pH区带逆流色谱法分离纯化马钱子中马钱子碱和士的宁

建立了pH区带逆流色谱分离制备马钱子中生物碱类成分马钱子碱和士的宁的方法。溶剂系统为V(甲基叔丁基醚):V(乙腈):V(水)=2:2:3,静置分层后,上相加入三乙胺,使其浓度为10mmol/L,作为固定相;下相加入HCl,使其浓度为10mmol/L,作为流动相。从308mg马钱子总生物碱中分离得到50mg马钱子碱和120mg士的宁,得率分别为72.8%和85.1%;纯度分别为96.8%和98.3%。并采用LC-ESI-MS和13CNMR对目标化合物的结构进行了鉴定。     

马钱子与甘草配伍前后生物碱成分的变化规律

采用电喷雾质谱技术和高效液相色谱法分别对马钱子配伍甘草前后主要生物碱的变化规律进行了系统研究。实验结果表明,马钱子配伍甘草后其主要生物碱士的宁和马钱子碱的含量均有不同程度的降低,其中士的宁的含量下降显著。电喷雾质谱的实验结果与高效液相色谱的结果相吻合,为进一步阐明甘草解马钱子类药物毒性和马钱子合理配伍用药提供了科学的实验依据。     

生附片化学成分的HPLC/ESI-MSn研究

采用高效液相色谱与电喷雾质谱联用技术, 对生附片的化学成分进行了系统的研究. 并辅以提取离子色谱方法, 发现微量的化学成分. 通过保留时间, 质荷比及多级串联质谱数据, 共鉴定了48个成分, 其中双酯型生物碱8个, 单酯型生物碱7个, 脂型生物碱29个. 其中双酯型生物碱是生附片中的主要成分, 而单酯型和脂型生物碱的含量和种类较少.     

生附片化学成分的HPLC/ESI-MSn研究

采用高效液相色谱与电喷雾质谱联用技术, 对生附片的化学成分进行了系统的研究. 并辅以提取离子色谱方法, 发现微量的化学成分. 通过保留时间, 质荷比及多级串联质谱数据, 共鉴定了48个成分, 其中双酯型生物碱8个, 单酯型生物碱7个, 脂型生物碱29个. 其中双酯型生物碱是生附片中的主要成分, 而单酯型和脂型生物碱的含量和种类较少.     

乌头类双酯型生物碱组分转化为单酯水解型及脂型生物碱组分的研究

建立了乌头类双酯型生物碱组分专一的转化为单酯水解型生物碱组分和脂型生物碱组分的方法,其转化率在90%以上,应用电喷雾多级串联质谱方法监测反应进程并对反应产物进行鉴定,同时可以考察反应中生成的副产物.     

草乌中二萜类生物碱的电喷雾串联质谱研究

利用电喷雾质谱技术对传统中药草乌中的二萜类生物碱进行直接分析鉴定.通过实验数据并对比文献发现,草乌中含有单酯型、双酯型、三酯型和脂类等共4种类型生物碱,其中三酯型和脂类生物碱在草乌中为首次发现.由于这些生物碱的结构相似,在电喷雾串联质谱中碎裂方式相同,因此根据电喷雾串联质谱结果确定了这些生物碱的结构.     

液相色谱-电喷雾串联质谱同时检测血液中8种有毒生物碱

建立了高效液相色谱-电喷雾串联质谱同时检测血液中8种有毒生物碱的方法.血液样品经过乙酸铵-氨水缓冲溶液(pH≈9)处理后,以甲醇提取,采用电喷雾电离(ESI)、多反应监测(MRM)方式,可同时对麻黄碱、毛果芸香碱、士的宁、阿托品、钩吻素子、马钱子碱、乌头碱、喜树碱8种有毒生物碱进行定性和定量分析.在优化的条件下,上述前4种组分在1～100 μg/L范围内线性关系良好,后4种组分在2.5～500 μg/L范围内线性关系良好.8种有毒生物碱的提取回收率在83.1%～104.0%范围内.士的宁、阿托品、马钱子碱、乌头碱和钩吻素子检出限为0.05 μg/L,定量限为0.1 μg/L;麻黄碱、毛果芸香碱、喜树碱的检出限为0.1 μg/L,定量限为0.5 μg/L.各组分的日内RSD小于9%,日间RSD小于10%.本方法操作简便快捷、选择性好、灵敏度高,适用于中毒诊断和法医毒物分析.     

