Integration of ion-exchange chromatography fractionation with reversed-phase liquid chromatography-atmospheric pressure chemical ionization mass spectrometer and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for isolation and identification of compounds in Psoralea corylifolia

Characterization of effective phytochemicals in traditional Chinese medicine by mass spectrometry

Traditional Chinese medicines (TCMs) have been widely used in clinical and healthcare applications around the world. The characterization of the phytochemical components in TCMs is very important for studying the therapeutic mechanism of TCMs. In the analysis process, sample preparation and instrument analysis are key steps to improve analysis performance and accuracy. In recent years, chromatography combined with mass spectrometry (MS) has been widely used for the separation and detection of trace components in complex TCM samples. This article reviews various sample preparation techniques and chromatography-MS techniques, including the application of gas chromatography-MS and liquid chromatography-MS and other MS techniques in the characterization of phytochemicals in TCM materials and Chinese medicine products. This article also describes a new ambient ionization MS method for rapid and high-throughput analysis of TCM components.

The Accumulation of Psoralen Contributes to Its Hepatotoxicity Revealed by Pharmacokinetic and Toxicokinetic Study after Repeated Administration

Psoralen is a furanocoumarin compound found in many herb medicines and is claimed to contribute to the hepatotoxicity caused by lots of traditional Chinese medicine. So far, there has been no research on the differences in pharmacokinetics of single and repeated dosing of psoralen. Moreover, the research on the cumulative toxicity of low concentration and long-term administration on cells has not been reported. Therefore, this study investigated the pharmacokinetic differences and the accumulated cytotoxicity of psoralen from repeated administration. The study found that after single or repeated administration of psoralen for 3 months at various dosages (14, 28, and 56 mg/kg), the pharmacokinetic parameters of female rats between single dose and repeated dose administration are totally different. Compared with a single administration, multiple administrations increased psoralen's in vivo exposure, prolonged the peak time, prolonged the half-life of the drug, reduced the drug clearance rate, and prolonged the drug's stay in the body. HepG2 cells were exposed to low doses (5, 10, 20, or 40 μM) of psoralen for 1, 2, 3, or 4 days. A 20 and 40 μM dose of psoralen did not induced cell death in the 1st day but significantly decreased the cell viability at the 3rd and 4th day of repeated administration, respectively. In addition, multiple administrations of psoralen decreased cell viability due to G2 arrest.

Analysis of Compounds Dissolved in Nonpolar Solvents by Electrospray Ionization on Conductive Nanomaterials

Electrospray ionization mass spectrometry (ESI-MS) technique has limitations in analysis of compounds that are dissolved in nonpolar solvents. In this study, ambient ionization of compounds in solvents that are not "friendly" to electrospray ionization, such as n-hexane, is achieved by conductive nanomaterials spray ionization (CNMSI) on nanomaterial emitters, including carbon nanotubes paper and mesodendritic silver covered metal, which applies high voltages to emitters made of these materials without the assistance of polar solvents. Although the time intensity curves (TIC) commonly vary from 4.5% to 23.7% over analyses, protonated molecular ions were found to be the most abundant species, demonstrating good reproducibility of the technique in terms of ionized species. Higher mass spectrometric responses are observed in analyzing nonpolar systems than polar systems. 2-Methoxyacetophenone, 4-methylacetophenone, benzothiazole, quinolone, and cycloheptanone as low as 2 pg in n-hexane can be directly detected using the developed method. The developed technique expands the analysis capability of ESI-MS for direct, online analysis of nonpolar systems, such as low polarity extracts, normal phase liquid chromatography eluates, and synthetic mixtures. Graphical Abstract.

A Comprehensive Characterisation of Rosemary tea Obtained from Rosmarinus officinalis L. Collected in a sub-Humid Area of Tunisia

INTRODUCTION

Rosemary (Rosmarinus officinalis L.) is an aromatic plant common in Tunisia and it is widely consumed as a tea in traditional cuisine and in folk medicine to treat various illnesses. Currently, most research efforts have been focused on rosemary essential oil, alcoholic and aqueous extracts, however, little is reported on rosemary infusion composition.

