Analysis of sodium adduct paeoniflorin, albiflorin and their derivatives by (+)ESI-MSn, DFT calculations and computer-aided mass spectrometry analysis program

Abelmoschus manihot (L.) medik. seeds alleviate rheumatoid arthritis by modulating JAK2/STAT3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Abelmoschus manihot (L.) Medik. Seeds (AMS, སོ་མ་ར་ཛ།), a Tibetan classical herbal in China, are rich in flavonoids and phenolic glycosides compounds, such as quercetin and its derivatives. Moreover, it has been found to possess anti-rheumatoid arthritis (RA) effects. Nonetheless, its anti-RA mechanism is yet unknown.

AIM OF THE STUDY

This research aimed to examine the active ingredients of AMS as well as potential pharmacological mechanisms in AMS on RA.

MATERIALS AND METHODS

The ultra-performance liquid chromatography-electrospray ionization-tandem multistage mass spectrometry (UPLC-ESI-IT-MSn) technique was used to determine the primary chemical components of AMS that were responsible for the therapeutic effects on RA. In addition, 36 male Wistar rats weighing between 200 and 220 g were classified at random into six groups [normal control group, collagen-induced arthritis (CIA) group, methotrexate group (positive control, 1.05 mg/kg), AMS group (157.5 mg/kg, 315 mg/kg, 630 mg/kg)]. CIA rats were given AMS extract by intragastric administration for 28 days, and their ankles were photographed to observe the degree of swelling. Further, the arthritis score, paws swelling, and body weight changes of CIA rats were determined to observe whether AMS has any effect on RA, and synovial and cartilage tissue injuries were identified by histopathology. Besides, the levels of IL-10, TNF-α, IL-1β, INF-γ, etc. in serum were estimated by ELISA. Western blot experiments were implemented to identify the expression levels of protein involved in the JAK2/STAT3 signaling pathway in the CIA rats' synovial tissues. Moreover, the mechanisms and targets of active ingredient therapy of AMS for RA were predicted using network pharmacology and then verified using molecular docking.

RESULT

In the present study, 12 compounds were detected by UPLC-ESI-IT-MSn, such as quercetin and its derivative which could be potential active ingredients that contribute to the anti-RA properties of AMS. Our in vivo studies on CIA rats revealed that an AMS-H dose of 630 mg/kg significantly improved joint damage while decreasing the arthritic index and paw swelling. Furthermore, AMS inhibited the INF-γ, IL-6, IL-17, IL-1β, and TNF-α, levels while upregulating the expression of anti-inflammatory cytokines IL-10 and IL-4 in serum. Besides, AMS inhibited the protein Bcl-2/Bax, STAT3, and JAK2 levels, and promoted the expression of Caspase3, SOCS1, and SOCS3 in the JAK2/STAT3 pathway. Additionally, the JAK/STAT signaling pathway was found to perform a remarkable function in the AMS therapy of RA as evidenced by enrichment in GO terms and KEGG pathways. Meanwhile, data from molecular docking experiments indicated that the core targets of PIK3CA, JAK2, and SRC bound stably to the active ingredients of mimuone, 4'-methoxy-bavachromanol, and quercetin.

CONCLUSION

According to these findings, the AMS could improve joint inflammation in CIA rats, and its underlying mechanism could be linked to the regulation of the JAK2/STAT3 pathway. Therefore, AMS might become a promising agent for alleviating inflammation in RA patients.

Fragmentation and Ionization Efficiency of Positional and Functional Isomers of Paeoniflorin Derivatives in Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

Paeoniflorin and albiflorin, which are functional isomers, are the major constituents of an herbal medicine derived from Paeonia lactiflora. Those functional isomers and their galloylated derivatives, which are positional isomers, were studied by matrix-assisted laser desorption/ionization–tandem mass spectrometry (MALDI-MS/MS). The resulting mass spectra are discussed based on the fragmentation patterns of the sodium adducts. The product ion spectra of 4-O-galloylalbiflorin and 4′-O-galloylpaeoniflorin differed, even though they were positional isomers. The fragmentations of the ester parts were influenced by the neighboring hydroxyl groups. The ionization efficiency of the sodium adduct of albiflorin was higher than that for paeoniflorin. These results indicate that the carboxylic ester group has a higher affinity for sodium ions than the acetal group, which can be attributed to the carbonyl oxygen being negatively polarized, allowing it to function as a Lewis base.

