27720036 PMCID: PMC5081227 DOI: 10.1016/j.plefa.2016.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/16/2016] [Indexed: 01/08/2023]
Abstract
Human studies and some animal work have shown more docosahexaenoic acid (DHA) and arachidonic acid (ARA) was accumulated or converted from precursors in females compared to males. This study explored in-depth the effect of gender on fatty acid composition and polyunsaturated fatty acid metabolism in rats fed one of two well-defined diets containing 10% total fat. One diet contained 15% of linoleic acid (LA) and 3% of α-linolenic acid (ALA) of the total fatty acids (LA+ALA diet), while the other diet contained 15% LA and 0.05% ALA (LA diet). At the age of 20 weeks, all animals were orally administered a single dose of a mixture of deuterium-labeled LA and ALA. Caudal venous blood was then drawn at 0, 2, 4, 8, 12, 24, 48, 96 and 168h. The concentrations of the deuterated precursors and their metabolites in plasma total lipids were quantified by GC/MS negative chemical ionization. Endogenous fatty acids were quantified by GC/FID analysis. When expressed as the percentage of oral dosage, female rats accumulated more precursors and more products, deuterated DHA and deuterated n-6 docosapentaenoic acid (2H5-DPAn-6), in plasma than did male rats in both the LA+ALA diet and the LA diet. For the endogenous non-labeled PUFA, greater concentrations of DHA and DPAn-6 were similarly observed in female rats compared to males within each diet. A lower concentration of non-labeled ARA was observed only in female rats fed the LA+ALA diet. In summary, greater endogenous and exogenous DHA and DPAn-6 was observed in female rat plasma and this was independent of dietary ALA status.
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Affiliation(s)
- Yu-Hong Lin
- Section of Nutritional Neuroscience, LMBB, NIAAA, NIH, Bethesda, MD, United States.
| | - James A Brown
- Section of Nutritional Neuroscience, LMBB, NIAAA, NIH, Bethesda, MD, United States
| | - Carmine DiMartino
- Section of Nutritional Neuroscience, LMBB, NIAAA, NIH, Bethesda, MD, United States
| | - Irina Dahms
- Nutritional Lipids, DSM Nutritional Products, LLC, Columbia, MD, United States
| | - Norman Salem
- Nutritional Lipids, DSM Nutritional Products, LLC, Columbia, MD, United States
| | - Joseph R Hibbeln
- Section of Nutritional Neuroscience, LMBB, NIAAA, NIH, Bethesda, MD, United States
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Allen DK, Bates PD, Tjellström H. Tracking the metabolic pulse of plant lipid production with isotopic labeling and flux analyses: Past, present and future. Prog Lipid Res 2015; 58:97-120. [PMID: 25773881 DOI: 10.1016/j.plipres.2015.02.002] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 01/30/2015] [Accepted: 02/11/2015] [Indexed: 11/25/2022]
Abstract
Metabolism is comprised of networks of chemical transformations, organized into integrated biochemical pathways that are the basis of cellular operation, and function to sustain life. Metabolism, and thus life, is not static. The rate of metabolites transitioning through biochemical pathways (i.e., flux) determines cellular phenotypes, and is constantly changing in response to genetic or environmental perturbations. Each change evokes a response in metabolic pathway flow, and the quantification of fluxes under varied conditions helps to elucidate major and minor routes, and regulatory aspects of metabolism. To measure fluxes requires experimental methods that assess the movements and transformations of metabolites without creating artifacts. Isotopic labeling fills this role and is a long-standing experimental approach to identify pathways and quantify their metabolic relevance in different tissues or under different conditions. The application of labeling techniques to plant science is however far from reaching it potential. In light of advances in genetics and molecular biology that provide a means to alter metabolism, and given recent improvements in instrumentation, computational tools and available isotopes, the use of isotopic labeling to probe metabolism is becoming more and more powerful. We review the principal analytical methods for isotopic labeling with a focus on seminal studies of pathways and fluxes in lipid metabolism and carbon partitioning through central metabolism. Central carbon metabolic steps are directly linked to lipid production by serving to generate the precursors for fatty acid biosynthesis and lipid assembly. Additionally some of the ideas for labeling techniques that may be most applicable for lipid metabolism in the future were originally developed to investigate other aspects of central metabolism. We conclude by describing recent advances that will play an important future role in quantifying flux and metabolic operation in plant tissues.
