Next Issue
Previous Issue

Table of Contents

Metabolites, Volume 8, Issue 2 (June 2018)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Cover Story (view full-size image) There is currently, limited understanding of the effect diet has on the bovine metabolome. This [...] Read more.
View options order results:
result details:
Displaying articles 1-15
Export citation of selected articles as:
Open AccessArticle LC-HRMS Metabolomics for Untargeted Diagnostic Screening in Clinical Laboratories: A Feasibility Study
Metabolites 2018, 8(2), 39; https://doi.org/10.3390/metabo8020039
Received: 19 April 2018 / Revised: 11 June 2018 / Accepted: 13 June 2018 / Published: 15 June 2018
Cited by 1 | Viewed by 967 | PDF Full-text (21096 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Today’s high-resolution mass spectrometers (HRMS) allow bioanalysts to perform untargeted/global determinations that can reveal unexpected compounds or concentrations in a patient’s sample. This could be performed for preliminary diagnosis attempts when usual diagnostic processes and targeted determinations fail. We have evaluated an untargeted
[...] Read more.
Today’s high-resolution mass spectrometers (HRMS) allow bioanalysts to perform untargeted/global determinations that can reveal unexpected compounds or concentrations in a patient’s sample. This could be performed for preliminary diagnosis attempts when usual diagnostic processes and targeted determinations fail. We have evaluated an untargeted diagnostic screening (UDS) procedure. UDS is a metabolome analysis that compares one sample (e.g., a patient) with control samples (a healthy population). Using liquid chromatography (LC)-HRMS full-scan analysis of human serum extracts and unsupervised data treatment, we have compared individual samples that were spiked with one xenobiotic or a higher level of one endogenous compound with control samples. After the use of different filters that drastically reduced the number of metabolites detected, the spiked compound was eventually revealed in each test sample and ranked. The proposed UDS procedure appears feasible and reliable to reveal unexpected xenobiotics (toxicology) or higher concentrations of endogenous metabolites. HRMS-based untargeted approaches could be useful as preliminary diagnostic screening when canonical processes do not reveal disease etiology nor establish a clear diagnosis and could reduce misdiagnosis. On the other hand, the risk of overdiagnosis of this approach should be reduced with mandatory biomedical interpretation of the patient’s UDS results and with confirmatory targeted and quantitative determinations. Full article
(This article belongs to the Special Issue Clinical Metabolomics)
Figures

Graphical abstract

Open AccessArticle Untargeted Metabolomic Analysis of Rat Neuroblastoma Cells as a Model System to Study the Biochemical Effects of the Acute Administration of Methamphetamine
Metabolites 2018, 8(2), 38; https://doi.org/10.3390/metabo8020038
Received: 30 April 2018 / Revised: 31 May 2018 / Accepted: 1 June 2018 / Published: 7 June 2018
Viewed by 566 | PDF Full-text (1014 KB) | HTML Full-text | XML Full-text
Abstract
Methamphetamine is an illicit psychostimulant drug that is linked to a number of diseases of the nervous system. The downstream biochemical effects of its primary mechanisms are not well understood, and the objective of this study was to investigate whether untargeted metabolomic analysis
[...] Read more.
Methamphetamine is an illicit psychostimulant drug that is linked to a number of diseases of the nervous system. The downstream biochemical effects of its primary mechanisms are not well understood, and the objective of this study was to investigate whether untargeted metabolomic analysis of an in vitro model could generate data relevant to what is already known about this drug. Rat B50 neuroblastoma cells were treated with 1 mM methamphetamine for 48 h, and both intracellular and extracellular metabolites were profiled using gas chromatography–mass spectrometry. Principal component analysis of the data identified 35 metabolites that contributed most to the difference in metabolite profiles. Of these metabolites, the most notable changes were in amino acids, with significant increases observed in glutamate, aspartate and methionine, and decreases in phenylalanine and serine. The data demonstrated that glutamate release and, subsequently, excitotoxicity and oxidative stress were important in the response of the neuronal cell to methamphetamine. Following this, the cells appeared to engage amino acid-based mechanisms to reduce glutamate levels. The potential of untargeted metabolomic analysis has been highlighted, as it has generated biochemically relevant data and identified pathways significantly affected by methamphetamine. This combination of technologies has clear uses as a model for the study of neuronal toxicology. Full article
(This article belongs to the Special Issue Metabolomics in Toxicology)
Figures