Chemical Fingerprinting and Quantitative Analysis of Cortex Moutan From Different Tree Peony Cultivars Using HPLC-ESI/MS

To evaluate the relationship between tree peony cultivars and the quality consistency of Cortex Moutan, a sensitive, reliable, and validated method based on high-performance liquid chromatography-electrospray ionization/mass spectrometry was developed for the quantitative analysis of paeonol and chemical fingerprinting of Cortex Moutan. Results from quantitative analysis showed that the content of paeonol in Paeonia ostii “Feng Dan” was the highest (24.51 ± 0.83 mg/g), followed by Paeonia suffruticosa “Luoyang Hong” (14.29 ± 0.76 mg/g), P. suffruticosa “Taiping Hong” (13.99±1.13 mg/g), and P. suffruticosa “Zhaofen” (13.08±0.85 mg/g). Paeonia ostii “Luoyang Feng Dan” was found to have the lowest content (8.76±0.46 mg/g) of paeonol. In qualitative analysis, 5 tree peony cultivars collected from different plantations in China were used to establish the fingerprint. For the fingerprint analysis, 17 characteristic peaks were used to evaluate similarities among tree peony cultivars, and they were found to show similarities. In short, the results of quantitative and qualitative analyses suggested that there was no significant difference in the chemical composition of Cortex Moutan from different tree peony varieties; however, there were significant differences in the levels of chemical components. The method developed in this study provides an important reference to establish a quality control method for other related traditional Chinese medicinal preparations.

Recent (2000-2015) developments in the analysis of minor unknown natural products based on characteristic fragment information using LC-MS

Liquid chromatography-Mass Spectrometry (LC-MS) has been widely used in natural product analysis. Global detection and identification of nontargeted components are desirable in natural product research, for example, in quality control of Chinese herbal medicine. Nontargeted components analysis continues to expand to exciting life science application domains such as metabonomics. With this background, the present review summarizes recent developments in the analysis of minor unknown natural products using LC-MS and mainly focuses on the determination of the molecular formulae, selection of precursor ions, and characteristic fragmentation patterns of the known compounds. This review consists of three parts. Firstly, the methods used to determine unique molecular formula of unknown compounds such as accurate mass measurements, MSⁿ spectra, or relative isotopic abundance information, are introduced. Secondly, the methods improving signal-to-noise ratio of MS/MS spectra by manual-MS/MS or workflow targeting-only signals were elucidated; pure precursor ions can be selected by changing the precursor ion isolated window. Lastly, characteristic fragmentation patterns such as Retro-Diels-Alder (RDA), McLafferty rearrangements, "internal residue loss," and so on, occurring in the molecular ions of natural products are summarized. Classical application of characteristic fragmentation patterns in identifying unknown compounds in extracts and relevant fragmentation mechanisms are presented (RDA reactions occurring readily in the molecular ions of flavanones or isoflavanones, McLafferty-type fragmentation reactions of some natural products such as epipolythiodioxopiperazines; fragmentation by "internal residue loss" possibly involving ion-neutral complex intermediates). © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:202-216, 2018.

Rapid Determination of Isomeric Benzoylpaeoniflorin and Benzoylalbiflorin in Rat Plasma by LC-MS/MS Method

Benzoylpaeoniflorin (BP) is a potential therapeutic agent against oxidative stress related Alzheimer's disease. In this study, a more rapid, selective, and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed to determine BP in rat plasma distinguishing with a monoterpene isomer, benzoylalbiflorin (BA). The method showed a linear response from 1 to 1000 ng/mL (r > 0.9950). The precision of the interday and intraday ranged from 2.03 to 12.48% and the accuracy values ranged from -8.00 to 10.33%. Each running of the method could be finished in 4 minutes. The LC-MS/MS method was validated for specificity, linearity, precision, accuracy, recovery, and stability and was found to be acceptable for bioanalytical application. Finally, this fully validated method was successfully applied to a pharmacokinetic study in rats following oral administration.

