Screening and analysis of bioactive compounds with biofingerprinting chromatogram analysis of traditional Chinese medicines targeting DNA by microdialysis/HPLC

Multi-target bioactive compound screening from the infructescence of Platycarya strobilacea Sieb. et Zucc. by affinity chromatography using immobilized β2 -adrenoceptor and muscarinic-3 acetylcholine receptor as the stationary phase

As a main source for the recognition and identification of lead compounds, traditional Chinese medicine plays a pivotal role in preventing diseases for years. However, screening bioactive compounds from traditional Chinese medicine remains challenging because of the complexity of the systems and the occurrence of the synergic effect of the compounds. The infructescence of Platycarya strobilacea Sieb. et Zucc is prescribed for allergic rhinitis treatment with unknown bioactive compounds and unclear mechanisms. Herein, we immobilized the β2 -adrenoceptor and muscarine-3 acetylcholine receptor onto the silica gel surface to prepare the stationary phase in a covalent bond through one step. The feasibility of the columns was investigated by the chromatographic method. Ellagic acid and catechin were identified as the bioactive compounds targeting the receptors. The binding constants of ellagic acid were calculated to be (1.56 ± 0.23)×107  M-1 for muscarine-3 acetylcholine receptor and (2.93 ± 0.15)×107  M-1 for β2 -adrenoceptor by frontal analysis. While catechin can bind with muscarine-3 acetylcholine receptor with an affinity of (3.21 ± 0.05)×105  M-1 . Hydrogen bonds and van der Waals' force were the main driving forces for the two compounds with the receptors. The established method provides an alternative for multi-target bioactive compound screening in complex matrices.

Attribution and identification of absorbed components by HPLC-DAD-ESI-MS after oral administration of Erhuang decoction

To realize the attribution and identification of absorbed components in rat serum after oral administration of Erhuang decoction prepared by semi-bionic enzyme extraction method, the fingerprints of serum samples were established using a HPLC-DAD-ESI-MS method. Thirty-two peaks in Erhuang decoction and 24 peaks in rat serum after oral administration of Erhuang decoction were detected. Among the 24 peaks detected in rat serum, 25 compounds were identified by comparing the retention time and mass spectrometry data with that of reference compounds, or by mass spectrometry analysis and retrieving the reference literatures. Among the identified 25 compounds in vivo, 24 were the original form of compounds absorbed from the detected compounds in vitro, and one was the metabolite compounds of licorice. By analyzing the mass spectrometry or ultraviolet absorption characteristics, other unidentified compounds in vivo were deduced to be the endogenous metabolites in serum or the original form and metabolites of the compounds existed in vivo. Results indicated that HPLC-DAD-ESI-MS is suitable for identifying the bioactive constituents in serum after oral administration of Erhuang decoction, and the findings would be beneficial to further research and development of the pharmacodynamic substance base of Erhuang decoction.

Tracking of β-Lactoglobulin Binding Compounds with Biofingerprinting Chromatogram Analysis of Natural Products

The addition of milk to tea has been shown to prevent the vascular protective effects of the tea. Thus we had an interest in evaluating the possible binding of compounds in extracts of black tea, Camellia sinensis (L.) O. Kunze, and nettle, Urtica dioica L, to β-lactoglobulin (βLG), which is the main proteinaceous component of whey. Since our previously miniaturised 96-well plate method based on fluorescence quenching is suitable only for pure compounds, we have developed a method of ultrafiltration sampling combined with HPLC to study the βLG-binding property of the extracts. The method development was made with extract of Piper nigrum L. (black pepper), because its major component is piperine, which has been earlier shown to bind to βLG. The results showed that piperine from P. nigrum was highly and rutin from U. dioica slightly bound to βLG. No components from C. sinensis were bound to βLG. We showed for the first time, that the ultrafiltration/HPLC system can be used in βLG-binding studies with plant extracts. Furthermore, we demonstrated that βLG could bind compounds from extracts and in this way either enhance, or decrease, their health benefits, for example in food preparations.

