Comprehensive profiling of Sanguisorba officinalis using offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography,tandem high-resolution mass spectrometry,and molecular network

The profiling of natural products is important in modern biological sciences and new drug development. However, the separation and characterization of complex herbal extracts are significantly challenging for researchers in the biochemical field. Herein, an offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography system is developed. Our system exhibits high orthogonality and is composed of a newly prepared stationary phase in the first dimension and a traditional C₁₈ phase in the second dimension, and is operated in combination with a high-resolution mass spectrometry and molecular network. Sanguisorba officinalis L. is studied using the proposed method owing to its bioactivity. With the aid of orthogonal separation, the ionization of the individual components is improved. The number of detected compounds and separated peaks are significantly increased when one-dimensional liquid chromatography is upgraded to two-dimensional liquid chromatography. In addition, 270 compounds (127 of which are tentatively characterized as new compounds, and further confirmation is needed) are successfully characterized based on their fragmentation patterns under the guidance of molecular network, while only 95 compounds are characterized using one-dimensional liquid chromatography and high-resolution mass spectrometry. The results indicate that the developed offline two-dimensional mixed-mode liquid chromatography × reversed-phase liquid chromatography, tandem high-resolution mass spectrometry, and molecular network method are effective for profiling complex samples.     

Liquid chromatography with mass spectrometry and NMR spectroscopy based discovery of cytotoxic principles from Daphne tangutica Maxim

An ethyl acetate extract from the barks of the ethnic Chinese medicine Daphne tangutica Maxim. exhibited antihepatocellular carcinoma activity against HepG2 and Hep3B cell lines. By using high‐performance liquid chromatography based activity profiling in combination with offline liquid chromatography with mass spectrometry and NMR analysis, we rapidly identified ten major components of the extract, including seven active principles, coumarins ( 1–4 ) and biscoumarins ( 7, 8, 10 ), along with three inactive flavonoids ( 5, 6, 9 ). This study demonstrated that our combined protocol can be used as an important strategy for chemical profiling, dereplication as well as the identification of bioactive compounds from herbal medicines.     

Global detection and analysis of volatile components from sun-dried and sulfur-fumigated herbal medicine by comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry

The sulfur-fumigation process can induce changes in the contents of volatile compounds and the chemical transformation of herbal medicines. Although literature has reported many methods for analyzing volatile target compounds from herbal medicine, all of them are largely limited to target compounds and sun-dried samples. This study provides a comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOF/MS) method based on a chemical profiling approach to identify non-target and target volatile compounds from sun-dried and sulfur-fumigated herbal medicine. Using Chrysanthemum morifolium as a model herbal medicine, the combined power of this approach is illustrated by the identification of 209 and 111 volatile compounds with match quality >80% from sun-dried and sulfur-fumigated Chrysanthemum morifolium, respectively. The study has also shown that sulfur-fumigated samples showed a significant loss of the main active compounds and a more destructive fingerprint profile compared to the sun-dried ones. 50 volatile compounds were lost in the sulfur-fumigated Chrysanthemum morifolium sample. The approach and methodology reported in this paper would be useful for identifying complicated target and non-target components from various complex mixtures such as herbal medicine and its preparations, biological and environmental samples. Furthermore, it can be applied for the intrinsic quality control of herbal medicine and its preparations.     

Chemical profiling of Qingfei Paidu Decoction by triplex off-line two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

Qingfei Paidu Decoction is a Chinese medicine formula that has been proved effective in the treatment of coronavirus disease 2019. However, the comprehensive separation and characterization of Qingfei Paidu Decoction are of a great challenge due to the diversity of chemical components in a wide range of polarity. In this study, a triplex off-line two-dimensional liquid chromatography coupled with quadrupole time-of-flight mass spectrometry is developed for the analysis of Qingfei Paidu Decoction. One reversed-phase liquid chromatography×hydrophilic interaction liquid chromatography system and two reversed-phase liquid chromatography×reversed phase liquid chromatography systems were constructed to separate polar components and weak-polar components in Qingfei Paidu Decoction, respectively. Benefiting from the good orthogonality of two-dimensional liquid chromatography and high sensitivity of quadrupole time-of-flight MS, chemical components with different polarities and content were discovered. A total of 749 peaks were detected in positive and negative ionization mode and presented as a four-dimensional data plot. Meanwhile, 498 compounds belonging to 14 categories were tentatively identified. These results provide good supplementary to elucidate the material basis of Qingfei Paidu Decoction. The triplex off-line two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry strategy can be a powerful and efficient tool for the separation and characterization of chemical substances in traditional Chinese medicine formulas.     

