大孔树脂-高速逆流色谱分离纯化薇甘菊中的黄酮类化合物

该文建立了大孔树脂-高速逆流色谱分离薇甘菊中黄酮类物质的方法。分离条件为:采用大孔树脂AB-8,洗脱液为50%（v/v）乙醇水溶液,高速逆流色谱溶剂体系为正丁醇-乙酸-水（4：1：5,v/v）。从薇甘菊中分离到4种黄酮类物质:槲皮素-3-O-芸香糖苷（纯度90.2%）、山奈酚-3-O-芸香糖苷（纯度98.55%）、木犀草苷（纯度98.33%）和紫云英苷（纯度99.23%）。建立的大孔树脂-高速逆流色谱方法简单、高效,可扩展应用于从其他植物中分离黄酮类物质。     

Electrochemical Sensor based on Indium Tin Oxide Glass Modified with Poly(Ethyleneimine)/Phosphomolybdic Acid Composite Multilayers

In this work, one novel electrochemical sensor was prepared by alternative deposition of phosphomolybdic acid (PMoA) and poly(ethyleneimine) (PEI) on an indium tin oxide glass substrate through layer‐by‐layer assembly. The performance of as‐prepared electrode was evaluated with both of oxidizing compounds of iodate and H₂O₂ and reducing compounds of dopamine and ascorbic acid as models. The results showed that corresponding current response of redox peak increased linearly with the concentration of above compounds increasing in certain ranges, respectively. Limits of detection to them were in the range of 1.0×10⁻⁴ ‐ 4.3×10⁻⁴ mg mL⁻¹ with cyclic voltammetry (CV) in 0.1 mol L⁻¹ NaAc‐HAc buffer (pH 5.0). The electrode showed high stability and remained 95 % of its initial activity even after 100 cycles of CV scan. When applied in real samples of table salts, juice and human serum, high recoveries of 96.84 to 100.33 % were achieved with relative standard deviations of 1.11‐3.96 % (n=3) at three spiked levels. Moreover, it was also successfully applied for the simultaneous determination of dopamine and ascorbic acid in human serum with differential pulse voltammetry. The results indicated that PMoA/PEI multilayer modified electrode can be used as a universal electrochemical sensor for sensitive detection of redox compounds.     

Synthesis and immunological study of a wall teichoic acid-based vaccine against E. faecium U0317

ABSTRACT

A repeat unit of cell wall teichoic acids (WTA) isolated from E. faecium U0317 was chemically synthesized efficiently by a stepwise strategy. It was derivatized with a 5-aminopentanyl linker to facilitate conjugation with carrier proteins KLH and HSA. Immunological studies of the KLH conjugate 1 demonstrated that it could provoke robust immune responses and high titers of IgG antibodies, which could successfully recognize the synthesized WTA repeat unit 3. This result suggested that synthetic glycoconjugate 1 could be a promising vaccine candidate against E. faecium for further studies.     

Synthesis of threo- and erythro-configured trihydroxy open chain lipophilic ketones as possible anti-mycobacterial agents

A series of threo- and erythro-configured open-chain trihydroxy ketones was synthesized starting from l- and d-ascorbic acid respectively as the starting material, through the use of Grignard reactions for the requisite CC bond formations. The lipophilic ketones were screened against Mycobacteriumtuberculosis for anti-proliferative activity. The lipophilic ketones with tetradecyl alkyl side chains were found to be moderately active against cell proliferation.     

基于几何过程和位相分布休假的两部件并联可修系统的可靠性分析

主要以两不同型部件组成的并联可修系统为研究对象.在系统对失效相位存在记忆的基础上,考虑了修理工可单重休假且休假时间服从位相(PH)分布.每个工作部件均有可能因受到两种不同类型的故障而失效,且均"修复非新".在假定部件的工作时间,修理时间分别服从PH分布的几何过程和负指数分布的条件下,利用马尔可夫过程和矩阵分析的方法,对可修系统进行了可靠性分析,并给出了相应可靠性指标的数值算例.     

Late stage modification of peptides via CH activation reactions

Recently developed strategies for late stage modification of peptides through CH activation, an arena of contemporary interest in chemical biology and drug discovery, are discussed. Through this tactic, non-polar amino acids in peptides have been selectively functionalized and CH activation enabled new CC and CX bond formations (arylation, alkynylation, fluorination, hydroxylation, azidation, etc.) are documented. Significant advances have been made in Pd or Au-catalyzed, racemization-free, tryptophan specific modifications of large peptides via CH arylation and alkynylation reactions without any protecting group requirement. Development of a new biaryl stapling technique for complex peptides, 18F radiofluorine introduction and diversity oriented post synthetic applications on bio-active cyclopeptides like valinomycin and aureobasidin are additional highlights which underscores the vast potential of late stage CH activation reactions in peptide based therapeutics research.     

Iodine-catalyzed aerobic oxidation of o-alkylazoarenes to 2H-indazoles

An iodine-catalyzed aerobic-oxidative C-H functionalization of o-alkylazoarenes to afford 2H-indazoles has been developed. CuI was found to be an effective additive to accelerate the regeneration of iodine in the catalytic cycle. This catalytic system is suitable for both electron-rich and electron-deficient azoarenes and tolerates a variety of functional groups with high yields. A gram-scale reaction was successfully conducted, proving the scalability of this reaction.