质谱分析导向的稳定同位素标记技术进展

介绍了近年来发展的一系列具有代表性的质谱分析导向的低残留稳定同位素标记技术:二甲氧基甲砜基嘧啶衍生化、低残留稳定同位素标记季铵化衍生化、新型胍剂化合物的衍生化等技术与方法。一些在常规电喷雾或基质辅助激光解吸电离条件下无法有效离子化的目标分子,在衍生化后产生新的正电荷中心或成为容易被电离物种而被质谱检测,从而提高了这类化合物的质谱学检测灵敏度。该类研究显著优势在于所开发的衍生化试剂本身不是离子型化合物,新产生的电荷中心或易于离子化的基团由衍生化反应引入。过量的衍生化试剂易于除去,不会对随后的质谱分析产生明显干扰。这一系列研究成果在代谢组学、食品安全分析、质谱成像以及单细胞分析等方面具有广泛的应用价值。     

酸碱净化-改进的衍生化气相色谱/质谱法测定土壤中11种酚类化合物

实现了土壤经有机溶剂快速提取,经酸碱净化,采用改进的五氟苄基溴方法衍生后,建立了气相色谱-质谱法同时测定土壤中11种酚类化合物的新方法。目标化合物通过SIM方式扫描,对保留时间和特征离子定性,通过内标法定量。土壤采用二氯甲烷/正己烷共同提取后,在酸碱净化过程中优化了不同萃取溶剂比例和不同体系下五氟苄基溴衍生效果的影响,以及考查了不同衍生温度和时间的作用。当取样量10 g时,11种酚类化合物方法检出限为1.06~4.21μg/kg,低、中、高基质加标回收率为75.9%~93.9%,相对标准偏差(RSDs)为4.6%~8.2%。     

新农药创新方法与应用(1)—中间体衍生化方法

介绍了一种发现新农药的创新研究方法——中间体衍生化方法。新农药创新涉及多领域间的合作,其过程非常复杂,中间体衍生化方法是从化学的角度出发,把复杂问题简单化,应用效果很好。通过多年的实践,总结其内涵有三:利用中间体进行化学反应,设计合成新化合物,然后筛选,发现先导化合物,再经优化发现新农药品种;利用简单的原料,通过化学反应合成新的中间体,利用该中间体替换已知农药或医药品种化学结构中的一部分,得到新的化合物,经进一步研究,得到新农药品种;利用已知的具有活性的化合物或农药品种作为中间体,进行化学反应,设计合成新化合物,经筛选、优化研究发现新农药品种。     

4,6-二甲氧基嘧啶衍生物的合成及生物活性测定

以4,6-二甲氧基-2-甲基磺酰基嘧啶为起始原料,采用中间体衍生化方法,合成了三类嘧啶类化合物.应用氢核磁共振、红外和元素分析验证了所合成化合物的结构.生物活性测试结果显示大部分化合物具有杀菌活性,其中化合物8在25 mg/L质量浓度下对水稻稻瘟病的抑制率达100%,化合物10c在400 mg/L质量浓度下对黄瓜霜霉病具有100%的防效.部分化合物具有一定的除草活性.     

杀螨剂嘧螨胺(SYP-11277)的创制经纬

概述了杀螨剂嘧螨胺(SYP-11277)的创制经纬.首先以取代嘧啶醇为中间体进行衍生化研究,合成了一系列化合物,从而发现了具有杀螨活性的先导化合物1(运用中间体衍生化方法发现先导化合物),然后通过结构修饰发现二次先导化合物2,进一步优化研究发现SYP-10913、SYP-11277、SYP-11992、SYP-11993等高活性化合物,最终确定嘧螨胺(SYP-11277)作为候选杀螨剂进行产业化开发.该药剂对红蜘蛛成、若、幼螨均具有很好的防治效果,而且表现了优异的杀卵活性.     

Identification of vitamin E-dependent water soluble fluorescent compounds in mouse tissues

The present paper describes the identification of two vitamin E-dependent, water soluble fluorescent compounds in mouse tissues. Ultraviolet and fluorescent spectroscopy, derivatization with 1-dimethylamino-naphtalene-5-sulfonyl chloride (dansyl chloride) and cochromatography using high performance liquid chromatography (HPLC) were utilized for the identification of the unknown compounds. The water soluble fluorescent compounds in mouse tissues were identified as tyrosine and tryptophan. The compounds were previously found to increase significantly in vitamin E deficiency in various tissues.     

