High-resolution 1H Nuclear Magnetic Resonance Research Articles

Complete 1H and 13C NMR assignment of cellulose oligomer in LiCl/DMSO

High-resolution solution-state 1H, 13C, and various 2D nuclear magnetic resonance (NMR) spectra of cellulose were obtained using cellulose oligomer dissolved in LiCl/dimethyl sulfoxide, which enabled the assignment of all 1H and 13C resonances. The observed resonances were classified into four groups of glucose rings, corresponding to internal residue, non-reducing end, and reducing ends with α- and β-anomeric configurations. This assignment included the OH protons, which are difficult to assign in cellulose using other solvent systems. NMR measurements and assignments were performed using different LiCl concentrations because information on the hydroxy protons is important for understanding the interaction between cellulose and the solvent. The resonances from the OH protons shifted downfield with increasing LiCl concentration, suggesting that LiCl was attracted to the hydroxy groups of cellulose in solution. Moreover, the magnitude of the shifts varied depending on the positions of the hydroxy groups, which indicated the regioselectivity of the interaction between LiCl and the cellulose hydroxy groups.Graphical abstract

1H NMR spectroscopic characterisation of HepG2 cells as a model metabolic system for toxicology studies

The immortalised human hepatocellular HepG2 cell line is commonly used for toxicology studies as an alternative to animal testing due to its characteristic liver-distinctive functions. However, little is known about the baseline metabolic changes within these cells upon toxin exposure. We have applied 1H Nuclear Magnetic Resonance (NMR) spectroscopy to characterise the biochemical composition of HepG2 cells at baseline and post-exposure to hydrogen peroxide (H2O2). Metabolic profiles of live cells, cell extracts, and their spent media supernatants were obtained using 1H high-resolution magic angle spinning (HR-MAS) NMR and 1H NMR spectroscopic techniques. Orthogonal partial least squares discriminant analysis (O-PLS-DA) was used to characterise the metabolites that differed between the baseline and H2O2 treated groups. The results showed that H2O2 caused alterations to 10 metabolites, including acetate, glutamate, lipids, phosphocholine, and creatine in the live cells; 25 metabolites, including acetate, alanine, adenosine diphosphate (ADP), aspartate, citrate, creatine, glucose, glutamine, glutathione, and lactate in the cell extracts, and 22 metabolites, including acetate, alanine, formate, glucose, pyruvate, phenylalanine, threonine, tryptophan, tyrosine, and valine in the cell supernatants. At least 10 biochemical pathways associated with these metabolites were disrupted upon toxin exposure, including those involved in energy, lipid, and amino acid metabolism. Our findings illustrate the ability of NMR-based metabolic profiling of immortalised human cells to detect metabolic effects on central metabolism due to toxin exposure. The established data sets will enable more subtle biochemical changes in the HepG2 model cell system to be identified in future toxicity testing.

Metabolome in Tibialis and Soleus Muscles in Wild-Type and Pin1 Knockout Mice through High-Resolution Magic Angle Spinning 1H Nuclear Magnetic Resonance Spectroscopy.

Skeletal muscles are heterogenous tissues composed of different myofiber types that can be classified as slow oxidative, fast oxidative, and fast glycolytic which are distinguished on the basis of their contractile and metabolic properties. Improving oxidative metabolism in skeletal muscles can prevent metabolic diseases and plays a protective role against muscle wasting in a number of neuromuscular diseases. Therefore, achieving a detailed understanding of the factors that regulate myofiber metabolic properties might provide new therapeutic opportunities for these diseases. Here, we investigated whether peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1) is involved in the control of myofiber metabolic behaviors. Indeed, PIN1 controls glucose and lipid metabolism in a number of tissues, and it is also abundant in adult skeletal muscles; however, its role in the control of energy homeostasis in this tissue is still to be defined. To start clarifying this topic, we compared the metabolome of the tibialis anterior muscle (mainly glycolytic) and soleus muscle (oxidative) in wild-type and Pin1 knockout mice with High-Resolution Magic Angle Spinning (HR-MAS) NMR on intact tissues. Our analysis reveals a clear demarcation between the metabolomes in the two types of muscles and allows us to decode a signature able to discriminate the glycolytic versus oxidative muscle phenotype. We also detected some changes in Pin1-depleted muscles that suggest a role for PIN1 in regulating the metabolic phenotype of skeletal muscles.

