草乌与诃子配伍前后醚提液中生物碱类成分的质谱研究

ESI-MS was adopted to detect the difference of alkaloids compounds between root of Kusnezoffii Monkshood(RKM) and the compatibility of RKM and Fructus Chebulae(FC). Contrast to the diethyl ether extract of RKM, the relative abundance of diester-alkaloids decreased significantly when Fructus Chebulae was added, whereas it of lipo-alkaloids increased markedly. The results indicated that the acid components of Fructus Chebulae reduced the dissolvability of diester-alkaloids in diethyl ether

米托蒽醌与双链及三链核酸相互作用的电喷雾质谱研究

The interaction of mitoxantrone (MXT) with duplex and triplex DNA, contain repeating sequence CTCT, CCTT and CTT were studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The 1:3 specific complexes of mitoxantrone and duplex DNA and 1:2 specific complexes of mitoxantrone and triplex DNA were observed. The results show that mitoxantrone has no remarkable sequence selectivity, however it has distinct structure selectivity, and destabilization the triplex.

Screening and Structural Characterization of alpha-Glucosidase Inhibitors from Hawthorn Leaf Flavonoids Extract by Ultrafiltration LC-DAD-MSn and SORI-CID FTICR MS

In vitro a-glucosidase inhibition assays and ultrafiltration liquid chromatography with photodiode array detection coupled to electrospray ionization tandem mass spectrometry (ultrafiltration LC-DAD-ESI-MSn) were combined to screen a-glucosidase inhibitors from hawthorn leaf flavonoids extract (HLFE). As a result, four compounds were identified as alpha-glucosidase inhibitors in the HLFE, and their structures were confirmed to be quercetin-3-O-rha-(1-4)-glc-rha and C-glycosylflavones (vitexin-2 ''-O-glucoside, vitexin-2 ''-O-rhamnoside and vitexin) by high-resolution sustained off resonance irradiation collision-induced dissociation (SORI-CID) data obtained by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS).

Studies on Triterpenoids and Flavones in Glycyrrhiza uralensis Fisch by HPLC-ESI-MSn and FT-ICR-MSn

Seven compounds, four flavones and three triterpenoids from Glycyrrhiza uralensis Fisch. extract are identified by high performance liquid chromatography coupled with electrospray ionization multi-tandem mass spectrometry (HPLC-ESI-MSn). The fragmentation pathways of these compounds are investigated by ESI-MSn and Fourier transform ion cyclotron resonance multiple-stage tandem mass spectrometry (FT-ICR-MSn). Comparing the retention times (t(R)) and mass spectra with those of reference compounds, seven components are identified in Glycyrrhiza uralensis Fisch. and their MSn data proposed plausible schemes for their fragmentation. All the experimental results show that ESI-MSn and FT-ICR-MSn are powerful tools for the structural characterization of triterpenoids and flavones

Investigation of Calmodulin-Peptide Interactions Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry

In this report, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) was used to study the binding interactions between calmodulin and two target peptides (melittin and substance P). Various matrix conditions were tested and the less acidic matrix DHAP and THAP were found to favor the survival of the intact calcium-calmodulin as well as the calmodulin-peptide complexes. However, the application of direct MALDI-MS to detect the intact complexes turned out to be very difficult due to the dissociation of the complexes and the formation of nonspecific aggregates. In contrast, the specific binding of the target peptides to calmodulin could be easily deduced using intensity-fading (IF) MALDI-MS. Compared with the nonbinding control, clear reduction in the ion abundances of the target peptides was observed with the addition of calmodulin.

Analysis of Saponins from Leaves of Aralia elata by Liquid Chromatography and Multi-stage Tandem Mass Spectrometry

Four saponins were isolated from the leaves of Aralia elata, and established using NMR and other spectroscopic methods, as well as data reported in the literature. Three Aralia saponins from the leaves of Aralia elata sharing the same structures as those isolated from the root bark suggested that the leaves would be a good substitute for the root bark of Aralia elata. These four Aralia saponins were then extensively investigated using complementarily positive and negative electrospray ionization multistage tandem mass spectrometry (ESI-MSn). Two isomers of saponins with different sugar linkages were then successfully differentiated by positive ESI-MSn and verified with different retention times and the collision-induced dissociation (CID) spectra by LC-MS. A simple and effective LC-MS method was thus developed for the rapid identification and screening of these saponins in plant extracts from leaves of Aralia elata.

Evaluation of Effects of Bivalent Cations on the Formation of Purine-rich Triple-Helix DNA by ESI-FT-MS

The GGA triplet repeats are widely dispersed throughout eukaryotic genomes. (GGA)n or (GGT)n oligonucleotides can interact with double-stranded DNA containing (GGA:CCT)n to form triple-stranded DNA. The effects of 8 divalent metal ions (3 alkaline-earth metals and 5 transition metals) on formation of these purine-rich triple-helix DNA were investigated by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-MS). In the absence of metal ions, no triplex but single-strand, duplex, and purine homodimer ions were observed in mass spectra. The triple-helix DNA complexes were observed only in the presence of certain divalent ions. The effects of different divalent cations on the formation of purine-rich triplexes were compared. Transition-metal ions, especially Co2+ and Ni2+, significantly boost the formation of triple-helix DNA, whereas alkaline-earth metal ions have no positive effects on triplex formation. In addition, Ba2+ is notably beneficial to the formation of homodimer instead of triplex.