DABS-Cl 试剂在反相高效液相色谱中的应用

选定了两套完全不同的色谱条件,并对 DABS-氨基酸进行了高效液相色谱分析实验。DABS-Cl 与氨基酸的衍生反应所需的时间不足 lh。     

聚醚多元醇中醛类组分的HPLC法测定

利用羰基化合物与2,4-二硝基苯肼（DNPH）反应生成腙,建立了柱前衍生、高效液相色谱（HPLC）法测定聚醚多元醇中醛类物质含量的方法,研究了样品衍生化条件,绘制了甲醛．DNPH、乙醛-DNPH、丙烯醛-DNPH及丙醛．DNPH的外标法校准曲线。结果表明,甲醛、乙醛、丙烯醛的线性范围为0．02～20．00μg／mL,丙醛的线性范围为0．80—800．00μg／mL;醛类物质的检测限在O．025μg／mL以下。用于聚醚多元醇样品中甲醛、乙醛、丙烯醛和丙醛的测定取得了满意的结果,该方法具有测定范围广、回收率高等优点,是一种测定聚醚多元醇中多种醛类物质含量的有效方法。     

Coumarin-based octopamine phototriggers and their effects on an insect octopamine receptor

We have developed and characterized efficient caged compounds of the neurotransmitter octopamine. For derivatization, we introduced [6-bromo-8-(diethylaminomethyl)-7-hydroxycoumarin-4-yl]methoxycarbonyl (DBHCMOC) and {6-bromo-7-hydroxy-8-[(piperazin-1-yl)methyl]coumarin-4-yl}methoxycarbonyl (PBHCMOC) moieties as novel photo-removable protecting groups. The caged compounds were functionally inactive when applied to heterologously expressed octopamine receptors (AmOctα1R). Upon irradiation with UV-visible or IR light, bioactive octopamine was released and evoked Ca2+ signals in AmOctα1R-expressing cells. The pronounced water solubility of compounds 2-4 in particular holds great promise for these substances as excellent phototriggers of this important neurotransmitter.     

Cerium and bismuth catalysis hand in hand—Synthesis of a eight-membered ring lactam library

Cerium-catalyzed C–C coupling of 1,3-dicarbonyl compounds with styrene derivatives and oxygen yielded compounds with a 1,4-dicarbonyl moiety after base induced Kornblum–DeLaMare fragmentation. Further conversion of these 1,4-diketones with primary amines in a bismuth-catalyzed reaction gave eight-membered ring lactams, which are a new and promising molecular scaffold for medicinal chemistry. Further derivatization was achieved by saponification of esters to their corresponding carboxylic acids and followed by amidation with primary amines with a coupling reagent. We furthermore investigated the synthesis of cogeners with an additional O, S, or N atom in the eight-membered ring, thus extending the diversity of our scaffold.     

A Highly Selective and Sensitive Chiral Derivatization Method for High- Performance Liquid Chromatographic Determination of the Stereoisomer Composition of Natural Products With Chiral Branched Alkyl Chains

In the study of chiral biologically active compounds such as pheromones, the analysis of the stereoisomer composition is essential to gain more insight into their stereochemical diversity, which affects the pheromone communication channels and therefore the diversification of species. This mini-review summarizes the development of fluorescence derivatization reagents for high-performance liquid chromatographic (HPLC) determination of the absolute configuration and stereoisomer composition of natural products with a chiral branched alkyl chain. The diastereomeric separation of anteiso fatty acids bearing a branched methyl group up to the C-26 position was achieved by reversed-phase HPLC under very low column temperature conditions using (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanol as a derivatization reagent, enabling fluorescent detection of these compounds at femtomole levels. This method was also applicable to chiral alcohols and amines with chiral branched methyl groups using similar reagents containing a carboxyl group. These reagents were successfully applied to determine the absolute configurations and stereoisomer composition of the chiral alkyl chain of natural compounds including some insect pheromones, miyakosyne A, and plakoside A. The combination of these reagents and two-dimensional HPLC constitutes a very powerful tool for the analysis of the stereoisomers of natural crude samples. Furthermore, the analysis of some natural bioactive substances using this method demonstrated that natural substances are not always optically pure, consisting instead of stereoisomer mixtures exhibiting stronger activity than optically pure enantiomers. These results cast doubts on the concept of biological homochirality and demonstrate that natural pheromones do not always show the highest activity among all stereoisomers.

