Affinity character analysis of magnolol and honokiol based on stepwise frontal analysis coupled with cell membrane chromatography.

Magnolol and honokiol have been reported to exhibit anti-cancer activity. However, few studies are in relation to the interaction of magnolol/honokiol with vascular endothelial growth factor 2 (VEGFR2). In this study, a membrane chromatography method based on VEGFR2 was established for the interaction characteristic analysis between drug and receptor. The selectivity, repeatability and stability of the chromatographic model were evaluated using drugs acting on different receptors. The affinity between VEGFR2 and magnolol/honokiol was verified by cell membrane chromatography. The binding sites of magnolol/honokiol and VEGFR2 were analyzed by zonal elution. Especially, the dissociation equilibrium constants (Kd) of magnolol/honokiol and VEGFR2 were measured by zonal elution and stepwise frontal analysis respectively. In addition, the actions of magnolol/honokiol on VEGFR2 were analyzed by stepwise frontal analysis at different temperatures. The results showed that the binding sites of magnolol and honokiol on VEGFR2 were different from sorafenib, indicating that magnolol and honokiol could be used as competitive agents for self-competitive displacement experiment. The Kd values (order of magnitude) of magnolol/honokiol with VEGFR2 measured by stepwise frontal analysis were consistent with the zonal elution results. Honokiol binds VEGFR2 with higher affinity than magnolol. The main forces that stabilize the interactions of honokiol with VEGFR2 are hydrogen bonds and van der Waal's forces, and the main force of magnolol is electrostatic forces. These discoveries could assist in the prediction of drug activity and understanding for the underlying mechanism.

Stepwise frontal analysis coupled with cell membrane chromatography for affinity screening and characterization analysis of bioactive constituent from the mature fruits of schisandra chinensis.

Cell membrane chromatography (CMC) is effective and widely used in drug screening, especially for the analysis of complex matrixes. However, it is time-consuming and costly given that cells or animals are employed for activity confirmation, which leads to a large amount of waste being produced if the result is negative. Stepwise frontal analysis is employed to saturate the affinity stationary phase, by using a series of low- to high-concentration solutions which resultantly form a staircase pattern. In doing so, the waste of samples, caused by the balancing process, can be avoided. In this study, stepwise frontal analysis coupled with a CMC system was performed for screening and characterizing the affinity of an active compound from wuweizi. Schizandrin A was screened and identified by α1A AR /CMC coupled with UHPLC-MS/MS. By comparing the values obtained with those related to the equilibrium dissociation constant (Kd) calculated by zonal elution, the accuracy of the stepwise frontal analysis was verified. Subsequently, the type of affinity force between Schizandrin A and α1A AR was studied by thermodynamic parameters. Moreover, schizandrin A showed an antagonistic effect on phenylephrine-induced contractions, which relax prostate muscle strips in a non-competitive antagonism manner. It has already suggested that the active compound, schizandrin A, could be used as a lead compound for the treatment of benign prostate hyperplasia (BPH) and should be further studied. Thus, the findings of this study are significant given that they could result in an online screening and affinity analysis method being utilized for the discovery of medicinal compounds as well as clarify the interaction characteristics between a drug and a receptor.

A novel cell membrane affinity sample pretreatment technique for recognition and preconcentration of active components from traditional Chinese medicine.

We describe a novel biomembrane affinity sample pretreatment technique to quickly screen and preconcentrate active components from traditional Chinese medicine (TCM), which adopts cell membrane coated silica particles (CMCSPs) as affinity ligands which benefit the biomembrane's ability to maximize simulation of drug-receptor interactions in vivo. In this study, the prepared CMCSPs formed by irreversible adsorption of fibroblast growth factor receptor 4 (FGFR4) cell membrane on the surface of silica were characterized using different spectroscopic and imaging instruments. Drug binding experiments showed the excellent adsorption rate and adsorption capacity of FGFR4/CMCSPs compared with non-coated silica particles. The FGFR4/CMCSPs were used as solid-phase extraction sorbents to pretreat the TCM Aconitum szechenyianum Gay. The resultant FGFR4/CMCSPs exhibited good performance. In addition, high selectivity and recognition ability of the FGFR4/CMCSPs were determined by selectivity experiments. Four alkaloid were screened and identified, one of these alkaloid, napellonine, showed favorable anti-tumor activity in preliminary pharmacological verification trials including cell proliferation and molecular docking assays. The proposed cell membrane affinity sample pretreatment method is a reliable, effective and time-saving method for fast screening and enriching active compounds and can be extended to pretreat other TCMs as leading compounds resources.

Analysis of low molecular weight compounds by MALDI-FTICR-MS.

This review focuses on recent applications of matrix-assisted laser desorption ionization-Fourier-transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS) in qualitative and quantitative analysis of low molecular weight compounds. The scope of the work includes amino acids, small peptides, mono and oligosaccharides, lipids, metabolic compounds, small molecule phytochemicals from medicinal herbs and even the volatile organic compounds from tobacco. We discuss both direct analysis and analysis following derivatization. In addition we review sample preparation strategies to reduce interferences in the low m/z range and to improve sensitivities by derivatization with charge tags. We also present coupling of head space techniques with MALDI-FTICR-MS. Furthermore, omics analyses based on MALDI-FTICR-MS were also discussed, including proteomics, metabolomics and lipidomics, as well as the relative MS imaging for bio-active low molecular weight compounds. Finally, we discussed the investigations on dissociation/rearrangement processes of low molecular weight compounds by MALDI-FTICR-MS.