OBJECTIVE

To investigate compounds present in rosemary tea obtained from Rosmarinus officinalis L. collected in a sub-humid area of Tunisia in order to assess whether the traditional rosemary tea preparation method could be considered as a reference method for rosemary's compounds extraction.

METHODOLOGY

Qualitative characterisation of Rosmarinus officinalis tea obtained after rosemary infusion in boiled water was determined by high performance liquid chromatography coupled with electrospray ionisation quadrupole time-of-flight mass spectrometry (HPLC-ESI-QTOF-MS). Quantitative analysis relies on high performance liquid chromatography with diode array detector (HPLC-DAD).

RESULTS

Forty-nine compounds belonging to six families, namely flavonoids, phenolic acids, phenolic terpenes, jasmonate, phenolic glycosides, and lignans were identified. To the best of the authors' knowledge eucommin A is characterised for the first time in rosemary. Rosmarinic acid (158.13 μg/g dried rosemary) was the main compound followed then by feruloylnepitrin (100.87 μg/g) and luteolin-3'-O-(2″-O-acetyl)-β-d-glucuronide (44.04 μg/g). Among quantified compounds, luteolin-7-O-rutinoside was the compound with the lowest concentration.

CONCLUSION

The infusion method allows several polyphenols present in rosemary tea to be extracted, therefore it could be a reference method for rosemary's compounds extraction. Moreover, traditional Tunisian Rosmarinus officinalis tea consumption is of interest for its rich phenolic content. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of isopsoralen on Smad7 in osteoblastic MC3T3-E1 cells

The primary pathological change in postmenopausal osteoporosis (PM-OP) is bone collagen loss caused by estrogen depletion. Osteoblasts synthesize type I collagen, which composes the organic matrix of bone. Although isopsoralen stimulates osteoblastic cell proliferation and differentiation, transforming growth factor (TGF)-β1 is an important cell signaling factor for stimulating collagen synthesis. To explore the association between isopsoralen and the synthesis of collagen in vitro, the molecular and biological association between isopsoralen and TGF-β signaling was examined. (CAGA) 12-luciferase-reporter gene was used to measure TGF-β1 signaling activity. Type I collagen was detected by semiquantitative reverse transcription polymerase chain reaction, and mothers against decapentaplegic homolog 7 (Smad7) protein expression levels were analyzed by western blotting. The expression of collagen in MC3T3-E1 cells stimulated with isopsoralen was significantly upregulated compared with the control groups (P<0.05). Conversely, isopsoralen significantly decreased Smad7 protein expression compared with the control groups (P<0.05). Moreover, it was observed that isopsoralen activates the TGF-β1 signaling pathway and ultimately promotes collagen synthesis through inhibition of Smad7 protein expression. Therefore, isopsoralen is a potential target for the treatment of PM-OP.

Chiral separation of bavachinin in Fructus Psoraleae and rat plasma by liquid chromatography using permethylated-β-CD as a chiral selector

A simple, sensitive and selective method of high-performance liquid chromatography (HPLC) has been successfully developed for separation of bavachinin enantiomers in Fructus Psoraleae and rat plasma. The separation and detection conditions of HPLC were optimized. Chiral bavachinin were separated with the mobile phase of methanol and water (70:30, v/v) at a flow rate of 1.0 mL/min. The linear ranges were in the range of 20–1000 μg/mL. The detection limits were tested as 4 ng/mL and 6 ng/mL for (+)-bavachinin and (−)-bavachinin, respectively. The method has been applied to analyze chiral bavachinin in rat plasma. HPLC–MS method was used to test the accuracy.

