Quantitative Analysis of Dairy Phospholipids by 31P NMR

1-Amino-1-deoxy-d-fructose ("fructosamine") and its derivatives

Fructosamine has long been considered as a key intermediate of the Maillard reaction, which to a large extent is responsible for specific aroma, taste, and color formation in thermally processed or dehydrated foods. Since the 1980s, however, as a product of the Amadori rearrangement reaction between glucose and biologically significant amines such as proteins, fructosamine has experienced a boom in biomedical research, mainly due to its relevance to pathologies in diabetes and aging. In this chapter, we assess the scope of the knowledge on and applications of fructosamine-related molecules in chemistry, food, and health sciences, as reflected mostly in publications within the past decade. Methods of fructosamine synthesis and analysis, its chemical, and biological properties, and degradation reactions, together with fructosamine-modifying and -recognizing proteins are surveyed.

Marine Fish-Derived Lysophosphatidylcholine: Properties, Extraction, Quantification, and Brain Health Application

Long-chain omega-3 fatty acids esterified in lysophosphatidylcholine (LPC-omega-3) are the most bioavailable omega-3 fatty acid form and are considered important for brain health. Lysophosphatidylcholine is a hydrolyzed phospholipid that is generated from the action of either phospholipase PLA1 or PLA2. There are two types of LPC; 1-LPC (where the omega-3 fatty acid at the sn-2 position is acylated) and 2-LPC (where the omega-3 fatty acid at the sn-1 position is acylated). The 2-LPC type is more highly bioavailable to the brain than the 1-LPC type. Given the biological and health aspects of LPC types, it is important to understand the structure, properties, extraction, quantification, functional role, and effect of the processing of LPC. This review examines various aspects involved in the extraction, characterization, and quantification of LPC. Further, the effects of processing methods on LPC and the potential biological roles of LPC in health and wellbeing are discussed. DHA-rich-LysoPLs, including LPC, can be enzymatically produced using lipases and phospholipases from wide microbial strains, and the highest yields were obtained by Lipozyme RM-IM®, Lipozyme TL-IM®, and Novozym 435®. Terrestrial-based phospholipids generally contain lower levels of long-chain omega-3 PUFAs, and therefore, they are considered less effective in providing the same health benefits as marine-based LPC. Processing (e.g., thermal, fermentation, and freezing) reduces the PL in fish. LPC containing omega-3 PUFA, mainly DHA (C22:6 omega-3) and eicosapentaenoic acid EPA (C20:5 omega-3) play important role in brain development and neuronal cell growth. Additionally, they have been implicated in supporting treatment programs for depression and Alzheimer’s. These activities appear to be facilitated by the acute function of a major facilitator superfamily domain-containing protein 2 (Mfsd2a), expressed in BBB endothelium, as a chief transporter for LPC-DHA uptake to the brain. LPC-based delivery systems also provide the opportunity to improve the properties of some bioactive compounds during storage and absorption. Overall, LPCs have great potential for improving brain health, but their safety and potentially negative effects should also be taken into consideration.

The lipidome of Crithidia fasiculataand its plasticity

Crithidia fasiculata belongs to the trypanosomatidae order of protozoan parasites, bearing close relation to other kinetoplastid parasites such as Trypanosoma brucei and Leishmania spp. As an early diverging lineage of eukaryotes, the study of kinetoplastid parasites has provided unique insights into alternative mechanisms to traditional eukaryotic metabolic pathways. Crithidia are a monogenetic parasite for mosquito species and have two distinct lifecycle stages both taking place in the mosquito gut. These consist of a motile choanomastigote form and an immotile amastigote form morphologically similar to amastigotes in Leishmania. Owing to their close relation to Leishmania, Crithidia are a growing research tool, with continuing interest in its use as a model organism for kinetoplastid research with the added benefit that they are non-pathogenic to humans and can be grown with no special equipment or requirements for biological containment. Although comparatively little research has taken place on Crithidia, similarities to other kinetoplast species has been shown in terms of energy metabolism and genetics. Crithidia also show similarities to kinetoplastids in their production of the monosaccharide D-arabinopyranose similar to Leishmania, which is incorporated into a lipoarabinogalactan a major cell surface GPI-anchored molecule. Additionally, Crithidia have been used as a eukaryotic expression system to express proteins from other kinetoplastids and potentially other eukaryotes including human proteins allowing various co- and post-translational protein modifications to the recombinant proteins. Despite the obvious usefulness and potential of this organism very little is known about its lipid metabolism. Here we describe a detailed lipidomic analyses and demonstrate the possible placidity of Crithidia’s lipid metabolis. This could have important implications for biotechnology approaches and how other kinetoplastids interact with, and scavenge nutrients from their hosts.

Development and Application of Feature-Based Molecular Networking for Phospholipidomics Analysis

Phospholipids are small but critical lipids in milk. Conventional lipidomics is a powerful method for the analysis of lipids in milk. Although the number of lipidomics software has drastically increased over the past five years, reducing false positives and obtaining structurally accurate annotations of phospholipids remain a significant challenge. In this study, we developed a rapid and accurate method for measuring a wide spectrum of phospholipids in milk. The developed approach that employed information-dependent acquisition (IDA) mode and feature-based molecular networking has exhibited better performance on data processing and lipid annotation when compared with sequential window acquisition of all theoretical mass spectra (SWATH) and MS-DIAL. This validated method was further evaluated using three kinds of sheep milk. A total of 150 phospholipids were identified, including rarely reported phospholipids containing ethers or vinyl ethers. The result indicated that phospholipids could be used as potential markers to distinguish sheep milk from different varieties and origins. The experimental and computational methods provide a rapid and reliable method for the investigation of phospholipids in milk.