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Affiliation(s)
- Doug K Allen
- United States Department of Agriculture, Agricultural Research Service, 975 North Warson Road, St. Louis, MO 63132, United States; Donald Danforth Plant Science Center, 975 North Warson Road, St. Louis, MO 63132, United States.
| | - Philip D Bates
- Department of Chemistry and Biochemistry, University of Southern Mississippi, Hattiesburg, MS 39406, United States
| | - Henrik Tjellström
- Department of Plant Biology, Michigan State University, East Lansing, MI 48824, United States; Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI 48824, United States
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Application of stable isotopes to investigate the metabolism of fatty acids, glycerophospholipid and sphingolipid species. Prog Lipid Res 2014; 54:14-31. [PMID: 24462586 DOI: 10.1016/j.plipres.2014.01.002] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2013] [Revised: 12/30/2013] [Accepted: 01/07/2014] [Indexed: 11/22/2022]
Abstract
Nature provides an enormous diversity of lipid molecules that originate from various pathways. To gain insight into the metabolism and dynamics of lipid species, the application of stable isotope-labeled tracers combined with mass spectrometric analysis represents a perfect tool. This review provides an overview of strategies to track fatty acid, glycerophospholipid, and sphingolipid metabolism. In particular, the selection of stable isotope-labeled precursors and their mass spectrometric analysis is discussed. Furthermore, examples of metabolic studies that were performed in cell culture, animal and clinical experiments are presented.
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Xu W, Zhang L, Huang Y, Yang Q, Xiao H, Zhang D. Urinary Fatty Acid Composition and Biomarkers Discovery for Type 2 Diabetic Patients Based on Ultra-Performance Liquid Chromatography-Quadrupole/Time of Flight Mass Spectrometry and Multivariate Statistical Analysis. ANAL LETT 2012. [DOI: 10.1080/00032719.2012.702180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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9
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Landry F, Chan CC, Huang Z, Leclair G, Li CS, Oballa R, Zhang L, Bateman K. Plasma-based approach to measure target engagement for liver-targeting stearoyl-CoA desaturase 1 inhibitors. J Lipid Res 2011; 52:1494-9. [PMID: 21642745 DOI: 10.1194/jlr.m013177] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A positive correlation between stearoyl-CoA desaturase (SCD)1 expression and metabolic diseases has been reported in rodents and humans. These findings indicate that SCD1 is a promising therapeutic target for the chronic treatment of diabetes and dyslipidemia. The SCD1 enzyme is expressed at high levels in several human tissues and is required for the biosynthesis of monounsaturated fatty acids, which are involved in many biological processes. Liver-targeted SCD inhibitors were designed to pharmacologically manipulate SCD1 activity in the liver to avoid adverse events due to systemic inhibition. This article describes the development of a plasma-based SCD assay to assess the level of SCD inhibition, which is defined in this article as target engagement. Essentially, animals are dosed with an exogenous deuterated tracer (d7-stearic acid) as substrate, and the converted d7-oleic acid product is measured to monitor SCD1 inhibition. This study reveals that this plasma-based assay correlates with liver SCD1 inhibition and can thus have clinical utility.