Molecular Profiling of Peanut under Raw, Roasting, and Autoclaving Conditions Using High-Resolution Magic Angle Spinning and Solution 1H NMR Spectroscopy.

Higher rates of peanut allergy have been observed in countries that commonly roast peanuts prior to consumption. Despite the importance of understanding the role of thermal processing in allergy and on peanut composition, studies toward generating signatures that identify molecular contents following processing are scant. Here, we identified spectral signatures to track changes and differences in the molecular composition of peanuts under raw, roasted, and high-pressure and high-temperature autoclaved conditions. We analyzed both the solid flesh of the seed and solutions derived from soaking peanuts using High-Resolution Magic Angle Spinning (HR-MAS) and solution 1H Nuclear Magnetic Resonance (NMR) spectroscopy, respectively. The NMR spectra of intact peanuts revealed triglycerides as the dominant species, assigned on the basis of multiplets at 4.1 and 4.3 ppm, and corresponding defatted flours revealed the presence of sugars. Sucrose assigned based on a doublet at 5.4 ppm (anomeric proton), and triglycerides were the most abundant small molecules observed, with little variation between conditions. Soaked peanut solutions were devoid of lipids, and their resulting spectra matched the profiles of defatted peanuts. Spectral signatures resulting from autoclaving differed strikingly between those from raw and roasted peanuts, with considerable line-broadening in regions corresponding to proteins and amino-acid side chains, from 0.5 to 2.0 ppm and 6.5 to 8.5 ppm. Taken together, by using complementary NMR methods to obtain a fingerprint of the molecular components in peanuts, we demonstrated that autoclaving led to a distinct composition, likely resulting from the hydrolytic cleavage of proteins, the most important molecule of the allergic reaction.

Water Dynamics in Dextran-Based Hydrogel Micro/Nanoparticles Studied by NMR Diffusometry and Relaxometry.

Water dynamics in mesoporous dextran hydrogel micro/nanoparticles was investigated by means of nuclear magnetic resonance (NMR) techniques. High-resolution 1H NMR spectra and pulsed field gradient (PFG) NMR diffusometry measurements obtained on swollen state dextran micro/nanogel revealed the existence of different fractions of water molecules based on their interaction with the gel matrix. In addition to the translational diffusion of bulk water, two more diffusion processes characterized with self-diffusion coefficients 1 and 2 orders of magnitude smaller than that of bulk water were identified. 1H spin-lattice relaxation dispersion profiles obtained for a broad range of Larmor frequencies using fast field cycling (FFC) and conventional NMR relaxometry techniques allowed us to further clarify the mechanisms of molecular motion. According to the water proton pool fractions and associated self-diffusion coefficients, it is shown that the relaxation contribution associated with reorientation-mediated translational motions (RMTDs) dominates the relaxation dispersion observed at intermediate frequencies. At very low frequencies, the spin-lattice relaxation rate is dominated by the slow solid-gel dynamics probed by the water molecules interacting with the pores' surface hydroxyl groups due to the rapid chemical exchange between surface hydroxyl groups and free water. The correlation time for the thumbling-like motion of the dextran gel was found to be in the submillisecond range. The values of the self-diffusion and coherence lengths associated with motion of water molecules interacting with the solid-gel particles are consistent with the particle size and pore size distributions obtained for the studied dextran gels.

1H-NMR analysis of fluoroquinolone (pyridopyrrole quinoxaline, PPQ) conjugated to gold nanoparticles for synergistic anticancer drug design

