Structural analysis of saponins from medicinal herbs using electrospray ionization tandem mass spectrometry

Comment on the "Does saponin in quinoa really embody the source of its bitterness?"

Saponins are considered the main source of the bitter taste of quinoa, however, it has not been confirmed by Song et al. (2024). These authors suggested that saponin extracts contribute to the umami taste, however, the stronger source of the bitter taste may be the flavonoids contained in the extracts. It is an interesting finding in view of the flavonoids role in the field of food sciences. The UPLC-MS results showed that besides saponins, also polyphenols were present in the analyzed samples. However, the presented results of UPLC-MS analysis should be substantially improved, mainly with respect to the reported accurate masses and retention times, as described in details in this comment.

An innovative processing driven efficient transformation of rare ginsenosides enhances anti-platelet aggregation potency of notoginseng by integrated analyses of processing-(chemical) profiling-pharmacodynamics

ETHNOPHARMACOLOGICAL RELEVANCE

Panax notoginseng (Burk.) F. H. Chen, a valuable Chinese herb medicine, shows a characteristic bi-directional regulation of hemostasis and activating blood circulation with ginsenosides as the predominant bioactive compounds and is a typical representative of "processing triggered heteropotency".

AIM OF THE STUDY

Processing triggered heteropotency, one of the unique theories and practices in traditional Chinese medicine, refers to that the processing will lead to change in physical and chemical properties, and eventually disparate efficacy of the crude drugs, yet the optimum process and underlying mechanism remains unclear. In this study, using Panax notoginseng (PN) as a representative sample, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was proposed to investigate the processing mechanism of PN.

MATERIALS AND METHODS

Firstly, a temperature programmed steaming process was designed to evaluate the steaming triggered chemical transformation of triterpene saponins and the corresponding enhancement in anti-platelet aggregation activity. The steaming process was programed from the conventional 100 °C-150 °C in a time course of 0-12 h, aiming to achieve the maximized conversion of rare ginsenosides (RGs), and dynamic profile of ginsenosides were constructed by a UPLC-Q-TOF-MS/MS analysis. Then, a processing-(chemical) profiling-pharmacodynamics (3-P) relationship was assessed by using the grey relational analysis (GRA) and orthogonal projections to latent structures (OPLS), and validated by bioactive fraction of 140 °C steamed PN. Subsequently, the P2Y12-ligand binding affinity of potential candidates was analyzed by molecular docking. Finally, the dynamic changes of ginsenosides during steaming of SPN were quantitatively detected by UPLC-QQQ-MS/MS.

RESULTS

A total of 48 differential ginsenosides were characterized and monitored including the primary and secondarily transformed saponins. The higher temperature steaming especially at 140 °C induces not only the predominant production of the RGs, but also the stronger anti-platelet aggregation activity. The 3-P relationship showed the fraction (3) of 140 °C steamed PN rich in RGs exhibits the most predominant efficacy, in which, a series of RGs including ginsenosides Rg5, Rk1, 20(S/R)-Rg3 were proven to be potent components. Molecular docking analysis suggested that ginsenosides Rg5 and Rk1 showed more strong interaction with the platelet P2Y12 receptor. Quantitative analysis found 140 °C-2h PN possessed highest contents of Rk1 and Rg5 and total RGs.

CONCLUSIONS

The integrated 3-P strategy uncovered the promising ginsenosides with anti-platelet effect, thereby revealing the material basis of PN steaming, which could provide a new enlightenment for the investigation of processing mechanism of traditional Chinese medicines.

MS/MS molecular networking-guided in-depth profiling of triterpenoid saponins from the fruit of Eleutherococcus senticosus and their neuroprotectivity evaluation

INTRODUCTION

Eleutherococcus senticosus fruit (ESF) is a natural health supplement resource that has been extensively applied as a tonic for the nervous system. The structures and neural bioactivities of triterpenoid saponins (TS), which are the major constituents of ESF, have not been comprehensively analyzed thus far.

OBJECTIVE

We conducted a complete in-depth MS/MS molecular networking (MN)-based targeted analysis of TS from the crude extract of ESF and investigated its neuroprotective value.

METHODS

An MS/MS MN-guided strategy was used to rapidly present a series of precursor ions (PIs) of TS in a compound cluster as TS-targeted information used in the discovery and characterization of TS. In addition, a prepared TS-rich fraction of ESF was assayed for its restraining effects on β-amyloid-induced inhibition of neurite outgrowth.