HPLC-MS, GC and NMR Profiling of Bioactive Lipids of Human Milk and Milk of Dairy Animals (Cow, Sheep, Goat, Buffalo, Camel, Red Deer)

For non-bovine milks, information regarding bioactive lipids is fragmented, unreliable or unavailable. The purpose of the current study was to analyse bioactive lipids in the milk of dairy animals using modern analytical methods to achieve the most reliable results. Bioactive lipids in human milk were also analysed and used as a reference. A suite of modern analytical methods was employed, namely High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS), Gas Chromatography (GC) and Nuclear Magnetic Resonance (NMR). The total lipid content was determined, and phospholipid, fatty acid, neutral glycosphingolipids and ganglioside (GM3 and GD3) levels were measured. Lipid classes in selected milks were reliably characterised for the first time, including gangliosides in deer, camel and sheep; cerebrosides in deer, camel and buffalo; plasmalogens in deer, buffalo and goat and phospholipids in deer. Our study demonstrated the advantage of utilising a range of analytical techniques in order to characterise a diverse set of bioactive lipids.

IN SITU SOLID-STATE NMR STUDY OF ANTIMICROBIAL PEPTIDE INTERACTIONs WITH ERYTHROCYTE MEMBRANES

Antimicrobial peptides are promising therapeutic agents to mitigate the global rise of antibiotic resistance. They generally act by perturbing the bacterial cell membrane and are thus less likely to induce resistance. Because they are membrane-active molecules, it is critical to verify and understand their potential action toward eukaryotic cells to help design effective and safe drugs. In this work, we studied the interaction of two antimicrobial peptides, aurein 1.2 and caerin 1.1, with red blood cell (RBC) membranes using in situ ³¹P and ²H solid-state NMR (SS-NMR). We established a protocol to integrate up to 25% of deuterated fatty acids in the membranes of ghosts, which are obtained when hemoglobin is removed from RBCs. Fatty acid incorporation and the integrity of the lipid bilayer were confirmed by SS-NMR and fluorescence confocal microscopy. Leakage assays were performed to assess the lytic power of the antimicrobial peptides. The in situ perturbation of the ghost membranes by aurein 1.2 and caerin 1.1 revealed by ³¹P and ²H SS-NMR is consistent with membrane perturbation through a carpet mechanism for aurein 1.2, whereas caerin 1.1 acts on RBCs via pore formation. These results are compatible with fluorescence microscopy images of the ghosts. The peptides interact with eukaryotic membranes following similar mechanisms that take place in bacteria, highlighting the importance of hydrophobicity when determining such interactions. Our work bridges model membranes and in vitro studies and provides an analytical toolbox to assess drug toxicity toward eukaryotic cells.

Dietary Sphingomyelin Metabolism and Roles in Gut Health and Cognitive Development

Sphingomyelin (SM) is a widely occurring sphingolipid that is a major plasma membrane constituent. Milk and dairy products are rich SM sources, and human milk has high SM content. Numerous studies have evaluated the roles of SM in maintaining cell membrane structure and cellular signal transduction. There has been a growing interest in exploring the role of dietary SM, especially from human milk, in imparting health benefits. This review focuses on recent publications regarding SM content in several dietary sources and dietary SM metabolism. SM digestion and absorption are slow and incomplete and mainly occur in the middle sections of the small intestine. This review also evaluates the effect of dietary SM on gut health and cognitive development. Studies indicate that SM may promote gut health by reducing intestinal cholesterol absorption in adults. However, there has been a lack of data supporting clinical trials. An association between milk SM and neural development is evident before childhood. Hence, additional studies and well-designed randomized controlled trials that incorporate dietary SM evaluation, SM metabolism, and its long-term functions on infants and children are required.

A pipeline for making 31P NMR accessible for small- and large-scale lipidomics studies

Detailed molecular analysis is of increasing importance in research into the regulation of biochemical pathways, organismal growth and disease. Lipidomics in particular is increasingly sought after as it provides insight into molecular species involved in energy storage, signalling and fundamental cellular structures. This has led to the use of a range of tools and techniques to acquire lipidomics data. 31P NMR for lipidomics offers well-resolved head group/lipid class analysis, structural data that can be used to inform and strengthen interpretation of mass spectrometry data and part of a priori structural determination. In the present study, we codify the use of 31P NMR for lipidomics studies to make the technique more accessible to new users and more useful for a wider range of questions. The technique can be used in isolation (phospholipidomics) or as a part of determining lipid composition (lipidomics). We describe the process from sample extraction to data processing and analysis. This pipeline is important because it allows greater thoroughness in lipidomics studies and increases scope for answering scientific questions about lipid-containing systems.

A promising 31P NMR-multivariate analysis approach for the identification of milk phosphorylated metabolites and for rapid authentication of milk samples

A fast and reliable method for the identification of milk from different mammalians was developed by using ³¹P NMR metabolite profile of milk serum coupled to multivariate analysis (PCA and classification models UNEQ, SIMCA and K-NN). Ten milk samples from six different mammalians, relevant to human nutrition (human, cow, donkey, mare, goat, sheep), were analyzed and eight monophosphorylated components were identified and quantified: phosphocreatine (PCr), glycerophosphorylcholine (GPC), glycerophosphorylethanolamine (GPE), N-acetylglucosamine-1-phosphate (NAcGlu-1P), lactose-1-phosphate (Lac-1P), galactose-1-phosphate (Gal-1P), phosphorylcholine (PC), glucose-6-phosphate (Glu-6P). PCA showed interesting clustering based on the animal genus. K-NN can be successfully used to discriminate between donkey and cow samples while UNEQ class-modeling resulted more suitable for compliance verification. Results confirm the natural variability of milk samples among different species. These data highlight the great potentials of NMR/multivariate analysis combined method in the rapid analysis of phosphorylated milk serum metabolites for milk origin assessment and milk adulteration detection.