The tethering mechanism between Pyrido Pyrrole Quinoxaline (PPQ) anticancer agent and gold nanoparticles (AuNPs) to form the PPQ/AuNPs complex as a promising anticancer reagent was investigated. Physicochemical properties, including viscosity, self-diffusion coefficients, and local molecular dynamics, of both PPQ and the PPQ/AuNPs complex were systematically examined using advanced techniques such as high-resolution 1H Nuclear Magnetic Resonance (1H-NMR), spin-lattice relaxation time (T1), and self-diffusion coefficient (D) analysis. Various PPQ/AuNPs systems were prepared and analyzed, encompassing concentrations of 0, 1.5, 4, 6.5, 8.3, 10.15, and 11.15 mg of PPQ. The results of T1demonstrated that the predominant intermolecular bonding occurs between AuNPs and fluorine atoms, particularly involving the neighboring proton to the fluorine and nitrogen atoms. Remarkably, the curve of self-diffusion coefficients displayed notable peaks at PPQ concentrations of approximately 4 mg and 8.3 mg. The interaction between PPQ molecules and AuNPs revealed a pronounced affinity for the fluorine sites and hydrogen atoms within the hydroxyl group of PPQ molecules when dissolved in aqueous solutions.

Nuclear Magnetic Resonance Metabolomic Profiling and Urine Chemistries in Incident Kidney Stone Formers Compared with Controls.

The urine metabolites and chemistries that contribute to kidney stone formation are not fully understood. This study examined differences between the urine metabolic and chemistries profiles of first-time stone formers and controls. High-resolution 1H-nuclear magnetic resonance (NMR) spectroscopy-based metabolomic analysis was performed in 24-hour urine samples from a prospective cohort of 418 first-time symptomatic kidney stone formers and 440 controls. In total, 48 NMR-quantified metabolites in addition to 12 standard urine chemistries were assayed. Analysis of covariance was used to determine the association of stone former status with urine metabolites or chemistries after adjusting for age and sex and correcting for the false discovery rate. Gradient-boosted machine methods with nested cross-validation were applied to predict stone former status. Among the standard urine chemistries, stone formers had lower urine oxalate and potassium and higher urine calcium, phosphate, and creatinine. Among NMR urine metabolites, stone formers had lower hippuric acid, trigonelline, 2-furoylglycine, imidazole, and citrate and higher creatine and alanine. A cross-validated model using urine chemistries, age, and sex yielded a mean AUC of 0.76 (95% CI, 0.73 to 0.79). A cross-validated model using urine chemistries, NMR-quantified metabolites, age, and sex did not meaningfully improve the discrimination (mean AUC, 0.78; 95% CI, 0.75 to 0.81). In this combined model, among the top ten discriminating features, four were urine chemistries and six NMR-quantified metabolites. Although NMR-quantified metabolites did not improve discrimination, several urine metabolic profiles were identified that may improve understanding of kidney stone pathogenesis.

Smoke point prediction of oxygenated fuels using neural networks

Smoke point (SP) is an important fuel property that characterizes the propensity of aviation jet fuels and kerosene to form soot. In the present study, an artificial neural network (ANN) model based on the artificial intelligence principle was developed to predict the SP of fuels with oxygenates (ethers and alcohols) and hydrocarbons (e.g., paraffins, olefins, naphthenes, aromatics, and their blends). An experimental dataset of 366 fuel mixtures comprising 113 pure compounds, 8 types of gasoline and diesels, and 245 fuel blends was used to improve the SP-prediction performance of the ANN model. One hundred and ten of the fuel blends used were various jet fuel surrogates collected from the literature. Experimental SP of 40 new mixtures consisting of diethyl ether, dibutyl ether, dioctyl ether, diphenyl ether, and methyl tert-butyl ether along with gasoline and diesel was measured as part of this work. The molecular composition of the fuels was expressed as the weight % of eight constituent functional groups present in the fuel. These functional groups along with two additional parameters (branching index and molecular weight) were provided as ten inputs to the model. The functional groups present in the gasoline and diesel samples were determined using high-resolution 1H nuclear magnetic resonance spectroscopy. The data were randomly split into three sets: training (70 %), validation (15 %), and test (15 %). The model was initially trained and validated simultaneously, and then; it was tested. A positive linear relation was observed between the measured and predicted SPs, as indicated by a correlation coefficient of 0.98. The mean absolute error of the predicted SP was 4.5. Results showed that the SP of the fuels depended on the aforementioned parameters that served as inputs for the model. The proposed model can be used to predict the SP of pure and blended form fuels containing the aforementioned functional groups.

