High-resolution 1H NMR Spectroscopy Research Articles

Rapid determination of alendronate to quality evaluation of tablets by high resolution 1H NMR spectroscopy

Determination of alendronate is crucial to routine quality control of alendronate tablets. However, tedious sample treatment processes such as derivatization were generally required by chromatographic separation of alendronate as its high polarity and no chromophore in the molecular structure. Here, we describe the use of 1H NMR for the quantification of alendronate sodium in tablets. Linearity, recovery, selectivity and sensitivity of the assay were validated to be satisfactory with quick sample preparation and acquisition. The contents of alendronate sodium in tablets from five manufacturers were determined, the results showed that all assayed tablets fell within the range of 90.0–110.0% of the label claim and the relative standard deviation was less than 6.0%. The method was also successfully employed for alendronate tablet dissolution assay in this study.

Milieu Dependence of Isomeric Composition of d-arabino-Hexo-2-ulose in Aqueous Solution Determined by High-Resolution NMR Spectroscopy

In this study, high-resolution (1)H NMR spectroscopy (600.03 MHz) and (13)C NMR spectroscopy (150.89 MHz) were used to elucidate the structures of equilibrating d-arabino-hexo-2-ulose (GLUC) (1) isomers in aqueous solution. Four isomers were formed from the investigated ketohexose, and their equilibrium is dependent on the pH value and temperature. Only hydrated GLUC (1) isomers were identified. The (2)C5-β-2,6-pyranoid and the β-2,5-furanoid GLUC (1) isomer were exclusively formed in aqueous solution. Thus, (4)C1-1,5-pyranoid isomers are predominating in the crystalline state. An increase in solution pH or temperature led to a pairwise conversion of configurative information. Thus, changing the measurement conditions permits control over the equilibrium's characteristic. Furthermore, all GLUC (1) isomers showed comparable reaction behavior regarding pH- and temperature-dependent degradation reactions.

Rhodamine-based ‘turn-on’ fluorescent probe for Cu(II) and its fluorescence imaging in living cells

A novel rhodamine spirolactam derivative 3′,6′-Bis(diethylamino)-2-(2-hydroxyethylamino) spiro[isoindoline-1,9′-xanthen]-3-one (RO1) was synthesized, and characterized by high-resolution mass spectrometry (HRMS), X-ray crystallography, Infrared spectroscopy (IR), and 1H NMR and 13C NMR spectroscopy. RO1 exhibited highly sensitive and exclusively selective fluorescence response toward Cu2+ over other metal ions with a detection limit of 0.56ppb in mixed aqueous solution. The fluorescence was pH-independent in the wide range pH 3.1–11.6. The turn-on fluorescence enhancement of the probe is based on Cu2+ induced ring-opening mechanism of the rhodamine spirolactam. Moreover, by means of fluorescence microscopy experiments, it was demonstrated that RO1 could monitor trace Cu2+ changes by live cell imaging.

Study of metabonomic profiles of human esophageal carcinoma by use of high-resolution magic-angle spinning 1H NMR spectroscopy and multivariate data analysis

Esophageal carcinoma (EC) is one of the most common malignant tumors. EC survival has remained disappointingly low because of the high malignancy of esophageal cancer and the lack of obvious clinical symptoms at an early stage. Early diagnosis is often difficult because the small tumor nodules are frequently missed. Metabonomics based on high-resolution magic-angle spinning (HRMAS) NMR has been popular for tumor detection because it is highly sensitive, provides rich biochemical information and requires no sample pretreatment. (1)H HRMAS spectra of non-involved adjacent esophageal tissues and of well differentiated and moderately differentiated esophageal carcinoma tumors were recorded and analyzed by use of multivariate and statistical analysis techniques. Moderately differentiated EC tumors were found to have increased total choline, alanine, and glutamate and reduced creatine, myo-inositol, and taurine compared with non-involved adjacent tissues. Moreover, clear differences between the metabonomic profiles of EC tissues enabled tumor differentiation. Furthermore, the integral Gly/MI ratio for samples of different tissue types were statistically significantly different; this was sufficient both for distinguishing non-involved tissues from esophageal carcinoma and for classification of well differentiated and moderately differentiated EC tumors.

