Screening of thrombin inhibitors from phenolic acids using enzyme-immobilized magnetic beads through direct covalent binding by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry

A magnetic beads-based ligand fishing method for rapid discovery of monoterpene indoles as monoamine oxidase A inhibitors from Hunteria zeylanica

In this study, a novel magnetic bead-based ligand fishing method was developed for rapid discovery of monoterpene indoles as monoamine oxidase A inhibitors from natural products. In order to improve the screening efficiency, two different magnetic beads, i.e. amine and carboxyl terminated magnetic beads, were comprehensively compared in terms of their ability to immobilize monoamine oxidase A (MAOA), biocatalytic activity and specific adsorption rates for affinity ligands. Carboxyl terminated magnetic beads performed better for MAOA immobilization and demonstrated superior performance in ligand fishing. The MAOA immobilized magnetic beads were applied to screen novel monoamine oxidase inhibitors in an alkaloid-rich plant, Hunteria zeylanica. Twelve MAOA affinity ligands were screened out, and ten of them were identified as monoterpene indole alkaloids by HPLC-Obitrap-MS/MS. Among them, six ligands, namely geissoschizol, vobasinol, yohimbol, dihydrocorynanthenol, eburnamine and (+)-isoeburnamine which exhibited inhibitory activity against MAOA with low IC50 values. To further explore their inhibitory mechanism, enzyme kinetic analysis and molecular docking studies were conducted.

A magnetic beads-based ligand fishing method Coupled with UHPLC-QTOF MS for screening and identification of α-glucosidase inhibitors from Houttuynia cordata Thunb

In this study, a method for the screening and identification of α-glucosidase inhibitors from natural products was developed. The α-glucosidase was immobilized on carboxyl terminated magnetic beads to form a ligand fishing system to screen the potential inhibitors. A total of 9 compounds were fishing out from the crude Houttuynia cordata Thunb. extract. Meanwhile, ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS) was used for the identification of the chemical structures, including 3 chlorogenic acid isomers, 2 flavone C-glycosides and 4 flavone O-glycosides. The combination of enzyme immobilization magnetic beads and UHPLC-QTOF MS could be used for the screening of bioactive multi-components from herbs with appropriate targets. Taking the advantage of the specificity of enzyme binding and the convenience of magnetic separation, the method has great potential for rapid screening of α-glucosidase inhibitors from complicated natural product extracts.

Shotgun Characterization of the Circulating IgM Antigenome of an Infectious Pathogen by Immunocapture-LC-MS/MS from Dried Serum Spots

One of the main challenges in compiling the complete collection of protein antigens from pathogens for the selection of vaccine candidates or intervention targets is to acquire a broad enough representation of them to be recognized by the highly diversified immunoglobulin repertoire in human populations. Dried serum spot sampling (DSS) retains a large repertoire of circulating immunoglobulins from each individual that can be representative of a population, according to the sample size. In this work, shotgun proteomics of an infectious pathogen based on DSS sampling coupled with IgM immunoprecipitation, liquid chromatography-mass spectrometry (LC-MS/MS), and bioinformatic analyses was combined to characterize the circulating IgM antigenome. Serum samples from a malaria endemic region at different clinical statuses were studied to optimize IgM binding efficiency and antibody leaching by varying serum/immunomagnetic bead ratios and elution conditions. The method was validated using Plasmodium falciparum extracts identifying 110 of its IgM-reactive antigens while minimizing the presence of human proteins and antibodies. Furthermore, the IgM antigen recognition profile differentiated between malaria-infected and noninfected individuals at the time of sampling. We conclude that a shotgun proteomics approach offers advantages in providing a high-throughput, reliable, and clean way to identify IgM-recognized antigens from trace amounts of serum. The mass spectrometry raw data and metadata have been deposited with ProteomeXchange via MassIVE with the PXD identifier PXD043800.