Metabolic composition of the cyanobacterium Nostoc muscorum as a function of culture time: A 1H NMR metabolomics study

Cyanobacteria are considered a factory of added-value compounds. However, knowledge about the array of interesting compounds that could be extracted from these prokaryotic organisms is still very limited. Nuclear Magnetic Resonance (NMR) spectroscopy is a widely used technique for metabolic profiling that allows an overview of the main metabolites present in complex biological matrices. In this work, high resolution 1H NMR was employed to screen the metabolic composition of the freshwater cyanobacterium Nostoc muscorum. This species showed high longevity, being able to grow for more than one hundred days without any medium supplementation. During the period of study, several interesting metabolites were detected, such as several sugars and oligosaccharides, lipids (e.g., glycolipids, ω-3 and ω-6 fatty acids), amino acids, including mycosporin-like, peptides, and pigments (e.g., chlorophyll a and carotenoids). Owing to the long-term monitoring implemented in this study, the production of these compounds could be associated to specific moments of the growth of N. muscorum, providing new insights into the most appropriate harvesting time points for the biotechnological exploitation of specific molecules.

Nuclear Magnetic Resonance Spectroscopic Analysis of the Evolution of Peroxidation Products Arising from Culinary Oils Exposed to Thermal Oxidation: An Investigation Employing 1H and 1H-1H COSY and TOCSY Techniques.

Scientific warnings on the deleterious health effects exerted by dietary lipid oxidation products (LOPs) present in thermally stressed culinary oils have, to date, not received adequate attention given that there has been an increase in the use and consumption of such oil products in everyday life. In this study, high-resolution 1H nuclear magnetic resonance (NMR) analysis was used to characterize and map chemical modifications to fatty acid (FA) acyl groups and the evolution of LOPs in saturated fatty acid (SFA)-rich ghee, monounsaturated fatty acid (MUFA)-rich groundnut, extra virgin olive, and macadamia oils, along with polyunsaturated fatty acid (PUFA)-rich sesame, corn and walnut oils, which were all thermally stressed at 180 °C, continuously and discontinuously for 300 and 480 min, respectively. Results acquired revealed that PUFA-rich culinary oils were more susceptible to thermo-oxidative stress than the others tested, as expected. However, ghee and macadamia oil both generated only low levels of toxic LOPs, and these results demonstrated a striking similarity. Furthermore, at the 120 min thermo-oxidation time-point, the discontinuous thermo-oxidation episodes produced higher concentrations of aldehydic LOPs than those produced during continuous thermo-oxidation sessions for the same duration. On completion of the thermo-oxidation period, a higher level of triacylglycerol chain degradation, and hence, higher concentrations of aldehydes, were registered in culinary oils thermally stressed continuously over those found in discontinuous thermo-oxidized oils. These findings may be crucial in setting targets and developing scientific methods for the suppression of LOPs in thermo-oxidized oils.

Quantitative probing of hydrogen environments in quasicrystals by high-resolution NMR spectroscopy

Metal-based quasicrystals with unique quasi-periodic atomic arrangements are known to store a large amount of hydrogen under reasonable pressure and temperature for practical application as energy storage materials. While details on the atomic environments around hydrogen are central to understanding their hydrogen-storage capacity, the experimental probing of hydrogen environments and direct estimation of hydrogen content in hydrogen-bearing metal compounds, including quasicrystals, remain the holy grail in metallurgy and materials science because of the lack of suitable spectroscopic probes of hydrogen in noncrystalline metal alloys. While 1H nuclear magnetic resonance (NMR) measurement under fast spinning has the potential to reveal the nature of bonding around hydrogen, applying NMR to these metallic compounds has been challenging. Here, we report the first 1H nuclear magnetic resonance (NMR) spectra of hydrogenated quasicrystals under fast sample spinning, revealing previously unknown details of the bonding environment and hydrogen content. The NMR spectra of TiZrNi quasicrystals show that the metal atoms in the first coordination shell of neutral hydrogen shift gradually from Zr to Ti to Ni with increasing hydrogen content. This trend accounts for Ni-induced increase in the hydrogen-storage capacity and the enhanced desorption kinetics observed near ambient conditions. The 1H peak maximum shifted linearly toward lower frequencies with increasing hydrogen content, highlighting the utility of fast-spinning NMR as a novel quantitative probe of hydrogenated quasicrystals. These results open a new window to access the nature of hydrogen and its content in diverse hydrogen-bearing energy materials based on metal alloys using high-resolution 1H NMR spectroscopy, providing improved prospects for the hydrogen economy.

