中国番荔枝科植物抗癌有效成分研究

介绍了近年来我们实验室中国番荔枝科植物抗癌有效成分研究工作。从番荔枝科5种紫玉盘属植物,5种哥纳香属植物,1种番荔枝属植物,1种囊瓣木属植物中分离得到59种新的番荔枝内酯,32种新的多氧取代环己烯,12种新的苯乙烯吡喃酮和3种新的生物碱,并通过化学和光谱方法鉴定了它们的结构。大部分化合物显示了较强的抗癌活性。并对抗癌活性成分海南哥纳香醇甲进行了全合成。     

景洪哥纳香化学成分研究

景洪哥纳香为蕃荔枝科哥纳香属植物,主要分布在我国云南省。为了从该属植物中寻长新类型的抗肿瘤化合物,我们通过药理筛选,发现哥纳香根的醇提取物对人肿瘤细胞培养系有较强的素毒性。以生物活性跟踪为手段,指导分离景洪哥纳香根的醇提取物,得到38个化合物,通过光谱学及化学方法,确定其中两个化合物是新化合物,分别命名为哥纳香醌及哥纳香呋喃并呋喃酮丙亚基化物。     

小叶九里香化学成分研究

芸香科九里香属(Murraya)无刺灌木或小乔木,约12种,分布于亚洲热带、亚热带地区,我国有6种,2个变种[1].具有丰富的植物资源,本属药用植物在我国自古供药用.小叶九里香为芸香科九里香属灌木或小乔木,又名满江香、七里香等,原产广东、广西、福建、云南等省区.九里香的花、叶、果均含精油,出油率为0.25%,精油可用于化妆品香精、食品香精;叶可作调味香料;枝叶入药,有行气止痛、活血散瘀之功效,可治胃痛、风湿痹痛,外用有局部麻醉作用,可治牙痛、跌扑肿痛、虫蛇咬伤等.味辛、苦,微温;有小毒.对破伤风以及流行性乙型脑炎有一定的治疗作用.此外,医药上还以之为强壮剂、健胃剂等.九里香属植物的化学成分研究,已报道约200多个化合物,其中以咔吧唑生物碱为主,并含有黄酮及其甙类,香豆素,苯丙素及其甙类等,由于咔吧唑类生物碱具有的较强生理活性而起研究者的广泛兴趣.     

鸡尾木生物碱的含量分析

鸡尾木（Excoecaria Venenata S．Lee et F．N.Wei）,大戟科,海漆属,1982年由李树刚、韦发南鉴定为一新树种。鸡尾木的化学成分研究刘绍华等人报道从该植物中分离鉴定出没食子酸、仅一香树脂醇和β-谷甾醇心,作者在该科属植物中发现含有异硫氰酸脂。确定其主要生物碱为2,2,6,6-四甲基-4-哌啶酮、金刚烷胺。本文对鸡尾木叶片中总生物碱及上述两个主要生物碱的含量做了进一步的分析测定。     

咔唑生物碱Murrayaquinone A的全合成

三环咔唑醌类生物碱MurrayaquinoneA是从九里香属植物中分离得到的,具有强心活性.以商品化的3-乙酰基吲哚为起始原料,首次将钯催化的分子内吲哚α-C—H烯基化反应应用于咔唑天然产物A环的构建,经8步反应、以8%的总收率实现了Murrayaquinone A的全合成.     

三尖杉属植物中几种生物碱的质谱裂解规律的研究

本文用高分辨质谱法研究了由三尖杉属植物分得的高刺桐碱类和三尖杉碱类的质谱裂解规律.高刺桐类生物碱的质谱中有三类特征性离子:(1)(M-15)离子;(2)C环的(RDA)及(RDA-H)反应产生的离子;(3)B环裂解的产物离子.三尖杉碱类化合物则依C环上双键位置的不同,经不同的中间离子,再重排得相应的质谱峰.阐明这两类生物碱的质谱裂解规律,将有助于同类型未知生物碱的结构推断.     

植物内生真菌生物碱活性成分的研究进展

大量的生物碱从植物内生真菌中分离了出来, 并表现出良好的生物活性. 对植物内生真菌所产生的生物碱, 按照酰胺类、有机胺类、吡咯类、喹啉和异喹啉类、吲哚类、吡啶类、喹唑啉类进行了综述, 并且介绍了这些生物碱的生物活性.     

贡甲根中生物碱的化学研究

从芸香科植物贡甲(Acronychia oligophylebia Merr.)的根中分得了九个生物碱1～9和β-谷甾醇(10),其中吴茱萸春(1)、香草木宁(3)、原茵芋碱(4)、茵芋碱(5)和斑点弗林定(6)是已知生物碱,1,4,6三个生物碱是第一次从山油柑属植物中分得.贡甲定碱(2)和贡甲辛定碱(9)是两个新化合物.贡甲辛碱(7)和贡甲碱(8)是首次从植物中分得.用光谱方法推断了2,7,8,9的结构,由合成证明7,9的结构. 7和8具广谱抗真菌作用,但作用较弱.     

