查找使用阿拉丁产品的科研文献

Investigation on chain segment motions of various starch molecules under different glycerol-water system

Liping Mei,Zhijie Zhu,Caihong Wang,Chengyi Sun,Peirong Chen,Huimei Cai,Xu Chen,Xianfeng Du

The molecular motion of starch at different glycerol concentrations (0, 20, 50, and 80 %) was investigated using Electron Paramagnetic Resonance (EPR) spectroscopy. Fourier-transform infrared (FTIR) spectroscopy and 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy confirmed that hydroxyl groups at the C2 and C3 positions of glucose units in corn starch (CS), waxy corn starch (WCS), and high amylose corn starch (HCS) were labeled with 4-amino-TEMPO. The crystallinities of CS, WCS, and HCS after spin-labeling decreased from 30.68 % to 3.21 %, 39.36 % to 1.65 %, and 28.54 % to 8.08 %, respectively. The pseudoplastic fluid properties of the spin-labeled starch remained shear-thin at different glycerol concentrations. EPR revealed the fast- and slow-motion components of the spin-labeled starch molecules dispersed in water. At a glycerol concentration of 20 %, the slow-motion component disappeared, indicating a faster rotational motion of the starch chain segments. As the glycerol concentration increased to 50 and 80 %, the rotational motion slowed because of high viscosity. In particular, the mobility of the spin-labeled WCS chains increased owing to easier access of glycerol and water to the branched structure. This study directly observed the dynamics of the molecular behavior of starch in glycerol-water systems.

Discovery of Novel 3,4-Dihydro-2(1H)-Quinolinone Sulfonamide Derivatives as New Tubulin Polymerization Inhibitors with Anti-Cancer Activity

Juan Ma,Guo-Hua Gong

In this paper, a small series of novel quinoline sulfonamide derivatives was synthesized, and their structure of the target compounds were confirmed by 1H NMR and MS. The screening of the news target compounds’ in vitro cytotoxic activities against tumor cell lines by the MTT method was performed. Among them, compoundD13(N-(4-methoxybenzyl)-2-oxo-N-(3,4,5-trimethoxyphenyl)-1,2,3,4-tetrahydroquinoline-6-sulfonamide exhibited the strongest inhibitory effect on the proliferation of HeLa (IC50: 1.34 μM), and this value correlated well with the inhibitory activities of the compound against tubulin polymerization (IC50: 6.74 μM). In summary, a new type of quinoline-sulfonamide derivative with tubulin polymerization inhibitory activity was discovered, and it can be used as a lead compound for further modification.Keywords:synthesis;quinoline-sulfonamide;anti-tumor;tubulin polymerization

Synthesis of 4,5,6-trisubstituted 2,3-pyridinediones via Mannich reaction and oxidation–Michael addition of 3-hydroxy-2(1H)-pyridinones

Xie Wen Lin,Xiao Chuang Ping,Xie Ling,Zhou Ying,Li Xue Feng,Tang Xu Fu,Yuan Chun Tao,Qiu Ming Hua

4 - Substituted 3-hydroxy-2(1 H )-pyridinones 2 were prepared by Mannich reaction of 3-hydroxy-2(1 H )-pyridinones with secondary amines and formaldehyde. The isolated products were then reacted with aromatic amines in the presence of NaIO 3 as oxidant via oxidation–Michael addition to yield 4,5,6-trisubstituted-2,3-pyridinediones 3 in good yields (80.2–88.9%). The structures of the products were characterized by 1 H NMR, ESI-MS, and IR, and elemental analysis.