Figure 1

Open AccessArticle Benzamide-4-Sulfonamides Are Effective Human Carbonic Anhydrase I, II, VII, and IX Inhibitors
Metabolites 2018, 8(2), 37; https://doi.org/10.3390/metabo8020037
Received: 11 May 2018 / Revised: 26 May 2018 / Accepted: 30 May 2018 / Published: 1 June 2018
Viewed by 679 | PDF Full-text (605 KB) | HTML Full-text | XML Full-text
Abstract
A series of benzamides incorporating 4-sulfamoyl moieties were obtained by reacting 4-sulfamoyl benzoic acid with primary and secondary amines and amino acids. These sulfonamides were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The human (h) isoforms hCA II, VII,
[...] Read more.
A series of benzamides incorporating 4-sulfamoyl moieties were obtained by reacting 4-sulfamoyl benzoic acid with primary and secondary amines and amino acids. These sulfonamides were investigated as inhibitors of the metalloenzyme carbonic anhydrase (CA, EC 4.2.1.1). The human (h) isoforms hCA II, VII, and IX were inhibited in the low nanomolar or subnanomolar ranges, whereas hCA I was slightly less sensitive to inhibition (KIs of 5.3–334 nM). The β- and γ-class CAs from pathogenic bacteria and fungi, such as Vibrio cholerae and Malassezia globosa, were inhibited in the micromolar range by the sulfonamides reported in the paper. The benzamide-4-sulfonamides are a promising class of highly effective CA inhibitors. Full article
(This article belongs to the Special Issue Carbonic Anhydrases and Metabolism)
Figures

Graphical abstract

Open AccessReview Amino Acids as Building Blocks for Carbonic Anhydrase Inhibitors
Metabolites 2018, 8(2), 36; https://doi.org/10.3390/metabo8020036
Received: 9 May 2018 / Revised: 23 May 2018 / Accepted: 23 May 2018 / Published: 24 May 2018
Cited by 1 | Viewed by 902 | PDF Full-text (8029 KB) | HTML Full-text | XML Full-text
Abstract
Carbonic anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life, classified into seven genetically different families (α–θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3) and protons (H+). Fifteen
[...] Read more.
Carbonic anhydrases (CAs) are a superfamily of metalloenzymes widespread in all life, classified into seven genetically different families (α–θ). These enzymes catalyse the reversible hydration of carbonic anhydride (CO2), generating bicarbonate (HCO3) and protons (H+). Fifteen isoforms of human CA (hCA I–XV) have been isolated, their presence being fundamental for the regulation of many physiological processes. In addition, overexpression of some isoforms has been associated with the outbreak or progression of several diseases. For this reason, for a long time CA inhibitors (CAIs) have been used in the control of glaucoma and as diuretics. Furthermore, the search for new potential CAIs for other pharmacological applications is a very active field. Amino acids constitute the smallest fundamental monomers of protein and, due to their useful bivalent chemical properties, are widely used in organic chemistry. Both proteinogenic and non-proteinogenic amino acids have been extensively used to synthesize CAIs. This article provides an overview of the different strategies that have been used to design new CAIs containing amino acids, and how these bivalent molecules influence the properties of the inhibitors. Full article
(This article belongs to the Special Issue Carbonic Anhydrases and Metabolism)
Figures

Graphical abstract

Open AccessReview In-Vivo NMR Spectroscopy: A Powerful and Complimentary Tool for Understanding Environmental Toxicity
Metabolites 2018, 8(2), 35; https://doi.org/10.3390/metabo8020035
Received: 26 April 2018 / Revised: 19 May 2018 / Accepted: 21 May 2018 / Published: 24 May 2018
Viewed by 979 | PDF Full-text (2557 KB) | HTML Full-text | XML Full-text
Abstract
Part review, part perspective, this article examines the applications and potential of in-vivo Nuclear Magnetic Resonance (NMR) for understanding environmental toxicity. In-vivo NMR can be applied in high field NMR spectrometers using either magic angle spinning based approaches, or flow systems. Solution-state NMR
[...] Read more.
Part review, part perspective, this article examines the applications and potential of in-vivo Nuclear Magnetic Resonance (NMR) for understanding environmental toxicity. In-vivo NMR can be applied in high field NMR spectrometers using either magic angle spinning based approaches, or flow systems. Solution-state NMR in combination with a flow system provides a low stress approach to monitor dissolved metabolites, while magic angle spinning NMR allows the detection of all components (solutions, gels and solids), albeit with additional stress caused by the rapid sample spinning. With in-vivo NMR it is possible to use the same organisms for control and exposure studies (controls are the same organisms prior to exposure inside the NMR). As such individual variability can be reduced while continual data collection over time provides the temporal resolution required to discern complex interconnected response pathways. When multidimensional NMR is combined with isotopic labelling, a wide range of metabolites can be identified in-vivo providing a unique window into the living metabolome that is highly complementary to more traditional metabolomics studies employing extracts, tissues, or biofluids. Full article
(This article belongs to the Special Issue Metabolomics in Toxicology)
Figures