Separation of isomeric bavachin and isobavachalcone in the fructus Psoraleae by capillary electrophoresis-mass spectrometry

Bavachin and isobavachalcone are the isomeric compounds in the fructus Psoraleae. The ion trap mass spectrometric fragmentation pathways of the bavachin and isobavachalcone in negative ion mode were elucidated for the identification. A novel method for determination of isomeric bavachin and isobavachalcone has been developed by capillary electrophoresis coupled with mass spectrometric detection. The effects of several factors such as concentration, pH of ammonium acetate buffer, separation voltage, composition and flow rate of the sheath liquid were investigated. Under optimal conditions, the linear concentration range for bavachin and isobavachalcone were 0.8-100 μg/mL with the correlation coefficient of 0.996 and 0.995, respectively. Relative standard deviations of migration time and peak areas were lower than 5%. The limits of detection (signal/noise = 3) were 60 ng/mL. The proposed method can be successfully applied to the determination of bavachin and isobavachalcone in the fructus Psoraleae and six fructus Psoraleae-containing preparations.

Simultaneous characterization of prenylated flavonoids and isoflavonoids in Psoralea corylifolia L. by liquid chromatography with diode-array detection and quadrupole time-of-flight mass spectrometry

RATIONALE

Prenylated flavonoids and isoflavonoids are widely distributed throughout the plant kingdom, with many biological effects. Psoralea corylifolia, which contains many kinds of prenylated components, has been widely used as a medicinal plant in Asia and India for thousands of years. The goal of this study was to characterize the components in P. corylifolia using a liquid chromatography with diode-array detection and quadrupole time-of-flight mass spectrometry (LC-DAD/Q-TOF-MS) method, and to elucidate the fragmentation behavior of the different prenyl substituent groups and their appropriate characteristic pathways in positive ion mode.

METHODS

The calculated accurate masses of the protonated molecules, the fragment ions, the retention behavior, and the data from UV spectra were used for identification of the components in P. corylifolia.

RESULTS

A total of 45 compounds, including 43 prenylated components, were identified or tentatively identified in P. corylifolia. Different diagnostic fragment ions and neutral losses were observed in different prenyl substructures: neutral loss of 56 Da (C(4)H(8)) and a fragment ion at m/z 69 (C(5)H(9)(+)) were generated by a prenyl chain; neutral losses of 42 Da (C(3)H(6)), 54 Da (C(4)H(6)), 15 Da (CH(3•)) and 16 Da (CH(4)) were observed in a ring-closed prenyl group; neutral losses of 72 Da (C(4)H(8)O), 60 Da (C(2)H(4)O(2)), 58 Da (C(3)H(6)O) and 18 Da (H(2)O) were detected in a 2,2-dimethyl-3,4-dihydroxydihydropyran ring; neutral losses of 72 Da (C(4)H(8)O), 60 Da (C(3)H(8)O) and 18 Da (H(2)O) were yielded from a 2,2-dimethyl-3-hydroxydihydropyran ring, a 2-(1-hydroxy-1-methylethyl)dihydrofuran ring or a 1-hydroxy-3-methylbut-3-enyl chain.

CONCLUSIONS

This method can be applied for analysis of prenylated components in P. corylifolia and other herbal medicines.

Separation, identification, and quantification of active constituents in Fructus Psoraleae by high-performance liquid chromatography with UV, ion trap mass spectrometry, and electrochemical detection

The qualitative and quantitative analysis of active constituents in Fructus Psoraleae is presented by high-performance liquid chromatography (HPLC) coupled with different detections. Extracts of Fructus Psoraleae were examined by HPLC with ion trap mass spectrometry (IT-MS) and 18 major compounds of coumarins, benzofuran glycosides, flavonoids, and meroterpene were identified. The determination of four major constituents including bavachin, isobavachalcone, bavachinin, and bakuchiol was accomplished by HPLC with UV, MS, and electrochemical detection (ECD). These methods were evaluated for a number of validation characteristics (repeatability, LOD, calibration range, and recovery). ECD obtained a high sensitivity for analysis of the four components; MS provided a high selectivity and sensitivity for determination of bavachin, isobavachalcone, and bavachinin in negative-ion mode. After optimization of the methods, separation, identification. and quantification of the four components in Fructus Psoraleae were comprehensively tested by HPLC with UV, MS, and ECD.