Quantitative 1H-NMR-Metabolomics Reveals Extensive Metabolic Reprogramming and the Effect of the Aquaglyceroporin FPS1 in Ethanol-Stressed Yeast Cells

A metabolomic analysis using high resolution 1H NMR spectroscopy coupled with multivariate statistical analysis was used to characterize the alterations in the endo- and exo-metabolome of S. cerevisiae BY4741 during the exponential phase of growth in minimal medium supplemented with different ethanol concentrations (0, 2, 4 and 6% v/v). This study provides evidence that supports the notion that ethanol stress induces reductive stress in yeast cells, which, in turn, appears to be counteracted by the increase in the rate of NAD+ regenerating bioreactions. Metabolomics data also shows increased intra- and extra-cellular accumulation of most amino acids and TCA cycle intermediates in yeast cells growing under ethanol stress suggesting a state of overflow metabolism in turn of the pyruvate branch-point. Given its previous implication in ethanol stress resistance in yeast, this study also focused on the effect of the expression of the aquaglyceroporin encoded by FPS1 in the yeast metabolome, in the absence or presence of ethanol stress. The metabolomics data collected herein shows that the deletion of the FPS1 gene in the absence of ethanol stress partially mimics the effect of ethanol stress in the parental strain. Moreover, the results obtained suggest that the reported action of Fps1 in mediating the passive diffusion of glycerol is a key factor in the maintenance of redox balance, an important feature for ethanol stress resistance, and may interfere with the ability of the yeast cell to accumulate trehalose. Overall, the obtained results corroborate the idea that metabolomic approaches may be crucial tools to understand the function and/or the effect of membrane transporters/porins, such as Fps1, and may be an important tool for the clear-cut design of improved process conditions and more robust yeast strains aiming to optimize industrial fermentation performance.

Metabonomic analysis of water extracts from Chinese and American ginsengs by 1H nuclear magnetic resonance: identification of chemical profile for quality control

BackgroundWith the gaining popularity of commercially prepared decoctions of herbal medicines on the market, an objective and efficient way to reveal the authenticity of such products is urgently needed. Previous attempts to use chromatographic or spectroscopic methods to identify ginseng samples made use of components derived from methanol extracts of the herb. It was not established that these herbs can be distinguished solely from consumable components, which are responsible for the clinical efficacy of the herb.In this study, metabonomics, or metabolic profiling, based on the application of 1H-Nuclear Magnetic Resonance (NMR), is applied to distinguish the water extracts of three closely related ginseng species: P. ginseng (from two different cultivated regions in China), P. notoginseng and P. quinquefolius.MethodsA water extraction protocol that mimics how ginseng decoctions are made for consumption was used to prepare triplicate samples from each herb for analysis. High-resolution 1H NMR spectroscopy was used to acquire metabolic profiles of the four ginseng samples. The spectral data were subjected to multivariate and univariate analysis to identify metabolites that were able to distinguish different types of ginseng.ResultsH NMR metabolic profiling was performed to distinguish the water extracts of P. ginseng cultivated in Hebei and Jilin of China, both of which were distinguished from extracts of P. notoginseng and P. quinquefolius, by unsupervised principle component analysis based on the entire 1H NMR spectral fingerprint Statistically significant differences were found for several discriminating features traced to common metabolites and the ginsenosides Rg1 and Rd, in the 1H NMR spectra.ConclusionThis study demonstrated that 1H NMR metabonomics can simultaneously distinguish different ginseng species and multiple samples of the same species that were cultivated in different regions. This technique is applicable to the authentication and quality control of ginseng products.

Milieu dependence of isomeric composition of 1-deoxy-d-erythro-hexo-2,3-diulose in aqueous solution determined by high-resolution NMR spectroscopy

In this study, high-resolution 1H (600.03MHz) and 13C NMR spectroscopy (150.89MHz) were used to elucidate the structures of the identifiable isomers of a complex mixture of equilibrating 1-deoxy-d-erythro-hexo-2,3-diulose (1-DG) (1) isomers in aqueous solution. Approximately 15 isomers were formed from the investigated deoxy-ketohexose, and the equilibrium of the isomers is dependent on the pH values and temperature. In contrast to non-hydrated isomers, hydrated 1-DG (1) isomers were exclusively formed in aqueous solution. Their relative concentration increased when the pH was increased to more basic conditions. An increase in solution temperature led to the elimination of water and an increase in the relative concentration of the non-hydrated 1-DG (1) isomers. The observed influence of different conditions on the isomeric composition was explained for all isomers. Also, these observations provided information for structure elucidation. Furthermore, the reaction behaviour of 1-DG (1) under basic conditions at high temperatures (up to 347.5K) was interpreted and described.