     

Mammalian Exocrine Secretions. XVIII: Chemical Characterization of Interdigital Secretion of Red Hartebeest, Alcelaphus buselaphus caama

Gas chromatography, coupled gas chromatography-mass spectrometry (electron impact mode and chemical ionization with methane as reactant gas), gas chromatography-infrared spectroscopy, and derivatization techniques were used to identity 53 compounds in the interdigital secretion of the red hartebeest, Alcelaphus buselaphus caama. These compounds included alkanes, isoalkanes, alcohols, ketones, carboxylic acids, oxiranes, furanoid linalool oxides, and a large number of branched and unbranched saturated and unsaturated aldehydes. The secretion probably plays a role in demarcation of territories by dominant bulls.     

杀菌剂丁香菌酯的创制经纬

概述了运用中间体衍生化方法发现杀菌剂丁香菌酯(SYP-3375)的过程:以取代香豆素环替换醚菌酯结构中的邻甲苯基,设计并合成了一系列化合物,发现先导化合物(反)-3-甲氧基-2-(2-((香豆素-7-基氧基)甲基)苯基)丙烯酸甲酯(3),通过优化研究发现SYP-2859、SYP-3200(甲香菌酯)等高活性化合物,最终发现了丁香菌酯,其对蔬菜和作物的多种病害如黄瓜霜霉病、黄瓜灰霉病、小麦白粉病、水稻纹枯病和苹果腐烂病等均有很好的防治效果,已于2010年获准临时登记。     

杀菌剂唑菌酯的创制经纬

概述了运用中间体衍生化方法发现杀菌剂唑菌酯(SYP-3343)的过程:以取代吡唑环替换丁香菌酯结构中的香豆素环,设计并合成了一系列化合物,发现先导化合物(2),通过优化研究发现多个高活性化合物,最终发现了(E)-2-(2-((3-(4-氯苯基)-1-甲基-1H-吡唑-5-基氧基)甲基)苯基)-3-甲氧基丙烯酸甲酯,即唑菌酯(SYP-3343),其具有广谱的杀菌活性,对蔬菜和作物的多种病害如霜霉病、稻瘟病、白粉病、炭疽病等均有很好的防治效果,同时SYP-3343具有明显的杀虫、杀螨活性,可达到病虫兼治之目的。已于2009年获准临时登记。     

Analytical methods for the determination of alkylpolyglucosides

This paper describes the repertoire of analytical methods which is currently available for the determination of Alkylpolyglucosides (APGs). The methods range from chromatographic techniques (hightemperature gas chromatography, high-performance liquid chromatography, thin-layer chromatography) to methods which allow a fast and easy (but unselective) determination of sum parameters. For the first time a derivatization method is described which converts APGs into anionic compounds that can be titrated potentiometrically.     

Head group-modified sophorolipids: Synthesis of new cationic, zwitterionic, and anionic surfactants

Amino acid-glycolipid conjugates were prepared using carbodiimide-mediated coupling methods. The amino acid units were multifunctional and possessed a para-aminobenzoic acid linker. The glycolipid used was a stearic sophoroside. The aim of preparing these modified sophorolipids was to increase their water solubility as well as to introduce sites at the polar head groups that permitted further chemical derivatization. After acidolytic or hydrogenolytic deprotection of the amino acid N-terminus or side chain, water-soluble compounds were obtained that displayed good surfactant properties. Critical micelle concentration values were clustered in the range of high 10⁻⁶ to low 10⁻⁵ M, and minimum surface tension values were below 40 mN m⁻¹. Two of the compounds represented more complicated structural classes, namely, gemini and bolaform surfactants.     