两种中药虎皮楠和交让木化学成分的研究

交让木(Daphniphyllum macropodum)和虎皮楠(Daphniphyllum angustifolium)属于虎皮楠科虎皮楠属,为小乔木.近年来,从虎皮楠属植物中分离得到一系列结构非常复杂的、独特的、生物活性多样的聚环生物碱[1,2],我们从交让木(D.macropodum)中分得7个此类生物碱,根据NMR和MS数据鉴定了3个化合物的结构,其中1个为新化合物.另外4个化合物的结构正在鉴定中.经文献查阅发现对该属植物非生物碱部分的研究很少,我们从虎皮楠)(D.angustifolium)非生物碱部位分得18个化合物,并根据NMR,UV,和MS等数据鉴定了它们的结构,其中7个为新化合物.新化合物的结构如下所示:     

苯并啡啶类生物碱及其衍生物合成研究进展

苯并啡啶类生物碱是一类广泛分布于罂粟科和芸香科植物中的天然含氮化合物,具有显著的抗肿瘤和广谱抗菌等多种生物活性.基于苯并啡啶类生物碱的生源合成途径的特殊性对天然苯并啡啶类生物碱结构类型进行了分类.综述了自1999年以来天然苯并啡啶类生物碱及其衍生物的合成方法研究进展,对各个合成路线的特点进行了讨论.     

红景天苷及其酯化产物的ESI MS和MS/MS裂解途径

糖苷广泛存在于自然界中,常以糖苷酯形式存在,这有效地提高了它们的酯溶性,增加它们在肠内和胞内的吸收[1-3]。红景天苷是一种具有抗疲劳、抗辐射、抗缺氧、提高记忆、延缓衰老等药理活性的天然糖苷[4-8],在此先导化合物的基础上合成了各种红景天苷酯。本文对这类红景天苷酯的E     

MS/MS: Cloned mass spectrometers

Coupling mass spectrometers in tandem (MS/MS) can greatly increase the specificity of MS analysis without significantly decreasing its unusual sensitivity and speed, particularly for trace levels of preselected compounds in complex organic mixtures. MS/MS also gives more detailed structural information for larger organic molecules in submicrogram quantities.     

Dual parallel electrospray ionization and atmospheric pressure chemical ionization mass spectrometry (MS), MS/MS and MS/MS/MS for the analysis of triacylglycerols and triacylglycerol oxidation products

Two mass spectrometers, in parallel, were employed simultaneously for analysis of triacylglycerols in canola oil, for analysis of triolein oxidation products, and for analysis of triacylglycerol positional isomers separated using reversed-phase high-performance liquid chromatography. A triple quadrupole mass spectrometer was interfaced via an atmospheric pressure chemical ionization (APCI) interface to two reversed-phase liquid chromatographic columns in series. An ion trap mass spectrometer was coupled to the same two columns using an electrospray ionization (ESI) interface, with ammonium formate added as electrolyte. Electrospray ionization mass spectrometry (ESI-MS) under these conditions produced abundant ammonium adduct ions from triacylglycerols, which were then fragmented to produce MS/MS spectra and then fragmented further to produce MS/MS/MS spectra. ESI-MS/MS of the ammoniated adduct ions gave product ion mass spectra which were similar to mass spectra obtained by APCI-MS. ESI-MS/MS produced diacylglycerol fragment ions, and additional fragmentation (MS/MS/MS) produced [RCO](+) (acylium) ions, [RCOO+58](+) ions, and other related ions which allowed assignment of individual acyl chain identities. APCI-MS of triacylglycerol oxidation products produced spectra like those reported previously using APCI-MS. APCI-MS/MS produced ions related to individual fatty acid chains. ESI-MS of triacylglycerol oxidation products produced abundant ammonium adduct ions, even for those molecules which previously produced little or no intact molecular ions under APCI-MS conditions. Fragmentation (MS/MS) of the [M+NH(4)](+) ions produced results similar to those obtained by APCI-MS. Further fragmentation (MS/MS/MS) of the diacylglycerol fragments of oxidation products provided information on the oxidized individual fatty acyl chains. ESI-MS and APCI-MS were found to be complementary techniques, which together contributed to a better understanding of the identities of the products formed by oxidation of triacylglycerols.     

