New hydrophobic L‐amino acid salts: maleates of L‐leucine,L‐isoleucine and L‐norvaline

Crystals of maleates of three amino acids with hydrophobic side chains [L‐leucenium hydrogen maleate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻, (I), L‐isoleucenium hydrogen maleate hemihydrate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻·0.5H₂O, (II), and L‐norvalinium hydrogen maleate–L‐norvaline (1/1), C₅H₁₁NO₂⁺·C₄H₃O₄⁻·C₅H₁₂NO₂, (III)], were obtained. The new structures contain C₂²(12) chains, or variants thereof, that are a common feature in the crystal structures of amino acid maleates. The L‐leucenium salt is remarkable due to a large number of symmetrically non‐equivalent units (Z′ = 3). The L‐isoleucenium salt is a hydrate despite the fact that L‐isoleucine is a nonpolar hydrophobic amino acid (previously known amino acid maleates formed hydrates only with lysine and histidine, which are polar and hydrophilic). The L‐norvalinium salt provides the first example where the dimeric cation L‐Nva...L‐NvaH⁺ was observed. All three compounds have layered noncentrosymmetric structures. Preliminary tests have shown the presence of the second harmonic generation (SGH) effect for all three compounds.     

Analysis of Pheniramine Naleate and Cblorpheniramine Maleate Via Their Fe (III) Cohplexes

Abstract

A new spectrophotoraetric method has been developed for the analysis of pheniramine maleate and chlorphenlramine maleste, based on their reaction with iron (III). Pheniramine maleate and ch lor pheniramine maleate were found to form a 2:1 complex with iron (III) with an average log. stability constant of 12.26 and 12.36, respectively. The iron (III) complexes of both drugs showed maximum absorption at 273 nm, at pH 5, with slopes equal to 0.710 and 0.898 for pheniramine maleate complex and chlorpheniramine maleate complex, respectively. The proposed method was used for the determination of pheniramine maleate and chlorpheniramine maleate in quantities ranging between 0.25 × 10^?4 M to 2.5 × 10^?4 M with mean percentage recoveries of 100.17 ± 1.09% and 100.00 ± 1.13% for both drugs, respectively. The results obtained were compared with that of the B.P. (1980) method.     

大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法对马来酸氯苯那敏的测定

建立了大体积进样-乙腈盐堆积-胶束扫集毛细管电动色谱法测定马来酸氯苯那敏片中马来酸氯苯那敏的新方法,并考察了样品中乙腈和NaCl浓度对分离效果的影响.结果表明,以12 mmol/L四硼酸钠-50 mmol/L硼酸- 50 mmol/L十二烷基硫酸钠(SDS)为缓冲液(含10%甲醇,pH9.1),以70%乙腈- 200m...     

Phase equilibria of (water-carboxylic acid-diethyl maleate) ternary liquid systems at 298.15 K

Liquid-liquid equilibrium (LLE) data for the ternary systems of (water-formic acid-diethyl maleate), (water-acetic acid-diethyl maleate), (water-propionic acid-diethyl maleate), (water-butyric acid-diethyl maleate), and (water-valeric acid-diethyl maleate) were investigated at 298.15 K and atmospheric pressure. Complete phase diagrams were obtained by determining solubility and the tie-line data. The tie-line data were compared with the results predicted by the UNIFAC and the modified UNIFAC (Dortmund) methods and correlated by means of UNIQUAC model. The reliability of the experimental tie-line data was confirmed by using the Othmer-Tobias correlation. Distribution coefficients and selectivity were evaluated for the immiscibility region.     

Synthesis and photophysical study of silver nanoparticles stabilized by unsaturated dicarboxylates

Solution-phase synthesis of nanometer-sized silver particles is reported by sodium borohydride reduction of AgNO_3. Two isomeric dicarboxylates (sodium maleate and sodium fumarate) have been used as stabilizing agents. The dicarboxylate-stabilized silver nanoparticles are characterized by UV-vis spectroscopy, high-resolution transmission electron microscopy (HR-TEM) and fourier transform infrared (FT-IR) spectroscopy. A qualitative comparison is made between the UV-vis spectral characteristic of the SPR band and the simulated curve obtained from modified Mie's theory. Silver nanoparticles prepared using these two isomeric dicarboxylates show intense fluorescence in the visible region. DFT with hybrid functional (B3LYP)-based frequency (IR) calculation of both the dicarboxylates and the respective nanoparticles are in good agreement with the experimental IR frequency. On the basis of this calculation a model has been proposed for the stabilization of silver nanoparticles by these two isomeric dicarboxylate anions.     

Translational medicine of the glutamate AMPA receptor

Psychiatric and neurological disorders severely hamper patient’s quality of life. Despite their high unmet needs, the development of diagnostics and therapeutics has only made slow progress. This is due to limited evidence on the biological basis of these disorders in humans. Synapses are essential structural units of neurotransmission, and neuropsychiatric disorders are considered as “synapse diseases”. Thus, a translational approach with synaptic physiology is crucial to tackle these disorders. Among a variety of synapses, excitatory glutamatergic synapses play central roles in neuronal functions. The glutamate α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) is a principal component of glutamatergic neurotransmission; therefore, it is considered to be a promising translational target. Here, we review the limitations of current diagnostics and therapeutics of neuropsychiatric disorders and advocate the urgent need for the promotion of translational medicine based on the synaptic physiology of AMPAR. Furthermore, we introduce our recent translational approach to these disorders by targeting at AMPARs.     

固体酸催化合成马来酸二辛酯

首次将铌酸用于催化合成马来酸二辛酯,在酐醇摩尔比1：3,回流反应1h,催化剂用量为5g/mol酐的条件下,转化率为99．3％,选择性为85．6％,催化剂不经处理,可循环使用多次,且不污染环境,相对于一些常见催化剂,具有明显的优点。     

基于VB的岭回归法测定扑热息痛等五组分含量的研究

将岭回归吸光光度法（LHG）应用于感冒液中扑热息痛,扑尔敏,咖啡因,愈创木酚甘油醚和对氮基酚等五组分含量的同时测定,运用VB语言进行程序设计。试验结果表明,该法样品各组分的平均回收率在97．9％－103．3％之间,样品不经分离即可测定,取得了满意的分析结果。     

3种药物分子的1H和13C NMR谱线全指定

应用1D和2D NMR技术,对3种药物分子：比卡鲁胺(Bicalutamide)、马来酸罗格列酮(Rosiglitazone Maleate)、氯吡格雷硫酸盐(Clopidogrel Hydrogensulfate)的¹H和¹³C NMR的谱峰进行了准确归属.     

Uncertainty assessment from robustness testing applied on an LC assay for R-timolol and other related substances in S-timolol maleate

The robustness testing of a normal-phase liquid chromatographic (LC) method for the determination of R-timolol and other related substances in S-timolol maleate was performed applying a two-level Plackett-Burman design. Two qualitative and five quantitative factors were examined. Two types of responses were considered, qualitative, i.e. chromatographic performance criteria, and quantitative ones. The latter were taken into account to determine if the analytical procedure was robust. The quantitative responses were the contents of R-timolol in two S-timolol maleate samples. Even though some significant factor effects were observed on the qualitative responses, the R-timolol contents were not significantly different from those observed at nominal conditions, which demonstrated the robustness of the procedure.Since the experiments of the Plackett-Burman design can be assimilated to laboratories in an interlaboratory study, uncertainty can be evaluated using the robustness test data. The robustness test was set-up in such a way that the required variances could be estimated. It was shown that the robustness set-up allows estimating the reproducibility uncertainty without performing an interlaboratory study.