Rapid identification of chemical compositions of three species of Schisandra chinensis by ultra-high-performance liquid chromatography quadrupole-orbitrap-mass spectrometry

Schisandra chinensis is a traditional Chinese medicine, which has played an important role in the field of medicine and food. In this study, ultra-high-performance liquid chromatography quadrupole-orbitrap-mass spectrometry was used to rapidly classify and identify the chemical compositions. Note that 32, 28, and 30 kinds of compounds were successfully identified from northern Schisandra chinensis, vinegar-processed Schisandra chinensis, and wine-processed Schisandra chinensis, respectively. The cleavage patterns of various components including lignans, organic acids, flavonoids, and terpenoids were summarized, and the effects of different processing methods on Schisandra chinensis were analyzed through chemical composition. This method realized the rapid classification and identification of raw Schisandra chinensis and two different processed products, and provided references for improving the traditional processing methods, strengthening quality control, and ensuring safe clinical application.     

一类一维在线单位聚类问题的随机近似算法

在给定的度量空间中, 单位聚类问题就是寻找最少的单位球来覆盖给定的所有点。这是一个众所周知的组合优化问题, 其在线版本为: 给定一个度量空间, 其中的n个点会一个接一个的到达任何可能的位置, 在点到达的时候必须给该点分配一个单位聚类, 而此时未来点的相关信息都是未知的, 问题的目标是最后使用的单位聚类数目最少。本文考虑的是带如下假设的一类一维在线单位聚类问题: 在相应离线问题的最优解中任意两个相邻聚类之间的距离都大于0.5。本文首先给出了两个在线算法和一些引理, 接着通过0.5的概率分别运行两个在线算法得到一个组合随机算法, 最后证明了这个组合随机算法的期望竞争比不超过1.5。     

Tracking antiangiogenic components from Glycyrrhiza uralensis Fisch. based on zebrafish assays using high-speed countercurrent chromatography

Natural products are some of the most important sources of lead compounds for drug discovery. The advanced isolation technique of lead compounds of natural origin using therapeutically relevant bioassays is capable of enhancing work efficiency from complex multiconstituent extracts. In the present study, a bioassay-guided isolation strategy combined with bioactivity screening was used to identify novel angiogenesis inhibitors from licorice (Glycyrrhiza uralensis Fisch.) based on the zebrafish model and rapid preparative separation by high-speed countercurrent chromatography. Zebrafish embryos at 24 h postfertilization were chosen as the angiogenesis inhibition model for bioactivity screening. A solvent system (n-hexane-ethyl acetate-methanol-water) with different ratios was optimized and applied in the high-speed countercurrent chromatography separation of two fractions, Fr5 and Fr6, from the ethyl acetate extract of licorice. Blood circulation and vascular outgrowth in intersegmental vessels were found to be simultaneously inhibited by isoliquiritigenin and isolicoflavonol in a dose-dependent manner. Thus, these two compounds were identified and considered as active inhibitors against angiogenesis. These experimental results indicate that zebrafish bioassays combined with high-speed countercurrent chromatography may provide an alternative pathway for the rapid isolation of bioactive natural products.     

Total synthesis of neopeltolide and analogs

Neopeltolide, a potent cytotoxin from a Carribean sponge, was synthesized through a brief sequence that highlights the use of ethers as oxocarbenium ion precursors. Other key steps include an acid-mediated etherification and sequence that features a Sonogashira reaction, an intramolecular alkyne hydrosilylation reaction, and a Tamao oxidation. The alkene that is required for the oxidative cyclization can be hydrogenated to provide access to the natural product or an epimer, or can be epoxidized or dihydroxylated to form polar analogs.     