Lipidomic signature of Pacific lean fish species head and skin using gas chromatography and nuclear magnetic resonance spectroscopy

The present study investigated the lipid profile (fatty acid profile, positional distribution of n-3 fatty acids and phospholipid content) of head and skin of three lean fishes (gurnard, ribaldo and snapper). Gurnard head (GH) and snapper head (SnH) were found to contain a higher amount of total lipid (5.9-6.3%) than other samples (1.2-3.9%) including a considerable amount of bioactive n-3 fatty acids such as EPA (GH = 9.05%; SnH = 5.06%), DPA (GH = 2.78% ; SnH = 2.93%) and DHA (GH = 12.8% ; SnH = 7.72%) in the polar lipid fraction. DHA was found to predominate in the sn-2 position for gurnard head and snapper head. Partial least squares discriminant analysis showed that both gurnard and snapper samples were positively correlated with the n-3 fatty acids (EPA, DPA and DHA). Gurnard and snapper head had higher phospholipid content than the skin. Therefore, among the studied samples, GH and SnH are the best source of bioactive n-3 phospholipids.

Milk Phospholipid Profiling Among Japanese Women with Differing Docosahexaenoic Acid Levels

To characterize the milk phospholipids (PLs) profile using phosphorus-31 nuclear magnetic resonance (³¹P-NMR) and to investigate the effect of elevated milk docosahexaenoic acid (DHA) levels on PLs profiles in Japanese mothers.

Methods

Milk samples from eligible patients with high and low DHA from a former cross-sectional study (n = 20; n = 10 for each group) were included. Fifteen milk PLs were analyzed using ³¹P-NMR, and the profiles were compared group-wise using Mann-Whitney U-test. The P value of <0.05 was considered statistically significant.

Results

The median DHA content in milk was 1.13% and 0.29% for the high and low milk DHA groups, respectively. Twelve PLs, excluding lysophosphatidylserine, cardiolipin, and phosphatidylglycerol, were detected in all participants with 100% positive results. The median concentrations and proportions of total PLs, sphingophospholipids, and glycerophospholipids were comparable between groups. The proportions of choline-containing glycerophospholipid were significantly higher in the high milk DHA group than that in the low milk DHA group (24.09% [median, interquartile range: 23.08%-26.38%] and 21.41% [20.74%-22.84%], P = 0.019). Although the proportions of phosphatidylinositol were significantly lower in the high milk DHA group than that in the low milk DHA group (6.62% [5.75%-6.72%] versus 7.63% [7.11%-8.16%], P = 0.002), while that of phosphatidylcholine (21.90% [18.51%-23.22%] versus 19.78% [18.17%-20.26%], P = 0.059) and alkyl-acyl phosphatidylcholine (0.60% [0.40%-0.74%] versus 0.33% [0.14%-0.51%], P = 0.059) were higher in the former than that in the latter.

Conclusions

Our results were comparable to that of the previous literature. Large variations in the milk DHA might affect the composition of choline-containing glycerophospholipids in Japanese mothers. However, possible confounders were not excluded in the study populations.

Correlations of Fat Content in Human Milk with Fat Droplet Size and Phospholipid Species

Fat globule size and phospholipid (PL) content in human milk (HM) were investigated. HM was classified into three groups depending on fat content (A < B < C). PL content (mg/100 g HM) was significantly higher in the C group (p < 0.05), indicating its positive relationship with HM fat content. When the PL content was normalized (mg/g fat), that of group A was significantly higher (p < 0.05) and fat droplet size in group C was slightly larger, suggesting that HM fat content is affected by fat droplet numbers to a larger extent than by fat droplet size. A correlation between PC and SM content in HM was observed regardless of fat content, while correlation between PE and either PC or SM increased in the order of C > B > A, hence the composition and content of PL species in HM varied according to its fat content.

Simple and Efficient One-Pot Extraction Method for Phospholipidomic Profiling of Total Oil and Lecithin by Phosphorus-31 Nuclear Magnetic Resonance Measurements

The present study reports an efficient method using ethanol and hexane for lipid extraction (ETHEX) that is simpler and faster than the FOLCH (methanol/chloroform) and PALC (ethanol/hexane, a multi-step and time-consuming method) methods for determination of the phospholipid (PL) and fatty acid contents, using hoki roe as a model system. Substantial differences were found with the PALC and ETHEX methods, resulting in higher total lipid (14.6 ± 0.35 and 14.3 ± 0.08%, respectively) and lecithin (4.95 ± 0.08 and 4.89 ± 0.35%, respectively) yields compared to the FOLCH method (total lipid, 12.9 ± 0.35%; lecithin, 3.15 ± 0.35%). Phospholipids (LDPG, CL, LPS, SM, PE, LPC, PI, and PC) were found to partition in the methanol aqueous layer with the FOLCH method. Better phosphorus-31 nuclear magnetic resonance resolution and detection of PL, including lyso-PL, was obtained using D2O. The best extraction and detection of PL was achieved with the novel ETHEX method using D2O.