Comparison of different extraction procedures for the comprehensive characterization of bioactive phenolic compounds in Rosmarinus officinalis by reversed-phase high-performance liquid chromatography with diode array detection coupled to electrospray time-of-flight mass spectrometry

In the present work, a comparative study between two environmentally friendly and selective extraction techniques, such as supercritical fluid extraction (SFE) and pressurized liquid extraction (PLE) have been carried out focusing in the bioactive phenolic compounds present in Rosmarinus officinalis. For the analysis of the SFE and PLE extracts, a new methodology for qualitative characterization has been developed, based on the use of reversed-phase high-performance liquid chromatography (RP-HPLC), equipped with two different detection systems coupled in series: diode array detector (DAD) and time of flight mass spectrometry (TOF-MS) detector connected via an electrospray ionization interface (ESI). The use of a small particle size C(18) column (1.8 μm) provided a great resolution and made possible the separation of several isomers. Moreover, UV-visible spectrophotometry is a valuable tool for identifying the class of phenolic compounds, whereas MS data enabled to structurally characterize the compounds present in the extracts. The applied methodology was useful for the determination of many well-known phenolic compounds present in R. officinalis, such as carnosol, carnosic acid, rosmadial, rosmanol, genkwanin, homoplantaginin, scutellarein, cirsimaritin and rosmarinic acid, as well as other phenolic compounds present in other species belonging to Lamiaceae family.

Screening Antitumor Compounds Psoralen and Isopsoralen from Psoralea corylifolia L. Seeds

Psoralea corylifolia L. (Fabaceae) is a widely used medical plant in China. This study was designed to screen and identify bioactive compounds with anticancer activity from the seeds of Psoralea corylifolia L. One volatile fraction (fraction I) and three other fractions (fraction II, III, IV) from methanol extraction of P. corylifolia L. were obtained. Bioactivities of these fractions were evaluated by the cytotoxicity on KB, KBv200, K562, K562/ADM cancer cells with MTT assay. Major components in the active fraction were identified by HPLC/MS(n). Fraction IV significantly inhibits the growth of cancer cells in a dose-dependent manner. The IC(50) values were 21.6, 24.4, 10.0 and 26.9, respectively. Psoralen and isopsoralen, isolated from fraction IV, were subject to bioactive assay and presented a dose-dependent anticancer activity in four cancer cell lines (KB, KBv200, K562 and K562/ADM). The IC(50) values of psoralen were 88.1, 86.6, 24.4 and 62.6, which of isopsoralen were 61.9, 49.4, 49.6 and 72.0, respectively. Apoptosis of tumor cell significantly increased after treated with psoralen and isopsoralen. Induction of apoptotic activity was confirmed by flow cytometry after staining with Annexin V/PI. These results suggested psoralen and isopsoralen contribute to anticancer effect of P. corylifolia L.

Metabolic Profiling of Human Blood by High Resolution Ion Mobility Mass Spectrometry (IM-MS)

A high resolution ion mobility time-of-flight mass spectrometer with electrospray ionization source (ESI-IM-MS) was evaluated as an analytical method for rapid analysis of complex biological samples such as human blood metabolome was investigated. The hybrid instrument (IM-MS) provided an average ion mobility resolving power of ~90 and a mass resolution of ~1500 (at m/z 100). A few µL of whole blood was extracted with methanol, centrifuged and infused into the IM-MS via an electrospray ionization source. Upon IM-MS profiling of the human blood metabolome approximately 1,100 metabolite ions were detected and 300 isomeric metabolites separated in short analyses time (30 minutes). Estimated concentration of the metabolites ranged from the low micromolar to the low nanomolar level. Various classes of metabolites (amino acids, organic acids, fatty acids, carbohydrates, purines and pyrimidines etc) were found to form characteristic mobility-mass correlation curves (MMCC) that aided in metabolite identification. Peaks corresponding to various sterol derivatives, estrogen derivatives, phosphocholines, prostaglandins, and cholesterol derivatives detected in the blood extract were found to occupy characteristic two dimensional IM-MS space. Low abundance metabolite peaks that can be lost in MS random noise were resolved from noise peaks by differentiation in mobility space. In addition, the peak capacity of MS increased six fold by coupling IMS prior to MS analysis.