Recent advances on discovery of enzyme inhibitors from natural products using bioactivity screening

The essence of enzymes is to keep the homeostasis and balance of human by catalyzing metabolic responses and modulating cell. Suppression of enzyme slows the progress of some diseases, making it a therapeutic target. Therefore, it is important to develop enzyme inhibitors by proper bioactivity screening strategies for the future treatment of some major diseases. In this review, we summarized the recent (2015-2020) applications of several screening strategies (electrophoretically mediated microanalysis, enzyme immobilization, affinity chromatography, and affinity ultrafiltration) in finding enzyme inhibitors from certain species of bioactive natural compounds of plant origin (flavonoids, alkaloids, phenolic acids, saponins, anthraquinones, coumarins). At the same time, the advantages and disadvantages of each strategy were also discussed, and the future possible development direction in enzyme inhibitor screening has prospected. To sum up, it is expected to help readers select suitable screening strategies for enzyme inhibitors and provide useful information for the study of the biological of specific kinds of natural products. This article is protected by copyright. All rights reserved.

Identifying of Anti-Thrombin Active Components From Curcumae Rhizoma by Affinity-Ultrafiltration Coupled With UPLC-Q-Exactive Orbitrap/MS

Recent studies concerning products that originate from natural plants have sought to clarify active ingredients, which both explains the mechanisms of the function and aids in quality control during production. As a traditional functional plant, Curcumae Rhizoma (CR) has been proven to be effective in promoting blood circulation and removing blood stasis. However, the components that play a role in its huge compound library are still unclear. The present study aimed to develop a high-throughput screening method to identify thrombin inhibitors in CR and validate them by in vitro and in vivo experiments. The effect of CR on thrombin in HUVECs cells was determined by ELISA, then an affinity-ultrafiltration-UPLC-Q-Exactive Orbitrap/MS approach was applied. Agatroban and adenosine were used as positive and negative drugs respectively to verify the reliability of the established method. The in vitro activity of the compounds was determined by specific substrate S-2238. The in vivo effect of the active ingredients was determined using zebrafish. Molecular docking was used to understand the internal interactions between compounds and enzymes. ELISA results showed that CR had an inhibitory effect on thrombin. The screening method established in this paper is reliable, by which a total of 15 active compounds were successfully identified. This study is the first to report that C7, 8, and 11 have in vitro thrombin-inhibitory activity and significantly inhibit thrombosis in zebrafish models at a safe dose. Molecular docking studies were employed to analyze the possible active binding sites, with the results suggesting that compound 16 is likely a better thrombin inhibitor compared with the other compounds. Based on the affinity-ultrafiltration-UPLC-Q-Exactive Orbitrap/MS approach, a precisely targeted therapy method using bio-active compounds from CR might be successfully established, which also provides a valuable reference for targeted therapy, mechanism exploration, and the quality control of traditional herbal medicine.

Magnetic particles for enzyme immobilization: A versatile support for ligand screening

Enzyme inhibitors represent a substantial fraction of all small molecules currently in clinical use. Therefore, the early stage of drug-discovery process and development efforts are focused on the identification of new enzyme inhibitors through screening assays. The use of immobilized enzymes on solid supports to probe ligand-enzyme interactions have been employed with success not only to identify and characterize but also to isolate new ligands from complex mixtures. Between the available solid supports, magnetic particles have emerged as a promising support for enzyme immobilization due to the high superficial area, easy separation from the reaction medium and versatility. Particularly, the ligand fishing assay has been employed as a very useful tool to rapidly isolate bioactive compounds from complex mixtures, and hence the use of magnetic particles for enzyme immobilization has been widespread. Thus, this review provides a critical overview of the screening assays using immobilized enzymes on magnetic particles between 2006 and 2021.

