Tracing antibacterial compounds from Acalypha australis Linn. by spectrum‐effect relationships and semi‐preparative HPLC

Several Acalypha australis Linn. species are used in traditional medicine in Southeast Asia. In this work, the ultra‐performance liquid chromatography/mass spectrometry fingerprints and the antibacterial activities of A. australis Linn. were investigated. An in‐depth discussion on the reliability of identifying and obtaining potentially active compounds by spectrum‐effect relationship and semi‐preparative high performance liquid chromatography was conducted. The result shows that gallic acid and a compound with molecular weight of 634.1 in the fingerprints were the main antibacterial compounds. Compared to the crude extract of A. australis Linn., both compounds increase the antibacterial efficacy 10 to 20 times. Compounds with molecular weights of 154.0, 292.0, and 485.1 in the fingerprints were the auxiliary antibacterial compounds. Through the entire isolation procedure, we obtained these antibacterial compounds with purities of 92.53, 87.98, 90.73, 89.36, and 88.14%, respectively. This work provides a general model of the combination of ultra‐performance liquid chromatography/mass spectrometry fingerprinting and antibacterial test to study the spectrum‐effect relationships of A. australis Linn. This model can be used to discover further the active compounds of this herb.     

Searching for the main anti-bacterial components in artificial Calculus bovis using UPLC and microcalorimetry coupled with multi-linear regression analysis

The fingerprints of artificial Calculus bovis extracts from different solvents were established by ultra-performance liquid chromatography (UPLC) and the anti-bacterial activities of artificial C. bovis extracts on Staphylococcus aureus (S. aureus) growth were studied by microcalorimetry. The UPLC fingerprints were evaluated using hierarchical clustering analysis. Some quantitative parameters obtained from the thermogenic curves of S. aureus growth affected by artificial C. bovis extracts were analyzed using principal component analysis. The spectrum-effect relationships between UPLC fingerprints and anti-bacterial activities were investigated using multi-linear regression analysis. The results showed that peak 1 (taurocholate sodium), peak 3 (unknown compound), peak 4 (cholic acid), and peak 6 (chenodeoxycholic acid) are more significant than the other peaks with the standard parameter estimate 0.453, -0.166, 0.749, 0.025, respectively. So, compounds cholic acid, taurocholate sodium, and chenodeoxycholic acid might be the major anti-bacterial components in artificial C. bovis. Altogether, this work provides a general model of the combination of UPLC chromatography and anti-bacterial effect to study the spectrum-effect relationships of artificial C. bovis extracts, which can be used to discover the main anti-bacterial components in artificial C. bovis or other Chinese herbal medicines with anti-bacterial effects.     

Screening and identification of α‐glucosidase inhibitors from Shenqi Jiangtang Granule by ultrafiltration liquid chromatography and mass spectrometry

Shenqi Jiangtang Granule, a well‐known traditional Chinese herbal preparation, has been widely used for the treatment of type II diabetes mellitus. In this work, an ultrafiltration liquid chromatography with quadrupole time‐of‐flight mass spectrometry method was proposed for the rapid identification of bioactive ingredients from Shenqi Jiangtang Granule using α‐glucosidase as an example. First, the chemical profile of this preparation was clarified, including 37 saponins, 17 flavonoids, 37 lignans, and seven other compounds. After incubation with α‐glucosidase in vitro, the methanol extract with an IC₅₀ value of 0.19 mg/mL exhibited significant inhibitory activity. Then, 18 specific binding peaks were screened, and 15 peaks were identified. Among these, ten compounds were reported to have potential α‐glucosidase inhibitory activity for the first time. Subsequently, the inhibitory activities of these active compounds were evaluated by ultraviolet spectrophotometry with p‐nitrophenyl α‐d‐ glucopyranoside as a substrate. As a result, gomisin J and gomisin D exhibited stronger α‐glucosidase inhibitory activities than other active compounds with IC₅₀ values of 77.69 and 133.85 μM, respectively. The results demonstrated that the integrated ultrafiltration liquid chromatography with mass spectrometry method was an effective and powerful tool for the discovery of active ingredients in Shenqi Jiangtang Granule.     