Functional properties of dairy phospholipid gels

In this study dairy phospholipid (PL) gels were made using 3 different concentrations of PL (15%, 30%, and 45%) and soybean oil to determine the gel-forming ability and functional traits that dairy PL have. After 24 h of storage the visual stability, crystal morphology, solid fat content, melting behavior, viscosity, and oil binding capacity of the gels were evaluated. All samples showed visual stability, whereas polarized light microscopy showed that high concentrations of PL reduced PL mobility, preventing tubular micelles from forming at high concentrations of PL (45%). Solid fat content increased with an increase in PL concentration. The melting enthalpy increased as the concentration of PL increased. The viscosity was assessed at 0.01, 0.1, and 1.0 1/s shear rates. A significant difference was observed between the 45% PL samples and the other samples at low and intermediate shear, but at high shear levels, a significant difference was only seen between the 15% PL sample and the other samples. The oil binding capacity showed a significant difference between the 45% PL sample and the other 2 samples. This study shows that dairy PL can be added to a vegetable oil to produce semi-solid material with appropriate functional properties.

Whole Goat Milk as a Source of Fat and Milk Fat Globule Membrane in Infant Formula

Cow milk is the most common dairy milk and has been extensively researched for its functional, technological and nutritional properties for a wide range of products. One such product category is infant formula, which is the most suitable alternative to feed infants, when breastfeeding is not possible. Most infant formulas are based on cow milk protein ingredients. For several reasons, consumers now seek alternatives such as goat milk, which has increasingly been used to manufacture infant, follow-on and young child formulas over the last 30 years. While similar in many aspects, compositional and functional differences exist between cow and goat milk. This offers the opportunity to explore different formulations or manufacturing options for formulas based on goat milk. The use of whole goat milk as the only source of proteins in formulas allows levels of milk fat, short and medium chain fatty acids, sn-2 palmitic acid, and milk fat globule membrane (MFGM) to be maximised. These features improve the composition and microstructure of whole goat milk-based infant formula, providing similarities to the complex human milk fat globules, and have been shown to benefit digestion, and cognitive and immune development. Recent research indicates a role for milk fat and MFGM on digestive health, the gut–brain axis and the gut–skin axis. This review highlights the lipid composition of whole goat milk-based infant formula and its potential for infant nutrition to support healthy digestion, brain development and immunity. Further work is warranted on the role of these components in allergy development and the advantages of goat milk fat and MFGM for infant nutrition and health.

In Vitro and In Vivo Anti-inflammatory Activity of Bovine Milkfat Globule (MFGM)-derived Complex Lipid Fractions

Numerous health related properties have been reported for bovine milk fat globule membrane (MFGM) and its components. Here we present novel data on the in vitro and in vivo anti-inflammatory activity of various MFGM preparations which confirm and extend the concept of MFGM as a dietary anti-inflammatory agent. Cell-based assays were used to test the ability of MFGM preparations to modulate levels of the inflammatory mediators IL-1β, nitric oxide, superoxide anion, cyclo-oxygenase-2, and neutrophil elastase. In rat models of arthritis, using MFGM fractions as dietary interventions, the phospholipid-enriched MFGM isolates were effective in reducing adjuvant-induced paw swelling while there was a tendency for the ganglioside-enriched isolate to reduce carrageenan-induced rat paw oedema. These results indicate that the anti-inflammatory activity of MFGM, rather than residing in a single component, is contributed to by an array of components acting in concert against various inflammatory targets. This confirms the potential of MFGM as a nutritional intervention for the mitigation of chronic and acute inflammatory conditions.

31P NMR Quantification of Phospholipids and Lysophospholipids in Food Emulsions

For food emulsions containing enzymatically modified egg yolk, the conventional Folch extraction does not fully recover the polar lysophospholipids. This can be overcome by repeated methanol extractions. After solvent evaporation, the extracted (lyso)phospholipids are solubilized into mixed micelles with cholate as a detergent. The solubilized (lyso)phospholipids can be accurately quantified by ³¹P NMR with recoveries ranging between 96% and 108%. Detection at a high (16.4 T) relative to a mainstream (9.4 T) magnetic field strength did not offer a significant advantage since the slow molecular tumbling of the mixed micelles increased line widths. This was due to field-strength-dependent chemical shift anisotropy relaxation. Method precision is similar at 9.4 and 16.4 T, with within-laboratory reproducibilities of 7-22% and 12-25%, respectively. The method can be implemented as a routine analytical procedure at 9.4 T (400 MHz NMR spectrometer), and the limits of detection and quantification are adequate for the verification of the standard of identity of a mayonnaise prepared with enzymatically modified egg yolk.

Milk Polar Lipids: Underappreciated Lipids with Emerging Health Benefits

Milk fat is encased in a polar lipid-containing tri-layer milk fat globule membrane (MFGM), composed of phospholipids (PLs) and sphingolipids (SLs). Milk PLs and SLs comprise about 1% of total milk lipids. The surfactant properties of PLs are important for dairy products; however, dairy products vary considerably in their polar lipid to total lipid content due to the existence of dairy foods with different fat content. Recent basic science and clinical research examining food sources and health effects of milk polar lipids suggest they may beneficially influence dysfunctional lipid metabolism, gut dysbiosis, inflammation, cardiovascular disease, gut health, and neurodevelopment. However, more research is warranted in clinical studies to confirm these effects in humans. Overall, there are a number of potential effects of consuming milk polar lipids, and they should be considered as food matrix factors that may directly confer health benefits and/or impact effects of other dietary lipids, with implications for full-fat vs. reduced-fat dairy.