Rapid screening and identification of anticoagulation component from carthami flos by two-dimensional thrombin affinity chromatography combined with HPLC-MS/MS

Carthami flos, commonly known as Honghua in China, is the dried floret of safflower and widely acknowledged as a blood stasis promoting herb. The study aimed at investigating the relationship between thrombin and carthami flos through a high-performance thrombin affinity chromatography combined with a high-performance liquid chromatography-tandem mass spectrometry system. First, thrombin was immobilized on the glutaraldehyde-modified amino silica gel to prepare the thrombin affinity stationary phase, which was packed into a small column (1.0 × 2.0 mm, id) for recognizing the anticoagulant active components of carthami flos. The target component was enriched and analyzed by the high-performance liquid chromatography-tandem mass spectrometry system. Finally, hydroxysafflor yellow A was screened out and identified as the active component. The anticoagulant effects of hydroxysafflor yellow A were analyzed by anticoagulant experiments in vitro, and the interaction of hydroxysafflor yellow A with thrombin was investigated by the molecular docking method. The results proved that hydroxysafflor yellow A (30 μg/mL, 0.05 mM) and carthami flos extract (30 μg/mL) could prolong activated partial thrombin time and thrombin time by 50 and 11%, respectively. Moreover, hydroxysafflor yellow A exhibits a good hydrogen bond field and stereo field matching with thrombin. Overall, it was concluded that hydroxysafflor yellow A might exert an anticoagulation effect by interacting with thrombin and thus could be potential anticoagulant drugs for the prevention and treatment of venous thrombosis.

Rapid screening of lipase inhibitors in licorice extract by using porcine pancreatic lipase immobilized on Fe3O4 magnetic nanoparticles

Chalcones, a class of natural lipase inhibitors, have received substantial attention from researchers in recent years. Although many kinds of chalcones are typically distributed in G. inflata, there is little literature about the anti-lipase activity of G. inflata extracts (GIEs). In the present study, a ligand fishing strategy for fast screening of lipase inhibitors from GIEs was thus proposed. Porcine pancreatic lipase (PPL) was firstly immobilized on carboxyl modified Fe3O4 magnetic nanoparticles (MNPs) to obtain PPL functionalized MNPs (PPL@MNPs), and then the PPL@MNPs were incubated with a bioactive fraction to fish out the ligands. Eight ligands were obtained and identified as one flavone together with seven chalcones. Licochalcone A, licochalcone D and licochalcone E inhibited pancreatic lipase (PL) with IC50 of 4.9, 3.2 and 5.8 μM, respectively. Meanwhile, investigation of the structure-activity relationship also revealed that isopentenyl and hydroxyl substituents at ring A were essential for the noncovalent inhibitory potency of the chalcones.

Large batch production of Galactooligosaccharides using β-glucosidase immobilized on chitosan-functionalized magnetic nanoparticle

β-glucosidase (BglA) immobilization from Thermotoga maritima on magnetic nanoparticles (MNPs) functionalized with chitosan (Cs) were efficiently investigated to improve lactose conversion and galactooligosaccharides (GOS) production. We used a batch method in order to improve the conversion of lactose to GOS. The efficiency and yield of immobilization were 79% and immobilized BglA was effectively recycled via a magnetic separation procedure through a batch-wise GOS with no activity lessening. Furthermore, analyses were done through screening kinetics of enzyme activity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). Proposed methodology of immobilization shows a potential application as it is stable which was proved through many methods including pH, temperature, heat treatment, storage, and kinetics of the enzyme. GOS and residual enzyme activity showed to be 28.76 and 40.44%, respectively. However, free enzyme synthesis of GOS yield was just 24% after 12 hr. This study proposed applying magnet in the immobilization process of BglA on Cs-MNPs to produce GOS as new method for immobilizing enzyme in a biostable and cost-efficient way. PRACTICAL APPLICATIONS: This paper focus on immobilization of BglA from T. maritima onto MNPs functionalized with CS to investigate their further possibility improving lactose conversion and GOS production. Interestingly, a successful immobilization of Tm-BglA on the substrates were achieved in Cs-MNPs. The obtained results from enzyme activity, SDS-PAGE, FT-IR, and TEM showed that the high binding capacity of BglA to Cs-MNPs was successfully obtained. Furthermore, the binding efficiency calculation indicated that the immobilized BglA-Cs-MNPs conserved 40.44% of its native activity at the end of its 6th repeated use. In addition, magnetic separation technique was successfully employed for reuse of the immobilized BglA for repetitive batch-wise GOS without significant loss of activity.