Metabolic profiling of Escherichia coli by ion mobility-mass spectrometry with MALDI ion source

Comprehensive metabolome analysis using mass spectrometry (MS) often results in a complex mass spectrum and difficult data analysis resulting from the signals of numerous small molecules in the metabolome. In addition, MS alone has difficulty measuring isobars and chiral, conformational and structural isomers. When a matrix-assisted laser desorption ionization (MALDI) source is added, the difficulty and complexity are further increased. Signal interference between analyte signals and matrix ion signals produced by MALDI in the low mass region (<1500 Da) cause detection and/or identification of metabolites difficult by MS alone. However, ion mobility spectrometry (IMS) coupled with MS (IM-MS) provides a rapid analytical tool for measuring subtle structural differences in chemicals. IMS separates gas-phase ions based on their size-to-charge ratio. This study, for the first time, reports the application of MALDI to the measurement of small molecules in a biological matrix by ion mobility-time of flight mass spectrometry (IM-TOFMS) and demonstrates the advantage of ion-signal dispersion in the second dimension. Qualitative comparisons between metabolic profiling of the Escherichia coli metabolome by MALDI-TOFMS, MALDI-IM-TOFMS and electrospray ionization (ESI)-IM-TOFMS are reported. Results demonstrate that mobility separation prior to mass analysis increases peak-capacity through added dimensionality in measurement. Mobility separation also allows detection of metabolites in the matrix-ion dominated low-mass range (m/z < 1500 Da) by separating matrix signals from non-matrix signals in mobility space.

Quality assessment of fructus psoraleae

Two newly-reported benzofuran glycosides, named psoralenoside and isopsoralenoside, along with two major coumarins, psoralen and isopsoralen, were simultaneously determined in twenty-three samples of Fructus Psoraleae collected from different growth areas in China. The quantitative method was validated, and the mean recovery rates from fortified samples (n=5) of psoralenoside, isopsoralenoside, psoralen and isopsoralen, were 96.5%, 97.1%, 100.7%, and 99.3% with variation coefficient of 3.1%, 3.6%, 2.3%, and 2.2%, respectively. An interesting biotransformation relationship between the glycosides and the coumarins was revealed on the basis of the quality analysis results. It was also suggested that psoralenoside and isopsoralenoside should be used as key quality markers for Fructus Psoraleae, together with the commonly used psoralen and isopsoralen.

Application of metabonomic analytical techniques in the modernization and toxicology research of traditional Chinese medicine

In the recent years, a wide range of metabonomic analytical techniques are widely used in the modern research of traditional Chinese medicine (TCM). At the same time, the international community has attached increasing importance to TCM toxicity problems. Thus, many studies have been implemented to investigate the toxicity mechanisms of TCM. Among these studies, many metabonomic-based methods have been implemented to facilitate TCM toxicity investigation. At present, the most prevailing methods for TCM toxicity research are mainly single analysis techniques using only one analytical means. These techniques include nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS), etc.; with these techniques, some favourable outcomes have been gained in the toxic reaction studies of TCM, such as the action target organs assay, the establishment of action pattern, the elucidation of action mechanism and the exploration of action material foundation. However, every analytical technique has its advantages and drawbacks, no existing analytical technique can be versatile. Multi-analysed techniques can partially overcome the shortcomings of single-analysed techniques. Combination of GC-MS and LC-MS metabolic profiling approaches has unravelled the pathological outcomes of aristolochic acid-induced nephrotoxicity, which can not be achieved by single-analysed techniques. It is believed that with the further development of metabonomic analytical techniques, especially multi-analysed techniques, metabonomics will greatly promote TCM toxicity research and be beneficial to the modernization of TCM in terms of extending the application of modern means in the TCM safety assessment, assisting the formulation of TCM safety norms and establishing the international standards indicators.