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Trufelli H, Famiglini G, Termopoli V, Cappiello A. Profiling of non-esterified fatty acids in human plasma using liquid chromatography-electron ionization mass spectrometry. Anal Bioanal Chem 2011; 400:2933-41. [DOI: 10.1007/s00216-011-4955-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 03/22/2011] [Accepted: 03/23/2011] [Indexed: 12/01/2022]
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Persson XMT, Blachnio-Zabielska AU, Jensen MD. Rapid measurement of plasma free fatty acid concentration and isotopic enrichment using LC/MS. J Lipid Res 2010; 51:2761-5. [PMID: 20526002 DOI: 10.1194/jlr.m008011] [Citation(s) in RCA: 99] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Measurements of plasma free fatty acids (FFA) concentration and isotopic enrichment are commonly used to evaluate FFA metabolism. Until now, gas chromatography-combustion-isotope ratio mass spectrometry (GC/C/IRMS) was the best method to measure isotopic enrichment in the methyl derivatives of (13)C-labeled fatty acids. Although IRMS is excellent for analyzing enrichment, it requires time-consuming derivatization steps and is not optimal for measuring FFA concentrations. We developed a new, rapid, and reliable method for simultaneous quantification of (13)C-labeled fatty acids in plasma using high-performance liquid chromatography-mass spectrometry (HPLC/MS). This method involves a very quick Dole extraction procedure and direct injection of the samples on the HPLC system. After chromatographic separation, the samples are directed to the mass spectrometer for electrospray ionization (ESI) and analysis in the negative mode using single ion monitoring. By employing equipment with two columns connected parallel to a mass spectrometer, we can double the throughput to the mass spectrometer, reducing the analysis time per sample to 5 min. Palmitate flux measured using this approach agreed well with the GC/C/IRMS method. This HPLC/MS method provides accurate and precise measures of FFA concentration and enrichment.
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12
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Godin JP, Ross AB, Rezzi S, Poussin C, Martin FP, Fuerholz A, Cléroux M, Mermoud AF, Tornier L, Arce Vera F, Pouteau E, Ramadan Z, Kochhar S, Fay LB. Isotopomics: A Top-Down Systems Biology Approach for Understanding Dynamic Metabolism in Rats Using [1,2-13C2] Acetate. Anal Chem 2009; 82:646-53. [DOI: 10.1021/ac902086g] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
| | - Alastair B. Ross
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Serge Rezzi
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Carine Poussin
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | | | - Andreas Fuerholz
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Marilyn Cléroux
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | | | - Lionel Tornier
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Francia Arce Vera
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Etienne Pouteau
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Ziad Ramadan
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
| | - Sunil Kochhar
- Nestlé Research Centre, Vers-Chez-les-Blanc, 1000 Lausanne 26, Switzerland
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Masood MA, Salem N. High-throughput analysis of plasma fatty acid methyl esters employing robotic transesterification and fast gas chromatography. Lipids 2007; 43:171-80. [PMID: 18084789 DOI: 10.1007/s11745-007-3130-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2007] [Accepted: 10/22/2007] [Indexed: 10/22/2022]
Abstract
Fatty acid analysis is an important research tool, and indices derived from essential fatty acid contents serve as useful biomarkers related to cardiovascular and other chronic disease risk. Both clinical and basic studies of essential fatty acid composition are becoming ever larger in magnitude leading to delays while the rather laborious lipid analyses are performed. A robotic transesterification procedure has been developed for high-throughput analysis of plasma fatty acid methyl esters. In this approach, robots perform most steps including plasma and reagent transfer, transesterification reaction via heating at 80 degrees C in open tubes with multiple reagent additions, followed by two-phase extraction and transfer of lipid extracts to GC vials. The vials are then placed directly onto a GC autosampler carousel for robotic sample injection. An improved fast GC method is presented in which the peaks of interest are eluted within 6 min. This method is readily scalable to prepare and analyze 200 samples per day (1,000 samples per week) so that large clinical trials can be accommodated.
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Affiliation(s)
- M Athar Masood
- Laboratory of Membrane Biochemistry and Biophysics, National Institutes on Alcohol Abuse and Alcoholism, National Institutes of Health, Rockville, MD, USA.