Marine omega-3 (n-3) phospholipids: A comprehensive review of their properties, sources, bioavailability, and relation to brain health

For several decades, there has been considerable interest in marine-derived long chain n-3 fatty acids (n-3 LCPUFAs) due to their outstanding health benefits. n-3 LCPUFAs can be found in nature either in triglycerides (TAGs) or in phospholipid (PL) form. From brain health point of view, PL n-3 is more bioavailable and potent compared to n-3 in TAG form, as only PL n-3 is able to cross the blood-brain barrier and can be involved in brain biochemical reactions. However, PL n-3 has been ignored in the fish oil industry and frequently removed as an impurity during degumming processes. As a result, PL products derived from marine sources are very limited compared to TAG products. Commercially, PLs are being used in pharmaceutical industries as drug carriers, in food manufacturing as emulsifiers and in cosmetic industries as skin care agents, but most of the PLs used in these applications are produced from vegetable sources that contain less (without EPA, DPA, and DHA) or sometimes no n-3 LCPUFAs. This review provides a comprehensive account of the properties, structures, and major sources of marine PLs, and provides focussed discussion of their relationship to brain health. Epidemiological, laboratory, and clinical studies on n-3 LCPUFAs enriched PLs using different model systems in relation to brain and mental health that have been published over the past few years are discussed in detail.

31P NMR-Based Phospholipid Fingerprinting of Powdered Infant Formula

Infant formula (IF), regarded as the optimal substitute for human breast milk, is very important for infant growth and development. Phospholipids (PLs) are ubiquitous components of infant formula as they have good emulsifier properties in addition to their nutritional and biological functions. In this study, the PL contents in four different commercial IF brands (indicated as A, M, O, and W) were characterized and quantified using optimized ³¹P NMR spectroscopy. PLs (nine) were identified and quantified, and among these, phosphatidylethanolamine and sphingomyelin occurred at lower concentrations (5.72 and 8.89 mg/100 g, respectively) in IFs from brand O, whereas phosphatidic acid was higher (2.83 mg/100 g) in IFs from brand W. In summary, ³¹P NMR spectroscopy, combined with the multivariate data analysis, proved to be an effective analytical toolbox for evaluating the PL contents in IF and the comparative differences between IF brands.

Analytical Evaluation of Low-Field 31P NMR Spectroscopy for Lipid Analysis

We investigate the potential of ³¹P NMR with simple, maintenance-free benchtop spectrometers to probe phospholipids in complex mixtures. ³¹P NMR-based lipidomics has become an important topic in a wide range of applications in food- and health-sciences, and the continuous improvements of compact, maintenance- and cryogen-free instruments opens new opportunities for NMR routine analyses. A prior milestone is the evaluation of the analytical performance provided by ³¹P NMR at low magnetic field. To address this, we assess the ability of state-of-the-art benchtop NMR spectrometers to detect, identify, and quantify several types of phospholipids in mixtures. Relying on heteronuclear cross-polarization experiments, phospholipids can be detected in 2 h with a limit of detection of 0.5 mM at 1 T and 0.2 mM at 2 T, while the headgroups of phosphatidylcholine (PC), phosphatidyl-ethanolamine (PE), phosphatidylinositol (PI), phosphatidylserine (PS), and phosphatidyl-glycerol (PG) can be unambiguously assigned based on 2D ¹H-³¹P total correlated spectroscopy (TOCSY) spectra. Furthermore, two quantitative methods to obtain absolute concentrations are proposed and discussed, and the performance is evaluated regarding precision and accuracy.

Reaction Specificity of Phospholipase D Prepared from Acinetobacter radioresistens a2 in Transphosphatidylation

Phospholipase D (PLD) can react with phospholipids as substrates, generally phosphatidylcholine (PtdCho), and the PLD-substrate intermediate can be cleaved by another alcohol, resulting in transphosphatidylation of the substrate, which can be used in the production of special lipids. In this study, the reaction conditions affecting the transphosphatidylation of PtdCho with serine were optimized and the reaction specificity of a novel PLD prepared from Acinetobacter radioresistens a2 was evaluated for transphosphatidylation with a variety of phospholipid substrates and head group donors. Based on the yield of phosphatidylserine, experimental kinetic data, maximum transphosphatidylation rate, and kinetic constant, the specificity of PLD in transphosphatidylation was found to be affected by unsaturated fatty-acid phospholipid substrates. The catalytic efficiency of PLD prepared from A. radioresistens a2 on the synthesis of natural phospholipids is on the order of l-serine > ethanolamine and glycerol ≫ inositol. Moreover, it was found that the transphosphatidylation of PtdCho with saccharides was related to the length of the carbon chain and the number of saccharide units.

Natural phospholipids: Occurrence, biosynthesis, separation, identification, and beneficial health aspects

During the last years, phospholipids (PLs) have attracted great attention because of their crucial roles in providing nutritional values, technological and medical applications. There are considerable proofs that PLs have unique nutritional benefits on human health, such as reducing cholesterol absorption, improving liver functions, and decreasing the risk of cardiovascular diseases. PLs are the main structural lipid components of cell and organelle membranes in all living organisms, and therefore, they occur in all organisms and the derived food products. PLs are distinguished by the presence of a hydrophilic head and a hydrophobic tail, consequently they possess amphiphilic features. Due to their unique characteristics, the extraction, separation, and identification of PLs are critical issues to be concerned. This review is focused on the content of PLs classes in several sources (including milk, vegetable oils, egg yolk, and mitochondria). As well, it highlights PLs biosynthesis, and the methodologies applied for PLs extraction and separation, such as solvent extraction and solid-phase extraction. In addition, the determination and quantification of PLs classes by using thin layer chromatography, high-performance liquid chromatography coupled with different detectors, and nuclear magnetic resonance spectroscopy techniques.