Stable magic angle spinning with Low-Cost 3D-Printed parts

A 3D-printed double-bearing magic angle spinning (MAS) system was developed with a home-built 4.0 mm MAS nuclear magnetic resonance (NMR) probe at 7 T. Various fused deposition modelling 3D printers were used to produce spinning modules of ignorable materials costs for rotors with a diameter of 7.0, 4.0, and 3.5 mm. High-performance MAS experiments on the 4.0 mm-diameter model using a pencil-type ceramic rotor and 3D-printed drive cap resulted in a high-resolution 1H NMR signal of silicone grease. The 3.5 mm-diameter MAS system reached a spinning frequency of 23 kHz. Furthermore, 3D-printed inserts were designed for various rotor sizes which can isolate the sample from humidity for a duration of more than a week. Single crystal inserts for MAS rotors of commercial probes can readily be printed using two-color printers. Those developments enable customized low-cost MAS NMR for both adapting existing and manufacturing new probes, respectively.

Comparative 1H NMR-Based Chemometric Evaluations of the Time-Dependent Generation of Aldehydic Lipid Oxidation Products in Culinary Oils Exposed to Laboratory-Simulated Shallow Frying Episodes: Differential Patterns Observed for Omega-3 Fatty Acid-Containing Soybean Oils.

Soybean oil is the second most exported oil from the United States and South America, and is widely marketed as a cooking oil product containing numerous health benefits for human consumers. However, culinary oils with high polyunsaturated fatty acid (PUFA) contents, are known to produce high quantities of lipid oxidation products (LOPs), including toxic aldehydes upon exposure to high-temperature frying episodes. Previous studies have demonstrated causal links between aldehyde ingestion and inhalation with deleterious health perturbations, including mutagenic and carcinogenic effects, along with cardiovascular and teratogenic actions. In this study, aldehydic LOPs were detected and quantified in commercially available samples of soybean, avocado, corn and extra-virgin olive oil products before and after their exposure to laboratory-simulated laboratory frying episodes (LSSFEs) using high-resolution 1H nuclear magnetic resonance (NMR) analysis. Results acquired demonstrated that PUFA-rich soybean and corn oils gave rise to the highest concentrations of oil aldehydes from the thermo-oxidation of unsaturated fatty acids, whereas monounsaturated fatty acid (MUFA)-laden avocado and olive oils were much more resistant to this peroxidation process, as expected. Multivariate chemometrics analyses provided evidence that an orthogonal component pattern of aldehydic LOPs featuring low-molecular-mass n-alkanals such as propanal, and 4-oxo-alkanals, arises from thermo-oxidation of the ω-3 fatty acid (FA) linolenic acid (present in soybean oils at levels of ca. 7% (w/w)), was able to at least partially distinguish this oil from corresponding samples of thermally-stressed corn oil. Despite having a similar total PUFA level, corn oil has only a negligible ω-3 FA content, and therefore generated significantly lower levels of these two aldehyde classes. In view of the adverse health effects associated with dietary LOP ingestion, alternative methodologies for the incorporation of soybean oils within high-temperature frying practices are proposed.

The Clinical Experiences of Urine Metabolomics of Genitourinary Urothelial Cancer in a Tertiary Hospital in Taiwan.