Figure 1

Open AccessArticle Investigation of Daphnia magna Sub-Lethal Exposure to Organophosphate Esters in the Presence of Dissolved Organic Matter Using 1H NMR-Based Metabolomics
Metabolites 2018, 8(2), 34; https://doi.org/10.3390/metabo8020034
Received: 10 April 2018 / Revised: 8 May 2018 / Accepted: 17 May 2018 / Published: 19 May 2018
Viewed by 832 | PDF Full-text (1424 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Organophosphate esters (OPEs) are frequently detected in aquatic environments. Hydrophobic OPEs with high octanol-water partition coefficients (Log KOW) will likely sorb to dissolved organic matter (DOM) and consequently alter OPE bioavailability and sub-lethal toxicity. 1H nuclear magnetic resonance (NMR)-based metabolomics
[...] Read more.
Organophosphate esters (OPEs) are frequently detected in aquatic environments. Hydrophobic OPEs with high octanol-water partition coefficients (Log KOW) will likely sorb to dissolved organic matter (DOM) and consequently alter OPE bioavailability and sub-lethal toxicity. 1H nuclear magnetic resonance (NMR)-based metabolomics was used to evaluate how DOM (5 mg organic carbon/L) alters the metabolic response of Daphnia magna exposed to sub-lethal concentrations of three individual OPEs with varying hydrophobicity. D. magna exposed to the hydrophilic contaminant (Log KOW = 1.43) tris(2-chloroethyl) phosphate (TCEP) did not have substantial metabolic changes and DOM did not alter the metabolic response. There were significant increases in amino acids and a decrease in glucose from exposure to the hydrophobic contaminant (Log KOW = 3.65) tris(2-butoxyethyl) phosphate (TBOEP) which DOM did not mitigate, likely due to the high sub-lethal toxicity of TBOEP. Exposure to DOM and the hydrophobic contaminant (Log KOW = 4.76) triphenyl phosphate (TPhP) resulted in a unique metabolic response which was unlike TPhP only exposure, perhaps because DOM may be an additional stressor with TPhP exposure. Therefore, Log KOW values may not always predict how sub-lethal contaminant toxicity will change with DOM and there should be more consideration to incorporate DOM in sub-lethal ecotoxicology testing. Full article
(This article belongs to the Special Issue Metabolomics in Toxicology)
Figures

Figure 1

Open AccessArticle Genetic Optimization Algorithm for Metabolic Engineering Revisited
Metabolites 2018, 8(2), 33; https://doi.org/10.3390/metabo8020033
Received: 27 March 2018 / Revised: 20 April 2018 / Accepted: 14 May 2018 / Published: 16 May 2018
Viewed by 919 | PDF Full-text (14836 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
To date, several independent methods and algorithms exist for exploiting constraint-based stoichiometric models to find metabolic engineering strategies that optimize microbial production performance. Optimization procedures based on metaheuristics facilitate a straightforward adaption and expansion of engineering objectives, as well as fitness functions, while
[...] Read more.
To date, several independent methods and algorithms exist for exploiting constraint-based stoichiometric models to find metabolic engineering strategies that optimize microbial production performance. Optimization procedures based on metaheuristics facilitate a straightforward adaption and expansion of engineering objectives, as well as fitness functions, while being particularly suited for solving problems of high complexity. With the increasing interest in multi-scale models and a need for solving advanced engineering problems, we strive to advance genetic algorithms, which stand out due to their intuitive optimization principles and the proven usefulness in this field of research. A drawback of genetic algorithms is that premature convergence to sub-optimal solutions easily occurs if the optimization parameters are not adapted to the specific problem. Here, we conducted comprehensive parameter sensitivity analyses to study their impact on finding optimal strain designs. We further demonstrate the capability of genetic algorithms to simultaneously handle (i) multiple, non-linear engineering objectives; (ii) the identification of gene target-sets according to logical gene-protein-reaction associations; (iii) minimization of the number of network perturbations; and (iv) the insertion of non-native reactions, while employing genome-scale metabolic models. This framework adds a level of sophistication in terms of strain design robustness, which is exemplarily tested on succinate overproduction in Escherichia coli. Full article
(This article belongs to the Special Issue Metabolism and Systems Biology Volume 2)
Figures