Applications of nuclear magnetic resonance in lipid analyses: An emerging powerful tool for lipidomics studies

The role of lipids in cell, tissue, and organ physiology is crucial; as many diseases, including cancer, diabetes, neurodegenerative, and infectious diseases, are closely related to absorption and metabolism of lipids. Mass spectrometry (MS) based methods are the most developed powerful tools to study the synthetic pathways and metabolic networks of cellular lipids in biological systems; leading to the birth of an emerging subject lipidomics, which has been extensively reviewed. Nuclear magnetic resonance (NMR), another powerful analytical tool, which allows the visualization of single atoms and molecules, is receiving increasing attention in lipidomics analyses. However, very little work focusing on lipidomic studies using NMR has been critically reviewed. This paper presents a first comprehensive summary of application of ¹H, ¹³C &³¹P NMR in lipids and lipidomics analyses. The scientific basis, principles and characteristic diagnostic peaks assigned to specific atoms/molecular structures of lipids are presented. Applications of 2D NMR in mapping and monitoring of the components and their changes in complex lipids systems, as well as alteration of lipid profiling over disease development are also reviewed. The applications of NMR lipidomics in diseases diagnosis and food adulteration are exemplified.

Analysis of sphingolipids, sterols, and phospholipids in human pathogenic Cryptococcus strains

Cryptococcus species cause invasive infections in humans. Lipids play an important role in the progression of these infections. Independent studies done by our group and others provide some detail about the functions of these lipids in Cryptococcus infections. However, the pathways of biosynthesis and the metabolism of these lipids are not completely understood. To thoroughly understand the physiological role of these Cryptococcus lipids, a proper structure and composition analysis of Cryptococcus lipids is demanded. In this study, a detailed spectroscopic analysis of lipid extracts from Cryptococcus gattii and Cryptococcus grubii strains is presented. Sphingolipid profiling by LC-ESI-MS/MS was used to analyze sphingosine, dihydrosphingosine, sphingosine-1-phosphate, dihydrosphingosine-1-phosphate, ceramide, dihydroceramide, glucosylceramide, phytosphingosine, phytosphingosine-1-phosphate, phytoceramide, α-hydroxy phytoceramide, and inositolphosphorylceramide species. A total of 13 sterol species were identified using GC-MS, where ergosterol is the most abundant species. The ³¹P-NMR-based phospholipid analysis identified phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidyl-N,N-dimethylethanolamine, phosphatidyl-N-monomethylethanolamine, phosphatidylglycerol, phosphatidic acid, and lysophosphatidylethanolamine. A comparison of lipid profiles among different Cryptococcus strains illustrates a marked change in the metabolic flux of these organisms, especially sphingolipid metabolism. These data improve our understanding of the structure, biosynthesis, and metabolism of common lipid groups of Cryptococcus and should be useful while studying their functional significance and designing therapeutic interventions.

The role of a dairy fraction rich in milk fat globule membrane in the suppression of postprandial inflammatory markers and bone turnover in obese and overweight adults: an exploratory study

BACKGROUND

Inflammation is associated with increased bone resorption; the role of inflammation in postprandial bone turnover has not been explored. Consumption of milk fat globule membrane (MFGM) reduces inflammation in animal models. This study aimed to measure postprandial changes in bone turnover after intake of high saturated fat test meals, with- and without the anti-inflammatory ingredient MFGM.

METHODS

Subjects (n = 36 adults) were obese (BMI 30-39.9 kg/m2) or overweight (BMI 25-29.9 kg/m2) with two traits of Metabolic Syndrome. Subjects consumed a different test meal on four occasions at random; blood draws were taken at baseline and 1, 3, and 6 h postprandial. Test meals included whipping cream (WC), WC + MFGM, palm oil (PO) and PO + MFGM. Biomarkers of bone turnover and inflammation were analyzed from all four time points.

RESULTS

Test meal (treatment) by time interactions were significant for bone resorption marker C-telopeptide of type 1 collagen (CTX) (p < 0.0001) and inflammatory marker interleukin 10 (IL-10) (p = 0.012). Significant differences in overall postprandial response among test meals were found for CTX and soluble intercellular adhesion molecule (sICAM), with the greatest overall postprandial suppression of CTX occurring in meals containing MFGM. However, test meal by MFGM interactions were non- significant for bone and inflammatory markers. Correlations between CTX and inflammatory markers were non-significant.

CONCLUSION

This exploratory analysis advances the study of postprandial suppression of bone turnover by demonstrating differing effects of high SFA meals that contained MFGM; however MFGM alone did not directly moderate the difference in postprandial CTX response among test meals in this analysis. These observations may be useful for identifying foods and ingredients which maximize the suppression of bone resorption, and for generating hypotheses to test in future studies examining the role of inflammation in postprandial bone turnover.

TRIAL REGISTRATION

Clinicaltrials.gov NCT01811329. Registered 11 March 2013.

Electroformation of Giant Unilamellar Vesicles on Stainless Steel Electrodes

Giant unilamellar vesicles (GUVs) are well-established model systems for studying membrane structure and dynamics. Electroformation, also referred to as electroswelling, is one of the most prevalent methods for producing GUVs, as it enables modulation of the lipid hydration process to form relatively monodisperse, defect-free vesicles. Currently, however, it is expensive and time-consuming compared with other methods. In this study, we demonstrate that 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine GUVs can be prepared readily at a fraction of the cost on stainless steel electrodes, such as commercially available syringe needles, without any evidence of lipid oxidation or hydrolysis.