Screening techniques for the identification of bioactive compounds in natural products

Natural products (NPs) have a long history of clinical use and are rich source of bioactive compounds. The development of tools and techniques for identifying and analyzing NP bioactive compounds to ensure their quality and discover new drugs is thus very important and still in demand. Screening techniques have proven highly useful for screening and analyzing active components in complex mixtures, which rely on cell culture, dialysis, ultrafiltration, chromatographic methods and target molecule immobilization, using biological targets to identify the active compounds. The recent progress in biological screening techniques in the field of natural products is reviewed here. This includes a review on the strategy and application of the screening methods, their detailed description and discussion of their existing limitations of the different models along with prospective in future development of screening techniques.

Adsorbed hollow fiber-based biological fingerprinting for the discovery of platelet aggregation inhibitors from Danshen-Honghua decoction

For lead compound discovery from natural products, hollow fiber cell fishing with chromatographic analysis is a newly developed method. In this study, an adsorbed hollow fiber-based biological fingerprinting method was firstly developed to discover potential platelet aggregation inhibitors from Danshen-Honghua decoction. Platelets were seeded on the fiber and their survival rate was tested. Results indicated that more than 92% platelets survived during the whole operation process. Ranitidine and tirofiban were used as positive and negative control respectively to verify the reliability of the presented approach. The main variables such as amount of extract and stirring time that affect the adsorbed hollow fiber-based biological fingerprinting process were optimized, and the repeatability of this method was also investigated. Finally, 12 potential active compounds in Danshen-Honghua decoction were successfully detected using the established approach and structures for nine of them were tentatively identified by liquid chromatography with mass spectrometry analysis. In addition, the in vitro platelet aggregation inhibition test was carried out for five of the nine hit compounds, and three active components, namely, lithospermic acid, salvianolic acid A, and salvianolic acid B were confirmed. These results proved that the proposed method could be an effective approach for screening platelet inhibitors from plant extracts.

Characterization of interaction property of multi-components in Gardenia jasminoides with aldose reductase by microdialysis combined with liquid chromatography coupled to mass spectrometry

RATIONALE

An application of microdialysis sampling for evaluation of the interaction property of small molecules to macromolecules is presented. Microdialysis combined with liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (LC/QTOF-MS/MS) was established for the purpose of screening of the multiple bioactive compounds in traditional Chinese medicines (TCMs).

METHODS

Microdialysis experiments were performed in vitro using a syringe pump and probes. Separation was achieved via liquid chromatography, and MS analysis was conducted by electrospray ionization quadrupole time-of-flight mass spectrometry in negative mode. The interaction property of compounds in TCMs with aldose reductase can be deduced from the comparison of the peak areas in chromatograms using a stable internal standard.

RESULTS

In this work, 23 compounds including iridoids, flavonoids, monoterpenoids, carotenoids and phenolic acids were identified by comparison with reference compounds, characteristic high-resolution mass spectrometry and the MS/MS fragmentations simultaneously. Binding degrees of 23 compounds in Gardenia jasminoides Eliis (G. jasminoide) with aldose reductase ranged from 13.91% to 66.25%. Also, microdialysis recoveries of 23 compounds in G. jasminoides were determined.

CONCLUSIONS

The Interaction properties of 23 compounds in G. jasminoides with aldose reductase were investigated and they are potential bioactive ingredients. Microdialysis coupled to LC/QTOF-MS/MS can be used for screening of bioactive multicomponents from TCMs with appropriate targets. Copyright © 2016 John Wiley & Sons, Ltd.

Unraveling the coptisine–ctDNA binding mechanism by multispectroscopic, electrochemical and molecular docking methods

This study provides evidences of coptisine–DNA intercalation, which may help to develop new efficient, safe probes for the fluorometric detection of DNA instead of traditional toxic and carcinogenic probes.