Effects of boiling duration in processing of White Paeony Root on its overall quality evaluated by ultra-high performance liquid chromatography quadrupole/time-of-flight mass spectrometry based metabolomics analysis and high performance liquid chromatography quantification

Boiling processing is commonly used in post-harvest handling of White Paeony Root (WPR), in order to whiten the herbal materials and preserve the bright color, since such WPR is empirically considered to possess a higher quality. The present study was designed to investigate whether and how the boiling processing affects overall quality of WPR. First, an ultra-high performance liquid chromatography quadrupole/time-of-flight mass spectrometry-based metabolomics approach coupled with multivariate statistical analysis was developed to compare the holistic quality of boiled and un-boiled WPR samples. Second, ten major components in WPR samples boiled for different durations were quantitatively determined using high performance liquid chromatography to further explore the effects of boiling time on the holistic quality of WPR, meanwhile the appearance of the processed herbal materials was observed. The results suggested that the boiling processing conspicuously affected the holistic quality of WPR by simultaneously and inconsistently altering the chemical compositions and that short-time boiling processing between 2 and 10 min could both make the WPR bright-colored and improve the contents of major bioactive components, which were not achieved either without boiling or with prolonged boiling. In conclusion, short-term boiling (2-10 min) is recommended for post-harvest handling of WPR.

Rapid discovery and identification of anti-inflammatory constituents from traditional Chinese medicine formula by activity index, LC-MS, and NMR

The traditional activity-guided approach has the shortcoming of low accuracy and efficiency in discovering active compounds from TCM. In this work, an approach was developed by integrating activity index (AI), liquid chromatography – mass spectrometry (LC-MS), and nuclear magnetic resonance (NMR) to rapidly predict and identify the potential active constituents from TCM. This approach was used to discover and identify the anti-inflammatory constituents from a TCM formula, Gui-Zhi-Jia-Shao-Yao-Tang (GZJSYT). The AI results indicated that, among the 903 constituents detected in GZJSYT by LC-MS, 61 constituents with higher AI values were very likely to have anti-inflammatory activities. And eight potential active constituents of them were isolated and validated to have significant inhibitory effects against NO production on LPS-induced RAW 264.7 cell model. Among them, glycyrrhisoflavone (836), glisoflavanone (893) and isoangustone A (902) were reported to have anti-inflammatory effects for the first time. The proposed approach could be generally applicable for rapid and high efficient discovery of anti-inflammatory constituents from other TCM formulae or natural products.

Analysis of the lithiated leucosceptroids from Leucosceptrum canum to facilitate their identification and differentiation by electrospray ionization tandem mass spectrometry

RATIONALE

Leucosceptroids, isolated from Leucosceptrum canum (L. canum), are sesterterpenoids with novel molecular scaffolds which possess potent antifeedant activities. Their molecular scaffolds comprise a 5,6,5-framework with a great diversity due to different hydroxylation and substituent positions. The biological activities of leucosceptroids are affected by the subtle structural differences. The structural characterization and differentiation of the leucosceptroid isomers are of great importance.

METHODS

Firstly, different kinds of cation adducts of leucosceptroids were examined by adding alkali metal ions to the solution, and the lithiated adducts of leucosceptroid were found to be readily formed and yielded characteristic fragment ions under collision-induced dissociation (CID). Then, a systematic mass spectrometric investigation of the [M + Li](+) ions was carried out to clarify their characteristic fragment pathways by electrospray ionization quadrupole time-of-flight-type tandem mass spectrometry (ESI-QTOF-MS/MS). The proposed fragmentation pathways were confirmed through ion trap ESI-MS(n) (n ≥ 3) spectra. Finally, the proposed MS/MS method was applied to investigate the extracts of L. canum.