Recent Advances in Phospholipids from Colostrum, Milk and Dairy By-Products

Milk is one of the most important foods for mammals, because it is the first form of feed providing energy, nutrients and immunological factors. In the last few years, milk lipids have attracted the attention of researchers due to the presence of several bioactive components in the lipid fraction. The lipid fraction of milk and dairy products contains several components of nutritional significance, such as ω-3 and ω-6 polyunsaturated fatty acids, CLA, short chain fatty acids, gangliosides and phospholipids. Prospective cohort evidence has shown that phospholipids play an important role in the human diet and reinforce the possible relationship between their consumption and prevention of several chronic diseases. Because of these potential benefits of phospholipids in the human diet, this review is focused on the recent advances in phospholipids from colostrum, milk and dairy by-products. Phospholipid composition, its main determination methods and the health activities of these compounds will be addressed.

Isolation and Analysis of Phospholipids in Dairy Foods

The lipid fraction of milk is one of the most complex matrixes in foodstuffs due to the presence of a high number of moieties with different physical and chemical properties. Glycerolipids include glycerol and two fatty acids esterified in positions sn-1 and sn-2 with higher concentration of unsaturated fatty acids than in the triglyceride fraction of milk. Sphingolipids consist of a sphingoid base linked to a fatty acid across an amide bond. Their amphiphilic nature makes them suitable to be added into a variety of foods and recent investigations show that phospholipids, mainly phosphatidylserine and sphingomyelin, can exert antimicrobial, antiviral, and anticancer activities as well as positive effects in Alzheimer's disease, stress, and memory decline. Polar lipids can be found as natural constituents in the membranes of all living organisms with soybean and eggs as the principal industrial sources, yet they have low contents in phosphatidylserine and sphingomyelin. Animal products are rich sources of these compounds but since there are legal restrictions to avoid transmission of prions, milk and dairy products are gaining interest as alternative sources. This review summarizes the analysis of polar lipids in dairy products including sample preparation (extraction and fractionation/isolation) and analysis by GC or HPLC and the latest research works using ELSD, CAD, and MS detectors.

Addition of a dairy fraction rich in milk fat globule membrane to a high-saturated fat meal reduces the postprandial insulinaemic and inflammatory response in overweight and obese adults

Meals high in SFA, particularly palmitate, are associated with postprandial inflammation and insulin resistance. Milk fat globule membrane (MFGM) has anti-inflammatory properties that may attenuate the negative effects of SFA-rich meals. Our objective was to examine the postprandial metabolic and inflammatory response to a high-fat meal composed of palm oil (PO) compared with PO with an added dairy fraction rich in MFGM (PO+MFGM) in overweight and obese men and women (n 36) in a randomised, double-blinded, cross-over trial. Participants consumed two isoenergetic high-fat meals composed of a smoothie enriched with PO with v. without a cream-derived complex milk lipid fraction ( dairy fraction rich in MFGM) separated by a washout of 1-2 weeks. Serum cytokines, adhesion molecules, cortisol and markers of inflammation were measured at fasting, and at 1, 3 and 6 h postprandially. Glucose, insulin and lipid profiles were analysed in plasma. Consumption of the PO + MFGM v. PO meal resulted in lower total cholesterol (P = 0·021), LDL-cholesterol (P = 0·046), soluble intracellular adhesion molecule (P = 0·005) and insulin (P = 0·005) incremental AUC, and increased IL-10 (P = 0·013). Individuals with high baseline C-reactive protein (CRP) concentrations (≥3 mg/l, n 17) had higher (P = 0·030) insulin at 1 h after the PO meal than individuals with CRP concentrations <3 mg/l (n 19). The addition of MFGM attenuated this difference between CRP groups. The addition of a dairy fraction rich in MFGM attenuated the negative effects of a high-SFA meal by reducing postprandial cholesterol, inflammatory markers and insulin response in overweight and obese individuals, particularly in those with elevated CRP.

Thermorudis pharmacophila sp. nov., a novel member of the class Thermomicrobia isolated from geothermal soil, and emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus

An aerobic, thermophilic and cellulolytic bacterium, designated strain WKT50.2T, was isolated from geothermal soil at Waikite, New Zealand. Strain WKT50.2T grew at 53-76 °C and at pH 5.9-8.2. The DNA G+C content was 58.4 mol%. The major fatty acids were 12-methyl C18 : 0 and C18 : 0. Polar lipids were all linked to long-chain 1,2-diols, and comprised 2-acylalkyldiol-1-O-phosphoinositol (diolPI), 2-acylalkyldiol-1-O-phosphoacylmannoside (diolP-acylMan), 2-acylalkyldiol-1-O-phosphoinositol acylmannoside (diolPI-acylMan) and 2-acylalkyldiol-1-O-phosphoinositol mannoside (diolPI-Man). Strain WKT50.2T utilized a range of cellulosic substrates, alcohols and organic acids for growth, but was unable to utilize monosaccharides. Robust growth of WKT50.2T was observed on protein derivatives. WKT50.2T was sensitive to ampicillin, chloramphenicol, kanamycin, neomycin, polymyxin B, streptomycin and vancomycin. Metronidazole, lasalocid A and trimethoprim stimulated growth. Phylogenetic analysis of 16S rRNA gene sequences showed that WKT50.2T belonged to the class Thermomicrobia within the phylum Chloroflexi, and was most closely related to Thermorudis peleae KI4T (99.6% similarity). DNA-DNA hybridization between WKT50.2T and Thermorudis peleae DSM 27169T was 18.0%. Physiological and biochemical tests confirmed the phenotypic and genotypic differentiation of strain WKT50.2T from Thermorudis peleae KI4T and other members of the Thermomicrobia. On the basis of its phylogenetic position and phenotypic characteristics, we propose that strain WKT50.2T represents a novel species, for which the name Thermorudis pharmacophila sp. nov. is proposed, with the type strain WKT50.2T ( = DSM 26011T = ICMP 20042T). Emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus are also proposed, and include the description of a novel respiratory quinone, MK-8 2,3-epoxide (23%), in Thermomicrobium roseum.