Quality control of traditional Chinese medicines: a review

Traditional Chinese medicines (TCMs) are in great demand all over the world, especially in the developing world, for primary health care due to their superior merits such as low cost, minimal side effects, better cultural acceptability, and compatibility with humans. However, Chinese medicines consist of several herbs which may contain tens, hundreds, or even thousands of constituents. How these constituents interact with each other, and what the special active ones are, may be the biggest bottleneck for the modernization and globalization of TCMs. Valid methods to evaluate the quality of TCMs are therefore essential and should be promoted and be developed further through advanced separation and chromatography techniques. This paper reviews the strategies used to control the quality of TCMs in a progressive perspective, from selecting single or several ingredients as the evaluation marker, to using different kinds of chromatography fingerprint methods. In summary, the analysis and quality control of TCMs are developing in a more effective and comprehensive manner to better address the inherent holistic nature of TCMs.

Study on Subcritical Water Extraction of Flavonoids from Scutellaria baicalenses

The extraction of baicalin, baicalein, wogonin and wogonoside from Scutellaria Baicalenses was performed using subcritical water. The effects of key operation conditions by varying the temperature (110-160 °C), extraction time (10-90 min), water loadings (2.0-4.0 mL)and particle sizes (>20- <100 mesh) were evaluated. The highest extraction yields of baicalin and wogonoside were obtained at extraction temperature of 160 °C, extraction time of 60 min, water loadings of 4.0 mL and 60-100 mesh. The highest extraction yields of baicalein and wogonin were obtained at extraction temperature of 110 °C, extraction time of 10 min, water loadings of 4.0 mL and 60-100 mesh. The subcritical water extraction was compared with the conventional extraction method. The total extraction yield by SCWE was higher than those obtained using ethanol as the solvent.

Biological Fingerprinting of Herbal Samples by Means of Liquid Chromatography

Biological chromatographic fingerprinting is a relatively new concept in the quality control of herbal samples. Originally it has been developed with the application of HPLC, and recently herbal samples' biological profiles have been obtained by means of thin-layer chromatography (TLC). This paper summarizes the application of liquid chromatographic techniques for the purpose of biological fingerprint analysis (BFA) of complex herbal samples. In case of biological TLC fingerprint, which is a relatively novel solution, perspectives of its further development are outlined in more detail. Apart from already published data, some novel results are also shown and briefly discussed. The paper aims at drawing scientists' attention to the unique solutions offered by biological fingerprint construction.

Luminescence and binding properties of two isoquinoline alkaloids chelerythrine and sanguinarine with ctDNA

The binding mode and mechanism of the interactions between two planar cationic alkaloids chelerythrine (Che) and sanguinarine (San) with calf thymus DNA (ctDNA) were systematically investigated at pH 5.40 using UV-vis absorption spectroscopy, fluorescence spectroscopy and cyclic voltammetry. Che and San show strong fluorescence at 570 and 589 nm, respectively. Che displays fluorescence enhancement with ctDNA whereas the fluorescence of San is quenched on interaction with ctDNA. In addition, UV-vis spectra of both alkaloids show apparent hypochromicity and are bathochromic shifted, indicating that they could intercalate into ctDNA bases. The fluorescence polarization of Che and San increases in the presence of ctDNA, again implying the intercalation of two alkaloids with ctDNA. This conclusion was also supported by the results obtained from anion quenching and cyclic voltammetry. The binding constants of both alkaloids with ctDNA were calculated in the order of 10(5)L/mol. San binds with ctDNA 3-fold stronger than Che. The stoichiometric bindings are five nucleotides per Che or San. Electrostatic binding also exists between the alkaloids and DNA helix. Finally, theoretical calculations show that only certain parts of Che and San molecules intercalate into the DNA helix.