Application of characteristic fragment filtering with ultra high performance liquid chromatography coupled with high‐resolution mass spectrometry for comprehensive identification of components in Schisandrae chinensis Fructus

An integrated strategy of characteristic fragment filtering combined with target database screening based on ultra‐high‐performance liquid chromatography coupled with high‐resolution mass spectrometry was proposed for comprehensive profiling of components in Schisandrae chinensis Fructus. The strategy consisted of following five steps: (1) Representative standards were analyzed by ultra high performance liquid chromatography coupled with linear ion trap‐Orbitrap mass spectrometer for characteristic fragments and fragmentation rules of each structure type. (2) The raw data of 70% methanol extract was collected by ultra high performance liquid chromatography quadrupole time‐of‐flight tandem mass spectrometry. (3) The chemical components database that consisted of names, chemical formulas and structures of potential components in Schisandrae chinensis Fructus was established by summarizing previous literature to screen the collected liquid chromatography with mass spectrometry data and obtain matched compounds. (4) Characteristic fragments, literature, and reference standards were used to verify the matches. (5) Characteristic fragment filtering combined with online database querying was used to deduce potential new compounds. As a result, a total of 94 compounds were identified or characterized and 16 of them were potential new compounds. The study provided a reference for comprehensive characterization of ingredients in herbal medicine and formed the foundation for pharmacodynamic study of Schisandrae chinensis Fructus.     

Rapid characterization of the chemical constituents of Cortex Fraxini by homogenate extraction followed by UHPLC coupled with Fourier transform ion cyclotron resonance mass spectrometry and GC–MS

Cortex Fraxini is an important traditional Chinese medicine. In this work, a rapid and reliable homogenate extraction method was applied for the fast extraction for Cortex Fraxini, and the method was optimized by response surface methodology. Ultra high performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry and gas chromatography with mass spectrometry were established for the separation and characterization of the constituents of Cortex Fraxini. Liquid chromatography separation was conducted on a C₁₈ column (150 mm × 2.1 mm, 1.8 μm), and gas chromatography separation was performed on a capillary with a 5% phenyl‐methylpolysiloxane stationary phase (30 m × 0.25 mm × 0.25 mm) by injection of silylated samples. According to the results, 33 chemical compounds were characterized by liquid chromatography with mass spectrometry, and 11 chemical compounds were characterized by gas chromatography with mass spectrometry, and coumarins were the major components characterized by both gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. The proposed homogenate extraction was an efficient and rapid method, and coumarins, phenylethanoid glycosides, iridoid glycosides, phenylpropanoids, and lignans were the main constituents of Cortex Fraxini. This work laid the foundation for further study of Cortex Fraxini and will be helpful for the rapid extraction and characterization of ingredients in other traditional Chinese medicines.     

Rapid screening,identification, and purification of neuraminidase inhibitors from Lithospermum erythrorhizon Sieb.et Zucc. by ultrafiltration with HPLC–ESI‐TOF‐MS combined with semipreparative HPLC

We put forward an efficient strategy based on bioassay guidance for the rapid screening, identification, and purification of the neuraminidase inhibitors from traditional Chinese medicines, and apply to the discovery of anti‐influenza components from Lithospermiun erythrorhizon Sieb.et Zucc. Ultrafiltration with high‐performance liquid chromatography and electrospray ionization time‐of‐flight mass spectrometry was employed for the rapid screening and preliminarily identification of anti‐influenza components from Zicao. Semipreparative high‐performance liquid chromatography was used for the rapid separation and purification of the target compounds. NMR spectroscopy, mass spectrometry, and UV spectroscopy were used for further structural identification, and the activity of the compounds was verified by in vitro assay. Five compounds were found to have neuraminidase inhibitory activity by this method. Subsequently, the five compounds were separated by semipreparative high‐performance liquid chromatography with the purity over 98% for all of them by high‐performance liquid chromatography test. Combined with the NMR spectroscopy, mass spectrometry, and UV spectroscopy data, they were identified as alkannin, acetylalkannin, isobutyrylalkannin, β,β‐dimethylacryloylalkannin and isovalerylalkannin. The in vitro assay showed that all five compounds had good neuraminidase inhibitory activities. These results suggested that the method is highly efficient, and it can provide platform and methodology supports for the rapid discovery of anti‐influenza active ingredients from complex Chinese herbal medicines.     