RESULTS

A total of 87 TS were discovered using a PI tracking strategy, 28 of which were characterized as potentially undescribed structures according to their high-resolution MS values. Furthermore, the TS-rich fraction can significantly reduce β-amyloid-induced damage to neural networks by promoting the outgrowth of neurites and axons.

CONCLUSION

Our findings reveal the richness of TS in ESF and will accelerate their application in the treatment of neurodegenerative diseases.

By-Product of the Red Ginseng Manufacturing Process as Potential Material for Use as Cosmetics: Chemical Profiling and In Vitro Antioxidant and Whitening Activities

Red ginseng (RG), which is obtained from heated Panax ginseng and is produced by steaming followed by drying, is a valuable herb in Asian countries. Steamed ginseng dew (SGD) is a by-product produced in processing red ginseng. In the present study, phytochemical profiling of extracts of red ginseng and steamed ginseng dew was carried out using gas chromatography-mass spectrometry (GC-MS) and rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) analysis. Additionally, antioxidant activities (DPPH, ·OH, and ABTS scavenging ability) and whitening activities (tyrosinase and elastase inhibitory activity) were analyzed. Phytochemical profiling revealed the presence of 66 and 28 compounds that were non-saponin components in chloroform extracts of red ginseng and steamed ginseng dew (RG-CE and SGD-CE), respectively. Meanwhile, there were 20 ginsenosides identified in n-butanol extracts of red ginseng and steamed ginseng dew (RG-NBE and SGD-NBE). By comparing the different polar extracts of red ginseng and steamed ginseng dew, it was found that the ethyl acetate extract of red ginseng (RG-EAE) had the best antioxidant capacity and whitening effect, the water extract of steamed ginseng dew (SGD-WE) had stronger antioxidant capacity, and the SGD-NBE and SGD-CE had a better whitening effect. This study shows that RG and SGD have tremendous potential to be used in the cosmetic industries.

Mass spectrometry-based profiling and imaging strategy, a fit-for-purpose tool for unveiling the transformations of ginsenosides in Panax notoginseng during processing

BACKGROUND

Panax notoginseng, a valuable medicinal plant, is traditionally used to treat trauma, body pain, and cardiovascular diseases in two clinical forms including raw (crude) and processed form. Processing-triggered compound transformation is responsible for the distinct bioactivity between raw and processed Panax notoginseng. Nevertheless, investigating the chemical diversity and dynamic transformation pattern of processed Panax notoginseng is challenging.

METHODS

A new approach, which integrates multi-components characterization, processing trajectory depiction, discovery of differential markers, transformation mechanism of metabolites, in situ spatial distribution and transformation of metabolites, was established to elucidate the role of processing on the holistic chemical transformations of Panax notoginseng (PN).

RESULTS

In this study, 136 ginsenosides (mainly rare ginsenosides) were identified or tentatively characterized and the temperature-dependent chemical variation trajectory was depicted via principal component analysis (PCA). Nineteen processing-associated markers were confirmed by orthogonal partial least squares-discriminant analysis (OPLS-DA). For the first time, the transformation pathway of ginsenosides during processing were elucidated by integrating the precursor ion scan (PIS) and mimic processing strategy that involves with deglycosylation, dehydration, hydration, acetylation, and isomerization. Results of mass spectrometry imaging (MSI) revealed the major ginsenosides M-Rb1, R1, Rg1, Rb1, Rd, and Re exhibited distinct spatial distribution pattern that are highly abundant in the xylem and showed a downward trend during processing. We firstly depicted the spatial distribution of processing-triggered rare ginsenosides (Rg3, Rk1, Rg5, etc.), and in situ transformation of ginsenosides was discovered in the process of steaming. Additionally, this variation trend was consistent with untargeted metabolomics results.

CONCLUSION

This study comprehensively revealed chemical diversity and dynamic transformation pattern and depicted the spatial distribution of ginsenosides of PN during processing. It could provide a clue for the distinct bioactivities between raw and processed PN and elucidate the role of processing on the holistic chemical transformations of natural products, more importantly, the proposed strategy is valuable for the quality evaluation and control of the processing of natural product.

Metal-ion-assisted structural and anomeric analysis of Amadori compounds by electrospray ionization mass spectrometry

RATIONALE

The Maillard reaction plays an important role in food, physiology and traditional Chinese medicine, and its primary reaction products are formed through Amadori rearrangement by reducing sugars and amino acids. The analysis of the characteristic fragmentation and of the glycosidic bond configuration of Amadori compounds will promote their fast discovery and identification by mass spectrometry.