Global detection and identification of nontarget components from herbal preparations by liquid chromatography hybrid ion trap time-of-flight mass spectrometry and a strategy

Although the current literature has recorded many reports of identifying components from herbal preparations, all of them were largely limited to target components. This paper provides a novel and generally applicable approach to identifying nontarget components from herbal preparations, based on the use of liquid chromatography ion trap time-of-flight mass spectrometry (LC/MS-IT-TOF). A simple program was originally developed for searching the common diagnostic ions from all experimentally generated ions. The components sharing the exact same ions (mass error < 5 mDa) were classified into a family. All families were then connected into a coherent network by the bridging components that are present in two or more families. With the benefit from such a network, it is feasible to sequentially characterize the structures of all diagnostic ions once a single component has been de novo identified. The structures of the diagnostic ions could then be used as "a priori" information for selecting the exact candidates containing the substructures of the corresponding diagnostic ions from the primary database hits. This strategy enables a nearly 7-fold narrowing of the database hits and thus substantially enhances the analytical efficiency and sharpness. With the use of such an approach, 43 out of 53 components incorporated into the network have been successfully identified from the test herbal preparation. For the rest, components failed to be identified using this approach; a complementary approach to screening by sequential loss of specific chemical groups, proposed from the accurate mass differences between fragments, was established to narrow the database hits. All of the 87 peaks detected have been successfully identified by combining the use of both approaches except failed to differentiate some isomers. The presently developed approach and methodology would be useful for the identifications of complicated nontarget components from various complex mixtures such as herbal preparations, biological, and environmental samples.

Traditional Chinese medicine and separation science

Traditional Chinese medicines (TCMs) are getting more and more popular nowadays in the whole world for improving health condition of human beings as well as preventing and healing diseases. TCM is a multi-component system with components mostly unknown, and only a few compounds are responsible for the pharmaceutical and/or toxic effects. The large numbers of other components in the TCM make the screening and analysis of the bioactive components extremely difficult. So, separation and analysis of the desired chemical components in TCM are very important subjects for modernization research of TCM. Thus, many novel separation techniques with significant advantages over conventional methods were introduced and applied to separation and analysis of the chemical constituents in TCM. This review presents just a brief outline of the applications of different separation methods for the isolation and analysis of TCM constituents.

Qualitative and quantitative analysis in quality control of traditional Chinese medicines

Separation techniques with high efficiency and sensitive detection have been widely used for quality control of traditional Chinese medicines (TCMs). High-performance liquid chromatography, gas chromatography, and capillary electrophoresis are commonly used to separate various components in TCMs. Ultraviolet detection, fluorescence detection, evaporative light-scattering detection, mass spectrometry and nuclear magnetic resonance can be applied to separation techniques for qualitative and quantitative analysis of TCMs. The development of quality control for TCMs based on quantitative and qualitative analysis from 2000 to 2007 are reviewed; the fingerprint technique is also discussed due to its broad application in the quality control of TCMs. Prospects for further research based on our primary results are also discussed.

Recent development of multi-dimensional chromatography strategies in proteome research

As a complementary approach to two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), multi-dimensional chromatography separation methods have been widely applied in all kinds of biological sample investigations. Multi-dimensional liquid chromatography (MDLC) coupled with bio-mass spectrometry (MS) is playing important roles in proteome research due to its high speed, high resolution and high sensitivity. Proteome analysis strategies mainly include bottom-up and top-down approaches which carry out biological sample separation based on peptide and protein levels, respectively. Electrophoretic methods combined with liquid chromatography like IEF-HPLC and HPLC-SDS-PAGE have been successful applied for protein separations. As for MDLC strategy, ion-exchange chromatography (IEX) together with reversed phase liquid chromatography (RPLC) is still a most widely used chromatography in proteome analysis, other chromatographic methods are also frequently used in protein pre-fractionations, while affinity chromatography is usually adopted for specific functional protein analysis. Recent MDLC technologies and applications to variety of proteome analysis have been achieved great development. A digest peptide-based approach as so-called "bottom-up" and intact protein-based approach "top-down" analysis of proteome samples were briefly reviewed in this paper. The diversity of combinations of different chromatography modes to set up MDLC systems was demonstrated and discussed. Novel developments of MDLC techniques such as high-abundance protein depletion and chromatography array were also included in this review.