Quantitative determination of fatty acid chain composition in pork meat products by high resolution 1H NMR spectroscopy

High resolution 1H NMR spectroscopy was proposed for the determination of the fatty acid chain profile of lipids in pork meat products during ripening. Two typical Mediterranean PDO salami produced in Calabria, a region in the Southern Italy, were chosen as a case of study. Quantitative NMR analysis provided the fatty acid chain profiles of total lipid extracts. The transesterification of total lipid extracts furnished FAME mixtures that enabled quantitation of fatty acid acyl chains in the acylglycerol and FFA portions. In all cases, oleyl chains were predominant, and high amounts of polyunsaturated fatty acid chains were observed. The proposed spectroscopic method allowed also the estimation of the most important nutritional parameters of dry fermented meat products.

Metabolic Changes Detected by Ex Vivo High Resolution 1H NMR Spectroscopy in the Striatum of 6-OHDA-Induced Parkinson’s Rat

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the progressive loss of the dopaminergic neurons; however, its crucial mechanism of the metabolic changes of neurotransmitters remains ambiguous. The pathological mechanism of PD might involve cerebral metabolism perturbations. In this study, ex vivo proton nuclear magnetic resonance ((1)H NMR) was used to determine the level changes of 13 metabolites in the bilateral striatum of 6-hydroxydopamine (6-OHDA)-induced PD rats. The results showed that, in the right striatum of 6-OHDA-induced PD rats, increased levels of glutamate (Glu) and γ-aminobutyric acid (GABA) concomitantly with decreased level of glutamine (Gln) were observed compared to the control. Whereas, in the left striatum of 6-OHDA-induced PD rats, increased level of Glu with decreased level of GABA and unchanged Gln were observed. Other cerebral metabolites including lactate, alanine, creatine, succinate, taurine, and glycine were also found to have some perturbations. The observed metabolic changes for Glu, Gln, and GABA are mostly likely the result of a shift in the steady-state equilibrium of the Gln-Glu-GABA metabolic cycle between astrocytes and neurons. The altered Gln and GABA levels are most likely as a strategy to protect neurons from Glu excitotoxic injury after striatal dopamine depletion. Changes in energy metabolism and tricarboxylic acid cycle might be involved in the pathogenesis of PD.

A fluorescent sensor for pH based on rhodamine fluorophore

In this study, an ‘Off–On’-type acidic pH fluorescent chemosensor, 3′,6′-Bis (ethylamino)-2′,7′-dimethyl-2-(2-oxoethylideneamino)spiro[isoindoline-1,9′-xanthen]-3-one (RG1) has been designed, synthesized, and characterized by high-resolution mass spectrometry (HRMS), X-ray crystallography, infrared spectroscopy (IR), and 1H NMR and 13C NMR spectroscopy. The design tactics for the sensor was based on the change in structure between spirocyclic (non-fluorescent) and ring-open (fluorescent) forms of rhodamine dyes. Fluorescence “off–on” behaviors of RG1 were investigated on the basis of variable acid concentrations. The pH titrations showed a ca. 581-fold increase in fluorescence intensity within the pH range of 7.5 to 1.1 with a pKa value of 2.32 in acetonitrile–water (1:1, v/v) solution when excited at 510 nm. The fluorescence change of RG1 was fully reversible and took place mainly within the pH range from 1.0 to 4.0, which was valuable for pH researches in acidic environments.

1H NMR investigations of the molecular nature of cobalt(II) ions in human saliva

High-resolution 1H NMR spectroscopy demonstrated that addition of Co(II) ions to isolated human salivary supernatants (HSSs) gave rise to its complexation by a variety of biomolecules. The relative efficacies of these complexants/chelators in this context were classifiable by the influence of added Co(II) on their line-widths and chemical shift values, and also the added Co(II) concentration-dependence of these spectral modifications. Those which were most affected by the addition of this metal ion were lactate > formate ≈histidinate > succinate, this order reflecting the ability of these complexants to compete for the available Co(II) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their HSS concentrations. Since many of these HSS Co(II) complexants (particularly lactate, formate and histidine) serve as powerful OH scavengers, the results acquired indicate that any of this radical generated from the Co(II) source in such complexes via pseudo-Fenton reactions may be ‘site-specifically’ scavenged. The significance of these observations regarding the in vivo corrosion of cobalt-containing metal alloy dental prostheses (e.g., Co–Cr alloys), the availability of trace levels of this metal ion in human saliva, and cobalt toxicity, is discussed.

