Micellization and Clouding Phenomenon of Phenothiazine Drug Promethazine Hydrochloride: Effect of NaCl and Urea Addition

Herein we report the micellization and clouding behavior of promethazine hydrochloride (PMT) in absence and presence of NaCl/ureas. The critical micelle concentration (CMC) of PMT is measured by conductivity method and the values decrease with increasing the NaCl concentration. With increasing the temperature, the CMC first increases then decreases. At 25°C, the maximum CMC values were obtained (with or without NaCl). The thermodynamic parameters are evaluated which indicate more stability of the PMT solution in presence of NaCl. PMT shows phase separation also. The cloud point (CP) of PMT decreases with increase in pH due to deprotonation of the drug molecules. Ureas decreased the CP and the behavior is explained on the basis of removal of water from the head group region.     

Quantitative analysis and pharmacokinetics study of tigecycline in human serum using a validated sensitive liquid chromatography with tandem mass spectrometry method

Tigecycline, a novel intravenously administered glycylcycline antibiotic, currently plays a key role in the management of complicated multiorganism infections. However, current liquid chromatography with tandem mass spectrometry methods briefly describe parameters and the only reported internal standard was sometimes difficult to obtain. In our study, an updated liquid chromatography with tandem mass spectrometry method for the quantitative analysis of tigecycline in human serum was developed. Sample preparation involved precipitation with 20% trichloroacetic acid. Chromatographic separation of tigecycline and tetracycline (internal standard) was achieved on a Hypersil GOLD C₁₈ column using gradient elution. The selected reaction monitoring transitions were performed at m/z 586.1→513.2 for tigecycline and m/z 445.1→410.2 for tetracycline. The assay was linear over the concentration range of 5–2000 ng/mL. The intra‐ and interday precisions at three concentration levels (10, 100, and 1600 ng/mL) were <15% and their accuracies were within the range of 95.1–106.1%. The mean recovery ranged from 94.3 to 105.6% and the matrix effect from 92.1 to 97.6%. Tigecycline was stable under all tested conditions. This validated method was successfully applied to a pharmacokinetic study in critically ill patients. The data demonstrated that our method allows quantification of tigecycline in serum in a quick and reliable manner for widespread application.     

A comparative study of two polymorphs of L‐aspartic acid hydrochloride

Two polymorphs of L‐aspartic acid hydrochloride, C₄H₈NO₄⁺·Cl⁻, were obtained from the same aqueous solution. Their crystal structures have been determined from single‐crystal data collected at 100 K. The crystal structures revealed three‐ and two‐dimensional hydrogen‐bonding networks for the triclinic and orthorhombic polymorphs, respectively. The cations and anions are connected to one another via N—H...Cl and O—H...Cl interactions and form alternating cation–anion layer‐like structures. The two polymorphs share common structural features; however, the conformations of the L‐aspartate cations and the crystal packings are different. Furthermore, the molecular packing of the orthorhombic polymorph contains more interesting interactions which seems to be a favourable factor for more efficient charge transfer within the crystal.     

纳米Ag/TiO_(2)纳米管阵列基底构建及表面增强拉曼散射光谱检测与降解盐酸四环素北大核心CSCD

将阳极氧化与光还原法结合,在TiO_(2)纳米管阵列(TiO_(2)NTAs)表面修饰Ag纳米粒子,获得一种均匀有序、稳定性高且可循环的TiO_(2)NTAs/Ag活性基底。采用X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(UV-Vis DRS)、表面增强拉曼散射光谱(SERS)和扫描电子显微镜(SEM)等手段对TiO_(2)NTAs/Ag的组成和结构进行了表征。进一步研究了该TiO_(2)-NTAs/Ag阵列对盐酸四环素(TC-HCl)的SERS响应,结果表明,该复合基底对TC-HCl具有较高的检测灵敏度,在水中检测限可达1×10^(−14) mol/L,而TiO_(2)-NTAs与Ag之间的协同效应对其检测性能的提高起着关键作用。此外,TiO_(2)NTAs/Ag基底在光照下对TC-HCl展示了优异的降解活性,且至少可循环使用8次。表明该TiO_(2)NTAs/Ag基底在环境中有机污染物的SERS检测和降解领域具有潜在的应用前景。     

Measurement and modeling of metoclopramide hydrochloride (anti-emetic drug) solubility in supercritical carbon dioxide

Knowledge of drug solubility data in supercritical carbon dioxide (SC-CO₂) is a fundamental step in producing nano and microparticles through supercritical fluid technology. In this work, for the first time, the solubility of metoclopramide hydrochloride (MCP) in SC-CO₂ was measured in pressure and temperature range of 12 to 27 MPa and 308 to 338 K, respectively. The results represented a range mole fractions of 0.15 × 10^-5 to 5.56 × 10^-5. To expand the application of the obtained data, six semi-empirical models and three models based on the Peng-Robinson equation of state (PR + VDW, PR + WS + Wilson and PR + MHV1 + COSMOSAC) with different mixing rules and various ways to describe intermolecular interactions were investigated. Furthermore, total enthalpy, sublimation enthalpy and solvation enthalpy relevant to MCP solvating in SC-CO₂ were estimated.     