Figure 1

Open AccessReview Profiling Redox and Energy Coenzymes in Whole Blood, Tissue and Cells Using NMR Spectroscopy
Metabolites 2018, 8(2), 32; https://doi.org/10.3390/metabo8020032
Received: 15 April 2018 / Revised: 10 May 2018 / Accepted: 12 May 2018 / Published: 14 May 2018
Viewed by 964 | PDF Full-text (5315 KB) | HTML Full-text | XML Full-text
Abstract
Coenzymes of cellular redox reactions and cellular energy, as well as antioxidants mediate biochemical reactions fundamental to the functioning of all living cells. Conventional analysis methods lack the opportunity to evaluate these important redox and energy coenzymes and antioxidants in a single step.
[...] Read more.
Coenzymes of cellular redox reactions and cellular energy, as well as antioxidants mediate biochemical reactions fundamental to the functioning of all living cells. Conventional analysis methods lack the opportunity to evaluate these important redox and energy coenzymes and antioxidants in a single step. Major coenzymes include redox coenzymes: NAD+ (oxidized nicotinamide adenine dinucleotide), NADH (reduced nicotinamide adenine dinucleotide), NADP+ (oxidized nicotinamide adenine dinucleotide phosphate) and NADPH (reduced nicotinamide adenine dinucleotide phosphate); energy coenzymes: ATP (adenosine triphosphate), ADP (adenosine diphosphate) and AMP (adenosine monophosphate); and antioxidants: GSSG (oxidized glutathione) and GSH (reduced glutathione). We show here that a simple 1H NMR experiment can measure these coenzymes and antioxidants in tissue and whole blood apart from a vast pool of other metabolites. In addition, focused on the goal of identification of coenzymes in subcellular fractions, we demonstrate analysis of coenzymes in the cytoplasm using breast cancer cells. Owing to their unstable nature, or low concentrations, most of the coenzymes either evade detection or lose their integrity when established sample preparation and analysis methods are used. To overcome this challenge, here we describe the development of new methods to detect these molecules without affecting the integrity of other metabolites. We used an array of 1D and 2D NMR methods, chemical shift databases, pH measurements and spiking with authentic compounds to establish the identity of peaks for the coenzymes and antioxidants in NMR spectra. Interestingly, while none of the coenzymes and antioxidants were detected in plasma, they were abundant in whole blood. Considering that the coenzymes and antioxidants represent a sensitive measure of human health and risk for numerous diseases, the presented NMR methods to measure them in one step potentially open new opportunities in the metabolomics field. Full article
Figures

Figure 1

Open AccessReview Software Tools and Approaches for Compound Identification of LC-MS/MS Data in Metabolomics
Metabolites 2018, 8(2), 31; https://doi.org/10.3390/metabo8020031
Received: 8 April 2018 / Revised: 26 April 2018 / Accepted: 6 May 2018 / Published: 10 May 2018
Cited by 3 | Viewed by 2939 | PDF Full-text (871 KB) | HTML Full-text | XML Full-text
Abstract
The annotation of small molecules remains a major challenge in untargeted mass spectrometry-based metabolomics. We here critically discuss structured elucidation approaches and software that are designed to help during the annotation of unknown compounds. Only by elucidating unknown metabolites first is it possible
[...] Read more.
The annotation of small molecules remains a major challenge in untargeted mass spectrometry-based metabolomics. We here critically discuss structured elucidation approaches and software that are designed to help during the annotation of unknown compounds. Only by elucidating unknown metabolites first is it possible to biologically interpret complex systems, to map compounds to pathways and to create reliable predictive metabolic models for translational and clinical research. These strategies include the construction and quality of tandem mass spectral databases such as the coalition of MassBank repositories and investigations of MS/MS matching confidence. We present in silico fragmentation tools such as MS-FINDER, CFM-ID, MetFrag, ChemDistiller and CSI:FingerID that can annotate compounds from existing structure databases and that have been used in the CASMI (critical assessment of small molecule identification) contests. Furthermore, the use of retention time models from liquid chromatography and the utility of collision cross-section modelling from ion mobility experiments are covered. Workflows and published examples of successfully annotated unknown compounds are included. Full article
(This article belongs to the Section Thematic Reviews)
Figures

