Steroidal Alkaloids from Veratrum maackii Regel with Genotoxicity on Brain‐Cell DNA in Mice

Two new steroidal alkaloids, 23‐methoxycyclopamine 3‐O‐β‐D ‐glucopyranoside ( 1 ) and isoecliptalbine ( 2 ), were isolated from the root and rhizoma of Veratrum maackii Regel , together with five known compounds, i.e., verussurine ( 3 ), verabenzoamine ( 4 ), verazine ( 5 ), isoverazine ( 6 ), and verazinine ( 7 ). Their structures were established by extensive analysis of spectroscopic data, as well as by comparison with literature data. Compounds 1 – 7 could cause DNA damage in the cerebellum and cerebral cortex of mice in a dose‐dependent manner by using single‐cell gel electrophoresis (comet assay).     

阴离子型聚丙烯酰胺与阳离子表面活性剂的相互作用

采用自由基水溶液共聚法制备了带有负电荷的水溶性聚丙烯酰胺,研究了水溶液中聚合物与阳离子表面活性剂的相互作用及所导致的水溶性、黏度和流变学性质的变化,为进一步研究驱油提供了理论基础.     

树形大分子基药物传输系统结合强度及构型的分子动力学研究

采用全原子分子动力学方法系统研究了聚酰胺(PAMAM)型树形大分子非共价搭载4种抗癌药物分子(CE6,DOX,MTX及SN38)的药物传输复合体系.考察了药物分子种类、数量及树形大分子的代数和聚乙二醇化表面修饰对复合体系的结合强度、尺寸及溶剂中扩散行为的影响.研究发现,PAMAM自身变形能对药物-PAMAM间的结合有重要影响.搭载较多的药物分子可以使PAMAM自身增大,但同样搭载条件下经过聚乙二醇化修饰过的PAMAM变化并不明显.PAMAM分子表面的聚乙二醇化可以更高的强度结合更多的药物分子,并减缓其扩散速度,因而提高药物分子的搭载效率和体内滞留时间.为新型树形大分子基药物传输体系的设计提供理论依据.     

二苯胺取代吖啶衍生物发光材料的合成、表征及电致发光性能

设计合成了2个苯胺取代吖啶衍生物N3,N3,N6,N6-四苯基吖啶基-3,6-二胺(1)和N3,N3,N6,N6-四对甲苯基吖啶基-3,6-二胺(2),通过化学修饰在吖啶核的两端引入二苯胺取代基可以调节化合物的能级和堆积结构等性质,从而使这些吖啶衍生物具有良好的发光性能,可用于制备电致发光器件.基于吖啶衍生物为掺杂发光材料制备的电致发光器件均呈现绿光发射,器件开启电压较低(2.4 V),以化合物1和2制备的器件最高功率效率分别为4.9和8.2 lm/W.考察了其光物理、电化学、热学和荧光量子效率等性能.结果表明,化合物1和2具有较高的量子效率及匹配的能级结构,这是获得较高电致发光效率的基础.     

Low‐temperature headspace‐trap gas chromatography with mass spectrometry for the determination of trace volatile compounds from the fruit of Lycium barbarum L.

The total saccharides content of Lycium barbarum L. is very high, and a high temperature would result in saccharide decomposition and the emergence of a large amount of water. Moreover, the volatile compounds from the fruit of L. barbarum L. are rather low in concentration. Hence, it is difficult for a conventional headspace method to study the volatile compounds from the fruit of L. barbarum L. Since headspace‐trap gas chromatography with mass spectrometry is an excellent method for trace analysis, a headspace‐trap gas chromatography with mass spectrometry method based on low‐temperature (30°C) enrichment and multiple headspace extraction was developed to explore the volatile compounds from the fruit of L. barbarum L. The headspace of the sample was extracted in 17 cycles at 30°C. Each time, the compounds extracted were concentrated in the trap (Tenax TA and Tenax GR, 1:1). Finally, all the volatile compounds were delivered into the gas chromatograph after thermal desorption. With the method described above, a total of 57 compounds were identified. The identification was completed by mass spectral search, retention index, and accurate mass measurement.     

Selective adsorption of metronidazole on conjugated microporous polymers

Conjugated microporous polymers (CMPs) have recently received extensive attention in oil/organic solvent-water separation field as a kind of ideal porous absorbents with tunable porosity, large surface areas, and super-hydrophobicity. However, reports on the application of CMPs in adsorption of hydrophilic contaminants from water are very few. In this work, we studied the adsorption of metronidazole (MNZ), a polar antibiotic, by two kinds of CMPs. The adsorption characteristics of MNZ by the CMPs, including adsorption kinetics, mechanism, and isotherm parameters were calculated. The adsorption kinetics of MNZ was well expressed by the pseudo-second-order model, and the adsorption process was found to be mainly controlled by film diffusion. The adsorption isotherm data agreed well with the Langmuir isotherm model, and the values of free energy E indicated that the adsorption nature of MNZ on the CMPs was physisorption. Increasing dispersion degree of the CMPs in MNZ solution resulted in greater adsorption. This work may provide fundamental guidance for the removal of antibiotics by CMPs.     