电喷雾多级串联质谱技术区分人乳寡糖异构体

利用四极杆-飞行时间(Q-TOF)电喷雾多级串联质谱(ESI-MS/MS)与诱导碰撞解离技术(C ID)在负离子模式下选择合适碰撞能量对几组互为异构体的人乳寡糖进行了分析,并对其碎裂机理进行了探讨。结果表明:在二级质谱中碰撞能量范围为15~30 eV时,寡糖异构体产生其特征碎片离子,据此可以快速灵敏地区分寡糖异构体。     

反相高效液相色谱法测定全血中马钱子碱和士的宁的含量

 建立了反相高效液相色谱法定量分析全血中马钱子碱和士的宁含量的方法。该方法应用Oasis  R ○ MCX固相萃取小柱进行提取、采用XTerra TM RP 18 色谱柱进行分离。在该条件下马钱子碱和士的宁的线性范围为0.05～10 mg/L ,最小检出限为0.15 ng。该方法测得马钱子碱和士的宁在低、中、高浓度下的回收率均在90%以上,日内、日间精密度均符合方法学要求。该方法灵敏、快速、准确,适用于临床血药浓度监测和法医毒化检验。     

苦参中黄酮类化合物的电喷雾质谱研究

采用电喷雾多级串联质谱对苦参中黄酮类化合物二氢黄酮及二氢黄酮醇类化合物的特征质谱行为进行了研究.实验结果表明,两类化合物在电喷雾多级串联质谱条件下均可以在C环发生开环断裂,但断裂的位点不同;两类化合物生成的碎片离子也有很大差异,提出了由二氢黄酮醇类化合物C环上3位连接的-OH所诱发的不同反应过程的质谱碎裂机理.     

Rapid structural characterization of triterpenoid saponins in crude extract from Symplocos chinensis using liquid chromatography combined with electrospray ionization tandem mass spectrometry

Triterpenoid saponins in bioactive crude extract from Symplocos chinensis were rapidly identified using electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) and liquid chromatography coupled with sequential mass spectrometry (LC-MSn). According to the characteristic fragmentation behavior of known glucuronide-type triterpenoid saponins isolated from this plant, a total of fourteen constituents in the crude extract were structurally characterized on the basis of their retention time and tandem mass spectrometric analysis, including five pairs of naturally occurring isomers. Except one known saponin formerly obtained, the other constituents were new compounds. The analytical method of LC-MSn combined with ESI-MSn in positive and negative ion modes has been developed for the direct structural elucidation of triterpenoid saponins of this kind in plant extracts.     

Rapid identification of C21 steroidal saponins in Cynanchum versicolor Bunge by electrospray ionization multi-stage tandem mass spectrometry and liquid chromatography/tandem mass spectrometry

