Quantitative analysis of ephedrine analogues from ephedra species using 1H-NMR

Four ephedrine analogues such as ephedrine, pseudoephedrine, methylephedrine, and methylpseudoephedrine were determined by (1)H-NMR from Ephedra species. In the region of delta 5.0-4.0, the signals of H-1 attached to the same carbon with a hydroxyl, were well separated from each other in CDCl(3). The amount of each alkaloid was calculated by the relative ratio of the intensity of H-1 signal to the known amount of internal standard, 200 microg of anthracene. This method allows rapid determination of the quantity of four ephedrine alkaloids from Ephedra species. The amount of these alkaloids was in the range of 1.0-2.0% of dry weight depending on the plant materials.     

Bioactive clerodane diterpenes from roots of Carex distachya

Two new clerodane diterpenes were isolated from roots of Carex distachya Desf., a perennial plant widely distributed in the coastal area of the Mediterranean basin. Chemical characterization of the metabolites was carried out mainly by 1D and 2D NMR spectroscopy. The isolated compounds influenced either positively or negatively the plant growth (root and shoot elongation) of three coexisting herbaceous species.     

The Effect of Blood Contained in the Samples on the Metabolomic Profile of Mouse Brain Tissue: A Study by NMR Spectroscopy

(1) Recently, metabolic profiling of the tissue in the native state or extracts of its metabolites has become increasingly important in the field of metabolomics. An important factor, in this case, is the presence of blood in a tissue sample, which can potentially lead to a change in the concentration of tissue metabolites and, as a result, distortion of experimental data and their interpretation. (2) In this paper, the metabolomic profiling based on NMR spectroscopy was performed to determine the effect of blood contained in the studied samples of brain tissue on their metabolomic profile. We used 13 male laboratory CD-1^® IGS mice for this study. The animals were divided into two groups. The first group of animals (n = 7) was subjected to the perfusion procedure, and the second group of animals (n = 6) was not perfused. The brain tissues of the animals were homogenized, and the metabolite fraction was extracted with a water/methanol/chloroform solution. Samples were studied by high-frequency ¹H-NMR spectroscopy with subsequent statistical data analysis. The group comparison was performed with the use of the Student’s test. We identified 36 metabolites in the brain tissue with the use of NMR spectroscopy. (3) For the major set of studied metabolites, no significant differences were found in the brain tissue metabolite concentrations in the native state and after the blood removal procedure. (4) Thus, it was shown that the presence of blood does not have a significant effect on the metabolomic profile of the brain in animals without pathologies.     

Phytochemical investigation and biological studies of Bombax malabaricum flowers

In this study, extracts of the flowers of the folk medicinal plant Bombax malabaricum DC were biologically and chemically screened. Chemical constituents in the n-hexane fraction from the flowers of B. malabaricum DC were investigated using gas-liquid chromatography (GLC) analysis, affording 14 compounds, including cholesterol, stigmasterol, campesterol and α-amyrin, while the residual 10 compounds are hydrocarbons. GLC analysis of the fatty acid (FA) esters established the majority abundance of the saturated FA over their unsaturated analogues. The polar methanol fraction afforded seven flavones: vicenin 2 (1), linarin (2), saponarin (3), cosmetin (4), isovitexin (5), xanthomicrol (6) and apigenin (7). Structures 1-7 were established by intensive studies of various spectral data (H-NMR, mass spectroscopy and UV) and comparison with authentic samples. Compounds 1-7 are described here for the first time from this plant. Extracts of n-hexane and methanol exhibited significant antioxidant and antimicrobial activities.     

Application of high-field proton nuclear magnetic resonance (1H-NMR) spectroscopy for the analysis of explosives and related compounds in groundwater samples – a comparison with the high-performance liquid chromatography (HPLC) method

High-field proton nuclear magnetic resonance (¹H-NMR) spectroscopy was applied to the analysis of nitroaromatics and nitramines in ammunition waste water. The ¹H-chemical shifts data of a variety of reference compounds are presented. Three groundwater samples, taken near the former ammunition plant Elsnig (Saxony), were analysed by high-performance liquid chromatography (HPLC) and by proton nuclear magnetic resonance spectroscopy. The results of HPLC and NMR analyses are compared and discussed.     