Combination of Adsorption and Cellulose Derivative Membrane Coating for Efficient Immobilization of Laccase

Immobilization of enzyme based on combination of adsorption and cellulose derivative membrane coating was established in this work for the first time. Laccase, a commonly used enzyme in varied fields, was chosen as the model enzyme to demonstrate this method. After investigating operational conditions, the optimal process was obtained as follows: diatomite or HPD-417 as the adsorption carrier, 0.5% (w/v) methylcellulose (40,000~50,000) acetone solution as the coating solution, 0.75% (w/v) polyethylene glycol or maltose as the protective agent, and drying at 4 °C for 9 h. Under the optimal conditions, the residual activities of diatomite and HPD-417 immobilized laccase reached 99.33% and 94.15%, respectively. The study on properties showed that the immobilized laccases held high pH tolerance and thermal stability. The immobilized laccases were further applied to the indigo decolorization and 2, 4-dichlorophenol degradation. They showed high catalytic efficiency and could be reused for several batches. On the whole, the immobilization method developed in this work can effectively avoid the inactivation of laccase during immobilization and improve the stability of immobilized laccase. The laccase immobilized by this method shows obvious potential for environmental governance.

Antithrombotic effect and action mechanism of Salvia miltiorrhiza and Panax notoginseng herbal pair on the zebrafish

Background

Salvia miltiorrhiza (Danshen, DS) and Panax notoginseng (Sanqi, SQ) are famous traditional Chinese herbs, and their herbal pair (DS–SQ) has been popular used as anti-thrombotic medicines. However, there is still a lack of sufficient scientific evidence to illustrate the optimum combination ratio of these two herbs as well as its action mechanisms. The purpose of this study is to investigate the anti-thrombotic effects of DS–SQ on zebrafish and explore its possible action mechanism.

Methods

Firstly, the chemical components in DS–SQ extract were analyzed by LC–ESI–MS/MS. Then, a phenylhydrazine (PHZ)-induced zebrafish thrombosis model was developed for evaluating the anti-thrombotic effects of DS–SQ extracts with different combination ratios and their nine pure compounds. Followed, Real-time quantitative PCR (RT-qPCR) assays were performed to investigate the potential antithrombotic mechanisms of DS–SQ.

Results

Thirty-three components were tentatively identified by LC–MS analysis. DS–SQ at the ratio of 10:1 presented the best anti-thrombotic effect, and rosmarinic acid, lithospermic acid and salvianolic acid B of DS showed good anti-thrombotic activity on zebrafish thrombosis model. The RT-qPCR assays indicated that DS–SQ (10:1) could cure the PHZ-induced thrombosis by downregulating the expression of PKCα, PKCβ, fga, fgb, fgg and vWF in zebrafish.

Conclusions

DS–SQ with the combination ratio of 10:1 showed optimum anti-thrombotic effect on PHZ-induced zebrafish thrombosis model, which provided a reference for reasonable clinical applications of DS–SQ herbal pair.

On-line immobilized trypsin microreactor for evaluating inhibitory activity of phenolic acids by capillary electrophoresis and molecular docking

Phenolic acids, which are important aromatic secondary metabolites, are widely distributed in plant foods. In this study, a simple, economical and fast on-line immobilized trypsin microreactor was developed for evaluating the inhibitory activity of phenolic acids by capillary electrophoresis. The Michaelis-Menten constant (K_m) of immobilized trypsin was determined as 0.99 mM, and the half-maximal inhibitory concentration (IC₅₀) and inhibition constant (K_i) of benzamidine were measured as 3.39 and 1.68 mM, respectively. Then, the developed strategy was applied to investigate the inhibitory activity of six phenolic acids on trypsin. The results showed that gallic acid, caffeic acid and ferulic acid had high inhibitory activity at concentration of 150 μM. Molecular docking results illustrated that gallic acid, caffeic acid and ferulic acid can interact indirectly with the catalytic and substrate-binding sites of trypsin. The developed strategy is an effective tool for evaluating inhibitory activity of phenolic acids on trypsin.