Bioactivity-based liquid chromatography-coupled electrospray ionization tandem ion trap/time of flight mass spectrometry for β₂AR agonist identification in alkaloidal extract of Alstonia scholaris

Although chromatographic fingerprinting combined with chemometrics, is a rational method for the quality control of traditional Chinese medicine (TCM), chemometrics cannot fully explore the relationship between chemical information and the efficacy of the potential activity. In the present work, a cell-based β₂ adrenergic receptor (β₂AR) agonist functional evaluation model coupled with high-performance liquid chromatography was developed to screen the potential β₂AR agonist components in the alkaloidal extract of Alstonia scholaris leaves. Using a liquid chromatography with ion trap time-of-flight mass spectrometry (LCMS-IT-TOF) system, the potential bioactive compounds in the prescription were identified and deduced based on the mass spectrometric fragmentation patterns, tandem mass spectrometry (MS/MS) data, and relevant literature. Several new β₂AR agonists of indole alkaloids were successfully found, and their activities were confirmed through an in vivo relaxant test on guinea pig tracheal muscles. The developed method is rapid and reliable compared with conventional fingerprinting and showed high sensitivity and resolution for the identification of β₂AR agonists in TCM prescriptions. This strategy clearly demonstrates that bioactivity-integrated fingerprinting is a powerful tool not only in screening and identifying potential lead compounds and in determining the therapeutic material basis of Chinese herbal prescriptions, but also in supplying suitable chemical markers for their quality control.

Subcritical water extraction of alkaloids in Sophora flavescens Ait. and determination by capillary electrophoresis with field-amplified sample stacking

The extraction and determination of cytisine, sophocarpine, matrine, sophoridine and oxymatrine in Sophora flavescens Ait. were performed using subcritical water extraction and capillary electrophoresis with field-amplified sample stacking. The effects of extraction temperature, pressure, time and cycle number on the extraction yields were investigated systematically for accelerated solvent extraction with ethanol (ASE) and accelerated solvent extraction with water (subcritical water extraction, SWE). The extraction yields obtained using SWE, ASE, water ultrasonic extraction and chloroform soaking extraction methods were compared. The electrophoresis separation buffer was monosodium phosphate (pH 3.0; 110 mM)-isopropanol (85:15, v/v). The effect of phosphoric acid added to the sample matrix on the reproducibility of the peak heights of the analytes was also examined. Cytisine, sophoridine and oxymatrine showed good linearity (R(2)>0.999) within 0.125-4.0 μg/mL, and sophocarpine and matrine exhibited good linearity (R(2)>0.998) within 0.0625-2.0 μg/mL, with the detection limits in the range of 0.004-0.0013 μg/mL. The five alkaloid contents in medicinal plants from different sources and Sophora instant granule were determined and compared.

Analysis of the interactions of multicomponents in Cornus officinalis Sieb. et Zucc. with human serum albumin using on-line dialysis coupled with HPLC

Interactions of three iridoid glycosides extracted from Cornus officinalis Sieb. et Zucc. (CIG) with protein were simultaneously explored by on-line dialysis sampling coupled with high-performance liquid chromatography (DS-HPLC). Three main compounds in CIG were unequivocally identified as loganin, sweroside and cornuside by comparing their t(R), MS data and UV spectra with those of reference compounds. Dialysis recoveries and quantitative characteristics of DS-HPLC for three iridoid glycosides were determined. Recoveries of dialysis sampling ranged from 73.9 to 91.7% with the RSD below 3.0%. Based on the determination of concentrations before and after interaction with human serum albumin (HSA), the binding parameters of loganin, sweroside and cornuside with HSA were obtained and the binding mechanisms were investigated.

Analysis of marker compounds with anti-platelet aggregation effects in Mailuoning injection using platelet binding assay combined with HPLC-DAD-ESI-MS and solid-phase extraction technique

INTRODUCTION

Mailuoning is prepared from a traditional formula of Chinese medicines and widely used as an antithrombotic agent. In this study, the platelet binding assay was used as a novel biospecific separation and analysis method to explore its active constituents, which could be considered as marker compounds for quality control.

OBJECTIVE

To establish a rapid and simple method to predict marker compounds in herbal medicine injection and evaluate the effects of those compounds.