Design, synthesis, and biological evaluation of 3-vinyl-quinoxalin-2(1H)-one derivatives as novel antitumor inhibitors of FGFR1

Zhiguo Liu,Shufang Yu,Di Chen,Guoliang Shen,Yu Wang,Leping Hou,Dan Lin,Jinsan Zhang,Faqing Ye

Synergism between SLC6A14 blockade and gemcitabine in pancreactic cancer: a 1H-NMR-based metabolomic study in pancreatic cancer cells

Cai Aimin,Zheng Hailun,Chen Zhiwei,Lin Xinlu,Li Chen,yao Qing,Bhutia Yangzom D.,Ganapathy Vadivel,Chen Ruijie,Kou Longfa

Gemcitabine is the first-line chemotherapy for pancreatic cancer. To overcome the often-acquired gemcitabine resistance, other drugs are used in combination with gemcitabine. It is well-known that cancer cells reprogram cellular metabolism, coupled with the up-regulation of selective nutrient transporters to feed into the altered metabolic pathways. Our previous studies have demonstrated that the amino acid transporter SLC6A14 is markedly up-regulated in pancreatic cancer and that it is a viable therapeutic target. α-Methyltryptophan (α-MT) is a blocker of SLC6A14 and is effective against pancreatic cancer in vitro and in vivo. In the present study, we tested the hypothesis that α-MT could synergize with gemcitabine in the treatment of pancreatic cancer. We investigated the effects of combination of α-MT and gemcitabine on proliferation, migration, and apoptosis in a human pancreatic cancer cell line, and examined the underlying mechanisms using 1H-NMR-based metabolomic analysis. These studies examined the intracellular metabolite profile and the extracellular metabolite profile separately. Combination of α-MT with gemcitabine elicited marked changes in a wide variety of metabolic pathways, particularly amino acid metabolism with notable alterations in pathways involving tryptophan, branched-chain amino acids, ketone bodies, and membrane phospholipids. The metabolomic profiles of untreated control cells and cells treated with gemcitabine or α-MT were distinctly separable, and the combination regimen showed a certain extent of overlap with the individual α-MT and gemcitabine groups. This represents the first study detailing the metabolomic basis of the anticancer efficacy of gemcitabine, α-MT and their combination.

Novelly quantitative analysis on mixtures of food supplements containing amino acids via high-resolution pure shift 1H NMR spectroscopy

Hui Ma,Na Gu,Yichuan Wu,Yanan Wang,Pu Qiu,Kefeng Wu,Jiancheng Zhao,Qi Zhao

Identifying and quantifying amino acids in complex systems of food supplements by conventional 1 H NMR spectroscopy is a challenging task. Extensive signal overlaps of a variety of amino acids in 1 H NMR spectra limit its application in the analysis of the complex amino acid systems. Triple spin echo PSYCHE (TSE-PSYCHE), a pure shift NMR analytical technique, can provide a simplified and high-resolution proton spectrum by removing the 1 H– 1 H homonuclear couplings. Hence, this TSE-PSYCHE NMR method can substantially alleviate the overlap problem so that it has a great potential for quantifying complex amino acid mixtures. Moreover, based on TSE-PSYCHE NMR we successfully quantified the components of two commercial amino acid nutrition tablets: the quantification regression analysis affords a satisfactory linearity with correlation coefficients higher than 0.9910 for all analytes, limit of detection (LOD, 0.075–0.66 mg/mL), limit of quantification (LOQ, 0.25–2.21 mg/mL), accuracy (bias %: 0.06–3.4), the recovery values between 92.38 and 109.0 %, and precision (the relative standard deviations, RSD %) at the range of 0.48–3.50. In this work, we developed a novel quantitative NMR for a global and direct analysis of amino acids of food supplement content.

A Novel Electrochromic Copolymer of bis(4-(1H-pyrrol-1-yl)phenyl)methane and 3,4-ethylenedioxythiophene Prepared via Electrocopolymerization

Mi Ouyang,Pingjing Wang,Zhiyan Fu,Cheng Zhang

A novel copolymer based on bis(4-(1H-pyrrol-1-yl)phenyl)methane (BPM) and 3,4-ethylenedioxythiophene (EDOT) is successfully synthesized and characterized through electrochemical methods. The polymer film exhibits three distinct colors (khaki, yellow green, midnight blue) under different potentials, reasonable optical contrast (10% at 422 nm, 5% at 1100 nm) and fast swiching time (2.6 s at 422 nm, 2.2 s at 1100 nm). Beside, SEM images illustrates that the copolymer film presents a much smoother surface than that of the respective homopolymers, which means that the copolymer film have great potential in electrochromic device fabrication.