METHODS

Four Amadori compounds that reduce disaccharides and proline/tryptophan were used to investigate the fragmentation mechanisms via tandem mass spectrometry (MS/MS) with different alkali metal ion adducts. Cu²⁺ could be used to distinguish glycosidic bond configurations of the reducing disaccharides in the full-scan mass spectra. Quantum calculations were also conducted for a single Amadori compound with Cu²⁺ for analysis of the most optimized configurations and binding energies of metal complexes.

RESULTS

MS/MS analysis of Amadori-alkali metal complexes revealed that the radius of the alkali metal ions had profound effects on the degree of fragmentation of such compounds, among which lithium-cationized ions produced the most extensive fragmentation. Amadori compounds with different glycosidic bonds formed differently proportioned metal complexes with Cu²⁺ , and the complexity of the copper complexes containing tryptophan moieties was higher than that of those containing proline moieties in the mass spectra. Quantum calculations showed that Amadori compounds with β-configurations can form more binding sites with Cu²⁺ than those with α-configurations, thus making the metal complex with a single ligand more stable. In addition, the chelation of tryptophan with copper ions increased the coordination binding energy, which showed that α-configured Amadori compounds were readily able to form multi-ligand copper complexes.

CONCLUSIONS

Metal-ion-assisted analysis provides crucial information for structural and anomeric analysis of Amadori compounds by electrospray ionization mass spectrometry. Elucidation of binding sites and binding energies by quantum calculations has significantly improved the knowledge of metal complexes in the gas phase and provides background information for determining the glycosidic configuration of Amadori isomers.

Online energy-resolved MS boosts the potential of LC-MS towards metabolite characterization of salidroside and tyrosol

Although currently serving as the workhorse for metabolite characterization, one of the most challenging tasks for LC-MS is isomeric differentiation because isomers frequently yield identical quasi-molecular ions and fragmented ion species. Our previous studies have demonstrated that online energy-resolved MS (ER-MS) is an orthogonal technique for MS/MS experiments to facilitate isomeric identification. Herein, attempts were made for the in-depth characterization of the metabolic profiles of an effective natural product named salidroside (SA) in rats using LC coupled with three-dimensional mass spectrometry (LC-3D MS) that was configured by MS¹, MS² and online ER-MS as 1^st, 2^nd, and 3^rd dimensions, respectively. Moreover, the metabolism characterization of its aglycone, namely, tyrosol (Try) was conducted in parallel to aid in proposing metabolic pathways. High-resolution MS¹ and MS² spectra were acquired by IT-TOF-MS, and subsequent data processing provided theoretical formula and sub-structures for each metabolite. Subsequently, online ER-MS was conducted for precursor > product ion transitions-of-interest to offer linkage information among the sub-structures via building breakdown graphs. As a result, ten (M1-10) and nine (M1, M2, and M5-11) metabolites were detected in SA- and Tyr-administrated biological samples, respectively, and their structures were qualitatively identified. Crucial metabolism occurred for either component. SA initially underwent hydrolysis to produce Tyr, and subsequently hydroxylation, oxidation, glucuronidation, and sulfation were observed as the primary metabolic pathways. To summarize, the metabolic fate of SA was understood in depth, and Tyr, as the hydrolytic product, was responsible for the occurrences of most metabolites (M1, M2, and M5-10). More importantly, identification confidences of the metabolites were significantly advanced by LC-3D MS, suggesting that it is eligible to serve as an integral part of the analyst's toolbox.

Supercritical CO2 Extraction and Identification of Ginsenosides in Russian and North Korean Ginseng by HPLC with Tandem Mass Spectrometry

Ginseng roots, Panax ginseng C.A. Meyer, obtained from cultivated ginseng grown in the Kaesong province (North Korea) and Primorye (Russia) were extracted using the supercritical CO₂ extraction method. The extracts were subsequently analyzed by high-performance liquid chromatography with tandem mass spectrometry identification. The results showed the spectral peaks of typical ginsenosides with some other minor groups, and major differences were observed between the spectra of the two ginseng samples. The use of a pressure of 400 bar and higher allowed an increase in the yield of ginsenosides in comparison with similar previous studies

Passiflora caerulea L. fruit extract and its metabolites ameliorate epileptic seizure, cognitive deficit and oxidative stress in pilocarpine-induced epileptic mice

