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Studies on Triterpenoids and Flavones in Glycyrrhiza uralensis Fisch. By HPLC-ESI-MSn and FT-ICR-MSn
应用高效液相色谱质谱联用方法(HPLC-ESI-MSn)研究了甘草提取物中的七种化合物,四种三萜类化合物和三种黄酮类化合物。通过多极串联质谱(ESI-MSn)和多极串联傅里叶变换回旋共振质谱(FT-ICR-MSn)法研究了它们的碎裂规律。通过比较保留时间和质谱数据对上述七种化合物进行了归属,并阐述了其可能的质谱裂解途径。以上结果显示ESI-MSn和FT-ICR-MSn是非常有效的分析三萜类化合物和黄酮类化合物结构的工具。 相似文献
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Irene Orera Jesús Orduna Javier Abadía Ana Álvarez‐Fernández 《Rapid communications in mass spectrometry : RCM》2010,24(1):109-119
Fertilizers based on synthetic polyaminocarboxylate ferric chelates have been known since the 1950s to be successful in supplying Fe to plants. In commercial Fe(III)‐chelate fertilizers, a significant part of the water‐soluble Fe‐fraction consists of still uncharacterized Fe byproducts, whose agronomical value is unknown. Although collision‐induced dissociation (CID) tandem mass spectrometry (MS/MS) is a valuable tool for the identification of such compounds, no fragmentation data have been reported for most Fe(III)‐chelate fertilizers. The aim of this study was to characterize the CID‐MS2 fragmentation patterns of the major synthetic Fe(III)‐chelates used as Fe‐fertilizers, and subsequently use this technique for the characterization of commercial fertilizers. Quadrupole‐time‐of‐flight (QTOF) and spherical ion trap mass analyzers equipped with an electrospray ionization (ESI) source were used. ESI‐CID‐MS2 spectra obtained were richer when using the QTOF device. Specific differences were found among Fe(III)‐chelate fragmentation patterns, even in the case of positional isomers. The analysis of a commercial Fe(III)‐chelate fertilizer by high‐performance liquid chromatography (HPLC) coupled to ESI‐MS(QTOF) revealed two previously unknown, Fe‐containing compounds, that were successfully identified by a comprehensive comparison of the ESI‐CID‐MS2(QTOF) spectra with those of pure chelates. This shows that HPLC/ESI‐CID‐MS2(QTOF), along with the Fe(III)‐chelate fragmentation patterns, could be a highly valuable tool to directly characterize the water‐soluble Fe fraction in Fe(III)‐chelate fertilizers. This could be of great importance in issues related to crop Fe‐fertilization, both from an agricultural and an environmental point of view. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Shu‐Ying Peng Ting Shi Ya‐Zhou Wang Li‐Gen Lin Yi‐Ming Yang Hua‐Liang Jiang Yang Ye 《Rapid communications in mass spectrometry : RCM》2009,23(23):3621-3631
The electrospray ionization (ESI) mass spectrometric behavior of five Stemona alkaloids, stemokerrin, oxystemokerrin, oxystemokerrilactone, oxystemokerrin N‐oxide and stemokerrin N‐oxide, was studied using an ESI tandem mass technique (MSn). These compounds, isolated from Stemona saxorum endemic in Vietnam, represent a class of alkaloids containing a pyrido[1,2‐a]azepine A,B‐ring core with a 1‐hydroxypropyl side chain attached to C‐4. Their fragmentation pathways were elucidated by ESI‐MSn results and the elemental composition of the major product ions was confirmed by accurate mass measurement. In order to rationalize some fragmentation pathways, the relative Gibbs free energies of some product ions were estimated using the B3LYP/6‐31+G(d) method. Based on the ESI‐MSn results of five reference compounds, a reversed‐phase high‐performance liquid chromatography with tandem mass spectrometry (RP‐HPLC/MSn) method was developed for the characterization of Stemona alkaloids with a pyrido[1,2‐a]azepine A,B‐ring core from the extract of S. saxorum. A total of 41 components were rapidly identified or tentatively characterized, of which 12 compounds were identified as Stemona alkaloids with a pyrido[1,2‐a]azepine A,B‐ring core, including four new compounds. This method is convenient and sensitive, especially for minor components in complex natural product extracts. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Yuanyan Liu Jianbei Li Jiuming He Zeper Abliz Jing Qu Shishan Yu Shuanggang Ma Jing Liu Dan Du 《Rapid communications in mass spectrometry : RCM》2009,23(5):667-679