Recent applications of immobilized biomaterials in herbal analysis

Immobilization of biomaterials developed rapidly due to the great promise in improving their stability, activity and even selectivity. In this review, the immobilization strategies of biomaterials, including physical adsorption, encapsulation, covalent attachment, cross-linking and affinity linkage, were briefly introduced. Then, the major emphasis was focused on the reported various types of immobilized biomaterials, including proteins, enzymes, cell membrane and artificial membrane, living cells, carbohydrates and bacteria, used in the herbal analysis for bioactive compound screening, drug-target interaction evaluation and chiral separation. In addition, a series of carrier materials applied in biomaterials immobilization, such as magnetic nanoparticles, metal-organic frameworks, silica capillary column, cellulose filter paper, cell membrane chromatography, immobilized artificial membrane chromatography and hollow fiber, were also discussed. Perspectives on further applications of immobilized biomaterials in herbal analysis were finally presented.

Systems Pharmacology-Based Approach to Comparatively Study the Independent and Synergistic Mechanisms of Danhong Injection and Naoxintong Capsule in Ischemic Stroke Treatment

To provide evidence for the better clinical use of traditional Chinese medicine preparations (TCMPs), comparison of the pharmacological mechanisms between TCMPs with similar therapeutic effect is necessary. However, methodology for dealing with this issue is still scarce. Danhong injection (DHI) and Naoxintong capsule (NXT) are representative TCMPs for ischemic stroke (IS) treatment, which are also frequently used in combination. Here they were employed as research objects to demonstrate the feasibility of systems pharmacology approach in elucidation of the independent and combined effect of TCMPs. By incorporating chemical screening, target prediction, and network construction, a feasible systems pharmacology model has been established to systematically uncover the underlying action mechanisms of DHI, NXT, or their pair in IS treatment. Systematic analysis of the created TCMP-Compound-Target-Disease network revealed that DHI and NXT shared common targets such as PTGS2, F2, ADRB1, IL6, ALDH2, and CCL2, which were involved in the vasomotor system regulation, blood-brain barrier disruption, redox imbalance, neurotrophin activity, and brain inflammation. In comparative mechanism study, the merged DHI/NXT-IS PPI network and pathway enrichment analysis indicated that DHI and NXT exerted the therapeutic effects mainly through immune system and VEGF signaling pathways. Meanwhile, they had their own unique pathways, e.g., calcium signaling pathway for DHI and gap junction for NXT. While for their synergistic mechanism, DHI and NXT participated in chemokine signaling pathway, T cell receptor signaling pathway, VEGF signaling pathway, gap junction, and so on. Our study provided an optimized strategy for dissecting the different and combined effect of TCMPs with similar actions.

A method using angiotensin converting enzyme immobilized on magnetic beads for inhibitor screening

Angiotensin converting enzyme (ACE), fusing with FLAG tag, was overexpressed in human embryonic kidney 293T cells. This recombinant FLAG-tagged ACE was immobilized on anti-FLAG antibody coated magnetic beads by affinity method in crude cell lysate for the first time. The enzyme-immobilized magnetic beads (ACE-MB), without further cleavage procedure, were used directly to establish a cost-effective and reliable method for screening ACE inhibitors by coupling with fluorescence detection. The enzymatic activity of the ACE-MB was validated based on its Michaelian kinetic behavior towards hippuryl-histidyl-leucine by UHPLC-MS/MS method firstly. Then, several conditions were optimized including amount of magnetic beads, incubation temperature and time in the procedure of ACE immobilization and amount of ACE-MB in the microplate operation. Moreover, this screening assay was validated with Z' factors between 0.71 and 0.81 using four known ACE inhibitors (captopril, lisinopril, fosinopril and fosinoprilat). The developed method was applied for the screening of ACE inhibitors from a small compound library of 45 natural products. As a result, epiberberine and fangchinoline with certain ACE inhibitory activities were screened out in the assay and validated. The results demonstrate the usefulness of this screening method using ACE immobilized on magnetic beads and the advantage of great efficiency with respect to both time and reagents for screening ACE inhibitors.