Characterization of dandelion species using 1H NMR- and GC-MS-based metabolite profiling

Taraxacum, known as dandelion, is a large genus of plants in the family Asteraceae. Pharmacological studies have shown that these plants display a wide variety of medicinal properties because Taraxacum extracts contain many pharmacologically active metabolites that display anti-inflammatory, antinociceptive, antioxidant, and anticancer activity. Each plant species displays several different natural constituents, the majority of which have not been studied as no global metabolite screen of the diverse Taraxacum species has been performed. In this study, we investigated the metabolite difference in three species of Taraxacum (T. coreanum, T. officinale, and T. platycarpum) by (1)H NMR spectroscopy and gas chromatography-mass spectrometry (GC-MS) coupled with multivariate statistical analyses. The aim of this study was to identify the different chemical compositions of the polar and nonpolar extracts in these species. A partial least-squares discriminant analysis showed a significantly higher separation among nonpolar extracts (mainly fatty acids and sterols) compared to polar extracts (mainly amino acids, organic acids, and sugars) between these species. A one-way ANOVA was performed to statistically certify the metabolite differences of these nonpolar extracts. Taken together, these data suggest that a metabolomic approach using combined (1)H NMR and GC-MS analysis is an effective analytical method to differentiate biochemical compositions among different species in plants.     

对羟基苯甲酸与对苯二甲酸乙二酯的共聚物研究

对羟基苯甲酸与对苯二甲酸乙二酯的共聚物研究张广利，阎丰琪，李勇，王震，潘景岐，张鸿志（北京大学化学系北京１００８７１）关键词液晶共聚酯，ＰＥＴ／ＰＨＢ共聚脂，序列分布Ｊａｃｂｏｎ和ＫｕｈｆｕＪ’ｌ于７０年代报道了对羟基苯甲酸（ＰＨＢ）一对苯二甲酸乙二...     

Metabolomic fingerprinting of plant extracts

The standardization and quality control of plant extracts is an important topic, in particular, when such extracts are used for medicinal purposes. Consequently, the development of fast and effective analytical methods for metabolomic fingerprinting of plant extracts is of high interest. In this investigation, electrospray mass spectrometry (ESI-MS) and (1)H NMR techniques were employed with further statistical analyses of the acquired data. The results showed that negative ion mode ESI-MS is particularly effective for characterization of plant extracts. Different samples of the same species appear well-clustered and separated from the other species. To verify the effectiveness of the method, two other batches of extracts from a species, in which the principal components were already identified (Cynara scolymus), were analyzed, and the components that were verified by the principal component analysis (PCA) were found to be within the region identified as characteristic of Cynara Scolymus extracts. The data from extracts of the other species were well separated from those pertaining to the species previously characterized. Only the case of a species that was strictly correlated from a botanical point of view, with extracts that were previously analyzed, showed overlapping.     

Solution structural characterization of an array of nanoscale aqueous inorganic Ga13–xInx (0 ≤ x ≤ 6) clusters by 1H-NMR and QM computations

NMR spectroscopy is the go-to technique for determining the solution structures of organic, organometallic, and even macromolecular species. However, structure determination of nanoscale aqueous inorganic clusters by NMR spectroscopy remains an unexplored territory. The few hydroxo-bridged inorganic species well characterized by ¹H Nuclear Magnetic Resonance spectroscopy (¹H-NMR) do not provide enough information for signal assignment and prediction of new samples. ¹H-NMR and quantum mechanical (QM) computations were used to characterize the NMR spectra of the entire array of inorganic flat-Ga_13–xIn_x (0 ≤ x ≤ 6) nanoscale clusters in solution. A brief review of the known signals for μ₂-OH and μ₃-OH bridges gives expected ranges for certain types of protons, but does not give enough information for exact peak assignment. Integration values and NOESY data were used to assign the peaks of several cluster species with simple ¹H-NMR spectra. Computations agree with these hydroxide signal assignments and allow for assignment of the complex spectra arising from the remaining cluster species. This work shows that ¹H-NMR spectroscopy provides a variety of information about the solution behavior of inorganic species previously thought to be inaccessible by NMR due to fast ligand and/or proton exchange in wet solvents.     

