The first syntheses of single enantiomers of the major methoxymycolic acid of Mycobacterium tuberculosis

The synthesis of three stereoisomers of a major homologue of the methoxymycolic acids present in Mycobacterium tuberculosis is described.     

Arabinofuranose disaccharide analogs as inhibitors of Mycobacterium tuberculosis

Several octyl 5-O-(α-d-arabinofuranosyl)-α-d-arabinofuranoside disaccharide analogs substituted at the 5-position of the non-reducing end sugar were synthesized and tested in vitro against Mycobacterium tuberculosis (M.tb.), Mycobacterium avium complex (MAC) as well as in a cell free assay system for arabinosyltransferase acceptor/inhibitor activity. A few compounds showed interesting inhibitory activity in the cell free assay as well as against the whole microorganism in vitro.     

Lansoprazole‐sulfide,pharmacokinetics of this promising anti‐tuberculous agent

Lansoprazole (LPZ) is a commercially available proton‐pump inhibitor whose primary metabolite, lansoprazole sulfide (LPZS) was recently reported to have in vitro and in vivo activity against Mycobacterium tuberculosis . It was also reported that a 300 mg kg⁻¹ oral administration of LPZS was necessary to reach therapeutic levels in the lung, with the equivalent human dose being unrealistic. A validated liquid chromatography–tandem mass spectrometric method (LC–MS/MS) for the simultaneous quantification LPZ and LPZS in rat plasma and lung homogenates was developed. We administered 15 mg kg⁻¹ oral doses of LPZ to a healthy rat model to determine the pharmacokinetics of its active metabolite, LPZS, in plasma and lung tissue. We found that the LPZS was present in amounts that were below the limit of quantification. This prompted us to administer the same dose of LPZS to the experimental animals intraperitoneally (i.p.). Using this approach, we found high concentrations of LPZS in plasma and lung, 7841.1 and 9761.2 ng mL⁻¹, respectively, which were significantly greater than the minimum inhibitory concentration (MIC) for Mycobacterium tuberculosis. While oral and i.p. administration of LPZ resulted in significant concentrations in the lung, it did not undergo sufficient cellular conversion to its anti‐TB metabolite. However, when LPZS itself was administered i.p., significant amounts penetrated the tissue. These results have implications for future in vivo studies exploring the potential of LPZS as an anti‐TB compound.     

Isatin hybrids and their anti-tuberculosis activity

Tuberculosis (TB) is one of the most common and even fatal infectious diseases known to mankind. Millions of new cases are reported every year over the world, and one-third of the world's population is potentially infected with mycobacteria tuberculosis (MTB). Research to develop novel anti-TB drugs led to the identification of several isatin-based antimycobacterial agents, among which a number of potential candidates displayed excellent antimycobacterial activity and were found to be free of cytotoxicity. This review outlines the advances in the application of isatin hybrids as antimycobacterial agents and the critical aspects of design and structure-activity relationship of these derivatives.     

Virtual screening and repositioning of inconclusive molecules of beta-lactamase Bioassays—A data mining approach

This study focuses on the best possible way forward in utilizing inconclusive molecules of PubChem bioassays AID 1332, AID 434987 and AID 434955, which are related to beta-lactamase inhibitors of Mycobacterium tuberculosis (Mtb). The inadequacy in the experimental methods that were observed during the invitro screening resulted in an inconclusive dataset. This could be due to certain moieties present within the molecules. In order to reconsider such molecules, insilico methods can be suggested in place of invitro methods For instance, datamining and medicinal chemistrymethods: have been adopted to prioritise the inconclusive dataset into active or inactive molecules. These include the Random Forest algorithm for dataminning, Lilly MedChem rules for virtually screening out the promiscuity, and Self Organizing Maps (SOM) for clustering the active molecules and enlisting them for repositioning through the use of artificial neural networks. These repositioned molecules could then be prioritized for downstream drug discovery analysis.     