Few studies have addressed the impact of diagnostic urine metabolites and the clinical outcomes associated with genitourinary urothelial (GU) cancer to date. Furthermore, longitudinal analysis of the dynamics of urine metabolites contributing to the detection of GU cancer has not yet been fully investigated; therefore, the discovery of novel diagnostic urine biomarkers is of enormous interest. We explored the correlation of the urine metabolomic profiles to GU cancers. The aqueous metabolites of the GU cancer and the control were also identified and analyzed through high-resolution1H nuclear magnetic resonance (NMR) spectroscopy. Compared with the control, the urine metabolites of the tumor were studied in relation to changes over time in a linear mixed model for repeated measures. The urine metabolites of sixty-three (44 male and 19 female) patients with GU cancers were systemically analyzed. The urine metabolite profile in GU cancer was significantly higher than those in the control group (p<0.05). Sevenurine metabolites including histidine, propylene glycol, valine, leucine, acetylsalicylate, glycine, and isoleucine as well as other pathways were identified statistically and were significantly associated with GU cancer detection with longitudinal analysis. We discovered that histidine, propylene glycol, valine, leucine, acetylsalicylate, glycine, isoleucine, succinic acid, lysine2-aminobutyric acid, and acetic acid are involved significantly in all types of male patients in whom the type (upper tract) of urine metabolites were found to be statistically significant compared with the control. We did not find any statistical significance in urine biomarkers between female and male patients. However, a statistically insignificant correlation was found among the grade and stage with the metabolites.

Nuclear magnetic resonance free ligand conformations and atomic resolution dynamics.

Knowledge of free ligand conformational preferences (energy minima) and conformational dynamics (rotational energy barriers) of small molecules in solution can guide drug design hypotheses and help rank ideas to bias syntheses towards more active compounds. Visualization of conformational exchange dynamics around torsion angles, by replica exchange with solute tempering molecular dynamics (REST-MD), gives results in agreement with high-resolution H nuclear magnetic resonance (NMR) spectra and complements free ligand conformational analyses. Rotational energy barriers around individual bonds are comparable between calculated and experimental values, making the in-silico method relevant to ranking prospective design ideas in drug discovery programs, particularly across a series of analogs. Prioritizing design ideas, based on calculations and analysis of measurements across a series, efficiently guides rational discovery towards the "right molecules" for effective medicines.

Blood plasma metabolomics of children and adolescents with sickle cell anaemia treated with hydroxycarbamide: a new tool for uncovering biochemical alterations.

Sickle cell anaemia (SCA) is a debilitating genetic haemoglobinopathy predominantly affecting the disenfranchised strata of society in Africa and the Americas. The most common pharmacological treatment for this disease is the administration of hydroxycarbamide (HC) for which questions remain regarding its mechanism of action, efficacy and long-term toxicity specifically in paediatric individuals. A multiplatform metabolomics approach was used to assess the metabolome of plasma samples from a population of children and adolescents with SCA with and without HC treatment along with non-SCA individuals. Fifty-three metabolites were identified by ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-HRMS) and 1 H nuclear magnetic resonance (NMR) with a predominance of membrane lipids, amino acids and organic acids. The partial least-squares discriminant analysis (PLS-DA) analysis allowed a clear discrimination between the different studied groups, revealing clear effects of the HC treatment in the patients' metabolome including rescue of specific metabolites to control levels. Increased creatine/creatinine levels under HC treatment suggests a possible increase in the arginine pool and increased NO synthesis, supporting existing models for HC action in SCA. The metabolomics results extend the current knowledge on the models for SCA pathophysiology including impairment of Lands' cycle and increased synthesis of sphingosine 1-phosphate. Putative novel biomarkers are suggested.

Identifying the Unknown Content of an Ancient Egyptian Sealed Alabaster Vase from Kha and Merit’s Tomb Using Multiple Techniques and Multicomponent Sample Analysis in an Interdisciplinary Applied Chemistry Course

This article highlights the multianalytical study of exuded liquid from an ancient Egyptian sealed alabaster vase by Master’s students in an applied chemistry for cultural heritage course. Master students are introduced to the field of Archaeometry that see the collaboration of experts in different areas of research such as conservators, curators of museums, physicists, chemists, etc. The sample is a residue exuded on the linen strip sealing an ancient Egyptian alabaster vase (inventory number S.8448) from the collection of the Museo Egizio in Turin (Italy). The students start to plan the noninvasive investigation by X-ray fluorescence (XRF), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) for the inorganic compounds characterization, followed by the extraction of the organic components (such as oils, fats, and waxes) to be analyzed by high-resolution 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and 2D NMR correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), and long-range heteronuclear correlation (HMBC) techniques and by gas chromatography coupled with mass spectrometry (GC/MS). Reference standards, spectral databases, and published data on similar artifacts served as the basis for the interpretation of the instrumental results. The approach was introduced in the course of Applied Chemistry for Cultural Heritage for Master students in Archaeology (University of Palermo, Italy), where the need is to know how to approach the scientific investigation together with the conservation scientists and how to manage with a very low amount of sample. Pedagogically, the approach introduces students to the main techniques currently used in the field of Archaeometry while reinforcing fundamental concepts in sample collecting and multicomponent microsample analysis. This interdisciplinary approach provides a unique experience that demonstrates chemistry’s broad applicability outside of the traditional laboratory. Students are guided to identify the inorganic and organic components of the exudate liquid: the first one is ascribable to clay minerals iron oxides, which could impart the brown color to the sample; the second one is ascribed to triglycerides of various kinds, which probably comes from vegetable oil.