The anticonvulsant potential of aqueous fruit extract of Passiflora caerulea (PCAE) was evaluated in swiss albino mice induced by pilocarpine. The antioxidant activities of PCAE were determined which showed strong antioxidant activity and the polyphenol compounds such as ginsenoside, naringenin, chrysoeriol 8-c-glucoside, luteolin-6-C-glucoside, apigenin-6,8-di-C-β-D-glucopyranoside were profiled through RP-HPLC and UPLC-ESI-MS/MS. Chronic effects of PCAE on pilocarpine (85 mg/kg; i.p)-induced convulsions were evaluated in Swiss adult male albino mice. PCAE at 100 and 200 mg/kg, (p.o.) and diazepam (5 mg/kg, i.p) were administered once daily for 15 days. In Y-maze test, percentage of correct entry by pilocarpine administered animals were significantly lower when compared to control, whereas PCAE at both doses improved the alteration score significantly. Administration of higher dose (200 mg/kg) of PCAE significantly delayed onset of convulsions and decreased duration of clonic convulsions. Association of ROS production during seizure period was further confirmed by histopathological studies revealing loss of normal neuronal cells in hippocampus region. The data obtained showed anticonvulsant activity and improved cognitive function; reduced the oxidative damage and significantly activated the cholinergic neurotransmission in a dose dependent manner similar to diazepam which is evident in the biochemical parameters and histopathological study, suggesting therapeutic potential for epilepsy and neurodegeneration.

Localization of malonyl and acetyl on substituted saikosaponins according to the full-scan mass spectra and the fragmentation of sodium-adduct ions in the positive mode

RATIONALE

Discriminating between aglycone-substituted and saccharide-substituted saikosaponins by liquid chromatography/tandem mass spectrometry (LC/MSⁿ ) is a long-standing issue that is still to be resolved. It is necessary to characterize the two types of substituted saikosaponins taking into consideration the potential significant difference in their bioactivity.

METHODS

Taking the substituents malonyl and acetyl as examples, we developed a MS strategy to discriminate between the aglycone-substituted and saccharide-substituted saikosaponins through comparing their Y₀  - nH₂ O (n = 1-2) ions from the protonated molecules in the full-scan mass spectra and their B ions in the MS² spectra of sodium-adduct molecules in the positive mode.

RESULTS

The deprotonated molecules of the aglycone-substituted saikosaponins presented similar fragmentation patterns to those of saccharide-substituted ones in the negative mode, which could not discriminate whether the substitutes were located on the aglycone or the saccharide. In contrast, the Y₀  - nH₂ O (n = 1-2) ions containing or no substituent were observed respectively in the mass fragmentation of the protonated molecules of aglycone-substituted or saccharide-substituted saikosaponins in the positive mode. In addition, the B ions containing or no substituent were observed respectively in the mass fragmentation of the sodium-adduct molecules of the saccharide-substituted or aglycone-substituted saikosaponins in the positive mode. Two aglycone-malonylated saikosaponins were reported for the first time.

CONCLUSIONS

Whether the substituents were located on the aglycone or the saccharide could be determined according to the Y₀  - nH₂ O (n = 1-2) ions from the protonated molecules in the full-scan mass spectra and the B ions in the MS² spectra of sodium-adduct molecules in the positive mode. Our results have updated the mass fragmentation patterns of substituted saikosaponins, which is helpful for the quality control of pharmaceutical preparations containing saikosaponins. More importantly, this MS strategy should be able to be extended to characterize other substituted saponins of bioactive significance in future studies.

Solvent Fractionation and Acetone Precipitation for Crude Saponins from Eurycoma longifolia Extract

Eurycoma longifolia is a popular folk medicine in South East Asia. This study was focused on saccharide-containing compounds including saponins, mainly because of their medical potentials. Different organic solvents such as ethyl acetate, butanol, and chloroform were used to fractionate the phytochemical groups, which were consequently precipitated in cold acetone. Solvent fractionation was found to increase the total saponin content based on colorimetric assay using vanillin and sulfuric acid. Ethyl acetate fraction and its precipitate were showed to have the highest crude saponins after acetone precipitation. The samples were shown to have anti-proliferative activity comparable with tamoxifen (IC50 = 110.6 µg/mL) against human breast cancer cells. The anti-proliferative activities of the samples were significantly improved from crude extract (IC50 = 616.3 µg/mL) to ethyl acetate fraction (IC50 = 185.4 µg/mL) and its precipitate (IC50 = 153.4 µg/mL). LC-DAD-MS/MS analysis revealed that the saccharide-containing compounds such as m/z 497, 610, 723, 836, and 949 were abundant in the samples, and they could be ionized in negative ion mode. The compounds consisted of 226 amu monomers with UV-absorbing property at 254 nm, and were tentatively identified as formylated hexoses. To conclude, solvent fractionation and acetone precipitation could produce saccharide-containing compounds including saponins with higher anti-proliferative activity than crude extract against MCF-7 cells. This is the first study to use non-toxic solvents for fractionation of bioactive compounds from highly complex plant extract of E. longifolia.