Photocatalytic removal of tetracycline by a Z-scheme heterojunction of bismuth oxyiodide/exfoliated g-C3N4: performance,mechanism, and degradation pathway

Antibiotics, once being released into the environment, become recalcitrant organic pollutants, which pose a potential risk to ecological balance and human health. In this study, a Z-scheme heterojunction of bismuth oxyiodide (BiOI)/exfoliated g-C₃N₄ (BiOI/ECN hereafter) was synthesized by the combination of thermal exfoliation of g-C₃N₄ and chemical precipitation of BiOI for efficient photocatalytic degradation of tetracycline in aqueous solutions under visible light irradiation. The optimized BiOI/ECN delivered an outstanding degradation rate at circa 0.0705 min^?1, which was 10 times higher than that of the bulk g-C₃N₄. The photocatalytic degradation efficiency of tetracycline remained almost unchanged in a pH range of 3–11, and the BiOI/ECN displayed an excellent photostability upon recycled usage. The photocatalytic mechanism of tetracycline was ascribed to the main reactive oxidation species of photogenerated holes and superoxide radicals. In addition, the possible degradation pathways of tetracycline were investigated by HPLC-MS to identify intermediates. The toxicity of photocatalytic-generated intermediates of tetracycline was found significantly alleviated according to the calculation of quantitative structure–activity relationship prediction. This work not only provides an attractive photocatalyst for the removal of tetracycline but also opens a new avenue for rational design of Z-scheme heterojunction composites for tetracycline degradation.     

Preparation and fabrication of porous-Fe2O3/carbon black nanocomposite: a portable electrochemical sensor for psychotropic drug detection in environmental samples

Herein, we reported the fabrication of porous iron oxide/carbon black (P–Fe₂O₃/CB) composite through a two-step engineering method. At first, Prussian blue microcubes were used as a precursor and further calcined to form P–Fe₂O₃ microcubes. The intercalation of CB nanoparticles with P–Fe₂O₃ nanocubes was processed through the ultrasonication method. The obtained P–Fe₂O₃/CB were successfully scrutinized through various physiochemical characterization methods. The proposed P–Fe₂O₃/CB-modified glassy carbon electrode sensor was successfully implemented in the electrochemical sensing of chlorpromazine hydrochloride due to its very low charge transfer resistance (R_ct) compared to the other electrode modifiers. The sensitive detection of CPMH through differential pulse voltammetry exemplifies an excellent electroanalytical performance such as a wide linear range of 0.5–1472 μM, a lower detection limit (0.001 μM), and an appraisable sensitivity of 1.99 μA/μM cm^?2 due to its availability of a high number of active sites and its large surface area, respectively. It also expresses excellent selectivity, repeatability, reproducibility, and stability results. Moreover, the practical feasibility of the as-fabricated P–Fe₂O₃/CB/glassy carbon electrode sensor shows exquisite recovery (98.1–100.8%) results with an appraisable current response in various biological, pharmaceutical, and environmental samples.     

Divergent and Overlapping Roles for Selected Phytochemicals in the Regulation of Pathological Cardiac Hypertrophy

Plant-based foods, like fruits, vegetables, whole grains, legumes, nuts, seeds and other foodstuffs, have been deemed as heart healthy. The chemicals within these plant-based foods, i.e., phytochemicals, are credited with protecting the heart. However, the mechanistic actions of phytochemicals, which prevent clinical endpoints, such as pathological cardiac hypertrophy, are still being elucidated. We sought to characterize the overlapping and divergent mechanisms by which 18 selected phytochemicals prevent phenylephrine- and phorbol 12-myristate 13-acetate-mediated cardiomyocyte enlargement. Of the tested 18 compounds, six attenuated PE- and PMA-mediated enlargement of neonatal rat ventricular myocytes. Cell viability assays showed that apigenin, baicalein, berberine hydrochloride, emodin, luteolin and quercetin dihydrate did not reduce cell size through cytotoxicity. Four of the six phytochemicals, apigenin, baicalein, berberine hydrochloride and emodin, robustly inhibited stress-induced hypertrophy and were analyzed further against intracellular signaling and genome-wide changes in mRNA expression. The four phytochemicals differentially regulated mitogen-activated protein kinases and protein kinase D. RNA-sequencing further showed divergence in gene regulation, while pathway analysis demonstrated overlap in the regulation of inflammatory pathways. Combined, this study provided a comprehensive analysis of cardioprotective phytochemicals. These data highlight two defining observations: (1) that these compounds predominantly target divergent gene pathways within cardiac myocytes and (2) that regulation of overlapping signaling and gene pathways may be of particular importance for the anti-hypertrophic actions of these phytochemicals. Despite these new findings, future works investigating rodent models of heart failure are still needed to understand the roles for these compounds in the heart.