Recent developments and contributions from Chinese scientists in multidimensional separations for proteomics and traditional Chinese medicines

The most basic task in proteomics remains the detection and identification of proteins from a biological sample, and the most traditional way to achieve this goal consists in protein separations performed by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Yet the 2-D PAGE-mass spectrometry (MS) approach has its drawbacks with regard to automation, sensitivity, and throughput. Consequently, considerable effort has been devoted to the development of non-gel-based proteome separation technologies in an effort to alleviate the shortcomings of 2-D PAGE. In addition, traditional Chinese medicines (TCMs), due to their long period of clinical testing and reliable therapeutic efficacy, are attracting increased global attention. However, hundreds or even thousands of components are usually present in TCMs, which results in great difficulties of separation. As a mainstream separation tool, multidimensional liquid separation systems have shown powerful separation ability, high peak capacity, and excellent detectability in the analysis of complex samples including biological samples and TCMs, etc. Therefore, this review emphasizes the most recent advances in multidimensional liquid chromatography and capillary electrophoresis-based separation techniques, and the corresponding applications in proteomics and TCMs. In view of the significant contributions from Chinese scientists, this review focuses mainly on the work of Chinese scientists in the above fields.

Role of carbon nano-materials in the analysis of biological materials by laser desorption/ionization-mass spectrometry

At present, carbon nano-materials are being utilized in various procedures, especially in laser desorption/ionization-mass spectrometry (LDI-MS) for analyzing a range of analytes, which include peptides, proteins, metabolites, and polymers. Matrix-oriented LDI-MS techniques are very well established, with weak organic acids as energy-absorbing substances. Carbon materials, such as nano-tubes and fullerenes are being successfully applied in the small-mass range, where routine matrices have strong background signals. In addition, the role of carbon nano-materials is very well established in the fractionation and purification fields. Modified diamond powder and surfaces are utilized in binding peptides and proteins from complex biological fluids and analyzed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry (MS). Polylysine-coated diamond is used for solid-phase extraction to pre-concentrate DNA oligonucleotides. Graphite is useful for desalting, pre-concentration, and as energy-absorbing material (matrix) in desorption/ionization. Carbon nano-tubes in their different derivatized forms are used as matrix materials for the analysis of a range of analytes, such as carbohydrates, amino acids, peptides, proteins, and some environmental samples by LDI-MS. Fullerenes are modified in different ways to bind serum entities analyzed through MALDI/TOF-MS and are subsequently utilized in their identifications. In addition, the fullerenes are a promising matrix in LDI-MS, but improvements are needed.

Recent developments in methods and technology for analysis of biological samples by MALDI-TOF-MS

Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) is widely used in a variety of fields because it has the characteristics of speed, ease of use, high sensitivity, and wide detectable mass range for obtaining molecular weights and for structural characterization of macromolecules. In this article we summarize recent developments in matrix additives, new matrices, and sample-pretreatment methods using off-probe or on-probe techniques or nanomaterials for MALDI-TOF-MS analysis of biological samples.

Psoralenoside and isopsoralenoside, two new benzofuran glycosides from Psoralea corylifolia

Two new benzofuran glycosides, called psoralenoside and isopsoralenoside, were isolated from the fruits of Psoralea corylifolia, together with nine known compounds. Their structures were elucidated by detailed spectral analyses including extensive two dimensional (2D) NMR spectra.