Triterpenoid saponins are the major bioactive constituents of Panax notoginseng. In the study reported here, the fragmentation behavior of triterpenoid saponins from P. notoginseng was investigated by electrospray ionization tandem mass spectrometry (ESI‐MSn)and high‐performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (HPLC/ESI‐MSn). Analyses revealed that product ions from glycosidic and cross‐ring cleavages can give a wealth of structural information regarding the nature of the aglycone, sugar types, the sequence and linkage information of sugar units. It is noted that different glycosylation positions remarkably influenced the fragmentation behaviors, which could assist in the differentiation of saponin analogues. To rationalize this characteristic, the collision energy required for various glycosidic cleavages was investigated. According to the summarized fragmentation rules, identification of triterpenoid saponins from the roots of P. notoginseng could be fulfilled, even when reference standards were unavailable. Furthermore, minor and trace constituents were enriched and detected by eliminating the major constituents in one of the saponin fractions. As a result, a total of 151 saponins, including 56 new trace ones, were identified or tentatively characterized from saponin fractions based on their retention times, HPLC/HRMS, HPLC/ESI‐MSn fragmentation behaviors and comparison with literature data. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Élida Alechaga Encarnación Moyano M. Teresa Galceran 《Journal of mass spectrometry : JMS》2013,48(11):1241-1251
In this work, the mass spectrometry behaviour of the veterinary drug family of phenicols, including chloramphenicol (CAP) and its related compounds thiamphenicol (TAP), florfenicol (FF) and FF amine (FFA), was studied. Several atmospheric pressure ionization sources, electrospray (ESI), atmospheric pressure chemical ionization and atmospheric pressure photoionization were compared. In all atmospheric pressure ionization sources, CAP, TAP and FF were ionized in both positive and negative modes; while for the metabolite FFA, only positive ionization was possible. In general, in positive mode, [M + H]+ dominated the mass spectrum for FFA, while the other compounds, CAP, TAP and FF, with lower proton affinity showed intense adducts with species present in the mobile phase. In negative mode, ESI and atmospheric pressure photoionization showed the deprotonated molecule [M–H]?, while atmospheric pressure chemical ionization provided the radical molecular ion by electron capture. All these ions were characterized by tandem mass spectrometry using the combined information obtained by multistage mass spectrometry and high‐resolution mass spectrometry in a quadrupole‐Orbitrap instrument. In general, the fragmentation occurred via cyclization and losses or fragmentation of the N‐(alkyl)acetamide group, and common fragmentation pathways were established for this family of compounds. A new chemical structure for the product ion at m/z 257 for CAP, on the basis of the MS3 and MS4 spectra is proposed. Thermally assisted ESI and selected reaction monitoring are proposed for the determination of these compounds by ultra high‐performance liquid chromatography coupled to tandem mass spectrometry, achieving instrumental detection limits down to 0.1 pg. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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N‐Boc/Fmoc/Z‐N′‐formyl‐gem‐diaminoalkyl derivatives, intermediates particularly useful in the synthesis of partially modified retro‐inverso peptides, have been characterized by both positive and negative ion electrospray ionization (ESI) ion‐trap multi‐stage mass spectrometry (MSn). The MS2 collision induced dissociation (CID) spectra of the sodium adduct of the formamides derived from the corresponding N‐Fmoc/Z‐amino acids, dipeptide and tripeptide acids show the [M + Na‐NH2CHO]+ ion, arising from the loss of formamide, as the base peak. Differently, the MS2 CID spectra of [M + Na]+ ion of all the N‐Boc derivatives yield the abundant [M + Na‐C4H8]+ and [M + Na‐Boc + H]+ ions because of the loss of isobutylene and CO2 from the Boc protecting function. Useful information on the type of amino acids and their sequence in the N‐protected dipeptidyl and tripeptidyl‐N′‐formamides is provided by MS2 and subsequent MSn experiments on the respective precursor ions. The negative ion ESI mass spectra of these oligomers show, in addition to [M‐H]?, [M + HCOO]? and [M + Cl]? ions, the presence of in‐source CID fragment ions deriving from the involvement of the N‐protecting group. Furthermore, MSn spectra of [M + Cl]? ion of N‐protected dipeptide and tripeptide derivatives show characteristic fragmentations that are useful for determining the nature of the C‐terminal gem‐diamino residue. The present paper represents an initial attempt to study the ESI‐MS behavior of these important intermediates and lays the groundwork for structural‐based studies on more complex partially modified retro‐inverso peptides. