Sicen Wang

A new A431/cell membrane chromatography and online high performance liquid chromatography/mass spectrometry method for screening epidermal growth factor receptor antagonists from Radix sophorae flavescentis

The intracellular kinase domains of epidermal growth factor receptor (EGFR) in some tumor cells such as human epidermal squamous cells (A(431) cells) are an important target for drug discovery. We have developed a new A(431)/cell membrane chromatography (A(431)/CMC)-online-high performance liquid chromatography/mass spectrometry (HPLC/MS) method for screening EGFR antagonists from medicinal herbs such as traditional Chinese medicines (TCMs). In this study, A(431) cells with high EGFR expression levels were used to prepare cell membrane stationary phase (CMSP) in an A(431)/CMC model. The retention fractions eluted from the CMSP column were enriched onto an ODS pre-column and then switched into an HPLC/MS system by combining a 10 port columns switching valve. The screening results found that oxymatrine and matrine from Radix sophorae flavescentis (RSF) were the targeted components which could act on EGFR in similar manner of gefitinib as a control drug. There was a good relationship of their inhibiting effects on EGFR secretion and A(431) cell growth in vitro. This new A(431)/CMC-online-HPLC/MS method can be applied for screening EGFR antagonists from TCMs such as RSF. It will be a useful method for drug discovery with natural medicinal herbs as a leading compound resource.

A vascular smooth muscle/cell membrane chromatography–offline-gas chromatography/mass spectrometry method for recognition, separation and identification of active components from traditional Chinese medicines

We describe an analytical method of vascular smooth muscle cell membrane chromatography (VSM/CMC) combined with gas chromatography/mass spectrometry (GC/MS) for recognition, separation and identification of active components from traditional Chinese medicines (TCMs). VSM cells by means of primary culture with rat thoracic aortas were used for preparation of the stationary phase in the CMC model. Retention components by the VSM-CMC model were collected and then analyzed by GC/MS under the optimized conditions in offline conditions. After investigating the suitability and reliability of the VSM/CMC-offline-GC/MS method using nifedipine and nitrendipine as standard compounds, this method was applied in screening active components from the extracts of TCMs such as Radix Angelicae Dahuricae (RAD), Rhizomza Seu Radix Notopterygii (RSRN), Radix Glehniae (RG) and Fructus Cnidii (FC). Retention components from the extracts in the VSM-CMC model were imperatorin and osthole identified by the GC/MS method. In vitro pharmacological trials indicated that imperatorin and osthole could concentration dependently relax the rat thoracic artery pre-contracted by KCl (P<0.05). The maximum relaxation effects (R(max)) were 63+/-5% and 40+/-6% for imperatorin and osthole, respectively. The VSM/CMC-offline-GC/MS method is an effective screening system that can rapidly detect and enrich target components from a complex sample and then accurately identify them.

A combined cell membrane chromatography and online HPLC/MS method for screening compounds from Radix Caulophylli acting on the human α1A-adrenoceptor

We have developed an online analytical method that combines alpha(1A)-adrenoceptor (alpha(1A)AR) cell membrane chromatography (alpha(1A)AR-CMC) with high performance liquid chromatography and mass spectrometry (HPLC/MS) for the identification of active components from Radix Caulophylli acting on the human alpha(1A)AR. Fractions retained by the alpha(1A)AR-CMC column were captured into a loop and the components were directly analyzed by combining an 8 port column switcher with an HPLC/MS system for separation and preliminary identification. Using methoxamine as a positive control drug, magnoflorine and caulophine from Radix Caulophylli were identified as the active molecules acting on the alpha(1A)AR. This new alpha(1A)AR-CMC-online-HPLC/MS method can be applied for screening active components acting on alpha(1A)AR from traditional Chinese medicines exemplified by Radix Caulophylli. This method will be of great utility in drug discovery using natural medicinal herbs as a source of novel compounds.