Potential antioxidant compounds in Mallotus species fingerprints. Part II: Fingerprint alignment,data analysis and peak identification

Some Mallotus species are commonly used as traditional medicine (TM) ingredients in Vietnam and China, but only a few are studied for their activities. In Part I, high-performance liquid chromatography (HPLC) fingerprints of 39 Mallotus samples (17 species) were developed and, because of the complexity of and the large differences between the samples, it was chosen to analyse the unaligned fingerprints. The peaks, potentially responsible for the antioxidant activity in given Mallotus species, were indicated by the regression coefficients from an orthogonal projections to latent structures (O-PLS) model. In the present study, an in depth discussion on the need for alignment of the Mallotus fingerprints for the indication of the potentially active compounds is made, as well as an experimental analysis and identification of the previously indicated peaks by HPLC–mass spectrometry (HPLC–MS). Additionally, to thoroughly study and discuss the alignment problem, the modelling and prediction of the antioxidant activity of green tea samples based on HPLC fingerprints were also considered.     

Study on chemical constituents and fingerprints of Phellodendron amurense Rupr. based on ultra-performance liquid chromatography–quadrupole–time-of-flight–mass spectrometry

The chemical constituents from Phellodendron amurense Rupr. were characterized systematically by ultra-performance liquid chromatography—quadrupole–time-of-flight–mass spectrometry method for collecting mass spectrometry data, and the fingerprints method was established, providing reference for its quality control. The chromatographic column was ACQUITY UPLC BEH-C₁₈ (100 mm×2.1 mm, 1.7 μm). The mobile phase was acetonitrile-0.1% formic acid aqueous solution and the compounds from P. amurense Rupr. were identified by Qualitative Analysis 10.0 software, reference substance, retention time, mass spectrometry fragmentation pattern and database retrieval. Meanwhile, liquid chromatography–mass spectrometry fingerprint methods of P. amurense Rupr. and Phellodendron chinense Schneid. were established by using the similarity evaluation system of chromatographic fingerprint of traditional Chinese medicine (2012 edition), and the differences were analyzed by multivariate statistical analysis methods. A total of 105 compounds were identified, including 102 alkaloids, two phenolic acids, and one lactone compound. Liquid chromatography–mass spectrometry fingerprint method was established with ideal precision, stability and repeatability, and 12 quality differential markers were recognized between the above two herbs. Liquid chromatography–mass spectrometry method can be used for qualitative analysis of the constituents of Phellodendron amurense Rupr., providing reference for clarifying the material basis and promoting the clinical precision medication and quality evaluation of P. amurense Rupr.     

Optimization of extraction for Anemarrhena asphodeloides Bge. using silica gel‐based vortex‐homogenized matrix solid‐phase dispersion and rapid identification of antioxidant substances

A novel and simple method was established for the extraction and determination of seven compounds in Anemarrhena asphodeloides Bge. using silica gel‐based vortex‐homogenized matrix solid‐phase dispersion and ultra‐high performance liquid chromatography quadrupole‐time of‐flight mass spectrometer. The conditions for the extraction were optimized. Silica gel was used as the dispersant, 50% methanol–water was selected as an elution solvent and the grinding time was 3 min. Compared with the traditional ultrasonic‐assisted extraction, the developed method was rapid and efficient. In order to screen potential antioxidants, extract dealing with the optimized method was applied to a polyamide chromatography column and a D‐101 macroporous resin column. Fr.2.2 showed the highest antioxidant activities with the most content of flavonoid. A total of 25 peaks were identified from the active fraction. A 2,2′‐diphenyl‐1‐picrylhydrazyl ultra‐high performance liquid chromatography coupled with mass spectrometry approach was adopted for the rapid and exact screening and identification of antioxidant compounds. It indicated that flavonoids exhibited potential antioxidant activities. The antioxidant activities of nine monomeric compounds in vivo were tested. Structure–activity relationships were discussed. Five flavonoids with the concentration of 500 µg/mL would reduce the oxidative stress of PC12 cells that were induced with 2,2′‐azobis[2‐methylpropionamidine] dihydrochloride.     

Screening of analgesic and anti‐inflammatory active component in Fructus Alpiniae zerumbet based on spectrum–effect relationship and GC–MS

Fructus Alpiniae zerumbet is widely used in Guizhou province as a miao folk herb with anti‐inflammatory, analgesic, protection against cardiovascular diseases, antihypertension and antioxidant activities. To further investigate the chemical material basis, the spectrum–effect relationship was established using gray relational analysis between the chromatographic fingerprint and its bioactivities. Herein, the fingerprints of essential oils from Fructus Alpiniae zerumbet (EOFAZ) from various sources were determined by gas chromatography mass spectrometry, and the analgesic and anti‐inflammatory bioactivities were investigated using the mouse model of acetic acid‐induced writhing test and dimethylbenzene‐induced mouse ear edema test. Finally, 17 common peaks were identified from nine batches of A. zerumbet, by comparison with the standard mass spectra in Nist2005, Wiley275 library. Meanwhile, the results showed significant analgesic and anti‐inflammatory effects in all of the different sources of EOFAZ. In particularly, peak 1 (α‐pipene), peak 3 (β‐pinene), peak 9 (camphor) and peak 16 (α‐cadinol) might be the main bioactive ingredients for analgesic and anti‐inflammatory activities. The model of the spectrum–effect relationships of EOFAZ was successfully discovered, which provided a novel platform for finding the bioactive components, a theoretical foundation for its further study and helping to establish quality control of Fructus A. zerumbet.     

