A validated method for analyzing polyunsaturated free fatty acids from dried blood spots using LC-MS/MS

Excipient-related impurities in liposome drug products

Liposomes are widely used in the pharmaceutical industry as drug delivery systems to increase the efficacy and reduce the off-target toxicity of active pharmaceutical ingredients (APIs). The liposomes are more complex drug delivery systems than the traditional dosage forms, and phospholipids and cholesterol are the major structural excipients. These two excipients undergo hydrolysis and/or oxidation during liposome preparation and storage, resulting in lipids hydrolyzed products (LHPs) and cholesterol oxidation products (COPs) in the final liposomal formulations. These excipient-related impurities at elevated concentrations may affect liposome stability and exert biological functions. This review focuses on LHPs and COPs, two major categories of excipient-related impurities in the liposomal formulations, and discusses factors affecting their formation, and analytical methods to determine these excipient-related impurities.

Development and validation of a HPLC-MS/MS method for the analysis of fatty acids - in the form of FAME ammonium adducts - in human whole blood and erythrocytes to determine omega-3 index

Recent scientific studies in the field of health and nutrition have unanimously affirmed the importance of consuming the omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), because of their cardioprotective properties. Fatty acid profiling in erythrocyte membranes allows the omega-3 index, which is a recognized indicator of the risk of developing cardiovascular disease, to be calculated. One consequence of the upward trend in healthy lifestyles and longevity is an increase in the number of studies into the omega-3 index, which requires a reliable method for the quantitative analysis of fatty acids. This article describes the development and validation of a sensitive and reproducible liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for the quantitative analysis of 23 fatty acids (in the form of fatty acid methyl esters, FAMEs) in 40 µl of whole blood and erythrocytes. The list of acids includes saturated, omega-9 unsaturated, omega-6 unsaturated and omega-3 unsaturated fatty acids as well as their trans-isomers. The limit of quantitation was 250 ng ml-1 for C12:0, C16:0 and C18:0; and 62.5 ng ml-1 for other FAMEs, including EPA, DHA and trans-isomers of FAME C16:1, C18:1 and C18:2 n-6. Sample preparation for fatty acid (FA) esterification/methylation with boron trifluoride-methanol (BF3) has been optimized. Chromatographic separation has been carried out on a C8 column in gradient mode using a mixture of acetonitrile, isopropanol and water with the addition of 0.1% formic acid and 5 mM ammonium formate. As a result, the problem of separating the cis- and trans-isomers of FAME C16:1, C18:1 and C18:2 n-6 has been solved. The electrospray ionization mass spectrometry (ESI-MS) detection of FAMEs, in the form of ammonium adducts, has been optimized for the first time, which has made the method more sensitive that when the protonated species are used. This method has been applied to 12 samples from healthy subjects that consumed omega-3 supplements and has proven to be a reliable tool for determining the omega-3 index.

Dried blood spots in clinical lipidomics: optimization and recent findings

Dried blood spots (DBS) are being considered as an alternative sampling method of blood collection that can be used in combination with lipidomic and other omic analysis. DBS are successfully used in the clinical context to collect samples for newborn screening for the measurement of specific fatty acid derivatives, such as acylcarnitines, and lipids from whole blood for diagnostic purposes. However, DBS are scarcely used for lipidomic analysis and investigations. Lipidomic studies using DBS are starting to emerge as a powerful method for sampling and storage in clinical lipidomic analysis, but the major research work is being done in the pre- and analytical steps and procedures, and few in clinical applications. This review presents a description of the impact factors and variables that can affect DBS lipidomic analysis, such as the type of DBS card, haematocrit, homogeneity of the blood drop, matrix/chromatographic effects, and the chemical and physical properties of the analyte. Additionally, a brief overview of lipidomic studies using DBS to unveil their application in clinical scenarios is also presented, considering the studies of method development and validation and, to a less extent, for clinical diagnosis using clinical lipidomics. DBS combined with lipidomic approaches proved to be as effective as whole blood samples, achieving high levels of sensitivity and specificity during MS and MS/MS analysis, which could be a useful tool for biomarker identification. Lipidomic profiling using MS/MS platforms enables significant insights into physiological changes, which could be useful in precision medicine.