Chemical profiling of Ziziphi spinosae semen using on-line comprehensive two-dimensional liquid chromatography-mass spectrometry based on a novel phthalic anhydride bonded stationary phase

Ziziphi spinosae semen has been widely used to treat insomnia and anxiety. To profile its chemical components, an online comprehensive two-dimensional liquid chromatography-mass spectrometry was developed. In this two-dimensional liquid chromatography system, a novel phthalic anhydride-bonded stationary phase column was combined with a C18 column. As a result, this new stationary phase exhibited remarkable differences in separation selectivity from C18, achieving a good orthogonality of 83.3%. Moreover, this new stationary phase with weaker hydrophobicity than C18 realized solvent compatibility in the online configuration. Coupled with tandem MS, 154 compounds were identified, including 51 unreported compounds. Compared with one-dimensional liquid chromatography-mass spectrometry, this online two-dimensional liquid chromatography-mass spectrometry system exhibited a much higher resolving power in isomer separation. This work provided an effective separation and characterization method for the material basis of Ziziphi spinosae semen. This strategy provides ideas for the material basis research of other traditional Chinese medicines.     

Deciphering chemical interactions between Glycyrrhizae Radix and Coptidis Rhizoma by liquid chromatography with transformed multiple reaction monitoring mass spectrometry

In this study, we propose an integrated strategy for the efficient identification and quantification of herbal constituents using liquid chromatography with mass spectrometry. First, liquid chromatography with quadrupole time‐of‐flight mass spectrometry was employed for the chemical profiling of herbs, where a targeted following nontargeted approach was developed to detect trace constituents by using structural correlations and extracted ion chromatograms. Next, ion pairs and parameters of MS² of quadrupole time‐of‐flight mass spectrometry were selected to design multiple reaction monitoring transitions for the identified compounds on liquid chromatography with triple quadrupole mass spectrometry. The relative concentration of each constituent was then calculated using a semiquantitative calibration curve. The proposed strategy was applied in a study of chemical interactions between Glycyrrhizae Radix and Coptidis Rhizoma. A total of 140 compounds were identified or tentatively characterized from the herbs, 132 of which were relatively quantified. The visualized quantitative results clearly showed codecoction produced significant constituent concentration variations especially for those with a low polarity. The case study also indicated that the present methodology could provide a reliable, accurate, and labor‐saving solution for chemical studies of herbal medicines.     

Characterization of the chemical composition of white chrysanthemum flowers of Hangzhou by using high‐performance ion trap mass spectrometry

In this study, high‐performance liquid chromatography coupled with amaZon SL high‐performance ion trap mass spectrometry was used to analyze the target components in white chrysanthemum flowers of Hangzhou. Twenty‐one components were detected and identified in both white chrysanthemum flowers of Hangzhou samples by using target compound analysis. Furthermore, seven new compounds in white chrysanthemum flowers of Hangzhou were found and identified by analyzing the fragment ion behavior in the mass spectra. The established method can be expedient for the global quality investigation of complex components in herbal medicines and food.     

Rapid characterization of the chemical constituents and rat metabolites of the Wen‐Jing decoction by ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry

The Wen‐Jing decoction, a traditional Chinese medicine formula, has been used as a blood‐activating and stasis‐eliminating drug to treat gynaecological syndromes, such as dysmenorrhea, amenorrhea, and menstrual disorders. However, its pharmacodynamic material basis and mechanism of action have not been thoroughly elucidated to date. The goal of this study was to characterize and identify multiple constituents and metabolites in Wen‐Jing decoction. An ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry method was established and validated in the present study for the first time. A total of 101 compounds, including 11 monoterpene glycosides, 19 flavonoids, 49 triterpene saponins, 5 phthalides, 3 phytoecdysones, and 14 others, were unambiguously or tentatively characterized by comparing their retention times and MS data with reference standards or with data reported in the literature. After oral administration of Wen‐Jing decoction, 27 compounds, including nine prototype compounds and 18 metabolites were detected in rat plasma. Thus, the ultra high performance liquid chromatography coupled with electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry method was found to be efficient for in‐depth structural elucidation of chemical compounds in complex matrices of herbal medicines, which will provide useful chemical information for quality control and mechanism‐of‐action research.     