Isolation and Identification of Fisetin: An Antioxidative Compound Obtained from Rhus verniciflua Seeds

The goal of this study was to provide basic data for the development of functional food and health materials for Rhus verniciflua (R. verniciflua) seeds. We investigated an antioxidative compound obtained from these seeds. Solvent fractionation was carried out on a 50%-ethanol extract of the seeds. The DPPH and ABTS radical-scavenging activity and superoxide dismutase (SOD) activity were measured, and high antioxidant activity was seen in the ethyl acetate fraction. The antioxidant compounds in the ethyl acetate fraction were isolated using silica-gel column chromatography by adjusting the solvent between chloroform and methanol. Fraction numbers 2–7 showed activity of more than 50%. Next, primary column chromatography was used to mix and concentrate the fractions that demonstrated antioxidant activity. The fractions were then subjected to secondary column chromatography to obtain subfraction 4, which showed high antioxidant activity. The separation of subfraction 4 was then performed using high-performance liquid chromatography (HPLC). Three peaks were identified and peak number 2 was judged to be the primary antioxidative compound, which was then isolated by pure separation. Finally, the purified subfraction peak number 2 was identified as a fisetin compound by liquid chromatography–mass spectrometry (LC–MS), nuclear magnetic resonance (NMR), and HPLC.     

Identification and quantitation of major phenolic compounds from penthorum chinense pursh. by HPLC with tandem mass spectrometry and HPLC with diode array detection

Penthorum chinense Pursh. is a traditional Chinese herbal medicine used for the treatment of various ailments specially related to liver. Gansu Granule, the medicine made from the extract of P. chinense, has been widely used in the clinical setting. But the information about its active ingredients is lacking. In this paper, the extract of P. chinense was analyzed by high performance liquid chromatography with electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Among the 27 compounds that were identified based on their mass spectrometry data, ten were reported for the first time from P. chinense. Chromatographic fingerprints generated by high‐performance liquid chromatography by analyzing 21 batches of P. chinense, displayed six common peaks. Finally, four major compounds were identified namely; gallic acid, brevifolin carboxylic acid, 2,6‐dihydroxyacetophenone‐4‐O‐β‐d‐ glucoside, and pinocembrin‐7‐O‐β‐d‐ glucoside. The average content of each compound was 24.58, 109.6, 15.52, and 18.81 mg/g, respectively. In addition, this study also suggests that the qualitative liquid chromatography with mass spectrometry and the quantitative high‐performance liquid chromatography analytical methods using monolithic columns are simple, rapid, accurate, and reproducible and have the potential to be used for the comprehensive quality control of P. chinense.     

Spectrum–effect relationship study between HPLC fingerprints and antioxidant of honeysuckle extract

Honeysuckle (Lonicera japonica flos) is a well‐known agent of edible and medicinal value in China and its antioxidative activity makes a major contribution to its dual use. However, the compounds responsible for its antioxidative activity are still unknown. In this study, 10 batches of honeysuckle were collected from different origins in China. The fingerprints were established by HPLC technique to investigate the compounds and a 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity assay was carried out to evaluate their antioxidant activity. partial least squares regression analysis was applied to set up the regression equation between DPPH radical scavenging activity and average peak area of common peaks of fingerprints. The results showed that peaks 10 (isochlorogenic acid B), 12 (isochlorogenic acid C), 11 (isochlorogenic acid A) and 9 (cynaroside) in the fingerprints were closely related to the antioxidant activity of 50% methanol extracts of honeysuckle. This study successfully established the spectrum–effect relationship between HPLC fingerprints and DPPH radical scavenging activity and provided a general model for exploring active components with a combination of chromatography and efficacy.     