Characterization of Temporary Metabolic Changes Following Cantonese Herbal Tea Intervention

Cantonese herbal tea (CHT) has been consumed in South China to alleviate feelings of discomfort due to the heat and humidity in the body according to the theory of traditional Chinese medicine (TCM). To understand the in vivo mechanism of CHT, a ¹H-NMR-based metabonomic approach was used to investigate the global biological characterization of rat serum following the intake of CHT and to understand the mechanisms of action of CHT. Serum samples from rats with consecutive CHT intake after 10, 20 and 30 days and corresponding control rats were analysed by high-resolution ¹H-NMR spectroscopy. Principal component analysis (PCA) and orthogonal projection on latent structures discriminant analysis (OPLS-DA) were utilized for ¹H-NMR spectra analysis and temporal metabolic changes identification. For the 10-day CHT intake group, no significant metabolic response was detected, whereas the 20-day group showed elevation of glucogeneogenesis and a shift in energy metabolism from carbohydrate metabolism to lipid metabolism. In addition, a notable decrease in pyruvate content with a consistent increase in lactate content, and significant decrease in both lipoprotein and glucose contents was observed for the 30-day group, indicating potential metabolic dysfunction. The metabonomics technique combining metabolic profiles with multivariate analysis enhanced our current understanding of the host's metabolic response to CHT intake.

ChemInform Abstract: Synthesis and Characterization of New 3‐(3‐Hydroxyphenyl)‐4‐alkyl‐3,4‐dihydrobenzo[e][1,3]oxazepine‐1,5‐dione Compounds.

AbstractCompounds (III) are purified by recrystallisation from 1,4‐dioxane.

Phenyl-substituted planar binuclear phthalo- and naphthalocyanines: synthesis and investigation of physicochemical properties

Dodeca-phenyl-substituted planar binuclear phthalocyanine magnesium complexes with an extended π-conjugation system were synthesized with high yields. Two approaches to the extension of the π-system were presented: extension of an aromatic bridge or a peripheral π-system. A maximum of near-IR absorption at 972 nm was observed in the case of the planar binuclear naphthalocyanine sharing a common benzene ring. Binuclear phthalo- and naphthalocyanines were characterized by high resolution MALDI-TOF mass spectrometry, UV/Vis/NIR and 1H NMR spectroscopy. DFT modeling of the structure and chemical shift GIAO calculations were made. The formation of nanoaggregates in a solid film was proven using AFM. The electrochemical properties of binuclear naphthalocyanine complexes were investigated for the first time.

Metabolic Profiling of Human Colorectal Cancer Using High Resolution 1H Nuclear Magnetic Resonance Spectroscopy

AbstractColorectal cancer (CRC) is the third commonest malignancy cancer worldwide. Clear understandings of global metabolic profiling of the normal mucosa and cancer tissues are vitally important to aid optimizing the clinical management strategy and understanding CRC biology. We studied metabolic characteristics of 20 CRC and 20 distant normal mucosa tissues extracts from 20 patients using high resolution 1H NMR spectroscopy in conjunction with multivariate analyses, such as principal component analysis (PCA). Compared with distant normal mucosa tissues, lactate, taurine, ornithine and polyamine were present at significantly higher levels in CRC tissue extracts whereas myo‐inositol was present at significantly lower level. Two metabolites ratios such as myo‐inositol/taurine and myo‐inositol/(ornithine+polyamine) appear to be the most valuable biomarkers for the differentiation CRC from normal mucosa tissues. Our data suggested that HR 1H NMR spectroscopy combined with multivariate analyses is a potentially useful technology for detecting malignant changes in the normal mucosa tissues, the technique may be further exploited for future CRC biomarker research or identification of targets for therapeutic manipulations.

A Metadata description of the data in "A metabolomic comparison of urinary changes in type 2 diabetes in mouse, rat, and human."

BackgroundMetabolomics is a rapidly developing functional genomic tool that has a wide range of applications in diverse fields in biology and medicine. However, unlike transcriptomics and proteomics there is currently no central repository for the depositing of data despite efforts by the Metabolomics Standard Initiative (MSI) to develop a standardised description of a metabolomic experiment.FindingsIn this manuscript we describe how the MSI description has been applied to a published dataset involving the identification of cross-species metabolic biomarkers associated with type II diabetes. The study describes sample collection of urine from mice, rats and human volunteers, and the subsequent acquisition of data by high resolution 1H NMR spectroscopy. The metadata is described to demonstrate how the MSI descriptions could be applied in a manuscript and the spectra have also been made available for the mouse and rat studies to allow others to process the data.ConclusionsThe intention of this manuscript is to stimulate discussion as to whether the MSI description is sufficient to describe the metadata associated with metabolomic experiments and encourage others to make their data available to other researchers.