A Cross-Shaped Monomer as Building Block for Molecular Textiles

The exploration of new materials is timeless. Especially 2D-materials have gotten much interest in the last decades. This work proposes a new route towards a fascinating class of 2D materials: molecular textiles. The suggested bottom-up approach focuses on the 2D self-assembly of a cross-shaped monomer at the water/air interface. A 3D cross-shaped motive was designed, synthesized, and characterized, which exhibits the required structural features, i. e., static and dynamic control. Analysis of the cross-shaped motive by ¹H-NMR spectroscopy, X-ray structure, and chiral stationary phase HPLC proved the rigidity and stability of the system, and thus also its potential for the here suggested new strategy towards molecular textiles. Three variants of a Schiff-base precursor pair functionalized monomer were synthesized and characterized by ¹H-NMR spectroscopy, ¹³C-NMR spectroscopy, and mass spectrometry. Finally, the network formation of the monomer is shown to be triggered by deprotonation of its ammonium salt, corroborated with FT-IR analysis.     

Preparation and spectroscopic studies of an inclusion complex of adenine with beta-cyclodextrin in solution and in the solid state

The interaction between adenine and beta-CD has been investigated in solution and in the solid state by several analytical techniques, primarily by 1H-NMR, 2D ROESY and fluorescence spectra, and secondarily by other important techniques, for example, Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). The association constant and 1:1 nature of the complex between adenine and beta-CD in solution were determined by fluorescence spectroscopy. A spatial configuration for the complex in solution is proposed from analysis of the 1H-NMR and 2D ROESY data. The Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) data are consistent with the formation of an inclusion complex. In addition, a solid inclusion complex of adenine with beta-CD was synthesized by the coprecipitation method.     

Characterization of 40 kDa poly(ethylene glycol) polymers by proton transfer reaction QTOF mass spectrometry and 1H-NMR spectroscopy

Several electrospray mass spectrometry (ESI-MS) techniques have been described during the past years to enable the characterization work of large poly(ethylene glycol)s (PEGs) and PEGylated proteins. The proton transfer reaction ESI-MS method utilizes amines to charge reduce the electrospray envelope of PEGs, hence PEG molecules are aminated instead of protonated. This method simplifies the mass spectrum of large PEGs, and enables the interpretation of the charge state of the observable envelopes (R ≥ 3,000 (FWHM) measured at the (M + 6H)⁶⁺ ion from 40 K PEG compound 7,324.19). Hence, deconvolution of the MS data can be performed and relative molecular masses of the individual chain lengths of the PEGs can be calculated. However, as the poly-dispersity of PEGs may vary from batch to batch and from sample to sample, it was of interest to examine if the method could distinguish between these kinds of different material. Therefore, sample materials of each intermediate obtained at five synthetic steps during synthesis of a 40 kDa PEG molecule were collected. These four intermediates, starting material and the target molecule were examined by ¹H-NMR spectroscopy and ESI-MS using a proton stripping base. The study revealed that the charge-stripping ESI-MS method is able to differentiate between even small changes in the structure of the polymeric molecules only when the analysis is assisted by ¹H-NMR spectroscopy. A proper characterization of polymer molecules requires besides relative molecular mass, also poly-dispersity and end-group characterization. No end-group information is obtained based on MS data. Examination of the PEG polymers by ¹H-NMR spectroscopy provides the needed information. In addition, the ¹H-NMR spectra clearly distinguishes the examined polymers.     