MATERIAL AND METHODS

Platelets were used to bind and separate constituents. Binding constituents were analysed and taken as potential active compounds for further evaluation. Solid-phase-extraction was adopted to improve sensitivity. HPLC-DAD and ESI-MS were used to determine the binding constituents.

RESULTS

Five compounds were extracted through the platelet binding process and identified as neochlorogenic acid, caffeic acid, isochlorogenic acid and their isomers. Caffeic acid was selected for the flow cytometric assay to test its effect on platelets activation, which was determined by CD62P (P-selectin) expression. The results indicated that caffeic acid could significantly inhibit platelet activation while chlorogenic acid did not.

CONCLUSION

Caffeic acid could be considered as a marker compound of Mailuoning injection due to its anti-platelet effect. The study also suggested that platelet binding assay combined with some preconcentration technique could be efficiently used to predict anti-platelet compounds in complicated herbal medicines.

Ligand fishing with functionalized magnetic nanoparticles coupled with mass spectrometry for herbal medicine analysis: ligand fishing for herbal medicine analysis

The chemical composition of herbal medicines is very complex, and their therapeutic effects are determined by multi-components with sophisticated synergistic and/or suppressive actions. Therefore, quality control of herbal medicines has been a formidable challenge. In this work, we describe a fast analytical method that can be used for quality assessment of herbal medicines. The method is based on ligand fishing using human-serum-albumin-functionalized magnetic nanoparticles (HSA-MNPs) and mass spectrometry. To demonstrate the applicability of the proposed method, eight samples of Dioscorea panthaica were analyzed. The sampled plants were of both wild and cultivated origins. They grew at different geographical locations and were harvested at different times. The ligands bound to HSA-MNPs were isolated from the plant extracts and detected by using direct infusion electrospray ionization mass spectrometry (DI-ESI-MS). Chemical identity has been confirmed for five of the ligands isolated. From more than 15 peaks in the ESI-MS spectrum, 11 common peaks were selected for calculating the correlation coefficient and cosine ratio. The values of correlation coefficient and cosine ratio were >0.9824 and >0.9988, respectively, for all the samples tested. The results indicated a high level of similarity among the eight D. panthaica samples. Compared with chromatographic fingerprint analysis, the proposed HSA-MNP-based DI-ESI-MS/MS approach was not only fast and easy to carry out but also biological-activity-oriented, promising a more effective data interpretation and thus reliable assessment conclusions.

Screening the bioactive compounds in aqueous extract of Coptidis rhizoma which specifically bind to rabbit lung tissues beta2-adrenoceptor using an affinity chromatographic selection method

A receptor affinity chromatographic selection method was developed for screening the bioactive compounds binding to beta(2)-adrenoceptor (beta(2)-AR) in Coptidis rhizome. The bioactive compounds were analyzed by molecular recognition with a beta(2)-AR affinity column. The retention compounds eluted from the beta(2)-AR column were separated online with reverse-phase high-performance liquid chromatography by column switching technology, and identified by a coupled ion-trap mass spectrometer. Four compounds were screened as the bioactive compounds of Coptidis rhizome and identified as 2,9,10-trimethoxy-3-hydroxyl-protoberberine (jateorhizine), 2,3-methylenedioxy-9-methoxy-protoberberine, 2,3,9,10-tetramethoxy-protoberberine (palmatine) and 2,3-methylenedioxy-9,10-dimethoxy-protoberberine (berberine). The association constants of jatrorrhizine, palmatine and berberine to the beta(2)-AR were determined by the zonal elution method with standards. Berberine and palmatine had only one type of binding site on the immobilized beta(2)-AR. Their association constants were (2.28+/-0.11)x10(4)/M and (3.00+/-0.10)x10(4)/M, respectively. Jatrorrhizine had at least two type of binding sites on the immobilized beta(2)-AR, and the corresponding association constants were (2.20+/-0.09)x10(-4)/M and (6.78+/-0.001)x10(5)/M.