Figure 1

Open AccessReview Adenosine 5′-Triphosphate Metabolism in Red Blood Cells as a Potential Biomarker for Post-Exercise Hypotension and a Drug Target for Cardiovascular Protection
Metabolites 2018, 8(2), 30; https://doi.org/10.3390/metabo8020030
Received: 6 April 2018 / Revised: 27 April 2018 / Accepted: 29 April 2018 / Published: 2 May 2018
Viewed by 1287 | PDF Full-text (2626 KB) | HTML Full-text | XML Full-text
Abstract
The importance of adenosine and ATP in regulating many biological functions has long been recognized, especially for their effects on the cardiovascular system, which may be used for management of hypertension and cardiometabolic diseases. In response to ischemia and cardiovascular injury, ATP is
[...] Read more.
The importance of adenosine and ATP in regulating many biological functions has long been recognized, especially for their effects on the cardiovascular system, which may be used for management of hypertension and cardiometabolic diseases. In response to ischemia and cardiovascular injury, ATP is broken down to release adenosine. The effect of adenosine is very short lived because it is rapidly taken up by erythrocytes (RBCs), myocardial and endothelial cells, and also rapidly catabolized to oxypurine metabolites. Intracellular adenosine is phosphorylated back to adenine nucleotides via a salvage pathway. Extracellular and intracellular ATP is broken down rapidly to ADP and AMP, and finally to adenosine by 5′-nucleotidase. These metabolic events are known to occur in the myocardium, endothelium as well as in RBCs. Exercise has been shown to increase metabolism of ATP in RBCs, which may be an important mechanism for post-exercise hypotension and cardiovascular protection. The post-exercise effect was greater in hypertensive than in normotensive rats. The review summarizes current evidence in support of ATP metabolism in the RBC as a potential surrogate biomarker for cardiovascular protection and toxicities. It also discusses the opportunities, challenges, and obstacles of exploiting ATP metabolism in RBCs as a target for drug development and precision medicine. Full article
(This article belongs to the Special Issue Metabolomics and/or Biomarkers for Drug Discovery)
Figures

Figure 1

Open AccessArticle Lipidomic Profiling of Murine Macrophages Treated with Fatty Acids of Varying Chain Length and Saturation Status
Metabolites 2018, 8(2), 29; https://doi.org/10.3390/metabo8020029
Received: 29 March 2018 / Revised: 17 April 2018 / Accepted: 18 April 2018 / Published: 23 April 2018
Cited by 2 | Viewed by 1459 | PDF Full-text (3253 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Macrophages are abundant within adipose tissue depots where they are exposed to fatty acids, leading to lipid accumulation. Herein, we have determined the effects of various fatty acids on the macrophage lipidome. Using targeted mass-spectrometry, we were able to detect 641 individual lipid
[...] Read more.
Macrophages are abundant within adipose tissue depots where they are exposed to fatty acids, leading to lipid accumulation. Herein, we have determined the effects of various fatty acids on the macrophage lipidome. Using targeted mass-spectrometry, we were able to detect 641 individual lipid species in primary murine macrophages treated with a variety of saturated fatty acids and an un-saturated fatty acid, either alone or in combination. The most pronounced effects were observed for the long-chain saturated fatty acid palmitate, which increased the total abundance of numerous classes of lipids. While other medium- and long-chain saturated fatty acids, as well as the long-chain unsaturated fatty acid, had less pronounced effects on the total abundance of specific lipid classes, all fatty acids induced marked alterations in the abundance of numerous lipid species within given lipid classes. Fatty acid treatment markedly altered overall phospholipid saturation status; these effects were most pronounced for phosphatidylcholine and ether-phosphatidylcholine lipid species. Finally, treatment of macrophages with either palmitate or stearate in combination with oleate prevented many of the changes that were observed in macrophages treated with palmitate or stearate alone. Collectively, our results reveal substantial and specific remodelling of the macrophage lipidome following treatment with fatty acids. Full article
(This article belongs to the Special Issue Nutritional and Food Metabolomics)
Figures