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14
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Gagné S, Crane S, Huang Z, Li CS, Bateman KP, Lévesque JF. Rapid measurement of deuterium-labeled long-chain fatty acids in plasma by HPLC-ESI-MS. J Lipid Res 2007; 48:252-9. [PMID: 17021362 DOI: 10.1194/jlr.d600037-jlr200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Imbalanced fatty acid metabolism contributes significantly to the increased incidence of metabolic disorders. Isotope-labeled fatty acids (2H, 13C) provide efficient means to trace fatty acid metabolism in vivo. This study reports a new and rapid method for the quantification of deuterium-labeled fatty acids in plasma by HPLC-MS. The sample preparation protocol developed required only hydrolysis, neutralization, and quenching steps followed by high-performance liquid chromatography-electrospray ionization-mass spectrometry analysis in negative ion mode using single ion monitoring. Deuterium-labeled stearic acid (d7-C18:0) was synthesized to reduce matrix interference observed with d5 analog, which improved the limit of detection (LOD) significantly, depending on the products analyzed. Linearity > 0.999 between the LOD (100 nM) and 30 microM, accuracy > 90%, precision > 88%, and adequate recovery in the dynamic range were obtained for d7-C18:0 and d7-oleic acid (C18:1). Upon oral dosing of d7-C18:0 in rats, the parent compound and its desaturation and beta-oxidation products, d7-C18:1 and d7-C16:0, were circulating with a maximal concentration ranging from 0.6 to 2.2 microM, with significant levels of d7-fatty acids detected for up to 72 h.
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Affiliation(s)
- Sébastien Gagné
- Merck Frosst Canada & Co., Medicinal Chemistry Department, Kirkland, Quebec, Canada H9H 3L1.
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15
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Mosley EE, Nudda A, Corato A, Rossi E, Jenkins T, McGuire MA. Differential biohydrogenation and isomerization of [U-13C]Oleic and [1-13C]Oleic acids by mixed ruminal microbes. Lipids 2006; 41:513-7. [PMID: 16933796 DOI: 10.1007/s11745-006-5125-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The additional mass associated with 13C in metabolic tracers may interfere with their metabolism. The comparative isomerization and biohydrogenation of oleic, [1-(13)C]oleic, and [U-13C]oleic acids by mixed ruminal microbes was used to evaluate this effect. The percent of stearic, cis-14 and -15, and trans-9 to -16 18:1 originating from oleic acid was decreased for [U-(13)C]oleic acid compared with [1-(13)C]oleic acid. Conversely, microbial utilization of [U-(13)C]oleic acid resulted in more of the 13C label in cis-9 18:1 compared with [1-(13)C]oleic acid (53.7 vs. 40.1%). The isomerization and biohydrogenation of oleic acid by ruminal microbes is affected by the mass of the labeled tracer.
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Affiliation(s)
- Erin E Mosley
- Department of Animal and Veterinary Science, University of Idaho, Moscow, Idaho 83844-2330, USA
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16
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Lin YH, Salem N. In vivo conversion of 18- and 20-C essential fatty acids in rats using the multiple simultaneous stable isotope method. J Lipid Res 2005; 46:1962-73. [PMID: 15930514 DOI: 10.1194/jlr.m500127-jlr200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An important question for mammalian nutrition is the relative efficiency of C18 versus C20 essential fatty acids (EFAs) for supporting the tissue composition of n-3 and n-6 pathway end products. One specific question is whether C22 EFAs are made available to tissues more effectively by dietary alpha-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) or by dietary eicosapentaenoic acid (20:5n-3) and dihomo-gamma-linolenic acid (20:3n-6). To address this question in a direct manner, four stable isotope compounds were given simultaneously in a novel paradigm. A single oral dose of a mixture of 2H5-18:3n-3, 13C-U-20:5n-3, 13C-U-18:2n-6, and 2H5-20:3n-6 was administered to rats given a defined diet. There was a preferential in vivo conversion of arachidonic acid (20:4n-6) to docosatetraenoic acid (22:4n-6) and of 22:4n-6 to n-6 docosapentaenoic acid (22:5n-6) when the substrates originated from the C18 precursors. However, when the end products docosahexaenoic acid (22:6n-3) or 22:5n-6 were expressed as the total amount in the plasma compartment divided by the dosage, this parameter was 11-fold greater for 20:5n-3 than for 18:3n-3 and 14-fold greater for 20:3n-6 than for 18:2n-6. Thus, on a per dosage basis, the total amounts of n-3 and n-6 end products accreted in plasma were considerably greater for C20 EFA precursors relative to C18.
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Affiliation(s)
- Yu Hong Lin
- Section of Nutritional Neuroscience, Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892-9410, USA
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