Characterization of the alkaloids in goldenseal (Hydrastis canadensis) root by high resolution Orbitrap LC-MSn

Liquid chromatography coupled to multistage mass spectrometry (LC-MSⁿ) is being used increasingly in pharmaceutical research and for quality control in herbal medicines because of its superior sensitivity and selectivity. In this study, a rapid, high-resolution liquid chromatography-mass spectrometry (LC-MSⁿ) method was developed to separate and identify alkaloids in the root extract of goldenseal, which is one of the 20 most popular herbal supplements used worldwide. In total, 28 alkaloids were separated and characterized including one novel compound and 21 identified, or tentatively identified, for the first time in goldenseal. The current high-resolution LC-MSⁿ method provides a rapid and definitive means of profiling the composition of goldenseal root and will provide a useful tool in understanding the bioactivity of this medicinal plant.

Applying characteristic fragment filtering for rapid detection and identification of ingredients in rhubarb by HPLC coupled with linear ion trap–Orbitrap mass spectrometry

Chemical characteristic fragment filtering in MSⁿ chromatograms was proposed to detect and identify the components in rhubarb rapidly using high‐performance liquid chromatography coupled with linear ion trap–Orbitrap mass spectrometry. Characteristic fragments consist of diagnostic ions and neutral loss fragments. Characteristic fragment filtering is a postacquisition data mining method for the targeted screening of groups with specific structures, including three steps: first, in order to comprehensively summarize characteristic fragments for global identification of the ingredients in rhubarb, representative authentic standards of dominant chemical categories contained in rhubarb were chosen, from which fragmentation rules and a characteristic fragments schedule were proposed; second, characteristic fragment filtering was used to rapidly recognize analogous skeletons; finally, combined with retention time, accurate mass, characteristic fragments, and previous literature, the structures of the filtered compounds were identified or tentatively characterized. As a result, a total of 271 compounds were detected and identified in rhubarb, including 34 anthraquinones, 83 anthrones, 46 tannins, 17 stilbenes, 24 phenylbutanones, 26 acylglucosides, 26 chromones, and 15 other compounds, 69 of which are potentially new compounds. The proposed characteristic fragment filtering strategy would be a reference for the large‐scale detection and identification of the ingredients of herbal medicines.     

A strategy for screening trypsin inhibitors from traditional Chinese medicine based on a monolithic capillary immobilized enzyme reactor coupled with offline liquid chromatography and mass spectrometry

A novel strategy was successfully developed for screening trypsin inhibitors in traditional Chinese medicines based on monolithic capillary immobilized enzyme reactors combined with liquid chromatography‐tandem mass spectrometry. Organic polymer based monolithic enzyme reactors were firstly prepared by covalently bonding trypsin to a poly(glycidyl methacrylate‐co‐poly (ethylene glycol) diacrylate) monolith by the ring‐opening reaction of epoxy groups. The activity and kinetic parameters of the obtained monolithic trypsin reactors were systematically evaluated using micro‐liquid chromatography. Fourier transform infrared spectroscopy and scanning electron microscopy were also used to characterize the monolithic trypsin reactors. The resulting functional and denatured monolithic trypsin reactors were applied as affinity solid‐phase extraction columns, and offline coupled with a liquid chromatography‐tandem mass spectrometry system to construct a binding affinity screening platform. Subsequently, the proposed platform was applied for screening trypsin binders in a Scutellaria baicalensis Georgi extract. Three compounds, namely scutellarin, baicalin, and wogonoside were identified, and their inhibitory activities were further confirmed via an in vitro enzymatic inhibition assay. Additionally, molecular docking was also performed to study the interactions between trypsin and these three compounds.     