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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A series of α‐acyloxyhydroperoxy aldehydes was analyzed with direct infusion electrospray ionization tandem mass spectrometry (ESI/MSn) as well as liquid chromatography coupled with the mass spectrometry (LC/MS). Standards of α‐acyloxyhydroperoxy aldehydes were prepared by liquid‐phase ozonolysis of cyclohexene in the presence of carboxylic acids. Stabilized Criegee intermediate (SCI), a by‐product of the ozone attack on the cyclohexene double bond, reacted with the selected carboxylic acids (SCI scavengers) leading to the formation of α‐acyloxyhydroperoxy aldehydes. Ionization conditions were optimized. [M + H]+ ions were not formed in ESI; consequently, α‐acyloxyhydroperoxy aldehydes were identified as their ammonia adducts for the first time. On the other hand, atmospheric‐pressure chemical ionization has led to decomposition of the compounds of interest. Analysis of the mass spectra (MS2 and MS3) of the [M + NH4]+ ions allowed recognizing the fragmentation pathways, common for all of the compounds under study. In order to get detailed insights into the fragmentation mechanism, a number of isotopically labeled analogs were also studied. To confirm that the fragmentation mechanism allows predicting the mass spectrum of different α‐acyloxyhydroperoxy aldehydes, ozonolysis of α‐pinene, a very important secondary organic aerosol precursor, was carried out. Spectra of the two ammonium cationized α‐acyloxyhydroperoxy aldehydes prepared with α‐pinene, cis‐pinonic acid as well as pinic acid were predicted very accurately. Possible applications of the method developed for the analysis of α‐acyloxyhydroperoxy aldehydes in SOA samples, as well as other compounds containing hydroperoxide moiety are discussed. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Yanchun Guo Shuxia Cao Donghui Wei Xiangkun Zong Xingbo Yuan Mingsheng Tang Yufen Zhao 《Journal of mass spectrometry : JMS》2009,44(8):1188-1194
The fragmentation pathways of deprotonated cyclic dipeptides have been studied by electrospray ionization multi‐stage mass spectrometry (ESI‐MSn) in negative mode. The results showed that the fragmentation pathways of deprotonated cyclic dipeptides depended significantly on the different substituents, the side chains of amino acid residues at the diketopiperazine ring. In the spectra of deprotonated cyclic dipeptides, the ion [M? H? substituent radical]? was firstly observed in the ESI mode. The characteristic fragment ions [M? H? substituent radical]? and [M? H? (substituent? H)]? could be used as the symbols of particular cyclic dipeptides. The hydrogen/deuterium (H/D) exchange experiment, the high‐resolution mass spectrometry (Q‐TOF) and theoretical calculations were used to rationalize the proposed fragmentation pathways and to verify the differences between the fragmentation pathways. The relative Gibbs free energies (ΔG) of the product ions and possible fragmentation pathways were estimated using the B3LYP/6–31++G(d, p) model. The results have some potential applications in the structural elucidation and interpretation of the mass spectra of homologous compounds and will enrich the gas‐phase ESI‐MS ion chemistry of cyclic dipeptides. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Erwann Guénin Marc Lecouvey Julie Hardouin 《Rapid communications in mass spectrometry : RCM》2009,23(9):1395-1400
1‐Hydroxymethylene‐1,1‐bisphosphonic acids (or bisphosphonates) are compounds that have interesting pharmacological applications. However, few mass spectrometric investigations have been carried out to determine their fragmentation patterns. Herein, we evaluated different matrices for the study by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) of the formation and fragmentation of the protonated, the cationized (MNa+ and MK+) and the deprotonated bisphosphonates. Some in‐source fragmentations were observed both in positive and in negative ion modes. The fragmentation patterns obtained in post‐source decay mode are also discussed. In contrast to previous electrospray ionization/multi‐stage mass spectrometry (ESI‐MSn) studies, some new fragmentation pathways were deduced and the effects of alkali ions on the fragmentation patterns were shown. The results summarized here completed the data previously recorded by ESI‐MSn and could be used for the characterization of bisphosphonates as alkali complexes in biological mixtures. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
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Ion tree‐based structure elucidation of acetophenone dimers (AtA) from Acronychia pedunculata and their identification in extracts by liquid chromatography electrospray ionization LTQ‐Orbitrap mass spectrometry
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Eirini Kouloura Alexios‐Leandros Skaltsounis Sylvie Michel Maria Halabalaki 《Journal of mass spectrometry : JMS》2015,50(3):495-512