Green sample pre-treatment technique coupled with UHPLC-MS/MS for the rapid biomonitoring of dietary poly-unsaturated (omega) fatty acids to predict health risks

Polyunsaturated fatty acids (PUFAs) consumption indicates beneficial effects on cardiovascular disease (CVD) and physiological processes in humans. However, the inappropriate ratio of omega-(ω)-PUFA levels in human blood is considered as raising the risk of CVD. Therefore, monitoring dietary ω-FAs in human serum is vital for early diagnosis for individuals to predict CVD risk. This work reports a fast green sample pre-treatment protocol for sensitive and simultaneous monitoring of ω-3-FAs and ω-6-FAs in serum by novel in-syringe-based ultrasonication-assisted alkaline hydrolysis coupled with vortex-induced liquid-liquid microextraction (IS-USAH-VI-LLME) technique connected with UHPLC-MS/MS analysis. Factors affecting extraction recoveries of ten ω-PUFAs by the presented method were well-studied. ω-3 and ω-6 PUFAs demonstrated excellent linearities between the concentrations between 0.1-10,000 ng mL^-1 with good regression coefficients between 0.9910-0.9997. The detection and quantification limits were between 0.05-0.35 and 0.16-1.07 ng mL^-1, demonstrating that the presented method is highly sensitive and versatile. The precision of the technique was <8.2% that deemed acceptable in clinical analysis. Further, the proposed method was applied for ω-PUFAs analysis in human blood samples, and spiked recoveries showed between 80.32-119.34% with <9.82% precision. Results proved that the developed method is green, sensitive, and reliable to simultaneously determine ten ω-PUFAs in human blood samples for clinical diagnosis applications for predicting health hazards.

Artificial Intelligence in Functional Food Ingredient Discovery and Characterisation: A Focus on Bioactive Plant and Food Peptides

Scientific research consistently demonstrates that diseases may be delayed, treated, or even prevented and, thereby, health may be maintained with health-promoting functional food ingredients (FFIs). Consumers are increasingly demanding sound information about food, nutrition, nutrients, and their associated health benefits. Consequently, a nutrition industry is being formed around natural foods and FFIs, the economic growth of which is increasingly driven by consumer decisions. Information technology, in particular artificial intelligence (AI), is primed to vastly expand the pool of characterised and annotated FFIs available to consumers, by systematically discovering and characterising natural, efficacious, and safe bioactive ingredients (bioactives) that address specific health needs. However, FFI-producing companies are lagging in adopting AI technology for their ingredient development pipelines for several reasons, resulting in a lack of efficient means for large-scale and high-throughput molecular and functional ingredient characterisation. The arrival of the AI-led technological revolution allows for the comprehensive characterisation and understanding of the universe of FFI molecules, enabling the mining of the food and natural product space in an unprecedented manner. In turn, this expansion of bioactives dramatically increases the repertoire of FFIs available to the consumer, ultimately resulting in bioactives being specifically developed to target unmet health needs.

Development of a novel analytical method for inflammation and immunity-related metabolites in serum based on liquid chromatography tandem mass spectrometry

Some metabolites have been found to play key roles in inflammation and immunity events that are associated with diseases such as cancer, diabetes and cytokine release syndrome. Characterization upon the inflammation and immunity-related metabolites (IIMs) will be helpful to the assessment of related pathological states. Although these metabolites have been partially reported in previous studies, the methods for specific measurement of them remain lacking. In the present study, a liquid chromatography - mass spectrometry based method was developed for the targeted analyses of 45 IIMs including amino acids, organic acids, phosphatidylcholines (PCs), polyunsaturated fatty acids and hormones selected based on the literature knowledge. Direct extraction with dansyl-chloride in acetonitrile was proved to be the most efficient and time-saving strategy, in which precipitation, extraction and derivatization were integrated. IIMs derivatized for 4 min and quenched for 2 min revealed the most comprehensive abundance. Based on the defined conditions, all the IIMs had a low limit of detection smaller than 1 ng/mL with the linear range greater than three orders of magnitude. The relative standard derivations of intra-day and inter-day precisions were ranged from 2.2% to 13.4% and 1.7% to 19.5%, respectively. The recovery rates and accuracy in low concentration were 98.9% ± 5.6% and 106.7% ± 11.6%, in medium concentration were 97.1% ± 6.8% and 106.9% ± 9.5%, and in high concentration were 98.4% ± 8.9% and 98.1% ± 8.1%, respectively. Matrix effect and stability were ranged from -37.8% to 35.6% and 2.9% to 14.2%, respectively. To show the usefulness of the method, serum IIMs in hepatitis B virus (HBV) infected patients and healthy subjects were determined and compared. Bile acids, lipoxygenase-mediated lipid mediators and non-enzymatic products showed global increases, whereas most of LysoPCs and cyclooxygenase-mediated prostaglandin D2 decreased in HBV serum samples. This study provided a robust approach for the characterization of IIMs.