Figure 1

Open AccessArticle Adipose Tissue Lactate Clearance but Not Blood Lactate Clearance Is Associated with Clinical Outcome in Sepsis or Septic Shock during the Post-Resuscitation Period
Metabolites 2018, 8(2), 28; https://doi.org/10.3390/metabo8020028
Received: 13 March 2018 / Revised: 16 April 2018 / Accepted: 20 April 2018 / Published: 21 April 2018
Viewed by 1183 | PDF Full-text (868 KB) | HTML Full-text | XML Full-text
Abstract
No study has directly measured tissue lactate clearance in patients with sepsis during the post-resuscitation period. In this study we aimed to assess in ICU patients with sepsis (n = 32) or septic shock (n = 79)—during the post-resuscitation phase—the relative
[...] Read more.
No study has directly measured tissue lactate clearance in patients with sepsis during the post-resuscitation period. In this study we aimed to assess in ICU patients with sepsis (n = 32) or septic shock (n = 79)—during the post-resuscitation phase—the relative kinetics of blood/tissue lactate clearances and to examine whether these are associated with outcome. We measured serially—over a 48-h period—blood and adipose tissue interstitial fluid lactate levels (with microdialysis) and we calculated lactate clearance. Statistics included mixed model analysis, Friedman’s analysis of variance, Wilcoxon’s test, Mann-Whitney’s test, receiver operating characteristics curves and logistic regression. Forty patients died (28-day mortality rate = 28%). Tissue lactate clearance was higher compared to blood lactate clearance at 0–8, 0–12, 0–16, 0–20 and 0–24 h (all p < 0.05). Tissue lactate clearance was higher in survivors compared to non-survivors at 0–12, 0–20 and 0–24 h (all p = 0.02). APACHE II along with tissue lactate clearance <30% at 0–12, 0–20 and 0–24 h were independent outcome predictors. We did not find blood lactate clearance to be related to survival. Thus, in critically ill septic patients, elevated tissue (but not blood) lactate clearance, was associated with a favorable clinical outcome. Full article
Figures

Figure 1

Open AccessArticle Pasture Feeding Changes the Bovine Rumen and Milk Metabolome
Metabolites 2018, 8(2), 27; https://doi.org/10.3390/metabo8020027
Received: 9 January 2018 / Revised: 26 March 2018 / Accepted: 26 March 2018 / Published: 6 April 2018
Cited by 2 | Viewed by 2141 | PDF Full-text (13005 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The purpose of this study was to examine the effects of two pasture feeding systems—perennial ryegrass (GRS) and perennial ryegrass and white clover (CLV)—and an indoor total mixed ration (TMR) system on the (a) rumen microbiome; (b) rumen fluid and milk metabolome; and
[...] Read more.
The purpose of this study was to examine the effects of two pasture feeding systems—perennial ryegrass (GRS) and perennial ryegrass and white clover (CLV)—and an indoor total mixed ration (TMR) system on the (a) rumen microbiome; (b) rumen fluid and milk metabolome; and (c) to assess the potential to distinguish milk from different feeding systems by their respective metabolomes. Rumen fluid was collected from nine rumen cannulated cows under the different feeding systems in early, mid and late lactation, and raw milk samples were collected from ten non-cannulated cows in mid-lactation from each of the feeding systems. The microbiota present in rumen liquid and solid portions were analysed using 16S rRNA gene sequencing, while 1H-NMR untargeted metabolomic analysis was performed on rumen fluid and raw milk samples. The rumen microbiota composition was not found to be significantly altered by any feeding system in this study, likely as a result of a shortened adaptation period (two weeks’ exposure time). In contrast, feeding system had a significant effect on both the rumen and milk metabolome. Increased concentrations of volatile fatty acids including acetic acid, an important source of energy for the cow, were detected in the rumen of TMR and CLV-fed cows. Pasture feeding resulted in significantly higher concentrations of isoacids in the rumen. The ruminal fluids of both CLV and GRS-fed cows were found to have increased concentrations of p-cresol, a product of microbiome metabolism. CLV feeding resulted in increased rumen concentrations of formate, a substrate compound for methanogenesis. The TMR feeding resulted in significantly higher rumen choline content, which contributes to animal health and milk production, and succinate, a product of carbohydrate metabolism. Milk and rumen-fluids were shown to have varying levels of dimethyl sulfone in each feeding system, which was found to be an important compound for distinguishing between the diets. CLV feeding resulted in increased concentrations of milk urea. Milk from pasture-based feeding systems was shown to have significantly higher concentrations of hippuric acid, a potential biomarker of pasture-derived milk. This study has demonstrated that 1H-NMR metabolomics coupled with multivariate analysis is capable of distinguishing both rumen-fluid and milk derived from cows on different feeding systems, specifically between indoor TMR and pasture-based diets used in this study. Full article
Figures