Acronychia‐type acetophenones (AtA) is a chemical group of compounds of important structural and biological interest, abundant in Acronychia species. However, there are no data available for their characterization using mass spectrometry. In the current work, AtA have been investigated by multistage high resolution mass spectrometry and both electrospray ionization and atmospheric pressure chemical ionization, in positive and negative mode, were utilized for their structure elucidation and identification. The analysis of AtA using a linear ion trap‐Orbitrap analyzer enabled the structural determination of key fragment ions and cleavages, which can be used for the structural characterization thereof. A systematic nomenclature based on protonated and deprotonated fragment ions under collision‐induced dissociation conditions and decision trees for the structural determination of AtA are proposed. Furthermore, taking advantage of the characteristic fragmentation patterns, a selective Ultra High Performance Liquid Chromatography Electrospray Ionization multistage Mass Spectrometry (UHPLC‐ESI(‐)‐MSn) method was developed and successfully applied for the dereplication of known AtA and the identification of potentially new ones in Acronychia extracts. Despite the structure similarity and the presence of isomers, accurate characterization of known and unknown AtA derivatives was possible. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Mass spectrometric profiling of valepotriates possessing various acyloxy groups from Valeriana jatamansi
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Xu Liang Xi Zhang Juan Su Peng Fu Di‐Ya Lv Lei Shan Yun‐Heng Shen Hui‐Liang Li Xian‐Wen Yang Wei‐Dong Zhang 《Journal of mass spectrometry : JMS》2015,50(11):1294-1304
Valepotriates, plant secondary metabolites of the family Valerianaceae, contain various acyloxy group linkages to the valepotriate nucleus and exhibit significant biological activities. Identification of valepotriates is important to uncover potential lead compounds for the development of new sedative and antitumor drugs. However, making their structure elucidation by nuclear magnetic resonance (NMR) experiments is too difficult to be realized because of the overlapped carbonyl carbon signals of acyloxy groups substituted at different positions. Thus, the mass spectrometric profiling of these compounds in positive ion mode was developed to unveil the exact linkage of acyloxy group and the core of valepotriate. In this study, electrospray ionization tandem multistage mass spectrometry (ESI‐MS/MSn) in ion trap and collision‐induced dissociation tandem MS were used to investigate the fragmentation pathways of four types of valepotriates in Valeriana jatamansi, including 5‐hydroxy‐5,6‐dihydrovaltrate hydrin (5‐hydroxy‐5,6‐dihydrovaltrate chlorohydrin), 5,6‐dihydrovaltrate hydrin (5,6‐dihydrovaltrate chlorohydrin), 5‐hydroxy‐5,6‐dihydrovaltrate and valtrate hydrin (valtrate chlorohydrin). The high‐resolution mass spectrum (HRMS) data of all the investigated valepotriates from quadrupole time‐of‐flight MS/MS were used as a supportive of the fragmentation rules we hypothesized from ion‐trap stepwise MSn. As a result, the loss sequence of acyloxy groups and the abundance of key product ions, in combination with the characteristic product ions corresponding to the valepotriate nucleus, could readily differentiate the four different types of valepotriates. The summarized fragmentation rules were also successfully exploited for the structural characterization of three new trace valepotriates from V. jatamansi. The results indicated that the developed analytical method could be employed as a rapid, effective technique for structural characterization of valepotriates, especially for the trace compounds that could not be identified by NMR techniques. This study may also arouse interest for further structural analysis of other valepotriate‐containing type herbal medicines. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Brian D. McGarvey Hui Liao Keyi Ding Xiaoling Wang 《Journal of mass spectrometry : JMS》2012,47(6):687-693