L-丙交酯/ε-己内酯共聚物分子链结构非均匀性的研究

利用升温淋洗分级(TREF)和连续自成核退火热分级(SSA)等方法研究了L-丙交酯(LLA)和ε-己内酯(ε-CL)共聚物(PLC)分子链结构的非均匀性.合成了2种不同摩尔比的PLC共聚物,用TREF的方法,将同一个共聚物分级出3个级份.用核磁共振氢谱(1H-NMR)和凝胶渗透色谱(GPC)等方法对每个级份的分子结构进行了表征.结果表明,随着淋洗温度的升高,共聚物级份中的ε-CL单元的含量明显降低,而且级份的数均分子量增大,分子量分布指数降低.在SSA热分级研究中,发现PLC各级份间存在明显的分子链间和分子链内结构上的差异,这种链结构差异使得各个级份表现出不同的熔融行为.     

Analysis of nitrophenols and other polar nitroaromatic compounds in ammunition wastewater by high-field proton nuclear magnetic resonance (1H-NMR) spectroscopy and chromatographic methods

 It is shown that by using high-field proton nuclear magnetic resonance (¹H-NMR) spectroscopy it is possible, without prior separation, to analyse nitrophenols and other acidic nitroaromatic compounds in the “pH 2 extract” of ammunition wastewater. The ¹H-NMR chemical shifts data of a variety of reference compounds are presented. Two groundwater samples from the former ammunition plant in Elsnig (Saxony) were analysed by ¹H-NMR and also by chromatographic methods (GC/MS, HPLC). The results are compared and discussed. Received: 17 January 1996/Revised: 15 May 1996/Accepted: 17 May 1996     

Analysis of nitrophenols and other polar nitroaromatic compounds in ammunition wastewater by high-field proton nuclear magnetic resonance (1H-NMR) spectroscopy and chromatographic methods

 It is shown that by using high-field proton nuclear magnetic resonance (¹H-NMR) spectroscopy it is possible, without prior separation, to analyse nitrophenols and other acidic nitroaromatic compounds in the “pH 2 extract” of ammunition wastewater. The ¹H-NMR chemical shifts data of a variety of reference compounds are presented. Two groundwater samples from the former ammunition plant in Elsnig (Saxony) were analysed by ¹H-NMR and also by chromatographic methods (GC/MS, HPLC). The results are compared and discussed. Received: 17 January 1996/Revised: 15 May 1996/Accepted: 17 May 1996     

A novel thiophene-fused polycyclic aromatic with a tetracene core: synthesis, characterization, optical and electrochemical properties

FeCl?-mediated oxidative cyclization was successfully used to construct an extended thiophene-pendant pyrene skeleton and synthesize a novel thiophene-fused polycyclic aromatic (THTP-C) with a tetracene core. The identity of the compound was confirmed by 1H-NMR, 13C-NMR, MS, and elemental analysis. Meanwhile, a single crystal of THTP-C was obtained and analyzed by X-ray single-crystal diffraction. THTP-C has a "saddle" shaped π-conjugated 1-D supramolecular structure, and favors highly ordered self-assembly by π-π interactions as evidenced by its concentration-dependent 1H-NMR spectra in solution. The optical properties of THTP-C were investigated by ultraviolet-visible (UV-Vis) and photoluminescence (PL) spectroscopy and its electrochemical properties were investigated by cyclic voltammetry (CV). The relatively large band gap (2.86 eV), low E(HOMO) level (-5.64 eV) and intermolecular π-π interactions imply that THTP-C has a high stability against photo-degradation and oxidation, and may be a promising candidate for stable hole-transporting materials.     

Characteristics of ternary clove/water/1-butanol microemulsions based drug delivery system for aspirin

This work was intended to characterize aspirin solubilized in microemulsion systems comprising clove oil, 1-butanol and water. Microemulsions demonstrated the unique ability to solubilize aspirin in polar media, thus having good potential in drug delivery. After incorporation of aspirin, four samples were selected in microstructure and be investigated by conductivity measurements, transmission electron microscope (TEM), and spectroscopic studies (¹H-NMR, UV-visible spectroscopy, and IR spectra). The percolation behavior with variation of weight fraction of aqueous phase (?) was confirmed by conductivity measurements. In order to study the effect of aspirin, the conductivity results of aspirin-loaded samples were compared with non-loaded ones. The proton transfer and The competitive H-bonding interactions between aspirin with butanol and water were also discussed in details using ¹H-NMR, UV-visible spectroscopy, and IR spectra. These measurements confirmed that the hydrogen-bonded ion pair structure dominated in the solutions.     