Pregnane Glycosides

Pregnane glycosides constitute a class of compounds widely distributed in the plant kingdom. Many of them have shown either anticarcinogenic or cancer inhibitory properties, besides other useful biological activities. New chromatographic techniques and advances in spectroscopic and spectrometric methods have accelerated the purification and structure determination of novel glycosides of this series. A compilation of the pregnane glycosides isolated from 1995 until the middle of 2005, along with their physical data, structures and occurrence are presented in this review, which also summarizes, with suitable examples, recent developments in isolation and purification techniques, and structural elucidation using modern spectrometric methods like ESIMS and tandem mass spectrometry, and 2D NMR spectroscopic strategies. The reported anticancer and other biological activities of pregnane glycosides are also discussed.

Pharmacokinetic and metabolic studies of ginsenoside Rb3 in rats using RRLC-Q-TOF-MS

Ginsenoside Rb3 is one of major ginsenosides in Panax ginseng with effect on cardio-vascular and central nervous system. The aim of this study is to develop a rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method for pharmacokinetic study of ginsenoside Rb3 and simultaneous determination of metabolites in rats. The results showed that the concentration-time profile of ginsenoside Rb3 conformed to a two-compartment pharmacokinetic model after intravenous administration at the dosage of 2.0 mg/kg for rats. The mean plasma elimination half-lives were 13.77 ± 1.23 min and 2045.70 ± 156.20 min for the distribution and exterminate phases t1/2α and t1/2β. In the metabolic study, prototype ginsenoside Rb3 and deglycosylation metabolites were characterized by comparison with the retention time of the standard compounds, accurate mass measurement and the characteristic fragment ions obtained from MS/MS. Two major metabolites Mb1 and M2' were tentatively identified in rat urine samples after intravenous administration, and four possible metabolites Mb1, F2, M2' and CK were detected in rat feces samples after oral administration. The deglycosylation was found to be the major metabolic pathways of ginsenoside Rb3 in rat. The in vivo metabolic pathway of ginsenoside Rb3 was summarized.

Multicomponent assessment and ginsenoside conversions of Panax quinquefolium L. roots before and after steaming by HPLC-MSn

Background

The structural conversions in ginsenosides induced by steaming or heating or acidic condition could improve red ginseng bioactivities significantly. In this paper, the chemical transformations of red American ginseng from fresh Panax quinquefolium L. under steaming were investigated, and the possible mechanisms were discussed.

Methods

A method with reversed-phase high-performance liquid chromatography coupled with linear ion trap mass spectrometry (HPLC-MSⁿ)-equipped electrospray ionization ion source was developed for structural analysis and quantitation of ginsenosides in dried and red American ginseng.

Results

In total, 59 ginsenosides of protopanaxadiol, protopanaxatriol, oleanane, and ocotillol types were identified in American ginseng before and after steaming process by matching the molecular weight and/or comparing MSⁿ fragmentation with that of standards and/or known published compounds, and some of them were determined to be disappeared or newly generated under different steaming time and temperature. The specific fragments of each aglycone-type ginsenosides were determined as well as aglycone hydrated and dehydrated ones. The mechanisms were deduced as hydrolysis, hydration, dehydration, and isomerization of neutral and acidic ginsenosides. Furthermore, the relative peak areas of detected compounds were calculated based on peak areas ratio.

Conclusion

The multicomponent assessment of American ginseng was conducted by HPLC-MSⁿ. The result is expected to provide possibility for holistic evaluation of the processing procedures of red American ginseng and a scientific basis for the usage of American ginseng in prescription.

Ionization characteristics of glycosides by direct analysis in real time quadrupole-time of flight mass spectrometry

Glycosides were ionized via various different reactions including (de)protonation, molecular ion formation, ISD fragmentation, and the formation of adducts.

Chemical transformation of ginsenoside Re by a heteropoly acid investigated using HPLC-MSn/HRMS

The mechanism and pathway of heteropoly acid-derived chemical transformation of ginsenoside Re are investigated using multistage tandem mass spectrometry and high-resolution mass spectrometry.