RESULTS

A specific fragmentation pathway of the lithiated adduct, which leads to the production of diagnostic ions of leucosceptroids, was observed. This fragmentation is initiated by cleavage of the C-ring and leads to formation of two types of ions by further dissociation. Both pathways could yield characteristic fragment ions, which could be used to define the substituents at the skeletal structure and at the C-ring. The representative characteristic fragmentations of [M + Li](+) ions and the proposed fragmentation pathways were successfully adopted to investigate the L. canum extracts, and a total of eleven leucosceptroids were identified or tentatively characterized.

CONCLUSIONS

The characteristic fragmentation pathways of [M + Li](+) species of leucosceptroid isomers were proposed. Three types of leucosceptroid isomers were successfully differentiated. Eleven leucosceptroids were characterized from L. canum extracts. The fragmentation knowledge will facilitate the analysis of leucosceptroids and other sesterterpenoids in future research. Copyright © 2016 John Wiley & Sons, Ltd.

Identification and determination of the major constituents in Traditional Chinese Medicinal formula Danggui-Shaoyao-San by HPLC-DAD-ESI-MS/MS

Danggui-Shaoyao-San (DSS), a famous traditional Chinese medicine formula consisting of six herbal medicines (Paeonia lactiflora, Angelica sinensis, Ligusticum chuanxiong, Poria cocos, Atractylodis macrocephalae and Rhizoma Alismatis), has been used as a classical gynecological remedy in China for centuries. However, its active substances have remained unknown. In this paper, an HPLC/DAD/ESI-MS/MS method was developed for the qualitative and quantitative analysis of the major constituents in DSS. The ESI-MS/MS fragmentation behavior of the reference compounds was proposed for aiding the structural identification of components in DSS extract. Forty-one compounds including monoterpene glycosides, phenolic acids, phathalides, sesquiterpenoids and triterpenes were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of authentic compounds or literature data, and 14 of them (gallic acid, albiflorin, paeoniflorin, ferulic acid, benzoic acid, senkyunolide I, coniferyl ferulate, senkyunolide A, 3-butylphthalide, Z-ligustilide, Z-butylidenephthalide, atractylcnolide II, atractylcnolide I and levistolide A) were determined by HPLC-DAD using a C18 column and gradient elution of acetonitrile/water-formic acid (100:0.1, v/v). The linearity, precision, accuracy, LOD and LOQ were validated for the quantification method, which proved sensitive, accurate and reproducible. The study might provide a basis for the quality control of DSS extracts and preparations.

Stereochemical differentiation of C-7 hydroxyltaxane isomers by electrospray ionization mass spectrometry

In this study, different electrospray ionization mass spectrometric (ESI-MS) methods were utilized to analyze several pairs of taxane stereoisomers including paclitaxel and 7-epi-paclitaxel. Both ESI-MS and tandem mass spectrometry (MS/MS) techniques provided stereochemically dependent mass spectra in negative-ion mode, and all studied stereoisomers could be easily distinguished based on their characteristic ions or distinct fragmentation patterns. MS/MS experiments for several taxane analogues at various collision energies were performed to elucidate potential dissociation pathways. The gas-phase deprotonation potentials were also calculated to estimate the most thermodynamically favorable deprotonation site using DFT B3LYP/6-31G(d). The results of the theoretical studies agreed well with the fragmentation patterns of paclitaxel and 7-epi-paclitaxel observed from MS/MS experiments. In addition, it was found that liquid chromatography (LC)/ESI-MS was a useful and sensitive technique for assignment of C-7 taxane stereoisomers from realistic samples.

Electrospray ionization tandem mass spectrometric analysis of ent-6,7-seco-kaurane diterpenoids from the Isodon species

Electrospray ionization tandem mass spectrometry (ESI-MS(n)) using an ion trap instrument and accurate mass measurement on a quadrupole time-of-flight (Q-TOF) mass spectrometer has aided the structural characterization and differentiation of the enmein and spiro-lactone types of ent-6,7-seco-kaurane diterpenoids from Isodon species. The mass spectral fragmentation data from both techniques was compared to obtain the mass spectrometric fragmentation pathways of the ent-6,7-seco-kaurane diterpenoids with high confidence. The analysis revealed that losses of CH(2)O and CO(2) are the predominant process for the enmein type of ent-kauranes in negative ion mode, and the loss of CO(2) is typical for the spiro-lactone type in positive ion mode. In addition, compounds of the spiro-lactone type with a conserved core structure but different substituent groups, such as acetyl, hydroxyl, and aldehyde moiety, resulted in diagnostic product ions by means of successive losses of AcOH, H(2)O, and CO, respectively. The fragmentation knowledge will facilitate the analysis and identification of the ent-6,7-seco-kauranes in future plant research.