New Methodologies for Conducting Maternal, Infant, and Child Nutrition Research in the Era of COVID-19

The severe acute respiratory syndrome coronavirus disease 2019 (COVID-19) outbreak rapidly became a worldwide pandemic in early 2020. In Australia, government-mandated restrictions on non-essential face-to-face contact in the healthcare setting have been crucial for limiting opportunities for COVID-19 transmission, but they have severely limited, and even halted, many research activities. Our institute's research practices in the vulnerable populations of pregnant women and young infants needed to adapt in order to continue without exposing participants, or staff, to an increased risk of exposure to COVID-19. Here, we discuss our pre-and-post COVID-19 methods for conducting research regarding nutrition during pregnancy, infancy, and early childhood. We discuss modifications to study methods implemented to avoid face-to-face contact when identifying and recruiting potential participants, gaining informed consent, conducting appointments, and collecting outcome data, and the implications of these changes. The COVID-19 pandemic has required numerous changes to the conduct of research activities, but many of those modifications will be useful in post-COVID-19 research settings.

Next-generation derivatization reagents optimized for enhanced product ion formation in photodissociation-mass spectrometry of fatty acids

Next-generation derivatives for photodissociation-mass spectrometry for fatty acids generating photoproduct yields of up to 97% at 266 nm.

Effect of parenteral lipid emulsion on preterm infant PUFAs and their downstream metabolites

OBJECTIVE

Oxylipins synthesized by oxidation of long-chain polyunsaturated fatty acids (LCPUFAs) are bioactive downstream lipid mediators. The aim of this study was to describe oxylipin levels in preterm infants born 30 to 33 weeks' gestation who were enrolled in a randomized controlled trial in which peripheral parenteral nutrition (P-PN), including lipid emulsion (containing soy, medium chain triglyceride, olive and fish oil), was compared with 10% glucose on growth during the transition to enteral feeds.

METHODS

Of the 92 infants randomized to the P-PN study, the first 72 (P-PN n = 34, control n = 38) had blood taken for fatty acid analyses. P-PN infants received parenteral nutrition including 3% protein, 8% glucose and 17% SMOFlipid® lipid (containing soy, medium chain triglyceride, olive and fish oil), and control infants 10% glucose. Both groups commenced enteral feeds when clinically stable. 32 oxylipins and 5 free fatty acids were screened (using ultra-high-performance liquid chromatography-tandem mass spectrometry), and 5 total LCPUFA were measured (using gas chromatography), on study days 1 (baseline), 2, 4, 7, 14 and 21.

RESULTS

Both total and free LA, ALA and EPA were significantly higher in the P-PN group compared with control over the first week of life. Whereas total AA was significantly lower and free DHA significantly higher over the same time period. All LA, ALA, EPA and four DHA derived oxylipins detected were significantly higher in the P-PN group compared with the control group during the first week of life, with three AA derived oxylipins significantly lower and one significantly higher.

CONCLUSIONS

Parenteral lipid emulsion resulted in a change in total and free fatty acids and related oxylipins with the profiles suggesting increased omega-6 driven inflammation. Further studies to investigate the association between the oxylipin levels and nutrition and to determine whether the oxylipin profiles influence the clinical outcome in preterm infants are warranted.