Screening active compounds acting on the epidermal growth factor receptor from Radix scutellariae via cell membrane chromatography online coupled with HPLC/MS

Radix scutellariae is a traditional Chinese medicine (TCM) and has many pharmacological effects, including antiviral, antibacterial, antifungal, antipyretic, hypotensive, anti-inflammatory and anti-anaphylaxis effects. However, few studies have screened the active compounds in this complex product for tumor therapy. In this study, a two-dimensional online method was developed to screen the active compounds from Radix scutellariae acting on the epidermal growth factor receptor. The screening results showed that wogonin from Radix scutellariae was the targeted component which acted on epidermal growth factor receptor specificity. The in vitro inhibitory activity of wogonin on the viability of cells with high epidermal growth factor receptor expression was tested using the MTT assay. In the dosage range of 0.40-50.0 μM, inhibition of HEK293/EGFR by wogonin was 8.94 ± 0.2, 20.64 ± 5.10, 34.16 ± 5.90 and 69.03 ± 7.80 at the concentrations of 0.4 × 10(-6), 2 × 10(-6), 10 × 10(-6) and 50 × 10(-6) molL(-1), respectively. These results showed that wogonin inhibited the growth of cells with high epidermal growth factor receptor expression in a dose-dependent manner.

Synthesis of magnetic molecularly imprinted polymers by reversible addition fragmentation chain transfer strategy and its application in the Sudan dyes residue analysis

Magnetic molecularly imprinted polymers (MMIPs) have become a hotspot owing to the dual functions of target recognition and magnetic separation. In this study, the MMIPs were obtained by the surface-initiated reversible addition fragmentation chain transfer (RAFT) polymerization using Sudan I as the template. The resultant MMIPs were characterized by transmission electron microscope, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, vibrating sample magnetometer, and X-ray diffraction. Benefiting from the controlled/living property of the RAFT strategy, the uniform MIP layer was successfully grafted on the surface of RAFT agent-modified Fe3O4@SiO2 nanoparticles, favoring the fast mass transfer and rapid binding kinetics. The developed MMIPs were used as the solid-phase extraction sorbents to selectively extract four Sudan dyes (Sudan I, II, III, and IV) from chili powder samples. The recoveries of the spiked samples in chili powder samples ranged from 74.1 to 93.3% with RSD lower than 6.4% and the relative standard uncertainty lower than 0.029. This work provided a good platform for the extraction and removal of Sudan dyes in complicated matrixes and demonstrated a bright future for the application of the well-constructed MMIPs in the field of solid-phase extraction.

Applications of HPLC/MS in the analysis of traditional Chinese medicines

In China, traditional Chinese medicines (TCMs) have been used in clinical applications for thousands of years. The successful hyphenation of high-Performance liquid chromatography (HPLC) and mass spectrometry (MS) has been applied widely in TCMs and biological samples analysis. Undoubtedly, HPLC/MS technique has facilitated the understanding of the treatment mechanism of TCMs. We reviewed more than 350 published papers within the last 5 years on HPLC/MS in the analysis of TCMs. The present review focused on the applications of HPLC/MS in the component analysis, metabolites analysis, and pharmacokinetics of TCMs etc. 50% of the literature is related to the component analysis of TCMs, which show that this field is the most populär type of research. In the metabolites analysis, HPLC coupled with electrospray ionization quadrupole time-of-flight tandem mass spectrometry has been demonstrated to be the powerful tool for the characterization of structural features and fragmentation behavior patterns. This paper presented a brief overview of the applications of HPLC/MS in the analysis of TCMs. HPLC/MS in the fingerprint analysis is reviewed elsewhere.

An online coupled cell membrane chromatography with LC/MS method for screening compounds from Aconitum carmichaeli Debx. acting on VEGFR-2.