High-performance liquid chromatographic profile and 1H quantitative nuclear magnetic resonance analyses for quality control of a Xinjiang licorice extract.

Various pharmacological properties of Xinjiang licorice flavonoids have been reported recently. We have investigated constituents corresponding to distinct peaks on the high-performance liquid chromatography (HPLC) profile of a flavonoid-rich extract from licorice, and identified 13 flavonoids, including licochalcone A (1), licochalcone B (3), glabrone (4), and echinatin (5), by isolating them and then performing high-resolution electrospray ionization mass spectrometry and 1H nuclear magnetic resonance (NMR) spectral analyses. We then applied the 1H quantitative NMR (qNMR) method for analysis of major flavonoids, 1 and 3-5 in the extract. The 1H qNMR results were supported by 13C NMR analysis. The results demonstrated the utility of the combination of HPLC profiling and qNMR analyses for quality control of Xinjiang licorice. Additionally, we observed a moderate inhibitory effect of the most abundant constituent, licochalcone A (1), on acetylcholine esterase activity, suggesting utility as a seed for drug development.

1H-NMR-Based salivary metabolomics from females with temporomandibular disorders – A pilot study

Although temporomandibular disorder (TMD) is the second most common musculoskeletal disorder in the general population, the disease is multifactorial and presents symptoms common to other conditions which misdiagnosis can lead to treatment failure. In this case-control study, we performed, for the first time, a high-resolution 1H-nuclear magnetic resonance spectroscopy metabolomic analysis of the saliva of 26 women with TMD of muscular origin (experimental group [EG]) at the beginning (EG-pre) and at the end (EG-post) of a conservative treatment, and of 27 normal women (control group [CG]) to identify a metabolic signature for TMD. One-way analysis of variance showed changes in the concentration of phenylacetate, dimethylamine, maltose, acetoin, and isovalerate. Partial least-square discriminant analysis showed that metabolite signals did not overlap in CG X EG-pre and EG-pre X EG-post, but overlapped in CG X EG-post. The area under the receiver operating characteristic curve was 1 in CG X EG-pre (95% CI, 1.000–1.000; p < 0.002), 0.993 in EG-pre X EG-post (95% CI, 0.963–1.000), and 0.832 in CG X EG-post (95% CI, 0.699–0.961). These results suggest that the metabolomic profiles of women with and without TMD differ, while after treatment there is a lower distinction and slight tendency towards overlapping between CG and EG-post compared to pre treatment. We also found that phenylacetate, dimethylamine, maltose, acetoin, and isovalerate are potential biomarkers for TMD of muscular origin.

Spatially-resolved metabolic profiling of living Drosophila in neurodegenerative conditions using 1H magic angle spinning NMR

Drosophila flies are versatile animal models for the study of gene mutations in neuronal pathologies. Their small size allows performing in vivo Magic Angle Spinning (MAS) experiments to obtain high-resolution 1H nuclear magnetic resonance (NMR) spectra. Here, we use spatially-resolved 1H high-resolution MAS NMR to investigate in vivo metabolite contents in different segments of the fly body. A comparative study of metabolic changes was performed for three neurodegenerative disorders: two cell-specific neuronal and glial models of Huntington disease (HD) and a model of glutamate excitotoxicity. It is shown that these pathologies are characterized by specific and sometimes anatomically localized variations in metabolite concentrations. In two cases, the modifications of 1H MAS NMR spectra localized in fly heads were significant enough to allow the creation of a predictive model.