Effect of omega-3 lcpufa supplementation on maternal fatty acid and oxylipin concentrations during pregnancy

INTRODUCTION

Omega-3 long chain polyunsaturated fatty acids (LCPUFA) have been associated with a reduction in risk for preterm birth. However, there is limited understanding of how fatty acids and their bioactive derivatives (oxylipins) change over the course of pregnancy. Here we document the changes in concentration of fatty acids and oxylipins during pregnancy and how fatty acid status and oxylipin concentrations are affected by supplementation with omega-3 LCPUFA. We also investigate the degree to which fatty acid and oxylipin changes across pregnancy are influenced by baseline omega-3 status.

MATERIALS AND METHODS

We profiled the fatty acids in all lipids in dried blood spots (total blood fatty acids) by gas chromatography and free (unesterified) fatty acids and their associated oxylipins in separate dried blood spot samples by LC-MS-MS collected from a random sample of 1263 women with a singleton pregnancy who participated in the ORIP (Omega-3 fats to Reduce the Incidence of Prematurity) trial. ORIP is a double-blind, randomized controlled trial involving 5544 participants and designed to determine the effect of supplementing the diets of pregnant women with omega-3 LCPUFA on the incidence of early preterm birth. Maternal whole blood finger prick samples were collected at baseline (~14 weeks gestation) and at completion of the study intervention period (34 weeks gestation).

RESULTS

The concentration of most total and free polyunsaturated fatty acids and their associated oxylipins declined over the course of pregnancy. Omega-3 LCPUFA supplementation increased total DHA and 7-HDHA and mitigated the decline in free DHA, 4-HDHA and 14-HDHA. The intervention had minimal or no effect on free EPA, LA, AA and their associated oxylipins. Omega-3 LCPUFA supplementation in women with higher omega-3 status at baseline was associated with a significant increase in 7-HDHA and 4-HDHA between the treatment and control whereas there were no differences between groups in 7-HDHA and 4-HDHA in women with intermediate or lower baseline omega-3 status.

CONCLUSION

Our data suggest a differential response with or without omega-3 supplementation for DHA and DHA-derived oxylipins, which may have an important role to play in modulating pregnancy duration. Further work is needed to understand their role, which may allow us to better tailor omega-3 supplementation for preterm birth prevention.

Gold and silver nanoparticles-based laser desorption/ionization mass spectrometry method for detection and quantification of carboxylic acids

A comparison of ionization efficiency for gold and silver nanoparticles used as an active media of matrix-less laser desorption/ionization (LDI) mass spectrometry (MS) methods was made for carboxylic acids including fatty acids. The matrix-assisted laser desorption/ionization (MALDI)-type targets containing monoisotopic cationic ¹⁰⁹ Ag nanoparticles (¹⁰⁹ AgNPs) and Au nanoparticles (AuNPs) were used for rapid MS measurements of 10 carboxylic acids of different chemical properties. Carboxylic acids were directly quantified in experiments with 10 000-fold concentration change conditions ranging from 1 mg/ml to 100 ng/ml which equates to 1 μg to 100 pg of carboxylic acids per measurement spot.

Polyunsaturated Fatty Acids in Newborn Bloodspots: Associations With Autism Spectrum Disorder and Correlation With Maternal Serum Levels