A four-dimensional separation approach by offline 2D-LC/IM-TOF-MS in combination with database-driven computational peak annotation facilitating the in-depth characterization of the multicomponents from Atractylodis Macrocephalae Rhizoma (Atractylodes macrocephala)

Plant metabolites represent complex chemical system, which renders it difficult to clarify the chemical composition by conventional liquid chromatography/mass spectrometry (LC/MS) due to the limited selectivity and peak capacity. The rhizomes of Atractylodes macrocephala have been utilized as a traditional Chinese medicine Atractylodis Macrocephalae Rhizoma (Bai-Zhu), and have been reported containing multiple categories of plant metabolites. Targeting the multicomponents from A. macrocephala, an integral approach by offline two-dimensional liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry (2D-LC/IM-QTOF-MS) was established and validated. By configuring an XBridge Amide column of Hydrophilic Interaction Chromatography and an Atlantis Premier BEH C18AX column of mixed ion exchange and reversed-phase modes, the established 2D-LC/IM-QTOF-MS system showed high orthogonality up to 0.91. Dimension-enhanced, data-independent high-definition MS^E (HDMS^E) in the positive ESI mode was conducted on a Vion IM-QTOF mass spectrometer, and its hyphenation to offline 2D-LC could enable the four-dimensional separation (each dimension in 2D-LC, IM, and MS). Particularly, HDMS^E facilitated the acquisition of high-definition MS¹ and MS² spectra. In-house library-driven computational peak annotation by the bioinformatics platform UNIFI could efficiently process and annotate the HDMS^E data for the structural elucidation. By integrating reference compounds comparison, we could identify or tentatively characterize 251 components from A. macrocephala (including 115 sesquiterpenoids, 90 polyacetylenes, 11 flavonoids, 9 benzoquinones, 12 coumarins, and 14 others), which indicated large improvement in identifying those minor plant components, compared with the conventional LC/MS approach. Conclusively, offline 2D-LC/IM-QTOF-HDMS^E in combination with computational data interpretation proves to be powerful facilitating the in-depth multicomponent characterization of herbal medicine.     

Cardiac Muscle/Cell Membrane Chromatography-Offline-Liquid Chromatography/Mass Spectrometry Method to Identify Bioactive Components from Traditional Chinese Medicines

An offline analytical method combining cardiac muscle/cell membrane chromatography (CM/CMC) with liquid chromatography/mass spectrometry (LC/MS) to identify bioactive components from traditional Chinese medicines (TCMs) such as Schisandrae Chinensis Fructus (SCF) and Schisandrae Sphenantherae Fructus (SSF) was developed. The stationary phase of the CM/CMC system employed rat cardiac muscle cell membranes. Fractions retained by the CM/CMC column were collected and analyzed by LC/MS under optimum offline conditions. After evaluating the suitability and reliability of the CM/CMC-offline-LC/MS method using nifedipine and nitrendipine as standards, this method was applied for screening and identification of bioactive components from the extracts of SCF and SSF. The main compounds in both species retained by CM/CMC were deoxyschizandrin (DSD) and schisantherin A (STA) as identified by LC/MS. In vivo pharmacological experiments suggested that DSD and STA could significantly decrease the myocardial-infarct size in rats injured by myocardial ischemia–reperfusion. Our CM/CMC-offline-LC/MS method could be used as an effective alternative for screening multiple receptor-binding bioactive components in TCMs such as FSC and FSS used to remedy cardiac diseases and may be useful for drug discovery using medicinal herbs as lead compounds.     

Software Assisted Multi-Tiered Mass Spectrometry Identification of Compounds in Traditional Chinese Medicine: Dalbergia odorifera as an Example

The complexity of metabolites in traditional Chinese medicine (TCM) hinders the comprehensive profiling and accurate identification of metabolites. In this study, an approach that integrates enhanced column separation, mass spectrometry post-processing and result verification was proposed and applied in the identification of flavonoids in Dalbergia odorifera. Firstly, column chromatography fractionation, followed by liquid chromatography–tandem mass spectrometry was used for systematic separation and detection. Secondly, a three-level data post-processing method was applied to the identification of flavonoids. Finally, fragmentation rules were used to verify the flavonoid compounds. As a result, a total of 197 flavonoids were characterized in D. odorifera, among which seven compounds were unambiguously identified in level 1, 80 compounds were tentatively identified by MS-DIAL and Compound Discoverer in level 2a, 95 compounds were annotated by Compound discoverer and Peogenesis QI in level 2b, and 15 compounds were exclusively annotated by using SIRIUS software in level 3. This study provides an approach for the rapid and efficient identification of the majority of components in herbal medicines.