A Closed Concept of Extractive Whole Cell Microbial Transformation of Benzaldehyde into l-Phenylacetylcarbinol by Saccharomyces cerevisiae in Novel Polyethylene-Glycol-Induced Cloud-Point System

Extractive microbial transformation of benzaldehyde into l-phenylacetylcarbinol (l-PAC) by Saccharomyces cerevisiae (Baker’s yeast) has been carried out in a novel polyethylene-glycol-induced cloud-point system (PEG-CPS). The extractive microbial transformation in the PEG-CPS and a downstream process for stripping of the product from the microbial transformation broth with microemulsion extraction are demonstrated. The results indicate that the PEG-CPS maintains the advantage of CPS for in situ extraction of polar product in the microbial transformation. At the same time, the utilization of hydrophilic nonionic surfactant in the PEG-CPS is favorable for stripping of product from the nonionic surfactant in the microbial transformation broth by Winsor I microemulsion extraction. Thus, a closed concept of in situ extraction of polar product in microbial transformation and its downstream process of product recovery are fulfilled at the same time.     

离子碰撞过程中电荷转移的理论研究

用经典轨道蒙托卡罗(CTMC)方法计算离子与氢原子碰撞过程电荷转移截面,并计算俘获电子的n(n为主量子数)壳层分布。对于多电荷离子的碰撞过程,利用约化变量得到了截面的q标度规律。计算结果与实验测量符合得很好。     

ALADDIN原子分子数据库

简介R.Hulse设计的ALADDIN(A Labelled Atomic Data Zaterface)系统的系统软件、数据文件和字典文件等基本特征,并通过一个例子介绍了该系统与用户程序连接的功能。     

Design,Synthesis, and Biological Evaluation of HDAC Degraders with CRBN E3 Ligase Ligands

Histone deacetylases (HDACs) play important roles in cell growth, cell differentiation, cell apoptosis, and many other cellular processes. The inhibition of different classes of HDACs has been shown to be closely related to the therapy of cancers and other diseases. In this study, a series of novel CRBN-recruiting HDAC PROTACs were designed and synthesized by linking hydroxamic acid and benzamide with lenalidomide, pomalidomide, and CC-220 through linkers of different lengths and types. One of these PROTACs, denoted 21a, with a new benzyl alcohol linker, exhibited comparably excellent HDAC inhibition activity on different HDAC classes, acceptable degradative activity, and even better in vitro anti-proliferative activities on the MM.1S cell line compared with SAHA. Moreover, we report for the first time the benzyl alcohol linker, which could also offer the potential to be used to develop more types of potent PROTACs for targeting more proteins of interest (POI).     

Dynamics of a Stochastic SIR Epidemic Model with Logistic Growth

In this paper, a stochastic SIR epidemic model with saturated treatment function, non-monotone incidence rate and logistic growth is studied. First, we prove that the stochastic model has a unique global positive solution. Next, by constructing a suitable Lyapunov function, we can show that there exists an ergodic stationary distribution in the random SIR model. Then, we show that a sufficient condition can make the disease tend to extinction. Finally, some numerical simulations are used to prove our analytical result.     

Rapid identification of chemical constituents in Hugan tablets by ultra-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry

Hugan tablet is a Chinese medicine preparation. It is composed of Bupleuri Radix, Artemisiae Scopariae Herba, Isatidis Radix, Schisandrae Chinensis Fructus, Suis Fellis Pulvis, and Vigna radiata L. It has the effects of dispersing stagnated liver qi, strengthening the spleen and eliminating food to be used for the treatment of chronic hepatitis and early cirrhosis. However, the chemical composition of Hugan tablet is complex and not fully understood, which hampers the research in pharmacology. In this study, a reliable method for the rapid analysis and identification of the chemical components in Hugan tablet by their characteristic fragments and neutral losses using ultra-performance liquid chromatography-quadrupole-exactive orbitrap mass spectrometry was developed. A total of 144 chemical components were tentatively identified, including 57 organic acids, 19 flavonoids, 23 alkaloids, 18 lignans, 7 saponins, and 20 others. These components may be the active ingredients of Hugan tablet. The established method can systematically and rapidly analyze the chemical components in Hugan tablet, which provides a basis for the pharmacodynamic substance study and is meaningful for the quality control of Hugan tablet.