2-Carboxamido-6-(1H-pyrazol-3-yl)-pyridines as ligands for efficient separation of americium(III) from europium(III)

Lianjun Song,Xueyu Wang,Dongqi Wang,Qian Xiao,Haowei Xu,Qiuju Li,Lanlan He,Songdong Ding

The synthesis, Eu 3+ complexation, and selective solvent extraction of Am 3+ over Eu 3+ in nitric acid solution by 2-carboxamido-6-(1 H -pyrazol-3-yl)-pyridines (A-PzPy) ligands were described. Without the aid of any lipophilic anion source, A-PzPy ligands in methyl isobutyl ketone (MIBK) diluent demonstrated a more favorable affinity of Am 3+ than Eu 3+ at high acidity levels. Slope analysis showed the formation of 1:2 metal/ligand extracted species. The extraction was a spontaneous exothermic process. The analyses of fluorescence titration, Fourier transform infrared (FT-IR), Raman, time-resolved laser fluorescence spectrum (TRLFS), electrospray ionization mass spectrometry (ESI-MS), conductivity and microcalorimetric titration revealed that the composition of complex is [Eu(NO 3 ) 2 (H 2 O)∙2(Et- p -Tol-A-PzPy)](NO 3 ). Combining the results of solvent extraction and complexation study, the extraction mechanism was proposed. Furthermore, the stability constants (log β ) and thermodynamic parameters (Δ H , Δ S , Δ G ) for complexation of Eu 3+ with Et- p -Tol-A-PzPy were also presented.

1H NMR and chemical analysis to characterize camellia oil obtained by different extraction methods: A comparative study using chemometrics

Ting Shi,Gangcheng Wu,Qingzhe Jin,Xingguo Wang

Camellia oil has become one of the most popular edible vegetable oils especially in China. It can be obtained by cold-pressing (CPE), soxhlet extraction (SE), aqueous enzymatic extraction (AEE), and supercritical carbon dioxide extraction (SC-CO 2 ), while research on their efficient identification is limited. Thus, in this study, proton nuclear magnetic resonance ( 1 H NMR) and conventional chemical analysis, respectively coupled to chemometrics, were employed to compare the camellia oils, produced by CPE, SE, AEE, and SC-CO 2 . The results showed an obviously overlapping among those four different extracted camellia oils, in both principal component analysis (PCA) and hierarchical clustering analysis (HCA), when using fatty acids as input variables. While two obtained PCA models showed good discrimination, according to the minor component compositions (α-tocopherol, squalene, stigmasterol, β-sitosterol, β-amyrin and lanosterol) and 1 H NMR spectra, respectively. Additionally, by means of variable importance for the projection (VIP) scores, less 10 dominant 1 H NMR spectra signals were screened out as detailed markers for different camellia oils classification. Therefore, 1 H NMR combined with chemometrics may be applied as an efficient technique to classify different extracted camellia oils and potentially other vegetable oils.

Simultaneous, Simple and Rapid Determination of Five Bioactive Free Anthraquinones in Radix et Rhizoma Rhei by Quantitative 1H NMR