Screening inhibitors of xanthine oxidase from natural products using enzyme immobilized magnetic beads by high-performance liquid chromatography coupled with tandem mass spectrometry

In this study, high-performance liquid chromatography coupled with tandem mass spectrometry was used to assess the results of bioactive compound screening from natural products using immobilized enzyme magnetic beads. We compared three commercial magnetic beads with modified amino, carboxy, and N-hydroxysuccinimide groups, respectively. Amino magnetic beads performed best for immobilization and were selected for further experiments. Xanthine oxidase was immobilized on amino magnetic beads and applied to screen potential inhibitors in fresh Zingiber officinale Roscoe, extracts of Scutellaria baicalensis Georgi, and Pueraria lobata Ohwi. In total, 12 potential xanthine oxidase ligands were identified from fresh Zingiber root and Scutellaria root extracts, of which eight were characterized and the concentration required for 50% inhibition was determined. Preliminary structure-function relationships were discussed based on these results. A convenient and effective method was therefore developed for the identification of active compounds from complex natural product mixtures.

Screening and Characterizing Tyrosinase Inhibitors from Salvia miltiorrhiza and Carthamus tinctorius by Spectrum-Effect Relationship Analysis and Molecular Docking

Tyrosinase (TYR) is a rate-limiting enzyme in the synthesis of melanin, while direct TYR inhibitors are a class of important clinical antimelanoma drugs. This study established a spectrum-effect relationship analysis method and high-performance liquid chromatography-mass spectrometry (LC-MS) analysis method to screen and identify the active ingredients that inhibited TYR in Salvia miltiorrhiza-Carthamus tinctorius (Danshen-Honghua, DH) herbal pair. Seventeen potential active compounds (peaks) in the extract of DH herbal pair were predicted, and thirteen of them were tentatively identified by LC-MS analysis. Furthermore, TYR inhibitory activities of five pure compounds obtained from the DH herbal pair were validated in the test in which kojic acid served as a positive control drug. Among them, three compounds including protocatechuic aldehyde, hydroxysafflor yellow A, and tanshinone IIA were verified to have high TYR inhibitory activity (IC50 value of 455, 498, and 1214 μM, resp.) and bind to the same amino acid residues in TYR catalytic pocket according to the results of the molecular docking test. However, the other two compounds lithospermic acid and salvianolic acid A had a weak effect on TYR, as they do not combine with the active amino acid residues or act on the active center of TYR. Therefore, the developed methods (spectrum-effect relationship analysis and molecular docking) could be used to effectively screen TYR inhibitors in complex mixtures such as natural products.

A strategy for screening of α-glucosidase inhibitors from Morus alba root bark based on the ligand fishing combined with high-performance liquid chromatography mass spectrometer and molecular docking

A new method based on ligand fishing combined with high-performance liquid chromatography quadrupole-time-of-flight mass spectrometer and molecular docking was established to screen α-glucosidase inhibitors from a traditional Chinese medicine Morus alba root bark. α-Glucosidase was immobilized on magnetic nanoparticles, used as a solid support to incubate with crude extract. After ligand fishing, the eluates were analyzed by high-performance liquid chromatography quadrupole-time-of-flight mass spectrometer, obtaining eleven ligands (1-4, 6-12) eventually. In order to discriminate the non-specific binders and discover powerful enzyme inhibitors, molecular docking was further performed and three of the eleven ligands were optimized to be excellent α-glucosidase inhibitors by the confirmation of isolation and bioassay of individual compounds. These three ligands, sanggenons G (6), O (7) and sanggenol G (12) exhibited striking inhibitory activities with extremely low IC₅₀ values. The results suggest that established method will be applied to a wide range of target protein to screen potential bioactive constituents from herbal medicines.