Identification of multiple constituents in the traditional Chinese medicine formula GuiZhiFuLing-Wan by HPLC-DAD-MS/MS

GuiZhiFuLing-Wan (GFW) has been used in China for centuries to improve blood stagnation. In this paper, a HPLC-DAD-MS/MS method was established for the efficient and rapid identification of the chemical constituents in extract of GuiZhiFuLing-Wan. Separation was performed on an Alltima C(18) analytical column by gradient elution with CH(3)CN/H(2)O-CH(3)COOH as mobile phase at a flow rate 1.0ml/min. 27 potentially bioactive compounds including monoterpene glycosides, galloyl glucoses, acetophenones, phenylallyl compounds and triterpenoids were identified or tentatively characterized by online ESI/MS/MS and the comparison with literature data and authentic compounds. After the identification, six different brands of GFW commercial products in various dosage forms were evaluated. The results demonstrated that capsule of GFW was superior to the other two dosage forms, honeyed pill and concentrated pill in administration. The points that should be paid more attention during the manufacturing process of GFW were also analyzed. The method can be the basis for the quality control of this commonly used herbal formula.

Analysis of caged xanthones from the resin of Garcinia hanburyi using ultra-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry

On-line ultra high-performance liquid chromatography (UHPLC) coupled with electrospray quadrupole time-of-flight tandem mass spectrometry (ESI-QTOF-MS/MS/MS) has been developed for the analysis of a series of caged xanthones in the resin of Garcinia hanburyi. The fragmentation of protonated molecular ions for 12 known cadged xanthones was carried out using low-energy collision-induced electrospray ionization tandem mass spectrometry. It was found that Retro-Diels-Alder rearrangement occurred in the CID processes and produced the characteristic fragment ions, which are especially valuable for the identification of this class of xanthones. The fragmentation differential between some cis-, trans-isomers was uncovered. Computation methods were utilized to rationalize the observed MS behaviors. On-line UHPLC-ESI-MS/MS/MS method has proved to be rapid and efficient in that within 6min, 15 caged scaffold xanthones, including three pairs of epimers and four pairs of isomers in gamboges, were effectively separated and identified. Among them, two known, namely isogambogenin (13) and isomorellinol (14) and one likely new caged Garcinia xanthones from the Garcinia hanburyi were tentatively characterized based on the tandem mass spectra of known ones.

Negative electrospray ionization tandem mass spectrometric investigation of ent-kaurane diterpenoids from the genus Isodon

ent-Kaurane diterpenoids are a class of natural compounds isolated from genus Isodon, which have been found to have important bioactivities. Negative electrospray ionization tandem mass spectrometry ((-)ESI-MS(n)) was used to investigate the fragmentation pattern of C-20-nonoxygenated ent-kauranes and two subtypes of C-20-oxygenated ent-kauranes by using an ion trap instrument and accurate mass measurement on an ESI-Q-time-of-flight (TOF) mass spectrometer. The analysis revealed that loss of CH(2)O or CO(2) is the predominant process for 7, 20-epoxy and 7, 20 : 14, 20-diepoxy subgroup of C-20-oxygenated ent-kauranes. In addition, compounds of C-20-nonoxygenated ent-kauranes with a conserved core structure but different substituent groups, such as a hydroxyl, aldehyde, carboxyl, and acetyl moiety, resulted in diagnostic product ions through losses of H(2)O, CO, CO(2), and AcOH, respectively. This work clearly demonstrates the utility of tandem mass spectrometry for studies on the rationalization of the diagnostic fragmentation of a series of compounds from two main types of the ent-kaurane diterpenoids.