Synthesis and Characterization of New 3‐(3‐Hydroxyphenyl)‐4‐ alkyl‐3,4‐dihydrobenzo[e][1,3]oxazepine‐1,5‐dione Compounds

AbstractA series of 3‐(3‐hydroxyphenyl)‐4‐alkyl‐3,4‐dihydrobenzo[e][1,3]oxazepine‐1,5‐dione compounds with general formula CnH2n+1CNO(CO)2C6H4(C6H4OH) in which n are even parity numbers from 2 to 18. The structure determinations on these compounds were performed by FT‐IR spectroscopy which indicated that the terminal alkyl chain attached to the oxazepine ring was fully extended. Conformational analysis in DMSO at ambient temperature was carried out for the first time via high resolution 1H NMR and 13C NMR spectroscopy.

Serum and Urine Metabolite Profiling Reveals Potential Biomarkers of Human Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a common malignancy in the world with high morbidity and mortality rate. Identification of novel biomarkers in HCC remains impeded primarily because of the heterogeneity of the disease in clinical presentations as well as the pathophysiological variations derived from underlying conditions such as cirrhosis and steatohepatitis. The aim of this study is to search for potential metabolite biomarkers of human HCC using serum and urine metabolomics approach. Sera and urine samples were collected from patients with HCC (n = 82), benign liver tumor patients (n = 24), and healthy controls (n = 71). Metabolite profiling was performed by gas chromatography time-of-flight mass spectrometry and ultra performance liquid chromatography-quadrupole time of flight mass spectrometry in conjunction with univariate and multivariate statistical analyses. Forty three serum metabolites and 31 urinary metabolites were identified in HCC patients involving several key metabolic pathways such as bile acids, free fatty acids, glycolysis, urea cycle, and methionine metabolism. Differentially expressed metabolites in HCC subjects, such as bile acids, histidine, and inosine are of great statistical significance and high fold changes, which warrant further validation as potential biomarkers for HCC. However, alterations of several bile acids seem to be affected by the condition of liver cirrhosis and hepatitis. Quantitative measurement and comparison of seven bile acids among benign liver tumor patients with liver cirrhosis and hepatitis, HCC patients with liver cirrhosis and hepatitis, HCC patients without liver cirrhosis and hepatitis, and healthy controls revealed that the abnormal levels of glycochenodeoxycholic acid, glycocholic acid, taurocholic acid, and chenodeoxycholic acid are associated with liver cirrhosis and hepatitis. HCC patients with alpha fetoprotein values lower than 20 ng/ml was successfully differentiated from healthy controls with an accuracy of 100% using a panel of metabolite markers. Our work shows that metabolomic profiling approach is a promising screening tool for the diagnosis and stratification of HCC patients.

Chemoenzymatic synthesis of a focused library of enantiopure structured 1- O-alkyl-2,3-diacyl- sn-glycerol type ether lipids

A highly efficient two-step chemoenzymatic synthesis of enantiopure structured ether lipids of the 1- O-alkyl-2,3-diacyl- sn-glycerol type has been developed. Chimyl, batyl and selachyl alcohols possessing pure saturated fatty acid (SFA) attached to the sn-3 position and pure EPA and DHA attached to the sn-2 position were obtained under full regiocontrol. This was offered by mild conditions and a highly efficient lipase that operated at room temperature. High-resolution 1H NMR spectroscopy was used to monitor the progress of the reactions and to evaluate the full regiocontrol of the reactions involved by keeping track of all prospective adducts involved in these reactions. This was extended to preparation of a focused library of eight monoacyl intermediate adducts for all even-numbered SFA ranging from C 2–C 16 and the corresponding EPA and DHA structured diacyl glycerol ethers (DAGE) products for chimyl, batyl and selachyl alcohols, the total of 72 compounds.

Metabolomic studies on the biochemical profile of urine from rats with acute cysteamine supplementation

This study investigates the effect of acute cysteamine (CS) supplementation on rat metabolism. A metabolomic strategy using high-resolution 1H-NMR spectroscopy in conjunction with principal component analysis was applied to examine rat biological responses to CS administration. Half of female Sprague–Dawley rats (2 groups of 6 rats) were each given doses of 150 mg CS/kg body weight intraperitoneally. Urine samples were collected twice daily (0–8 and 8–24 h) from the rats following CS administration. The identifiable biochemical effects associated with CS supplementation included decreased urinary concentrations of hippurate, succinate, citric acid, and 2-oxoglutarate, as well as increased urinary concentrations of dimethylamine, dimethylglycine, glycine, and taurine. These effects were predominately seen within the first 8 h after CS administration. Clear differences in succinate, citric acid, and 2-oxoglutarate were observed 8–24 h following CS. The results suggest that CS supplementation in the rats resulted in modulation of intestinal microbial metabolism and metabolic perturbation of the tricarboxylic acid cycle.