Pharmacokinetic and brain distribution study of an anti-glioblastoma agent in mice by HPLC–MS/MS

Previously compound I showed great anti-glioblastoma activity without toxicity in a mouse xenograft study. In this study, a sensitive and rapid high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) method was developed and validated to investigate the pharmacokinetics and brain distribution of compound I in mice. The protein precipitation method was applied to extract the compound from mouse plasma and brain homogenates, and it was then separated using a Kinetex C₁₈ column with a mobile phase consisting of acetonitrile–0.1% formic acid water (50:50, v/v). The analytes were detected with multiple reaction monitoring for the quantitative response of the compounds. The inter- and intra-day precisions were <8.29 and 3.85%, respectively, and the accuracy range was within ±7.33%. The method was successfully applied to evaluate the pharmacokinetics of compound I in mouse plasma and brain tissue. The peak concentration in plasma was achieved within 1 h. The apparent elimination half-life was 4.06 h. The peak concentration of compound I in brain tissue was 0.88 μg/g. The results indicated that compound I was rapidly distributed and could cross the blood–brain barrier. The pharmacokinetic profile summarized provides valuable information for the further investigation of compound I as a potential anti-glioblastoma agent.     

铁皮石斛的裂解气相色谱指纹图谱及其系统聚类分析

采用裂解气相色谱/质谱法(Py-GC/MS)测定了10种不同产地的铁皮石斛并结合系统聚类分析法比较了这些铁皮石斛的指纹图谱,采用释放气体分析法考察了裂解温度对指纹图谱的影响。结果表明,0.4 mg样品在450 ℃下可瞬间裂解,10种样品的指纹图谱具有相似性,且重现性好;采用系统聚类分析能区别不同产地的样品。本法快速、简便、准确,不失为药材质量控制的良好方法。     

Analysis of Trace-Level Volatile Compounds in Fresh Turf Crop （Lolium perenne L.） by Gas Chromatography Quadrupole Time-of-Flight Mass Spectrometry

In the traditional research of volatile compounds, some trace-level compounds could not be identified by gas chromatography-mass spectrometry. Target and post-targeted methods were applied in the investigation of trace-level volatile compounds in fresh turf crop （Lolium perenne L.） based on gas chromatography in combination with hybrid quadrupole time-of-flight mass spectrometry. According to literatures published, a target analysis was performed by using retention index, accurate masses of characteristic ions and second-stage mass spectra （MS2 spectra）. And a series of experiments showed that low electron impact energy was beneficial to the improvement of the abundances of low abundance molecular ion peak. peak was beneficial to qualitative analysis. Totally, 60 Enhancing the abundances of low abundance molecular ion volatile compounds were identified, the great majority cornpounds of which were benzeneacetaldehyde （14.8%）, 2,5-dimethyl-pyrazine （9.6%）, and hexanal （9.3%）. Identification was complied by mass spectral search, retention index and accurate masses of characteristic ions.     

α-Glucosidase inhibitors screening from Cyclocarya paliurus based on spectrum–effect relationship and UPLC–MS/MS

Cyclocarya paliurus is an edible and medicinal plant exhibiting significant hypoglycemic effect. However, its active components are still unclear and need further elucidation. In this research, the active components of the leaves of C. paliurus responsible for the α-glucosidase inhibitory activity were screened and identified based on a spectrum–effect relationship study in combination with ultra-performance liquid chromatography tandem mass spectrometry (UPLC–MS/MS) analysis. The 70% ethanol eluate fraction of the leaves of C. paliurus with the strongest α-glucosidase inhibitory activity was obtained after extraction and purification with macroporous resin. Their chromatographic fingerprints (15 batches) were established by UPLC analysis and 32 common peaks were specified by similarity analysis. Their IC₅₀ values for α-glucosidase inhibition were measured by an enzymatic reaction. Several multivariate statistical analysis methods including hierarchical cluster analysis, principal component analysis, partial least square analysis and gray relational analysis were applied to explore the spectrum–effect relationship between common peaks and IC₅₀ values, and the chromatographic peaks making a large contribution to efficacy were screened out. To further elucidate the active components of leaves of C. paliurus, the 70% ethanol eluate fraction was characterized by UPLC–MS/MS analysis, and 10 compounds were identified. This study provides a valuable reference for further research and development of hypoglycemic active components of C. paliurus.     

Kovats and lee retention indices determined by gas chromatography/mass spectrometry for organic compounds of environmental interest

Retention indices of standard organic compounds of environmental interest were determined by gas chromatography/mass spectrometry, using a DB-5 fused-silica capillary column. Retention indices are useful references for tentative compound identification by gas chromatography, or confirmation by gas chromatography/mass spectrometry. They provide elution order for isomers that might be indistinguishable based on mass spectra. Modified Kovats and Lee retention indices are given for polycyclic aromatic hydrocarbons; sulfur heterocycles; nitrogen heterocycles; aromatic amines; oxygen heterocycles; phenols; alcohols; ketones; alkanes; nitriles; and methylesters of fatty, dicarboxylic, and aromatic acids for comparison and reference. Retention index values for heterocycles by gas chromatography/mass spectrometry are comparable with gas chromatography values previously reported.     