Potent antitrypanosomal triterpenoid saponins from Mussaenda luteola

Five new triterpenoid saponins, heinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (1), heinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (2), 2α-hydroxyheinsiagenin A 3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-β-d-glucopyranoside (3), 2α-hydroxyheinsiagenin A 3-O-[β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (4) and N-(2S, 3R, 4R-3-methyl-4-pentanolid-2-yl)-18-hydroxylanosta-8 (9), 22E, 24E-trien-27-amide-3-O-[α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→4)]-β-d-glucopyranoside (5) were isolated from the aerial parts of Mussaenda luteola Delile (Rubiaceae). Structural elucidation was based on the analysis of spectroscopic data (1D and 2D NMR) and HR-ESI-MS. Compound 1 showed potent antitrypanosomal activity with an IC50 value of 8.80μM. Compounds 2-4 showed highly potent antitrypanosomal activity with IC50 values ranging between (2.57-2.84μM) and IC90 values ranging between (3.36-4.35μM), which are 5 fold greater than the positive control DFMO (IC50 and IC90 values of 13.06 and 28.99μM, respectively). Compounds 1 and 2 showed moderate affinity to μ-opioid receptors with Ki values of 9.936μM and 0.872μM, respectively compared to a Ki value of 1.958nM for the positive control, naloxone HCl.

Structural Characterization of Ginsenosides from Flower Buds of Panax ginseng by RRLC-Q-TOF MS

Ginseng flower bud as a part of Panax ginseng has received much attention as a valuable functional food with medicinal potential. A few studies focused on systematic and comprehensive studies on its major ingredients. This study aims to rapidly characterize ginsenosides in ginseng flower buds and provide scientific basis for developing functional food, exploiting pharmaceutical effects and making full use of ginseng resources. A rapid resolution liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method was developed for rapid qualitative and quantitative analysis of ginsenosides in ginseng flower buds. The compounds were identified by comparing retention time of the reference standards, accurate mass measurement and the fragment ions obtained from RRLC-Q-TOF-MS/MS analyses. A total of 14 kinds of ginsenosides were identified and 5 kinds of malonyl-ginsenosides were first tentatively identified in ginseng flower buds. Ten kinds of main ginsenosides were quantitatively analyzed. The developed RRLC-Q-TOF-MS method was demonstrated as an effective analytical means for rapid characterization of the ginsenosides in flower buds of P. ginseng. The research result is valuable for quality control, assessment of authenticity and stability evaluation of ginseng flower buds.

Rapid separation and identification of 31 major saponins in Shizhu ginseng by ultra-high performance liquid chromatography-electron spray ionization-MS/MS

Background

Among the various ginseng strains, Shizhu ginseng is endemic to China, mainly distributed in Kuandian Manchu Autonomous County (Liaoning Province, China); however, not much is known about the compounds (especially saponins) in Shizhu ginseng.

Methods

A rapid, sensitive, and reliable ultra-high performance liquid chromatography coupled with MS/MS (UHPLC–MS/MS) method was developed to separate and identify saponins in Shizhu ginseng.

Results

The separation was carried out on a Waters ACQUITY UPLC BEH C₁₈ column (100 mm × 2.1 mm, 1.7 μm) with acetonitrile and 0.1% formic acid aqueous solution as the mobile phase under a gradient elution at 40°C. The detection was performed on a Micromass Quattro Micro API mass spectrometer equipped with electrospray ionization source in both positive and negative modes. Under the optimized conditions, a total of 31 saponins were identified or tentatively characterized by comparing retention time and MS data with related literatures and reference substances.

Conclusion

The developed UHPLC–MS/MS method was suitable for identifying and characterizing the chemical constituents in Shizhu ginseng, which provided a helpful chemical basis for further research on Shizhu ginseng.

An integrated high resolution mass spectrometric data acquisition method for rapid screening of saponins in Panax notoginseng (Sanqi)

The aim of this study was to develop a convenient method without pretreatments for nontarget discovery of interested compounds. The segment and exposure strategy, coupled with two mass spectrometer data acquisition methods was firstly proposed for screening the saponins in extract of Panax notoginseng (Sanqi) via high-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-QTOF/MS). By gradually removing certain major or moderate interference compounds, the developed segment and exposure strategy could significantly improve the detection efficiency for trace compounds. Moreover, the newly developed five-point screening approach based on a modified mass defect filter strategy and the visual isotopic ion technique was verified to be efficient and reliable in picking out the interested precursor ions. In total, 234 ginsenosides including 67 potential new ones were characterized or tentatively identified from the extract of Sanqi. Particularly, some unusual compounds containing the branched glycosyl group or new substituted acyl groups were firstly reported. The proposed integrated strategy held a strong promise for analyses of the complex mixtures.