Green Synthesis of Gold,Iron and Selenium Nanoparticles Using Phytoconstituents: Preliminary Evaluation of Antioxidant and Biocompatibility Potential

This study aimed at fabricating gold (Au), iron (Fe) and selenium (Se) nanoparticles (NPs) using various natural plant extracts from the Fertile Crescent area and evaluating their potential application as antioxidant and biocompatible agents to be used in the pharmaceutical field, especially in drug delivery. The Au-NPs were synthesized using Ephedra alata and Pistacia lentiscus extracts, whereas the Fe-NPs and Se-NPs were synthesized using peel, fruit and seed extracts of Punica granatum. The phytofabricated NPs were characterized by the UV-visible spectroscopy, scanning electron microscope, Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and energy-dispersive X-ray (EDS) spectroscopy. Scanning electron microscope technique showed that the synthesized NPs surface was spherical, and the particle size analysis confirmed a particle size of 50 nm. The crystalline nature of the NPs was confirmed by the XRD analysis. All synthesized NPs were found to be biocompatible in the fibroblast and human erythroleukemic cell lines. Se-NPs showed a dose-dependent antitumor activity as evidenced from the experimental results with breast cancer (MCF-7) cells. A dose-dependent, free-radical scavenging effect of the Au-NPs and Se-NPs was observed in the DPPH (2,2-Diphenyl-1-picrylhydrazyl) assay, with the highest effect recorded for Au-NPs.     

Photochemically catalyzed reaction of ochratoxin A with D- and L-cysteine

The photolysis (>300 nm) of ochratoxin A (OTA, N-[[(3R)-5-chloro-8-hydroxy-3-methyl-1-oxo-7-isochromanyl]carbonyl]-3-phenyl-L-alanine, 1) in the presence of excess (2 and 12 molar equiv) cysteine (CySH) has been investigated and found to yield sulfur adducts 5 and 6 that are characterized by liquid chromatography-mass spectrometry and 1H-NMR spectroscopy. The adduct 5 was ascribed to the Michael addition conjugate resulting from covalent attachment of CySH to the ochratoxin quinone (4) generated by photooxidation of OTA. This species was also formed by photolysis of a synthetic sample of the hydroquinone of OTA (ochratoxin hydroquinone, 3) in the presence of 12 equiv L-CySH. The conjugate 5 derived from photolysis of 3 with L-CySH was used for 1H-NMR analysis. The sulfur adduct 6 was the major species detected from covalent attachment of CySH to photoactivated OTA, and it resulted from direct displacement of the OTA Cl atom by CySH. The implications of the cysteinyl adducts to the in vivo toxicity of OTA are discussed, with particular emphasis given to conjugate 5, as products from the photooxidative pathway may be of relevance to the nephrotoxic properties of OTA.     

Product analyses and crosslink mechanism of plasma-polymerized methyl methacrylate

Plasma-polymerized methyl methacrylate (PPMMA) film was produced by a radio-frequency glow discharge of methyl methacrylate (MMA) gas with argon. PPMMA deposited under a plasma of mild energy was separated into a soluble fraction (sol-PPMMA) and an insoluble matrix (insol-PPMMA), which is highly crosslinked, by solvent-extraction and filtration. The chemical structure of the sol-PPMMA was determined by pyrolysis/gas chromatography, IR spectroscopy, ¹H-NMR, ¹³C-NMR, and elemental analysis techniques. On the other hand, the structure of the insol-PPMMA was examined with IR spectroscopy, ¹³C-NMR with CP/MAS method, and elemental analysis. The crosslinking mechanism in the plasma polymerization of MMA is discussed on the basis of product analyses of the sol-PPMMA and the insol-PPMMA.