An Antibacterial β‐Lactone Kills Mycobacterium tuberculosis by Disrupting Mycolic Acid Biosynthesis

The spread of antibiotic resistance is a major challenge for the treatment of Mycobacterium tuberculosis infections. In addition, the efficacy of drugs is often limited by the restricted permeability of the mycomembrane. Frontline antibiotics inhibit mycomembrane biosynthesis, leading to rapid cell death. Inspired by this mechanism, we exploited β‐lactones as putative mycolic acid mimics to block serine hydrolases involved in their biosynthesis. Among a collection of β‐lactones, we found one hit with potent anti‐mycobacterial and bactericidal activity. Chemical proteomics using an alkynylated probe identified Pks13 and Ag85 serine hydrolases as major targets. Validation through enzyme assays and customized ¹³C metabolite profiling showed that both targets are functionally impaired by the β‐lactone. Co‐administration with front‐line antibiotics enhanced the potency against M. tuberculosis by more than 100‐fold, thus demonstrating the therapeutic potential of targeting mycomembrane biosynthesis serine hydrolases.     

毛细管电泳法检测结核杆菌蛋白多肽类抗原活性成分研究

采用毛细管电泳法分离检测结核杆菌耐热抗原样品中的活性成分。熔融石英毛细管55cm(40cm处检测窗口)×50μm i.d.;缓冲液:0.15mol·L-1硼酸盐(含5g·L-1PEG-4000,pH=10.92);分离电压:+12 kV;进样压力:0.5 psi(3.45 kPa),进样时间3.0s;分离温度:25℃;UV-Vis检测器检测波长:200nm。本方法能分离溶菌酶标准蛋白和牛血清白蛋白标准品,根据分子量大小能有效分离结核杆菌耐热抗原样品活性成分,线性回归方程相关系数r2在0.99673以上,定量限在19.47μg·mL-1左右。样品加标回收率在96.09%左右,相对标准偏差小于8.13%,本方法与快速蛋白液相色谱法结果一致。该方法简便、灵敏、快速、可靠、重现性好,能用于结核杆菌耐热抗原样品中活性成分测定。     

硝基呋喃亚甲基哌啶类化合物的合成与抗结核活性

结核是由结核分枝杆菌引起的一种慢性呼吸道传染病,对人类的健康构成严重威胁。 本文利用药效团拼接原理,将片段硝基呋喃和苯基噻唑组合,得到了19个2-(1-((5-硝基呋喃-2-基)甲基)哌啶-4-基)噻唑(5)和2-(1-((5-硝基呋喃-2-基)甲基)哌啶-4-基)-4-苯噻唑(6)系列化合物,测试了所有化合物在1和0.1 μmol/L浓度下对结核分枝杆菌H37Ra的抑制率。 构效关系分析表明,苯环上有取代基有利于活性,且苯环上对位取代普遍优于间位和邻位取代,对位吸电子基团取代活性优于对位供电子基团取代活性。在苯环对位吸电子基团取代中,—CF₃取代的化合物2-(1-((5-硝基呋喃-2-基)甲基)哌啶-4-基)-4-(4-三氟甲基)苯基)噻唑(6f)活性最高,在1和0.1 μmol/L浓度下,抑制率分别为99.6%和93.4%。 鉴于新化合物具有抗结核高活性,化合物6f可作为抗结核候选化合物进一步研究。     

Fast identification of mycobacterium species by GC analysis with trimethylsulfonium hydroxide (TMSH) for transesterification

Trimethylsulfonium hydroxide (TMSH) reproducibly converts fatty acids bound in, e.g., biomolecules such as phospholipids and/or glycerides, into the corresponding fatty acid methyl esters (FAMEs). The transesterification can be performed at room temperature in a fast single step reaction. Surprisingly, secondary alcohols and mycolic acid cleavage products (MACPs) are also released from mycobacteria under these conditions. The complex reaction mixtures containing FAMEs, MACPs, and secondary alcohols can easily be separated by high resolution temperature-programmed capillary GC. Different species of mycobacteria give rise to characteristic chromatographic patterns and the amount of lipids from a single colony of mycobacteria is sufficient for reliable identification of the bacteria. The profiles of the chromatograms match well those obtained from other sample preparation techniques. The TMSH method of identification of mycobacteria from the patterns of the gas chromatograms is faster and more sensitive than conventional methods, which also involve transesterification. The identification of mycobacterial species by microbiological culture techniques is difficult to perform and requires several weeks.