LC/MS and LC/MS/MS determination of protein tryptic digests

Tryptic digests were analyzed by means of online microbore liquid chromatography combined with mass spectrometry (LC/MS) for some common proteins. Following conventional enzymatic digestion with trypsin, the freeze-dried residues were dissolved in high-performance liquid chromatography (HPLC) eluent and subjected to gradient reversed-phase microbore HPLC separation with mass spectrometric detection. The latter was done in the full-scan single or tandem (MS/MS) mass spectrometry mode. The formation of gas-phase ions from dissolved analytes was accomplished at atmospheric pressure by pneumatically assisted electrospray (ion spray) ionization. This produced field-assisted ion evaporation of dissolved ions, which could then be mass-analyzed for molecular mass or structure. In the full-scan LC/MS mode, the masses for the peptide fragments in the tryptic digests can be determined as either their singly or multiply charged ions. When the molecular weights of the peptides lie outside the mass range of the mass spectrometer, the multiply charged feature of these experimental conditions still provides reliable molecular weight determinations. In addition, collision-activated dissociation (CAD) on selected peptide precursor ions provides online LC/MS/MS sequence information for the tryptic fragments. Results are shown for the tryptic digests of horse heart cytochrome c, bovine β-lactoglobulin A, and bovine β-lactoglobulin B.     

Analytical performance of the various acquisition modes in Orbitrap MS and MS/MS

Quadrupole Orbitrap instruments (Q Orbitrap) permit high‐resolution mass spectrometry‐based full scan acquisitions and have a number of acquisition modes where the quadrupole isolates a particular mass range prior to a possible fragmentation and high‐resolution mass spectrometry‐based acquisition. Selecting the proper acquisition mode(s) is essential if trace analytes are to be quantified in complex matrix extracts. Depending on the particular requirements, such as sensitivity, selectivity of detection, linear dynamic range, and speed of analysis, different acquisition modes may have to be chosen. This is particularly important in the field of multi‐residue analysis (eg, pesticides or veterinary drugs in food samples) where a large number of analytes within a complex matrix have to be detected and reliably quantified. Meeting the specific detection and quantification performance criteria for every targeted compound may be challenging. It is the aim of this paper to describe the strengths and the limitations of the currently available Q Orbitrap acquisition modes. In addition, the incorporation of targeted acquisitions between full scan experiments is discussed. This approach is intended to integrate compounds that require an additional degree of sensitivity or selectivity into multi‐residue methods.     

Selective detection and identification of phosphopeptides by dansyl MS/MS/MS fragmentation

Protein phosphorylation regulates many cellular processes and pathways, such as cell cycle progression, signal transduction cascades and gene expression. Selective detection of phosphopeptides from proteolytic digests is a challenging and highly relevant task in many proteomics applications. Often phosphopeptides are present in small amounts and need selective isolation or enrichment before identification. Here we report a novel approach to label selectively phospho-Ser/-Thr residues by exploiting the features of a novel linear ion trap mass spectrometer. Using dansyl labelling and MS3 fragmentation, we developed a method useful for the large-scale proteomic profiling of phosphorylation sites. The new residues in the sequence were stable and easily identifiable under general conditions for tandem mass spectrometric sequencing.     

Analysis of MS/MS fragmentation of taxoids

The fragmentation pathways of seven types of taxoids were investigated by using a LC-MS/MS method, namely: (1) neutral taxoids with a C-4(20) double bond; (2) taxoids with a C-4(20) double bond and oxygenation at C-14; (3) 5-cinnamoyl taxoids with a C-4(20) double bond; (4) a basic taxoid with a C-4(20) double bond; (5) a taxoid with a C-4(20) epoxide; (6) taxoids with an oxetane ring; and (7) taxoids with an oxetane ring and a phenylisoserine C-13 side chain. Depending on the class of core structure and the substitution pattern, each taxoid gave either the molecular adduct ion [M+NH4]+ or [M+H]+. In the MS/MS, the molecular adduct ion gave characteristic product ions corresponding to the loss of water, acetic acid, benzoic acid, and cinnamic acid or the phenylisoserine group. These could reflect the difference of the substitutions and structural modifications and should be utilized for the structure elucidation oftaxoids by LC-MS.     

An impulse-driven liquid-droplet deposition interface for combining LC with MALDI MS and MS/MS

A simple and robust impulse-driven droplet deposition system was developed for off-line liquid chromatography matrix-assisted laser desorption ionization mass spectrometry (LC-MALDI MS). The system uses a solenoid operated with a pulsed voltage power supply to generate impulses that dislodge the hanging droplets from the LC outlet directly to a MALDI plate via a momentum transfer process. There is no contact between the LC outlet and the collection surface. The system is compatible with solvents of varying polarity and viscosity, and accommodates the use of hydrophobic and hydrophilic MALDI matrices. MALDI spots are produced on-line with the separation, and do not require further processing before MS analysis. It is shown that high quality MALDI spectra from 5 fmol of pyro-Glu-fibrinopeptide deposition after LC separation could be obtained using the device, indicating that there was no sample loss in the interface. To demonstrate the analytical performance of the system as a proteome analysis tool, a range of BSA digest concentrations covering about 3 orders of magnitude, from 5 fmol to 1 pmol, were analyzed by LC-MALDI quadrupole time-of-flight MS, yielding 6 and 57% amino acid sequence coverage, respectively. In addition, a complex protein mixture of an E. coli cell extract was tryptically digested and analyzed by LC-MALDI MS, resulting in the detection of a total of 409 unique peptides from 100 fractions of 15-s intervals.