We conducted a population-based case-control study to examine newborn polyunsaturated fatty acid (PUFA) levels in association with autism spectrum disorder (ASD) and assess PUFA correlation across two time points. ASD cases (n = 200) were identified through the Department of Developmental Services and matched to live-birth population controls (n = 200) on birth month, year (2010-2011), and sex. Nonesterified PUFAs were measured by isotope dilution liquid chromatography-high resolution mass spectrometry from archived newborn dried blood spots and maternal mid-pregnancy serum samples. Crude and adjusted conditional logistic regression models were used to examine the association between neonatal PUFA levels, categorized in quartiles and according to distributional extremes, and ASD. Cubic splines were utilized to examine nonlinear relationships between continuous neonatal PUFAs and ASD. The correlation between neonatal and maternal levels was examined using Pearson correlation coefficients. In adjusted analyses of neonatal PUFA levels, no clear trends emerged, though there was an elevated odds ratio of ASD for the third quartile of linoleic acid, relative to the first (adjusted odds ratio = 2.49, 95% confidence interval: 1.31, 4.70). Cubic spline analysis suggested a nonlinear association between linoleic acid and ASD, though this was not robust to sensitivity analyses. While individual PUFAs were significantly correlated with one another within a given time point, aside from docohexaseanoic acid, PUFAs were not correlated across maternal and neonatal samples. Overall, our findings do not support an association between neonatal PUFA levels and ASD. Future work should confirm and expand these findings by examining associations with phenotypic subgroups and considering PUFAs in other time points. LAY SUMMARY: In this study, we examined whether levels of fats known as polyunsaturated fatty acids, measured in newborns, were related to later child diagnosis of autism spectrum disorder (ASD). Overall, we did not find strong evidence for hypothesized reduction in risk of ASD based on newborn levels of these fats. Future studies in larger samples and considering other time points may be useful to explain whether these fats are important in brain development related to ASD. Autism Res 2020, 13: 1601-1613. © 2020 International Society for Autism Research, Wiley Periodicals, Inc.

Untargeted foodomics strategy using high-resolution mass spectrometry reveals potential indicators for fish freshness

Fish among other food can easily become spoilage. However, the existing literature endeavouring into a holistic investigation of fish metabolome during storage is scarce. There is a need for a powerful tool for more in-depth determinations. The present study is leveraging high-resolution mass spectrometry (HRMS)-based untargeted foodomics in the exploration of potential indicators for fish freshness. Three batches of fish fillets were stored in the refrigerator (+4 °C) for 0, 24, 48, and 72 h. Features were detected via UPLC-Q-Orbitrap HRMS and hereby undergone selection, identification, and verification. Eight sensitive indicators with significant time-dependent responses were yielded. The loss of freshness in fish is manifested in the upregulation of uracil, hypoxanthine, and inosine (involved in nucleotide changes) and α-linolenic acid, docosahexaenoic acid, arachidonic acid, and linoleic acid (involved in lipid hydrolysis) as well as in the downregulation of decanoylcarnitine (involved in fatty acid metabolism). Our work provides a promising approach to assess the quality of fish during storage and gain deeper insights into the metabolic reaction.

Intravenous fat induces changes in PUFA and their bioactive metabolites: Comparison between Japanese and Australian preterm infants

OBJECTIVE

Oxylipins are biologically active signaling molecules that initiate and resolve inflammation; they are synthesized by oxidation of polyunsaturated fatty acids (PUFAs) and reflect PUFA intake and status. The PUFA intake in preterm infants differs between countries because of the type of lipid emulsions used and the PUFA content of breast milk. We compared total blood PUFA, free PUFA and their oxylipin levels in dried whole blood samples from preterm infants born in Australia and Japan.

METHODS

We enrolled 30 and 14 preterm infants born less than 31 weeks' gestation, from Adelaide and Japan respectively. Blood samples were obtained from cord blood, and on postnatal days 4, 7, 14 and 28. Total PUFAs were measured using gas chromatography, while free fatty acids and oxylipins were screened using ultra high-performance liquid chromatography mass spectroscopy.

RESULTS

Differences in the levels of blood PUFA between the centres were found which were in line with the timing and type of lipid emulsion administration. Significant differences in longitudinal levels were seen more often in free PUFA and their oxylipins than in total blood PUFA. This was particularly true for AA and DHA. In contrast, differences in the levels could be seen in total blood EPA, as well as in free EPA and its oxylipins. Further, levels of many free PUFA and their oxylipins were higher in Japanese infants than in Australian infants.

CONCLUSION

Differences in total and free fatty acids and unesterified oxylipins, were observed during the first weeks of life and between preterm infants born in Australia and Japan, which were likely a reflection of the type of lipid emulsion and timing of administration. The clinical significance of these changes remains to be explored.