Dong Jian-Wei,Cai Le,Fang Yun-Shan,Duan Wei-He,Li Zhen-Jie,Ding Zhong-Tao

Radix et Rhizoma Rhei has been recognized for centuries in traditional medicine for its multiple pharmacological actions. The free anthraquinones including physcion, chrysophanol, emodin, rhein, and aloe-emodin are the main bioactive components in Radix et Rhizoma Rhei. In the present study, a fast quantitative 1H nuclear magnetic resonance (q-HNMR) method for the determination and quantitation of five free anthraquinones in Radix et Rhizoma Rhei was developed. Validation of the quantitative method was performed in terms of specificity, accuracy, precision, and stability. The results showed that the solvent acetone-d6 enabled satisfactory separation of the signals to be integrated. Five anthraquinones in Radix et Rhizoma Rhei could be quantified accurately using featured signals from 1H NMR. This work implied that q-HNMR represents a feasible alternative to high-performance liquid chromatography (HPLC)-based methods for quantitation of anthraquinones in Radix et Rhizoma Rhei and is suitable for the quality control of Radix et Rhizoma Rhei.

Determination of cis/trans fatty acid contents in edible oils by 1H NMR spectroscopy in association with multivariate calibration

Xiuming Jiang,Denghui Yang,Guoqiang Xiang,Leqian Hu

In this work, cis and trans fatty acid (FA) contents in edible oils was determined using 1 H nuclear magnetic resonance ( 1 H NMR) spectroscopy. The comparison of 1 H NMR spectra of edible oil and cis-trans isomerized oil showed that they were different in three regions: (1) 2.880 - 2.650 ppm caused by bis-allylic protons; (2) 2.140 - 1.900 ppm due to allylic protons; and (3) 1.030 - 0.930 ppm due to methyl protons of linolenic acyl groups. The 1 H NMR signals in these regions were combined with partial least squares method to predict contents of cis/trans fatty acids in edible oils. The results showed that the predicted values were consistent with the gas chromatography-measured values and had a good linear relationship with a correlation coefficient (R 2 ) of above 0.98. This work demonstrates that 1 H NMR spectroscopy was successfully used to determine the composition of both cis and trans fatty acids in edible oils.

Catalytic co-pyrolysis of 5-Amino-1H-Tetrazole assembled with copper and boron powder: Pyrolysis kinetics and reaction mechanism

Jiu Chen,Bin Li,Cheng-Yang Cao,Si-Yuan Zhou,Li-Feng Xie,Dan Zhang

As a novel rich nitrogen content material, 5-Amino-1 H -Tetrazole (5AT) has been considerably popularized in the propellants area recently. The pyrolysis is deemed as the prelude of combustion for solid phase 5AT, which plays a crucial role in combustion process and grasping the pyrolysis characteristics will be more beneficial to further explore the combustion properties of 5AT-based propellant. In this paper, several efforts have been made to enhance the pyrolysis behaviors of 5AT, including employing metal particles as catalysts, and modifying the surface treatment method. Due to the calorific value, the boron and copper powder are selected as the potential catalysts. The solvent/non-solvent (S/NS) and solution recrystallization method are compared to explore the impact of these two modification methods. TG-FTIR technique is applied to capture evolved signals of organic compounds to further deduce the most probable decomposition pathway. Moreover, model-free and model-fitting methods are both employed to calculate the kinetic parameters. The results reveal that, for the modified 5AT samples with the same boron powder catalyst, the activation energies and reaction model (all governed by F4) in the initial stage (100–330 °C) are not significantly impacted by these two modification methods. However, during the latter stages (400–750 °C), the catalytic actions of boron powder appear to be more active, and solution recrystallization method exerts better modification effect, the activation energies was reduced 18.3 kJ/mol and 10.9 kJ/mol respectively for the latter stages compared to S/SN method. Also, the reaction model is transformed from n th -dimensional model (D3) to n th -order model (F1) in the third stage. Particularly, the catalytic actions of copper powder results in the simplification of decomposition steps for 5AT, the activation energies was 138.8 kJ/mol and the catalytic effect of which was improved about 25% compared to the catalytic effect of boron powder in the first stage and its reaction model is also found to be changed into F3. It illustrates that copper powder could embody a better catalytic effect than boron powder under the same modification method. The conclusions of this study could provide a worthwhile guidance for the understanding, designs and applications of the 5AT-based propellants.