Quantitative 31P-NMR spectroscopy for the determination of fosfomycin and impurity A in pharmaceutical products of fosfomycin sodium or calcium

A quantitative 31P-NMR method for the determination of fosfomycin and impurity A in pharmaceutical products of fosfomycin sodium or calcium has been developed. In this method, coaxial inserts containing trimethyl phosphate are used as external standard. The method is convenient and robust, and gives both high accuracy and precision. It is shown that an accurate determination is possible using different probes and coaxial inserts.

Chlamydia trachomatis Relies on Autonomous Phospholipid Synthesis for Membrane Biogenesis

The obligate intracellular parasite Chlamydia trachomatis has a reduced genome and is thought to rely on its mammalian host cell for nutrients. Although several lines of evidence suggest C. trachomatis utilizes host phospholipids, the bacterium encodes all the genes necessary for fatty acid and phospholipid synthesis found in free living Gram-negative bacteria. Bacterially derived phospholipids significantly increased in infected HeLa cell cultures. These new phospholipids had a distinct molecular species composition consisting of saturated and branched-chain fatty acids. Biochemical analysis established the role of C. trachomatis-encoded acyltransferases in producing the new disaturated molecular species. There was no evidence for the remodeling of host phospholipids and no change in the size or molecular species composition of the phosphatidylcholine pool in infected HeLa cells. Host sphingomyelin was associated with C. trachomatis isolated by detergent extraction, but it may represent contamination with detergent-insoluble host lipids rather than being an integral bacterial membrane component. C. trachomatis assembles its membrane systems from the unique phospholipid molecular species produced by its own fatty acid and phospholipid biosynthetic machinery utilizing glucose, isoleucine, and serine.

Limisphaera ngatamarikiensis gen. nov., sp. nov., a thermophilic, pink-pigmented coccus isolated from subaqueous mud of a geothermal hotspring

A novel bacterial strain, NGM72.4T, was isolated from a hot spring in the Ngatamariki geothermal field, New Zealand. Phylogenetic analysis based on 16S rRNA gene sequences grouped it into the phylum Verrucomicrobia and class level group 3 (also known as OPB35 soil group). NGM72.4T stained Gram-negative, and was catalase- and oxidase-positive. Cells were small cocci, 0.5–0.8 µm in diameter, which were motile by means of single flagella. Transmission electron micrograph (TEM) imaging showed an unusual pirellulosome-like intracytoplasmic membrane. The peptidoglycan content was very small with only trace levels of diaminopimelic acid detected. No peptidoglycan structure was visible in TEM imaging. The predominant isoprenoid quinone was MK-7 (92 %). The major fatty acids (>15 %) were C16 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. Major phospholipids were phosphatidylethanolamine (PE), phosphatidylmonomethylethanolamine (PMME) and cardiolipin (CL), and a novel analogous series of phospholipids where diacylglycerol was replaced with diacylserinol (sPE, sPMME, sCL). The DNA G+C content was 65.6 mol%. Cells displayed an oxidative chemoheterotrophic metabolism. NGM72.4T is a strictly aerobic thermophile (growth optimum 60–65 °C), has a slightly alkaliphilic pH growth optimum (optimum pH 8.1–8.4) and has a NaCl tolerance of up to 8 g l−1. Colonies were small, circular and pigmented pale pink. The distinct phylogenetic position and phenotypic traits of strain NGM72.4T distinguish it from all other described species of the phylum Verrucomicrobia and, therefore, it is considered to represent a novel species in a new genus for which we propose the name Limisphaera ngatamarikiensis gen. nov., sp. nov. The type strain is NGM72.4T ( = ICMP 20182T = DSM 27329T).

Paenibacillus darwinianus sp. nov., isolated from gamma-irradiated Antarctic soil

A novel bacterium, strain Br(T), was isolated from gamma-irradiated soils of the Britannia drift, Lake Wellman Region, Antarctica. This isolate was rod-shaped, endospore forming, Gram-stain-variable, catalase-positive, oxidase-negative and strictly aerobic. Cells possessed a monotrichous flagellum. Optimal growth was observed at 18 °C, pH 7.0 in PYGV or R2A broth. The major cellular fatty acid was anteiso-C15 : 0 (63.4 %). Primary identified lipids included phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. Total phospholipid was 60 % (w/w) of the total lipid extract. MK-7 was the dominant isoprenoid quinone. The genomic DNA G+C content was 55.6 mol%. Based on 16S rRNA gene sequence similarity, strain Br(T) clusters within the genus Paenibacillus with similarity values ranging from 93.9 to 95.1 %. Phylogenetic analyses by maximum-likelihood, maximum-parsimony and neighbour-joining methods revealed that strain Br(T) clusters with Paenibacillus daejeonensis (AF290916), Paenibacillus tarimensis (EF125184) and Paenibacillus pinihumi (GQ423057), albeit with weak bootstrap support. On the basis of phenotypic, chemotaxonomic and phylogenetic characteristics, we propose that strain Br(T) represents a novel species, Paenibacillus darwinianus sp. nov. The type strain is Br(T) ( = DSM 27245(T) = ICMP 19912(T)).