Metabolic indices of polyunsaturated fatty acids: current evidence, research controversies, and clinical utility

The n-3 and n-6 polyunsaturated fatty acids (PUFA) are among the most studied nutrients in human metabolism. In the past few decades, prospective studies and controlled trials have supported the view that the effects of these essential fatty acids are clinically relevant. PUFA profiles in different blood compartments are reflections of both diet and metabolism, and their levels may be related to disease risk. Despite widespread interest, there is no consensus regarding which biomarkers best reflect PUFA status in the body. The measurement of PUFA levels is not straight-forward, and a wide variety of indices have been used in clinical studies, producing conflicting results. A major source of heterogeneity among studies is associated with research design, sampling, and laboratory analyses. To date, the n-3 index, n-6/n-3 ratio, and arachidonic acid (AA)/eicosapentaenoic acid (EPA) ratio are the most promising biomarkers associated with PUFA metabolism. Although hotly debated, these indices may be considered at least markers, if not risk factors, for several diseases, especially cardiovascular events and brain disorders. Here, we summarize the most updated evidence of n-3 and n-6 PUFA effects on human health, reviewing current controversies on the aforementioned indices and whether they can be considered valuable predictors of clinical outcomes.

The NEURAPRO Biomarker Analysis: Long-Chain Omega-3 Fatty Acids Improve 6-Month and 12-Month Outcomes in Youths at Ultra-High Risk for Psychosis

BACKGROUND

NEURAPRO was a multicenter, placebo-controlled trial of long-chain omega-3 polyunsaturated fatty acids (n-3 PUFAs) (fish oil) in 304 individuals at ultra-high risk for psychotic disorders. The study failed to show benefits of n-3 PUFAs over placebo. Although the randomized controlled trial design is placed at the top of the evidence hierarchy, this methodology has limitations in fish oil randomized controlled trials, as not only is the test agent present in the intervention group, but also n-3 fats are present in the diet and the body tissue of all participants.

METHODS

Analysis of biomarker data (eicosapentaenoic acid [EPA], docosahexaenoic acid [DHA], n-3 index, EPA+DHA) collected as part of NEURAPRO was conducted on 218 participants with longitudinal biomarker data to determine if n-3 PUFAs measured in erythrocytes at baseline and month 6 predicted clinical outcomes.

RESULTS

Increases of the n-3 index, EPA, and DHA predicted less severe psychopathology and better functioning at both follow-up time points. Higher baseline levels and increases of n-3 index also predicted overall clinical improvement at month 6 (n-3 index baseline: adjusted odds ratio [95% confidence interval (CI)] = 1.79 [1.30-2.48]; n-3 PUFA increase: adjusted odds ratio [95% CI] = 1.43 [1.16-1.76]) and at month 12 (n-3 index baseline: adjusted odds ratio [95% CI] = 2.60 [1.71-3.97]; n-3 PUFA increase: adjusted odds ratio [95% CI] = 1.36 [1.06-1.74]).

CONCLUSIONS

These data suggest that n-3 PUFAs can exert therapeutic effects in ultra-high-risk individuals. This finding has implications for early intervention and treatment guidelines, as n-3 PUFA supplementation can easily and safely be used in a wide variety of settings, from primary care to specialist services.

Linoleic acid-derived metabolites constitute the majority of oxylipins in the rat pup brain and stimulate axonal growth in primary rat cortical neuron-glia co-cultures in a sex-dependent manner

In adult rats, omega-6 linoleic acid (LA, 18:2n-6) serves as a precursor to oxidized LA metabolites (OXLAMs) known to regulate multiple signaling processes in the brain. However, little is known regarding the levels or role(s) of LA and its metabolites during brain development. To address this gap, fatty acids within various brain lipid pools, and their oxidized metabolites (oxylipins) were quantified in brains from 1-day-old male and female pups using gas chromatography and liquid chromatography coupled to tandem mass spectrometry, respectively. Primary neuron-glia co-cultures derived from postnatal day 0-1 male and female rat neocortex were exposed to vehicle (0.1% ethanol), LA, the OXLAM 13-hydroxyoctadecadienoic acid (13-HODE), or prostaglandin E2 at 10-1000 nM for 48 h to test their effects on neuronal morphology. In both male and female pups, LA accounted for 1-3% of fatty acids detected in brain phospholipids and cholesteryl esters. It was not detected in triacylglycerols, and free fatty acids. Unesterified OXLAMs constituted 47-53% of measured unesterified oxylipins in males and females (vs. ~5-7% reported in adult rat brain). Of these, 13-HODE was the most abundant, accounting for 30-33% of measured OXLAMs. Brain fatty acid and OXLAM concentrations did not differ between sexes. LA and 13-HODE significantly increased axonal outgrowth. Separate analyses of cultures derived from male versus female pups revealed that LA at 1, 50, and 1000 nM, significantly increased axonal outgrowth in female but not male cortical neurons, whereas 13-HODE at 100 nM significantly increased axonal outgrowth in male but not female cortical neurons. prostaglandin E2 did not alter neuronal outgrowth in either sex. This study demonstrates that OXLAMs constitute the majority of unesterified oxylipins in the developing rat brain despite low relative abundance of their LA precursor, and highlights a novel role of LA and 13-HODE in differentially influencing neuronal morphogenesis in the developing male and female brain.