Figure 1

Open AccessArticle GC-MS Based Metabolomics and NMR Spectroscopy Investigation of Food Intake Biomarkers for Milk and Cheese in Serum of Healthy Humans
Metabolites 2018, 8(2), 26; https://doi.org/10.3390/metabo8020026
Received: 23 January 2018 / Revised: 14 March 2018 / Accepted: 20 March 2018 / Published: 23 March 2018
Cited by 2 | Viewed by 1523 | PDF Full-text (27597 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The identification and validation of food intake biomarkers (FIBs) in human biofluids is a key objective for the evaluation of dietary intake. We report here the analysis of the GC-MS and 1H-NMR metabolomes of serum samples from a randomized cross-over study in 11
[...] Read more.
The identification and validation of food intake biomarkers (FIBs) in human biofluids is a key objective for the evaluation of dietary intake. We report here the analysis of the GC-MS and 1H-NMR metabolomes of serum samples from a randomized cross-over study in 11 healthy volunteers having consumed isocaloric amounts of milk, cheese, and a soy drink as non-dairy alternative. Serum was collected at baseline, postprandially up to 6 h, and 24 h after consumption. A multivariate analysis of the untargeted serum metabolomes, combined with a targeted analysis of candidate FIBs previously reported in urine samples from the same study, identified galactitol, galactonate, and galactono-1,5-lactone (milk), 3-phenyllactic acid (cheese), and pinitol (soy drink) as candidate FIBs for these products. Serum metabolites not previously identified in the urine samples, e.g., 3-hydroxyisobutyrate after cheese intake, were detected. Finally, an analysis of the postprandial behavior of candidate FIBs, in particular the dairy fatty acids pentadecanoic acid and heptadecanoic acid, revealed specific kinetic patterns of relevance to their detection in future validation studies. Taken together, promising candidate FIBs for dairy intake appear to be lactose and metabolites thereof, for lactose-containing products, and microbial metabolites derived from amino acids, for fermented dairy products such as cheese. Full article
(This article belongs to the Special Issue Nutritional and Food Metabolomics)
Figures

Graphical abstract

Open AccessEditorial Carbonic Anhydrases and Metabolism
Metabolites 2018, 8(2), 25; https://doi.org/10.3390/metabo8020025
Received: 18 March 2018 / Revised: 20 March 2018 / Accepted: 20 March 2018 / Published: 21 March 2018
Cited by 9 | Viewed by 933 | PDF Full-text (239 KB) | HTML Full-text | XML Full-text
Abstract
Although the role of carbonic anhydrases (CAs, EC 4.2.1.1) in metabolism is well-established, pharmacological applications of this phenomenon started to be considered only recently. In organisms all over the phylogenetic tree, the seven CA genetic families known to date are involved in biosynthetic
[...] Read more.
Although the role of carbonic anhydrases (CAs, EC 4.2.1.1) in metabolism is well-established, pharmacological applications of this phenomenon started to be considered only recently. In organisms all over the phylogenetic tree, the seven CA genetic families known to date are involved in biosynthetic processes and pH modulation, which may influence metabolism in multiple ways, with both processes being amenable to pharmacologic intervention. CA inhibitors possess antiobesity action directly by inhibiting lipogenesis, whereas the hypoxic tumor metabolism is highly controlled by the transmembrane isoforms CA IX and XII, which contribute to the acidic extracellular environment of tumors and supply bicarbonate for their high proliferation rates. Many of the articles from this special issue deal with the role of cancer CAs in tumor metabolism and how these phenomena can be used for designing innovative antitumor therapies/imaging agents. The metabolic roles of CAs in bacteria and algae are also discussed. Full article
(This article belongs to the Special Issue Carbonic Anhydrases and Metabolism)
Back to Top