An online analytical method coupling high expression vascular endothelial growth factor receptor (VEGFR) cell membrane chromatography (VEGFR-CMC) with high performance liquid chromatography mass spectrometry (LC/MS) for screening and identification of active component from traditional Chinese herb Aconitum carmichaeli Debx. acting on VEGFR-2 was established. Through a 10-port column switcher, factions separated by VEGFR-CMC column (first dimension) were transferred and were adsorbed on an enrichment column. Then, these fractions were sent into LC/MS system (second dimension) immediately and directly for separation and preliminary identification, respectively. Sunitinib malate (SN) was used as positive control, while nifedipine (NF), dexamethasone acetate (DX), methoxyamine hydrochloride (MT) and atenolol (AT) as negative controls. The specification of this VEGFR-CMC-online-LC/MS method was validated by competitive displacement test. As a result, mesaconitine (MSC), aconitine (AC), and hypaconitine (HPC) were identified as the active constituents acting on VEGFR-2. The in vitro inhibition activity of starting extract of Aconitum carmichaeli Debx., MSC, AC, and HPC on HEK293/VEGFR cell viability by MTT test, separately. The in vitro inhibition activity of MSC, AC, and HPC on vascular endothelial growth factor (VEGF) secretion of HEK293/VEGFR cell was tested by VEGF-ELISA assay. The screening results given by the system offered additional exemplification supporting this online coupling method and gave new evidence to the development of anti-tumor drug from natural products.

Discovery of novel taspine derivatives as antiangiogenic agents

VEGFR-2 plays a critical role in vasculogenesis and inhibitors of VEGFR-2 could be used in the treatment of cancer. Taspine was one of the active ingredients screened by using an endothelial cell membrane chromatography and showed inhibition against VEGFR-2. In our research, we explored how the lactone ring and biphenyl scaffold in taspine influence its potent in vitro anticancer and antiangiogenesis activities. Accordingly, we report the design, synthesis, and preliminary evaluation of four novel taspine derivatives as VEGFR-2 inhibitors. The preliminary biological test showed that one of the compounds showed much better inhibitory activities against CACO-2 (IC(50)=52.5nM) and ECV304 (IC(50)=2.67nM) than taspine. This result enlarges the interest in ring-opened taspine derivative skeleton in the search of new antiangiogenesis agents.

A combined A431 cell membrane chromatography and online high performance liquid chromatography/mass spectrometry method for screening compounds from total alkaloid of Radix Caulophylli acting on the human EGFR

We have developed an online analytical method that combines A431 cell membrane chromatography (A431/CMC) with high performance liquid chromatography and mass spectrometry (LC/MS) for identifying active components from Radix Caulophylli acting on human EGFR. Retention fractions on A431/CMC model were captured onto an enrichment column and the components were directly analyzed by combining a 10-port column switcher with an LC/MS system for separation and preliminary identification. Using Sorafenib tosylate as a positive control, taspine and caulophine from Radix Caulophylli were identified as the active molecules which could act on the EGFR. This A431/CMC-online-LC/MS method can be applied for screening active components acting on EGFR from traditional Chinese medicines exemplified by Radix Caulophylli and will be of great utility in drug discovery using natural medicinal herbs as a source of novel compounds.

Combined fibroblast growth factor receptor 4 cell membrane chromatography online with high performance liquid chromatography/mass spectrometry to screen active compounds in Brassica albla

We investigated an analytical method for the recognition separation, and identification of active components from the traditional Chinese medicinal plant Brassica albla L. using fibroblast growth factor receptor 4 cell membrane chromatography (FGFR4/CMC) with high performance liquid chromatography/mass spectrometry (HPLC/MS). HEK293-FGFR4 cells were obtained by stable transfection of the HEK293 cell line with pcDNA3.1 vector containing the FGFR4 gene. Crude extracts of B. albla L. were firstly subjected to FGFR4/CMC column, and the retain contents on the FGFR4/CMC column were then transferred and enriched using a pre-column, and a ten port column switcher were used between FGFR4/CMC column and HPLC. The retained components on FGFR4/CMC column were then directly delivered to the HPLC/MS system for separation and identification. Gefitinib, nicotine, atenolol, and nimodipine were used in order to verify FGFR4/CMC-HPLC/MS system specificity. Subsequently, we investigated the reproducibility and reliability of the FGFR4/CMC-HPLC/MS system. Finally, sinapine was identified as an active component of B. albla L. The MTT colorimetric assay revealed sinapine could inhibit the proliferation of HEK293-FGFR4 cells with dose dependence. Competitive displacement assay approved getitinib could occupy binding site of sinapine with competition way. And FleX dock simulation further exhibited sinapine and gefitinib could bind with the FGFR4 tyrosine active domain. Thus, sinapine is a potential tumor antagonist that acts on the tyrosine kinase domain.