大青叶正丁醇提取物化学成分的HPLC/ESI-MSn研究

High performance liquid chromatography-electrospray ionization mass spectrometry(HPLC/ESI-MSn) was applied to analyze the chemical constituents from n-BuOH extract of Folium Isatidis.The data of retention time,UV spectra,molar masses and structural information on the compounds were obtained.Seventeen compounds are found in extract from n-BuOH.There are four nucleosides,two purines and eleven flavones.

Bimolecular quadruplexes and their transitions to higher-order molecular structures detected by ESI-FTICR-MS

Four individual quadruplexes, which are self-assembled in ammonium acetate solution from telomeric sequences of closely related DNA strands - d(G(4)T(4)G(4)), d(G(3)T(4)G(4)), d(G(3)T(4)G(3)), and d(G(4)T(4)G(3)) - have been detected in the gas phase using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The bimolecular quadruplexes associate with the same number of NH4+ in the gas phase as NMR shows that they do in solution. The quadruplex structures formed in solution are maintained in the gas phase. Furthermore, the mass spectra show that the bimolecular quadruplexes generated by the strands d(G(3)T(4)G(3)) and d(G(4)T(4)G(3)) are unstable, being converted into trimolecular and tetramolecular structures with increasing concentrations of NH4+ in the solution. Circular dichroism (CD) spectra reveal structural changes during the process of strand stoichiometric transitions, in which the relative orientation of strands in the quadruplexes changes from an antiparallel to a parallel arrangement. Such changes were observed for the strand d(G(4)T(4)G(3)), but not for the strand d(G(3)T(4)G(3)). The present work provides a significant insight into the formation of various DNA quadruplexes, especially the higher-order species.

Studies on the content variation of chemical constituents during the combination of ginseng with veratrum nigrum by ESI-MS and HPLC-ESI-MS

To study the content variation of ginsenosides and alkaloids during combination of ginseng with veratrum nigrum, the ginsenosides and alkaloids in the decoction of ginseng with veratrum nigrum were analyzed and compared by high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) and electrospray ionization-mass spectrometry (ESI-MS). In the compatible decoction, eight ginsenosides and eight alkaloids. were detected, and the contents of six ginsenosides were found to be reduced, on the contrary, the contents of six alkaloids were increased. During combination of ginseng with veratrum nigrum, the contents of ginsenosides were reduced and those of the toxic alkaloids were increased. From the chemical point of view, the traditional theory is right that ginseng and veratrum nigrum are incompatible with each other.

Study on the variation of chemical constituents during combination of ginseng with trogopteroum feces and semen raphani by high performance liquid chromatography-mass spectrometry

A high performance liquid chroatography-electrospray ionization-mass spectrometric method was developed for analysis and identification of ginsenosides from the decoction of ginseng, ginseng with trogopteroum feces and ginseng with semen raphani. Ten ginsenosides were separated and detected. The content variation of these ginsenosides was researched. The experimental results showed, that ginsenosides were less in compatible decoction than in separate one expect Ro. the stripping of ginsenosides were restrained by semen raphani and during combination of ginseng with trogopteroum feces, the precipitates were produced by ginsenosides.

Studies on the alkaloid components in Strychnos nux-vomical L. uncombined and combined with Glycyrrhiza Uralensis Fisch

The alkaloid components in Strychnos nux-vomical L. uncombined and combined with Glycyrrhiza uralensis Fisch have been investigated by electrospray ionization tandem mass spectrometry ( ESI-MSn) and HPLC. The experimental results demonstrated that the number of strychnine and brucine all declined in combined Strychnos nux-vomical L. with Glycyrrhiza uralensis Fisch, and the concentration level of strychnine fell obviously. The results of ESI-MS were identical to those of HPLC, which provided scientific basis for explanation of detoxicity of Glycyrrhiza uralensis Fisch and the reasonable combination of Strychnos nux-vomical L.

A study of isomeric diglycosyl flavonoids by SORI CID of Fourier transform ion cyclotron mass Spectrometry in negative ion mode

High-resolution Sustained off resonance irradiation (SORI) CID was employed to distinguish four pairs of isomeric diglycosyl flavonoids in the negative mode using the electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS). All of these isomers can be distinguished via MS/MS data. For these diglycosyl flavones and flavanones, the deprotonated alpha 1-->6 linkage diglycosyl flavonoids produce fewer fragments than the alpha 1-->2 linkage type compounds and the Retro-Diels-Alder (RDA) reaction in MS/MS only takes place when the aglycone is a flavanone and glycosylated with an alpha 1-->2 intersaccharide linkage disaccharide. The deprotonation sites after collisional activation are discussed according to the high mass accuracy and high-resolution data of tandem spectrometry. Some of these high-resolution SORI CID product ions from alpha 1-->2 linkage diglycosyl flavonoids involve multibond cleavages; the possible mechanism is discussed based on the computer modeling using Gaussian 03 program package at the B3LYP/6-31G level of theory. Unambiguous elementary composition data provides fragmentation information that has not been reported previously.

两种黄酮醇苷同分异构体的电喷雾质谱区分

Two flavonol glycoside isomers of Icariside Ⅰ and Caohuoside C were differentiated by electrospray ionization tandem mass spectrometry (ESI-MSn) method.In the negative ion mode,the two compounds with different glycosyl moieties showed the same ESI-MS spectrum,but obvious different MS2 spectra and thus they can be distinguished rapidly,accurately and easily by ESI-MS.

黄芩苷与环糊精非共价复合物的电喷雾串联质谱研究

黄芩苷(Baicalin)是中药黄芩的有效成分,具有抑菌,抗炎,抗变态反应等药理作用[1].