Structure elucidation of new acetylated saponins, Lessoniosides A, B, C, D, and E, and non-acetylated saponins, Lessoniosides F and G, from the viscera of the sea cucumber Holothuria lessoni

Sea cucumbers produce numerous compounds with a wide range of chemical structural diversity. Among these, saponins are the most diverse and include sulfated, non-sulfated, acetylated and methylated congeners with different aglycone and sugar moieties. In this study, MALDI and ESI tandem mass spectrometry, in the positive ion mode, were used to elucidate the structure of new saponins extracted from the viscera of H. lessoni. Fragmentation of the aglycone provided structural information on the presence of the acetyl group. The presence of the O-acetyl group was confirmed by observing the mass transition of 60 u corresponding to the loss of a molecule of acetic acid. Ion fingerprints from the glycosidic cleavage provided information on the mass of the aglycone (core), and the sequence and type of monosaccharides that constitute the sugar moiety. The tandem mass spectra of the saponin precursor ions [M + Na]⁺ provided a wealth of detailed structural information on the glycosidic bond cleavages. As a result, and in conjunction with existing literature, we characterized the structure of five new acetylated saponins, Lessoniosides A–E, along with two non-acetylated saponins Lessoniosides F and G at m/z 1477.7, which are promising candidates for future drug development. The presented strategy allows a rapid, reliable and complete analysis of native saponins.

Profiling and multivariate statistical analysis of Panax ginseng based on ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry

An ultra-high-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) method was developed for the detection and structural analysis of ginsenosides in white ginseng and related processed products (red ginseng). Original neutral, malonyl, and chemically transformed ginsenosides were identified in white and red ginseng samples. The aglycone types of ginsenosides were determined by MS/MS as PPD (m/z 459), PPT (m/z 475), C-24, -25 hydrated-PPD or PPT (m/z 477 or m/z 493), and Δ20(21)-or Δ20(22)-dehydrated-PPD or PPT (m/z 441 or m/z 457). Following the structural determination, the UHPLC-Q-TOF-MS-based chemical profiling coupled with multivariate statistical analysis method was applied for global analysis of white and processed ginseng samples. The chemical markers present between the processed products red ginseng and white ginseng could be assigned. Process-mediated chemical changes were recognized as the hydrolysis of ginsenosides with large molecular weight, chemical transformations of ginsenosides, changes in malonyl-ginsenosides, and generation of 20-(R)-ginsenoside enantiomers. The relative contents of compounds classified as PPD, PPT, malonyl, and transformed ginsenosides were calculated based on peak areas in ginseng before and after processing. This study provides possibility to monitor multiple components for the quality control and global evaluation of ginseng products during processing.

Structure elucidation of five novel isomeric saponins from the viscera of the sea cucumber Holothuria lessoni

Sea cucumbers are prolific producers of a wide range of bioactive compounds. This study aimed to purify and characterize one class of compound, the saponins, from the viscera of the Australian sea cucumber Holothuria lessoni. The saponins were obtained by ethanolic extraction of the viscera and enriched by a liquid-liquid partition process and adsorption column chromatography. A high performance centrifugal partition chromatography (HPCPC) was applied to the saponin-enriched mixture to obtain saponins with high purity. The resultant purified saponins were profiled using MALDI-MS/MS and ESI-MS/MS which revealed the structure of isomeric saponins to contain multiple aglycones and/or sugar residues. We have elucidated the structure of five novel saponins, Holothurins D/E and Holothurinosides X/Y/Z, along with seven reported triterpene glycosides, including sulfated and non-sulfated saponins containing a range of aglycones and sugar moieties, from the viscera of H. lessoni. The abundance of novel compounds from this species holds promise for biotechnological applications.

Discovery of novel saponins from the viscera of the sea cucumber Holothuria lessoni

Sea cucumbers, sometimes referred to as marine ginseng, produce numerous compounds with diverse functions and are potential sources of active ingredients for agricultural, nutraceutical, pharmaceutical and cosmeceutical products. We examined the viscera of an Australian sea cucumber Holothuria lessoni Massin et al. 2009, for novel bioactive compounds, with an emphasis on the triterpene glycosides, saponins. The viscera were extracted with 70% ethanol, and this extract was purified by a liquid-liquid partition process and column chromatography, followed by isobutanol extraction. The isobutanol saponin-enriched mixture was further purified by high performance centrifugal partition chromatography (HPCPC) with high purity and recovery. The resultant purified polar samples were analyzed using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS)/MS and electrospray ionization mass spectrometry (ESI-MS)/MS to identify saponins and characterize their molecular structures. As a result, at least 39 new saponins were identified in the viscera of H. lessoni with a high structural diversity, and another 36 reported triterpene glycosides, containing different aglycones and sugar moieties. Viscera samples have provided a higher diversity and yield of compounds than observed from the body wall. The high structural diversity and novelty of saponins from H. lessoni with potential functional activities presents a great opportunity to exploit their applications for industrial, agricultural and pharmaceutical use.