Pure omega 3 polyunsaturated fatty acids (EPA, DPA or DHA) are associated with increased plasma levels of 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) in a short-term study in women

3-Carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF) is a metabolite of furan fatty acids found in plasma and urine. Our data show that purified EPA, DPA and DHA may also be precursors of CMPF; however the metabolic pathway(s) remain unclear.

Oxylipins and Free Fatty Acids in Parenteral Lipid Emulsions Currently Used in Preterm Infant Care: An In Vitro Study

Lipid emulsions used to support nutrition in preterm infants contain long-chain polyunsaturated fatty acids (LCPUFAs) as a source of essential fatty acids; these LCPUFAs and their parent polyunsaturated fatty acid (PUFA) can be oxidized by a variety of mechanisms to bioactive molecules called oxylipins, which are signaling molecules that initiate and/or resolve inflammation. The aim of this study was to explore levels of free LCPUFA and their related oxylipins in 3 commercially available lipid emulsions (Intralipid, SMOFlipid, and ClinOleic) using ultra high-performance liquid chromatography mass spectroscopy. Free LCPUFA were detected in all lipid emulsions tested. Seven, 8, and 9 different oxylipin compounds were detected in the 3 emulsions, respectively. The oxylipins detected were mainly derived from omega-6 PUFAs; these included 13-hydroxyoctadecadienoic acid from linoleic acid and 5-hydroxyeicosatetraenoic acid derived from arachidonic acid. It may be clinically important to know that oxylipins exist in lipid emulsions and to evaluate their potential effects on preterm infants.

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.

A stable method for routine analysis of oxylipins from dried blood spots using ultra-high performance liquid chromatography-tandem mass spectrometry

Oxylipins are biologically important lipid mediators that are derived enzymatically from polyunsaturated fatty acids (PUFA) and have a major role in regulating inflammatory processes. The currently available methods for measuring oxylipins from human biological samples have limitations, which restricts their use in large studies. We have developed a novel method for measuring 21 oxylipins from dried blood spot (DBS) using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and stable isotope dilution analysis. Our new method is reproducible and precise and enables the high throughput analysis and quantitation of bioactive oxylipins in small volumes of blood. In the future, this new method can be readily applied to measure oxylipins in large studies. Abstract Oxylipins are downstream lipid mediators enzymatically-produced from polyunsaturated fatty acids (PUFA) that are implicated as the biological effectors of these fatty acids. Recently reported methods for the quantitation of oxylipins require complex extraction procedures. In this study, we report the development and validation of a novel system for the quantitation of 21 individual oxylipins from a dried blood spot (DBS) using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and stable isotope dilution analysis. Linearity and precision of the method were determined and the stabilities of the 12 most abundant oxylipins were tested during 2 months of storage at room temperature, after being spiked into blood and prepared as DBS on PUFAcoat™ paper. Responses were linear across the concentration range analysed for all oxylipins (r² values ranged from 0.953 to 0.998). Intra-day and inter-day variations were ≤16% for all oxylipins. Recovery of oxylipins from the DBS ranged from 80 - 115%. The 12 spiked oxylipins were stable for 2 months when stored as DBS at room temperature. Our method is reproducible and precise, and provides the opportunity to accurately quantitate these oxylipins in a small sample volume.