In the search for novel natural products in plants, particularly those with potential bioactivity, it is important to efficiently distinguish novel compounds from previously isolated, known compounds, a process known as dereplication. In this study, electrospray ionization‐multiple stage tandem mass spectrometry (ESI‐MSn) was used to study the behaviour of 12 pregnane glycosides and genins previously isolated from Marsdenia tenacissima, a traditional Chinese medicinal plant, as a basis for dereplication of compounds in a plant extract. In addition to [M + Na]+ and [M + NH4]+ ions, a characteristic [M‐glycosyl + H]+ ion was observed in full‐scan mode with in‐source fragmentation. Sequential in‐trap collision‐induced dissociation of [M + Na]+ ions from 11,12‐diesters revealed consistent preferred losses of substituents first from C‐12, then from C‐11, followed by losses of monosaccharide fragments from the C‐3 tri‐ and tetrasaccharide substituents. A crude methanol extract of M. tenacissima stems was analysed using high‐performance liquid chromatography coupled to ESI‐MS. Several previously isolated pregnane glycosides were dereplicated, and the presence of an additional nine novel pregnane glycosides is predicted on the basis of the primary and fragment ions observed, including two with a previously unreported C4H7O C‐11/C‐12 substituent of pregnane glycosides. This study is the first report of prediction of the structures of novel pregnane glycosides in a crude plant extract by a combination of in‐source fragmentation and in‐trap collision‐induced dissociation and supports the usefulness of LC‐ESI‐MSn not only for dereplication of active compounds in extracts of medicinal plants but also for detecting the presence of novel related compounds. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The use of chemical warfare agents has become an issue of emerging concern. One of the challenges in analytical monitoring of the extremely toxic ‘V’‐type chemical weapons [O‐alkyl S‐(2‐dialkylamino)ethyl alkylphosphonothiolates] is to distinguish and identify compounds of similar structure. MS analysis of these compounds reveals mostly fragment/product ions representing the amine‐containing residue. Hence, isomers or derivatives with the same amine residue exhibit similar mass spectral patterns in both classical EI/MS and electrospray ionization‐MS, leading to unavoidable ambiguity in the identification of the phosphonate moiety. A set of five ‘V’‐type agents, including O‐ethyl S‐(2‐diisopropylamino)ethyl methylphosphonothiolate (VX), O‐isobutyl S‐(2‐diethylamino)ethyl methylphosphonothiolate (RVX) and O‐ethyl S‐(2‐diethylamino)ethyl methylphosphonothiolate (VM) were studied by liquid chromatography/electrospray ionization/MS, utilizing a QTRAP mass detector. MS/MS enhanced product ion scans and multistage MS3 experiments were carried out. Based on the results, possible fragmentation pathways were proposed, and a method for the differentiation and identification of structural isomers and derivatives of ‘V’‐type chemical warfare agents was obtained. MS/MS enhanced product ion scans at various collision energies provided information‐rich spectra, although many of the product ions obtained were at low abundance. Employing MS3 experiments enhanced the selectivity for those low abundance product ions and provided spectra indicative of the different phosphonate groups. Study of the fragmentation pathways, revealing some less expected structures, was carried out and allowed the formulation of mechanistic rules and the determination of sets of ions typical of specific groups, for example, methylphosphonothiolates versus ethylphosphonothiolates. The new group‐specific ions elucidated in this work are also useful for screening unknown ‘V’‐type agents and related compounds, utilizing precursor ion scan experiments. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Mona AbdelTawab Ute Bahr Bruno Danieli Steffen Gebhardt Michael Karas Sergio Riva Manfred Schubert‐Zsilavecz 《Helvetica chimica acta》2000,83(4):739-747
The ginsenosides Rb1 ( 3 ) and Rg1 ( 4 ) isolated from Panax ginseng were enzymatically modified with galactosyltransferase to furnish new derivatives carrying galactose units in one or both sugar chains at position C(20) and/or C(3) or C(6) of the protopanaxadiol and protopanaxatriol aglycones 1 and 2 , respectively. To determine the linkage position(s) of the introduced galactose unit(s), an electrospray‐ionization MS analysis with consecutive fragmentation steps (ESI‐MSn) was carried out using an ion‐trap mass spectrometer (Figs. 2 and 3). It was shown that both sugar moieties, located at different positions of the protopanaxadiol and protopanaxatriol aglycone, can be easily differentiated and analyzed in the subsequent fragmentation steps. Collision‐induced dissociation (CID) of the Na+‐ionized molecule (MS2) leads to cleavage of the most labile O−C(20) glycosidic bond, liberating the C(20) oligosaccharide fragment ion that can be analyzed in a subsequent fragmentation step (MS3). MS3 of the C(20) monodeglycosylated ginsenoside leads to cleavage of the second sugar moiety, allowing structure analysis of this fragment ion (MS4). By this method, the linkages of the monosaccharides and branching positions can be rapidly determined using only a few μl of a 10−5 M sample solution. 相似文献