Supramolecularly engineered phospholipids constructed by nucleobase molecular recognition: upgraded generation of phospholipids for drug delivery

Despite of great advances of phospholipids and liposomes in clinical therapy, very limited success has been achieved in the preparation of smart phospholipids and controlled-release liposomes for in vivo drug delivery and clinical trials. Here we report a supramolecular approach to synthesize novel supramolecularly engineered phospholipids based on complementary hydrogen bonding of nucleosides, which greatly reduces the need of tedious chemical synthesis, including reducing the strict requirements for multistep chemical reactions, and the purification of the intermediates and the amount of waste generated relative more traditional approaches. These upgraded phospholipids self-assemble into liposome-like bilayer structures in aqueous solution, exhibiting fast stimuli-responsive ability due to the hydrogen bonding connection. In vitro and in vivo evaluations show the resulted supramolecular liposomes from nucleoside phospholipids could effectively transport drug into tumor tissue, rapidly enter tumor cells, and controllably release their payload in response to an intracellular acidic environment, thus resulting in a much higher antitumor activity than conventional liposomes. The present supramolecularly engineered phospholipids represent an important evolution in comparison to conventional covalent-bonded phospholipid systems.     

Effect of nonlinear electrodynamics on shadows of slowly rotating black holes

In this study, we investigate the effect of nonlinear electrodynamics on the shadows of charged, slowly rotating black holes with the presence of a cosmological constant. Rather than the null geodesic of the background black hole spacetime, the trajectory of a photon, as a perturbation of the nonlinear electrodynamic field, is governed by an effective metric. The latter can be derived by analyzing the propagation of a discontinuity of the electromagnetic waveform. Subsequently, the image of the black hole and its shadow can be evaluated using the backward ray-tracing technique. We explore the properties of the resultant black hole shadows of two different scenarios of nonlinear electrodynamics, namely, the logarithmic and exponential forms. In particular, the effects of nonlinear electrodynamics on the optical image are investigated, as well as the image's dependence on other metric parameters, such as the black hole spin and charge. The resulting black hole image and shadow display rich features that potentially lead to observational implications.     

热熔灌输法制备三维骨架支撑金属锂复合负极

金属锂因具有极高的理论比容量(3860 mAh/g)和最低的电化学势(相对于标准氢电极为-3.04 V),被认为是下一代高比能锂离子电池的首选负极材料。然而,金属锂负极在电池循环过程中发生的刺状枝晶生长和体积变化等问题严重阻碍了其产业化应用进程。近年来研究表明,通过在金属锂中引入具有三维(3D)结构的宿主骨架,不但能有效抑制锂枝晶的生长,而且可以缓解金属锂负极的体积变化,从而提高金属锂电池的循环性能与安全性。因此,设计3D骨架/金属锂复合负极被认为是一种能有效解决金属锂问题的新兴策略。本文综述了热熔灌输法制备3D骨架/金属锂复合负极的研究进展。首先讨论了当前基于3D骨架的预存金属锂技术,然后着重分析了热熔灌输策略中3D骨架锂润湿性的影响因素,以及不同3D骨架修饰特征和改性方法。最后对3D骨架/金属锂复合负极和热熔灌输策略现存问题进行了总结并提出未来的发展方向。     

Targeted isolation of 1,1-diphenyl-2-picrylhydrazyl inhibitors from Saxifraga atrata and their antioxidant activities

Saxifraga atrata is an important traditional Tibetan medicine used to treat cough and pneumonia, and has tremendous medicinal potential. In this study, we devised a technique to separate 1,1-diphenyl-2-picrylhydrazyl inhibitors from a methanol extract of S. atrata. The material was first processed using MCI GEL CHP20P medium-pressure liquid chromatography, yielding 1.1 g of the target fraction Fr2. Subsequently, online hydrophilic interaction liquid chromatography-1,1-diphenyl-2-picrylhydrazyl assay was used to identify prospective 1,1-diphenyl-2-picrylhydrazyl inhibitors, and two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25) were identified from Fr2. Then, medium-pressure preparation was continued using an XIon column to separate two 1,1-diphenyl-2-picrylhydrazyl inhibitor fractions (Fr24 and Fr25). The target compound was concentrated in fractions Fr24 and Fr25 using reverse-phase liquid chromatography during further separation procedures. Finally, the purity, structure, and 1,1-diphenyl-2-picrylhydrazyl inhibitory activity of the isolated 1,1-diphenyl-2-picrylhydrazyl inhibitors were determined. Two 1,1-diphenyl-2-picrylhydrazyl inhibitors (adenosine with the half maximal inhibitory concentration of 66.87 ± 14.33 μM and (-)-4-O-(E)-caffeoyl-l -threonic acid with the half maximal inhibitory concentration of 59.06 ± 5.02 μM) were isolated with purities exceeding 95%. The results showed that this technology is effective in the targeted separation of antioxidants from natural products.