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn) and liquid chromatography coupled with on-line electrospray ionization tandem mass spectrometry (LC/ESI-MSn) were performed to elucidate the clearage rule of nine investigated C21 steroidal saponins and identify them in the saponin fraction of 90% ethanolic extracts from the root and rhizome of Cynanchum versicolor Bunge. The fragments of C21 steroidal saponins in positive and negative ESI-MSn were used to deduce their mass spectral fragmentation mechanisms, and their structures were further confirmed by ESI-MSn in positive mode. The MSn spectra of the [M+Na]+ ions for saponins provided a wealth of structural information on glycosidic bond cleavage, which allowed a straightforward interpretation of spectra, with respect to the identifications of features such as the sequences of sugars attached to saponins and sugar type. By using LC/ESI-MSn, nine C21 steroidal saponins were detected in the saponin fraction of C. versicolor, and an isomer of atratoglaucoside A was elucidated simultaneously. All nine compounds showed an abundant ion for the loss of 46 Da (HCOOH) from [M+Na]+. The losses of monosaccharide sequences and aglycone as neutral fragmentation from [M+Na-HCOOH]+ were also acquired as the characteristic ions of these C21 steroidal saponins. It provided important information on monosaccharide sequences and in particular on sugar types and could be used to identify and elucidate other C21 steroidal saponins. These studies allowed us to rapidly identify C21 steroidal saponins from Radix cynanchi atrati. It is indicated that the described method had wide applicability to rapidly screen and provide structural confirmation on C21 steroidal saponins in crude materials.     

Multistage electrospray ionization mass spectrometric analyses of sulfur-containing iridoid glucosides in Paederia scandens

Paederia scandens is a traditional Chinese herbal medicine that possesses important bioactive sulfur-containing iridoid glucosides. This study reports the investigation of the fragmentation behavior of four sulfur-containing iridoid glucosides isolated from P. scandens by ion trap electrospray ionization tandem mass spectrometry (ESI-MSn). Both multistage electrospray ionization (ESI-MSn) experiments in an ion trap instrument and high-resolution and accurate mass measurement in an ESI-Q-TOF mass spectrometer in positive mode were used to elucidate the main fragmentation pathways of these compounds. These experiments yielded essentially the same product ions in both ion trap and Q-TOF instruments, and their fragmentation patterns were found useful for their characterization, which were applied to elucidate a trace compound in the extracts of P. scandens by on-line LC/ESI-MSn. Major and diagnostic product ions have been identified and their origins are proposed.     

Characterization of phenolic acids and flavonoids in dandelion (Taraxacum officinale WEB. ex WIGG.) root and herb by high-performance liquid chromatography/electrospray ionization mass spectrometry

Phenolic acids and flavonoids were extracted from a dandelion (Taraxacum officinale WEB. ex WIGG.) root and herb juice and characterized by high-performance liquid chromatography/electrospray ionization mass spectrometry. Among the 43 compounds detected, 5 mono- and dicaffeoylquinic acids, 5 tartaric acid derivatives, 8 flavone and 8 flavonol glycosides were characterized based on their UV spectra and their fragmentation patterns in collision-induced dissociation experiments. The predominant compound was chicoric acid (dicaffeoyltartaric acid). Furthermore, several caffeoylquinic acid isomers were distinguished in dandelion extracts for the first time by their specific mass spectral data. The present study reveals that even more quercetin glycosides were found in dandelion than hitherto assumed. The occurrence of di- and triglycosylated flavonoids in particular has not yet been described. This paper marks the first report on HPLC-DAD/ESI-MSn investigations of phenolic compounds in dandelion.     

Structural evaluation of the glucuronides of morphine and formoterol using chemical derivatization with 1,2-dimethylimidazole-4-sulfonyl chloride and liquid chromatography/ion trap mass spectrometry

For the first time chemical derivatization of isomeric drug glucuronides with 1,2-dimethylimidazole-4-sulfonyl chloride (DMISC) has been successfully applied as a tool for determining the site of conjugation. This provides a way to differentiate between glucuronide isomers containing aliphatic and phenolic hydroxyl groups. The analyses were performed with liquid chromatography/electrospray ion trap mass spectrometry (LC/ESI-MSn). DMISC has previously been shown to react selectively with phenols in estrogens, thus improving sensitivity in ESI-MS. The model compounds selected for this study were commercially available standards of formoterol, morphine, morphine-3-glucuronide (M3G), and morphine-6-glucuronide (M6G). Formoterol glucuronides were produced with an enzymatic method in house. Both formoterol and morphine possess one phenolic and one aliphatic hydroxyl group where glucuronidation could take place. The product ion mass spectra of the native morphine glucuronides were indistinguishable due to the initial neutral loss of monodehydrated glucuronic acid (176 u). However, a significant difference between the isomers was observed with DMISC derivatization, as only the form with a free phenol, M6G, gave a detectable reaction product. Formoterol formed two detectable glucuronide isomers in the enzymatic reaction. Their respective sites of conjugation could not be directly determined from the product ion spectra. Reaction with DMISC, however, gave a detectable product with only one of the isomers. Based on previous experience of the preferred DMISC reactions with phenols, and interpretation of the fragmentation pattern of the derivative, it was concluded that the reactive isomer had a free phenol, and was thus conjugated on the aliphatic chain.     