Activation of Sirtuin 2 Inhibitors Employing Photoswitchable Geometry and Aqueous Solubility

Because isoenzymes of the experimentally and therapeutically extremely relevant sirtuin family show high similarity, addressing the unique selectivity pocket of sirtuin 2 is a promising strategy towards selective inhibitors. An unrelated approach towards selective inhibition of isoenzymes with varied tissue distribution is targeted drug delivery or spatiotemporal activation by photochemical activation. Azologization of two nicotinamide-mimicking lead structures was undertaken to combine both approaches and yielded a set of 33 azobenzenes and azopyridines that have been evaluated for their photochemical behaviour and bioactivity. For some compounds, inhibitory activity reached the sub-micromolar range in their thermodynamically favoured E form and could be decreased by photoisomerization to the metastable Z form. Besides, derivatization with long-chain fatty acids yielded potent sirtuin 2 inhibitors, featuring another intriguing aspect of azo-based photoswitches. In these compounds, switching to the Z isomer increased aqueous solubility and thereby enhanced biological activity by up to a factor of 21. The biological activity of two compounds was confirmed by hyperacetylation of sirtuin specific histone proteins in a cell-based activity assay.     

Nickel-Catalyzed Reductive Coupling of Vinyl Triflates and 1,4-Dicyanobenzene to Access Alkenyl Nitriles

We report a vinyl cyanation reaction of vinyl triflates and readily available 1,4-dicyanobenzene through a nickel-catalyzed reductive coupling process. The reaction is operated under mild conditions with remarkable functional-group compatibility. Cyclic vinyl triflates with various ring sizes and substituents at different positions all reacted smoothly. The synthetic utility is demonstrated by the derivatization of pharmaceutical and natural compounds, a scale-up synthesis, and various functional group transformations. Preliminary mechanistic studies demonstrate that vinyl triflates are more reactive than 1,4-dicyanobenzene towards the oxidative addition to nickel catalyst.     

Quantification of Pentafluorobenzyl Oxime Derivatives of Long Chain Aldehydes by GC–MS Analysis

Negative ion mass spectrometric techniques, for compounds having good ionization properties, such as pentafluorobenzyl derivatives, are believed to be more sensitive than positive ion methods. Preparation of PFB oximes of fatty aldehydes from crude lipid extracts is problematic due to the release of free aldehydes from plasmalogens during derivatization. Accordingly, in these studies plasmalogens were removed by silicic acid column chromatography prior to pentafluorobenzyl derivatization. This simple purification step to remove plasmalogens is shown to facilitate the quantification of long-chain aldehydes by analysis of their pentafluorobenzyl oxime derivatives utilizing gas chromatography–mass spectrometry in the negative ion chemical ionization mode. The limit of detection for long chain fatty aldehydes using this method is 0.5 pmol and it is linear over two orders of magnitude. Silicic acid column chromatography followed by electrospray ionization mass spectrometry demonstrated that plasmalogens were removed (the detection limit for this analyses was ≤0.3 pmol). Furthermore, we have exploited the utility and sensitivity of this method to identify increases in hexadecanal and octadecanal in 3-amino-1,2,4-triazole treated human neutrophils. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Relating chemical and biological diversity space: a tunable system for efficient gene transfection

Polyethyleneimine (PEI), a well-established nonviral transfection reagent, was combinatorially modified with varying proportions of methyl, benzyl, and n-dodecyl groups to create a library of 435 derivatized polymers. Screening of this library for transfection, DNA binding, and toxicity allows systematic correlation of the biological properties of our polymers to their derivatizations. Combinations of derivatizations bring about a 100-fold variation in transfection efficiency between library members. The best PEI derivatives exhibit increases in transfection efficiency of more than 80-fold over unmodified PEI (up to 28+/-7 % of cells transfected) and rival commercial reagents such as Lipofectamine 2000 (21+/-10 %) and JetPEI (32+/-5.0 %). In addition, we can identify compounds that are specifically tuned for efficient transfection in CHO-K1 over Ishikawa cells and vice versa, demonstrating that the approach can lead to cell-type selectivity of at least one order of magnitude. This work demonstrates that multivalent derivatization of a polymeric framework can create functional diversity substantially greater than the structural diversity of the derivatization building blocks and suggests an approach to a better understanding of the molecular underpinnings of transfection as well as their exploitation.