Recent analytical approaches in quality control of traditional Chinese medicines--a review

Traditional Chinese medicines (TCMs) are gaining more and more attention all over the world, due to their specific theory and long historical clinical practice. But the uncontrollable quality is a bottleneck for its modernization and globalization. This paper reviewed the recent analytical methods in the quality control of TCMs, including screening strategies of bioactive markers from TCMs through biochromatographic methods, the traditional chromatographic methods, DNA methods, as well as the spectroscopic methods, including FT-IR, NIR and NMR. The comprehensive methods, such as fingerprint and multi-component quantification are emphasized; hyphenated techniques, like HPLC-MS, GC-MS, CE-MS, LC-NMR, chemometric methods, and combination of chemical and biological methods, such as biofingerprint, metabolic fingerprint are now more and more widely used in TCMs. In a few word, the analysis and quality control of TCMs are moving towards an integrative and comprehensive direction, in order to better address the inherent holistic nature of TCMs.

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.

Screening and identification of permeable components in a combined prescription of Danggui Buxue decoction using a liposome equilibrium dialysis system followed by HPLC and LC-MS

A new method, i.e., liposome equilibrium dialysis followed by HPLC and LC-MS analysis, has been developed for the screening of permeable components in combined prescriptions of Danggui Buxue decoction (CPDBD). Multiple permeable components were simultaneously predicted by comparison of chromatograms of CPDBD extract before and after interaction with liposome membranes. A diode-array detector (DAD) and an evaporative light scattering detector (ELSD) were used, and the permeable compounds were identified by comparison with the available reference compounds and confirmed by on-line LC-MS. About fifteen compounds in a CPDBD extract were found to interact with liposome membranes. They were identified as calycosin-7-O-beta-D-glucoside (1), senkyunolide I or H (2), ononin (3), (6alphaR,11alphaR)-9,10-dimethoxypterocarpan-3-O-beta-D-glucoside (4), (3R)-2'-hydroxy-3',4'-dimethoxyisoflavan-7-O-beta-D-glucoside (5), calycosin (6), astragaloside IV (7), isoastragaloside II (8), formononetin (9), (6alphaR, 11alphaR),-3-hydroxy-9,10-dimethoxypterocarpan (10), (3R)-7,2'-dihydroxy-3',4'-dimethoxyisoflavan (11), astragaloside I (12), isoastragaloside I (13), E-ligustilide (14), and Z-ligustilide (15), respectively. Among all permeable components, 1, 3, 6, and 9 (flavonoids), 2, 14, and 15 (phthalides), and 7 (saponins) have been considered as major bioactive components in CPDBD. Therefore, this new method appears useful as a first step in the screening of bioactive components in natural products including Traditional Chinese Medicines (TCMs).

Analysis of interaction property of bioactive components in Danggui Buxue Decoction with protein by microdialysis coupled with HPLC–DAD–MS

Interaction of a commonly used combined prescription of Danggui Buxue Decoction (CPDBD) with protein was studied by microdialysis coupled with HPLC-DAD-MS. Nine compounds in CPDBD were unequivocally identified by comparing with their t(R), MS data and UV spectra with those of reference compounds, and simultaneously quantified. Microdialysis recoveries and binding degrees of 20 compounds in CPDBD with bovine serum albumin (BSA) were determined. Recoveries of microdialysis sampling ranged from 66.9 to 91.5% with RSD below 3.0%, and the binding degrees of those to BSA ranged from 6.3 to 59.8% (0.3mM BSA) and from 6.9 to 86.6% (0.6mM BSA). The results were determined at pH 7.4 and the influence of different pH value was investigated. Furthermore, the binding degrees of eight reference compounds were determined separately under the same conditions, indicating a significant effect of the interaction of compounds with each other on their binding degrees to BSA. By comparing their binding degrees with BSA with those of proven active compounds in CPDBD, i.e. chlorogenic acid (3), ferulic acid (6), ononin (12) and calycosin (16), other five compounds were found to possess potential activities, which were tentatively identified as calycosin-7-O-beta-D-glucoside-6-O-malonate (9), senkyunolide I or H (10), formononetin-7-O-beta-D-glucoside-6-O-malonate (17), and two unknown compounds.