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Hisayuki Horai Masanori Arita Shigehiko Kanaya Yoshito Nihei Tasuku Ikeda Kazuhiro Suwa Yuya Ojima Kenichi Tanaka Satoshi Tanaka Ken Aoshima Yoshiya Oda Yuji Kakazu Miyako Kusano Takayuki Tohge Fumio Matsuda Yuji Sawada Masami Yokota Hirai Hiroki Nakanishi Kazutaka Ikeda Naoshige Akimoto Takashi Maoka Hiroki Takahashi Takeshi Ara Nozomu Sakurai Hideyuki Suzuki Daisuke Shibata Steffen Neumann Takashi Iida Ken Tanaka Kimito Funatsu Fumito Matsuura Tomoyoshi Soga Ryo Taguchi Kazuki Saito Takaaki Nishioka 《Journal of mass spectrometry : JMS》2010,45(7):703-714
MassBank is the first public repository of mass spectra of small chemical compounds for life sciences (<3000 Da). The database contains 605 electron‐ionization mass spectrometry(EI‐MS), 137 fast atom bombardment MS and 9276 electrospray ionization (ESI)‐MSn data of 2337 authentic compounds of metabolites, 11 545 EI‐MS and 834 other‐MS data of 10 286 volatile natural and synthetic compounds, and 3045 ESI‐MS2 data of 679 synthetic drugs contributed by 16 research groups (January 2010). ESI‐MS2 data were analyzed under nonstandardized, independent experimental conditions. MassBank is a distributed database. Each research group provides data from its own MassBank data servers distributed on the Internet. MassBank users can access either all of the MassBank data or a subset of the data by specifying one or more experimental conditions. In a spectral search to retrieve mass spectra similar to a query mass spectrum, the similarity score is calculated by a weighted cosine correlation in which weighting exponents on peak intensity and the mass‐to‐charge ratio are optimized to the ESI‐MS2 data. MassBank also provides a merged spectrum for each compound prepared by merging the analyzed ESI‐MS2 data on an identical compound under different collision‐induced dissociation conditions. Data merging has significantly improved the precision of the identification of a chemical compound by 21–23% at a similarity score of 0.6. Thus, MassBank is useful for the identification of chemical compounds and the publication of experimental data. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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E‐Hu Liu Ting Zhou Guo‐Bin Li Jing Li Xiu‐Ning Huang Feng Pan Ning Gao 《Journal of separation science》2012,35(2):263-272
The multiple bioactive constituents in Hedyotis diffusa Willd. (H. diffusa) were extracted and characterized by high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry (HPLC‐ESI‐MSn). The optimized separation condition was obtained using an Agilent ZorBax SB‐C18 column (4.6×150 mm, 5 μm) and gradient elution with water (containing 0.1% formic acid) and acetonitrile (containing 0.1% formic acid), under which baseline separation for the majority of compounds was achieved. Among the compounds detected, 14 iridoid glucosides, 10 flavonoids, 7 anthraquinones, 1 coumarin and 1 triterpene were unambiguously identified or tentatively characterized based on their retention times and mass spectra in comparison with the data from standards or references. The fragmentation behavior for different types of constituents was also investigated, which could contribute to the elucidation of these constituents in H. diffusa. The present study reveals that even more iridoid glycosides were found in H. diffusa than hitherto assumed. The occurrence of two iridoid glucosides and five flavonoids in particular has not yet been described. This paper marks the first report on the structural characterization of chemical compounds in H. diffusa by a developed HPLC‐ESI‐MSn method. 相似文献
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A semi‐quantitative method of mass spectrometry (MS) has been described for the analysis of metabolites of aconitine by rat intestinal bacteria at different pH. At pH 7.0, the rat intestinal bacteria exhibit optimal activity for the metabolism of aconitine. A high‐performance liquid chromatography‐electrospray ionization multiple‐stage mass spectrometry (HPLC/ESI‐MSn) method has been applied to investigate the characteristic product ions of metabolites. Then, the logical fragmentation pathways of metabolites have been proposed. By comparing the retention time (tR) of HPLC and the ESI‐MSn data with the data of standard compounds and reports from literature, ten metabolites have been identified and a distinctive metabolite (15‐deoxyaconitine) has been deduced first time. The experimental results demonstrate that HPLC/ESI‐MSn is a specific and useful method for the identification of metabolites of aconitine. Also, in the present paper, the HPLC‐MS method was introduced to determine the synthetical metabolite prior to the study of the toxicity by the method of Bliss. 相似文献