A multiple biomarker assay for quality assessment of botanical drugs using a versatile microfluidic chip

Quality control is critical for ensuring the safety and effectiveness of drugs. Current quality control method for botanical drugs is mainly based on chemical testing. However, chemical testing alone may not be sufficient as it may not capture all constituents of botanical drugs. Therefore, it is necessary to establish a bioassay correlating with the drug's known mechanism of action to ensure its potency and activity. Herein we developed a multiple biomarker assay to assess the quality of botanicals using microfluidics, where enzyme inhibition was employed to indicate the drug's activity and thereby evaluate biological consistency. This approach was exemplified on QiShenYiQi Pills using thrombin and angiotensin converting enzyme as "quality biomarkers". Our results demonstrated that there existed variations in potency across different batches of the intermediates and preparations. Compared with chromatographic fingerprinting, the bioassay provided better discrimination ability for some abnormal samples. Moreover, the chip could function as "affinity chromatography" to identify bioactive phytochemicals bound to the enzymes. This work proposed a multiple-biomarker strategy for quality assessment of botanical drugs, while demonstrating for the first time the feasibility of microfluidics in this field.

Rapid ultrasonic and microwave-assisted micellar extraction of zingiberone, shogaol and gingerols from gingers using biosurfactants

Two kinds of extraction methods ultrasonic-assisted micellar extraction (UAME) and microwave-assisted micellar extraction (MAME) coupled with ultra-high performance liquid chromatography with ultraviolet detector (UHPLC-UV) were developed and evaluated for extraction and determination of zingerone, 6-gingerol, 8-gingerol, 6-shogaol and 10-gingerol in Rhizoma Zingiberis and Rhizoma Zingiberis Preparata. A biosurfactant, hyodeoxycholic acid sodium salt, was used in micellar extraction. Several experimental parameters were studied separately by a univariate method. The result indicated that the MAME was more efficient than UAME. The optimal conditions of MAME were as follows: 100mM of hyodeoxycholic acid sodium salt was used as surfactant, the irradiation time was set at 10s and the extraction temperature was set at 60°C. The validation results indicated that the limits of detection were in the range of 3.80-8.11ng/mL. The average recoveries were in the range of 87.32-103.12% for the two samples at two spiking levels. Compared with other reported methods, the proposed MAME-UHPLC-UV method was more effective, quicker (10s) and more eco-friendly.

An ultrafiltration and high performance liquid chromatography coupled with diode array detector and mass spectrometry approach for screening and characterizing thrombin inhibitors from Rhizoma Chuanxiong

Thrombin (THR) plays a significant role in thromboembolic diseases, direct THR inhibitors are a class of important clinical anticoagulant drugs. This study established a THR in-solution based biospecific extraction combined with ultrafiltration and high performance liquid chromatography coupled with diode array detector and mass spectrometry analysis (TUA) method to screen and identify ligands for THR in Rhizoma Chuanxiong. After evaluating the reliability of the present TUA method using positive (argatroban) and negative (adenosine, tirofiban, ticagrelor) control drugs, this method was successfully applied to detect eight potential active compounds in Rhizoma Chuanxiong. Two new THR-targeted compounds isochlorogenic acid C and senkyunolide I with high THR inhibitory activity (IC50 206.48 and 197.23μM, respectively) were identified by liquid chromatography/mass spectrometry and enzyme inhibitory activity test finally. They were reported with direct THR inhibition activity for the first time and their ligand-THR interactions were explored by in silico molecular docking research. In addition, based on the TUA screening result, four compounds gained similar structure with the two hit compounds were also investigated as promising candidates targeting THR with high binding energy (>5.0kcal/mol). These results may prove that the proposed method could effectively screen THR inhibitors in complex mixtures.