Development and validation of a quantification method for ziyuglycoside I and II in rat plasma: Application to their pharmacokinetic studies

This study provided a novel and generally applicable method to determine ziyuglycoside I and ziyuglycoside II in rat plasma based on liquid chromatography with tandem mass spectrometry. A single step of liquid–liquid extraction with n‐butanol was utilized, and ginsenoside Rg3 was chosen as internal standard. Final extracts were analyzed based on liquid chromatography with tandem mass spectrometry. Chromatographic separation was achieved using a Thermo Golden C₁₈ column, and the applied gradient elution program allowed for the simultaneous determination of two ziyuglycosides in a one‐step chromatographic separation with a total run time of 10 min. The fully validated methodology for both analytes demonstrated high sensitivity (the lower limit of quantitation was 2.0 ng/mL), good accuracy (% RE ≤ ± 15) and precision (% RSD ≤ 15). The average recoveries of both ziyuglycosides and internal standard were all above 75% and no obvious matrix effect was found. This method was then successfully applied to the preclinical pharmacokinetic studies of ziyuglycoside I and ziyuglycoside II. The presently developed methodology would be useful for the preclinical and clinical pharmacokinetic studies for ziyuglycoside I and ziyuglycoside II.     

Characterization of N-acyl-D-biotinols by particle-beam liquid chromatography-mass spectrometry. An alternative to probe mass spectrometry for thermally labile samples.

In the course of preparing biotin-labeled nucleic acid probes, it was necessary to verify structures of intermediate N-acyl derivatives of biotinol. Characterization by mass spectrometry (MS) involved use of particle-beam liquid chromatography (LC)-mass spectrometry MS to supplement standard heated-solids probe techniques. The probe data for a sample of N-toluoylbiotinol indicated it to be a mixture of mono- and di-toluoylbiotinols which was inconsistent with other analytical information. Analysis of the same sample by LC-MS on a reversed-phase column with a water-acetonitrile gradient showed a single major peak with spectrum consistent with that for the monotoluoyl species. These results suggested that a thermal transacylation reaction might be occurring in the probe during heating prior to volatilization and ionization. This was confirmed by heating the sample to 200 degrees C and then repeating the LC-MS analysis to find peaks now present for biotinol and ditoluoylbiotinol as well as the starting material. These results demonstrate the value of particle-beam LC-MS as a technique for obtaining electron-impact mass spectra of thermally sensitive compounds.     

Determination of the volatile constituents of ChineseCoriandrum sativum L. by gas chromatography—Mass spectrometry with solid-phase microextraction

Summary Fifteen main volatile compounds in ChineseCoriandrum sativum L. were separated and identified by gas chromatography—mass spectrometry (GC-MS) combined with solid-phase microextraction (SPME). Fresh ChineseCoriandrum sativum L. was ground and its volatile compounds were extracted by SPME with a 100 μm polydimethylsiloxane fiber. The fibers were desorbed in a GC injection liner at 250°C for 3 min. More than 15 peaks were separated by headspace SPME-GC-MS analysis. The main compounds in headspace ofCoriandrum sativum L. identified by mass spectrometry included decanal, 2-decenal, 1-decanol,trans-2-decen-1-ol,trans-2-decen-1-al,trans-2-tridecenal etc, which were verified by reference compounds. Their relative contents were calculated on basis of peak areas. SPME extraction conditions and capillary chromatography column used to separate the volatile compounds were investigated.     

Development of the Fingerprints for the Quality Evaluation of Scutellariae Radix by HPLC-DAD and LC-MS-MS

A high-performance liquid chromatography coupled with photodiode array detection and electrospray ionization tandem mass spectrometry (HPLC-DAD-ESI-MS²) method was firstly developed for a chemical fingerprint analysis of Scutellariae Radix and rapid identification of major compounds in the fingerprints. The experimental data for chromatography were used for hierarchical clustering analysis and similarity calculation, and those for UV and MS spectra were applied for identifying characteristic peaks. Twenty samples including S. baicalensis Georgi., S. viscidula Bge. and S. amoena C. H. Wright were classified into three groups. By comparing the UV and MS spectra data with those of the authentic standards and literature, 20 main peaks in the fingerprints were identified for the first time. The developed fingerprint assay was specific and could be readily utilized for comprehensive evaluation of Scutellariae Radix.