Electrospray ionization tandem mass spectral analysis of oxidation products of precursors of sulfur mustards

Electrospray ionization tandem mass spectral (ESI-MSn) analysis of thiodiglycol, bis(2-hydroxyethylthio)alkanes (BHETAs) and their mono-, di-, tri-, and tetraoxygenated compounds was carried out to obtain their characteristic spectra for ESI-MS analysis. These compounds are important markers of chemical warfare agents, namely sulfur mustards. ESI-MSn (n > or = 3) analysis of a compound by collisionally induced dissociation in an ion trap gives rise to mass spectra that are somewhat similar to electron ionization mass spectra. These ESI-MSn spectra can be used for compound identification. Under ESI-MS and ESI-MS/MS the compounds mostly produced [M+NH4]+, [M+H]+ and [M+H--H2O]+ ions. Fragmentations of these even-electron precursors in the ion trap gave rise to characteristic product ions via neutral loss of O2, H2O, C2H4, HCHO, C2H4O, C2H4S, HSC2H4OH and C2H4SO. Fragmentation routes of these compounds are proposed that rationalize the formation of product ions in ESI-MSn analysis.     

Rapid structural determination of new trace cassaine-type diterpenoid amides in fractions from Erythrophleum fordii by liquid chromatography-diode-array detection/electrospray ionization tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance

Electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn), and combination with HPLC (HPLC/ESI-MSn), have been extensively applied to on-line analysis of natural products. Hyphenation of liquid chromatography to nuclear magnetic resonance spectroscopy (HPLC/NMR) has been developed in the last decade, which is utilized for the analysis of metabolites and drug impurities. In the study reported here, the fragmentation behaviors of eight cassaine-type diterpenoid amides from Erythrophleum fordii were investigated by ESI-MSn. The fragmentation rules and NMR spectral characteristics are summarized, and the relationship among the rules, characteristics and the structures is described. According to the fragmentation rules and NMR spectral characteristics, seven trace constituents and two formerly obtained compounds of cassaine-type diterpenoid amides in the fractions from E. fordii were structurally characterized on the basis of HPLC/HRMS, HPLC-DAD/ESI-MSn, HPLC/1H NMR and HPLC/1H-1H COSY rapidly. Among them, constituents 1-5 are new compounds, and 6 and 7 are reported from E. fordii for the first time. The aim is to develop an effective analytical method for structural identification of new trace natural products in plants.     

缩酚酸醚类化合物的电喷雾多级串联质谱研究

采用电喷雾多级质谱方法, 研究了三个从地衣中提取到的缩酚酸醚类化合物在电喷雾电离质谱中的裂解行为, 结果表明它们在电喷雾多级质谱中能得到较多碎片离子, 其裂解途径能体现它们的基本结构特征.     

Structural analysis of selected characteristic flavones by electrospray tandem mass spectrometry.

Seven structure analogical flavonoid aglycones have been analyzed using electrospray ionization tandem mass spectrometry (ESI-MSn) in the negative-ion mode. The spectra obtained ESI-MSn allowed us to propose plausible schemes for their fragmentation mechanism. By analyzing the product ions spectra of deprotonated molecule ions [M-H](-), some neutral diagnostic losses and specific retro Diels-Alder fragments were obtained. By using all of these characteristic fragment ions we can specially differentiate the flavone isomer.