Affinity chromatography with immobilized DNA stationary phase for biological fingerprinting analysis of traditional Chinese medicines

A stationary phase for high performance affinity chromatography with immobilization of DNA onto silica gel was prepared and characterized. The effect of the ionic strength, concentration of Mg2+, EDTA and CH3CN in the mobile phase on the retention of alkaloids were investigated. With this stationary phase, biological fingerprinting analysis of traditional Chinese medicines (TCMs) Coptis chinensis Franch and Rheum palmatum L. was performed with both one-dimensional (1-D) and two-dimensional (2-D) chromatography. The 1-D chromatography was performed with isocratic and gradient elution and 2-D chromatography was developed with immobilized DNA column combined with silica monolithic ODS column. It was found that 7 compounds in Coptis chinensis Franch including berberine, palmatine and jatrorrhizine, 14 compounds in Rheum palmatum L. including aloe-emodin, rhein, emodin, chrysophannol-8-O-glucophranoside and physionl-8-O-glucophranoside were active in binding to the immobilized DNA.

Characterization of enantioselective binding of racemic natural tetrahydropalmatine to DNA by chromatographic methods

A racemate from natural product, tetrahydropalmatine (THP), was characterized on its enantioselective binding to DNA by the chromatographic methods including microdialysis/HPLC, centrifugal ultrifiltration/HPLC and immobilized DNA affinity chromatography. It was found that its (+)-enantiomer was preferential to binding on B-form duplex DNA including calf thymus DNA, AT and GC sequence oligo DNA, as well as triplex oligo DNA. The binding constants of the THP enantiomers to ct-DNA were determined with the methods of microdialysis/HPLC and frontal affinity chromatography. In addition, the DNA structural preference of either enantiomer was evaluated with the chromatographic methods.

Biological fingerprinting analysis of the interactome of a kinase inhibitor in human plasma by a chemiproteomic approach

In this study, a gel free chemiproteomic method based on chromatography was developed and applied for the biological fingerprinting analysis of complex biological system. p-Aminobenzamidine (ABA), an inhibitor of trypsin-like serine proteases, was immobilized for characterizing their interacting proteins in human plasma. By the proteomic analysis method, 214 proteins were identified with obvious affinity to the immobilized ABA. By searching the sequences of above proteins with consensus patterns of the two active sites, seven proteins belong to trypsin-like serine protease group were found. Based on the Gene Ontology annotation, the identified trypsin-like serine proteases have the function of catalytic activity and calcium ion binding, and are mainly involved in the biological process of blood coagulation. Eight more other proteins related to calcium ion binding and blood coagulation were found. Nearly all of these proteins cannot be identified by directly analyzing the plasma sample demonstrating the chemiproteomics a useful approach to characterize interacting proteins in the low abundance range.

Comprehensive two-dimensional HPLC to study the interaction of multiple components inRheum palmatum L. with HSA by coupling a silica-bonded HSA column to a silica monolithic ODS column

A mode of comprehensive 2-D LC was developed by coupling a silica-bonded HSA column to a silica monolithic ODS column. This system combined the affinity property of the HSA column and the high-speed separation ability of the monolithic ODS column. The affinity chromatography with HSA-immobilized stationary phase was applied to study the interaction of multiple components in traditional Chinese medicines (TCMs) with HSA according to their affinity to protein in the first dimension. Then the unresolved components retained on the HSA column were further separated on the silica monolithic ODS column in the second dimension. By hyphenating the 2-D separation system to diode array detector and MS detectors, the UV and molecular weight information of the separated compounds can also be obtained. The developed separation system was applied to analysis of the extract of Rheum palmatum L., a number of low-abundant components can be separated on a single peak from the HSA column after normalization of peak heights. Six compounds were preliminarily identified according to their UV and MS spectra. It showed that this system was very useful for biological fingerprinting analysis of the components in TCMs and natural products.