Glycosylated platycosides: identification by enzymatic hydrolysis and structural determination by LC-MS/MS

In this study, enzymatic hydrolysis and chemometric methods were utilized to discriminate glycosylated platycosides in the extract of Platycodi Radix by LC-MS. Laminarinase, whose enzymatic activity was evaluated using gentiobiose and laminaritriose, was a suitable enzyme to identify the glycosylated platycosides. The laminarinase produced deapi-platycodin D and platycodin D from the isolated deapi-platycoside E and platycoside E through the loss of two glucose units by enzymatic reaction, respectively. After hydrolyzing a crude extract by laminarinase, the reconstructed total ion chromatogram generated by a chemometric technique sorted peaks of deglycosylated platycosides easily. Structural information of the glycosylated isomers was revealed through fragment ions generated by the sodiated C0β ion corresponding to reduced disaccharides in the positive MS(4) spectra. Characteristic fragment ions of Glc-(1→6)-Glc moieties were observed through ring cleavages of (0,2)A0β, (0,3)A0β, and (0,4)A0β, whereas Glc-(1→3)-Glc moieties produced only (0,3)A0β ions. Lithium-adducted platycosides allowed more detailed structural analysis of glycosidic bond cleavage corresponding to Y1β and B1β in addition to ring cleavage.

Studies on the interactions between ginsenosides and liposome by equilibrium dialysis combined with ultrahigh performance liquid chromatography-tandem mass spectrometry

To study the interactions between components of Panax Ginseng and liposome biomembrane, we applied the equilibrium dialysis system combined with ultrahigh performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) approach to analyze and identify the bioactive components of ginseng. Moreover, the effect of pH value has also been investigated on their interactions between the ginsenosides of ginseng extract and biomembrane. The result shows that seven kinds of ginsenosides have obvious interactions with biomembrane in comparison with the standards in terms of tandem mass spectrometry (MS/MS) data along with retention time, including four panaxadiol ginsenosides (Rb1, Rb2, Rc, Rd) and three panaxatriol ginsenosides (Re, Rf, Rg2). The value of binding degree decreased with the increase of molecular weight. The sugar moieties which are attached to C-20 were the main factor affecting the binding degree of panaxadiol ginsenosides. The interactions between panaxadiol ginsenosides and biomembrane correlate to the type and number of sugar moieties in ginsenosides. The sugar moieties which are at C-6 and C-20 have been shown to influence the value of binding degree for panaxatriol ginsenosides. In addition, the pH value has been shown to have an impact on the interactions. Overall, ginsenoside Rd has a better absorption character among the seven ginsenosides. In the study, we have screened the potential bioactive components of ginseng in vitro using the equilibrium dialysis-UPLC-MS/MS method, and then predicted the potential bioactivities of ginseng, which contribute to the investigation of the efficacy of ginseng.

Quantification of ginsenosides Rh4 and Rk3 in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pre-clinical pharmacokinetic study

Ginsenoside Rh4 (Rh4) and ginsenoside Rk3 (Rk3) are two active substances isolated from the processed Panax species. To further explore their potential medicinal application, a reliable liquid chromatography-tandem mass spectrometry method (LC/MS/MS) was developed and validated for the quantification of Rh4 and Rk3 in rat plasma. Multiple ion monitoring and multiple reaction monitoring experiments were performed in negative ionization mode. This LC/MS/MS method had good selectivity, sensitivity (lower limit of quantification = 10 ng/mL), precision (intra- and inter-day relative standard deviation ≤ 10.1) and accuracy (analytical recovery within 100 ± 10%). The pharmacokinetic profiles of Rh4 and Rk3 were subsequently assessed in Sprague-Dawley rats. Similar to many other ginsenosides, the oral bioavailability of Rh4 and Rk3 was unfavorable, and Rh4 and Rk3 did not have any measurable plasma exposure after oral administration (20 mg/kg). Fortunately, upon intravenous administration (5 mg/kg), both Rh4 and Rk3 possessed abundant plasma exposure, moderate clearance (Cl = 50.2 ± 7.7 and 23.8 ± 1.4 mL·min(-1)·kg(-1), respectively) and terminal elimination half-life (t(1/2 λZ) = 157.2 ± 65.2 and 99.5 ± 37.8 min, respectively). As Rh4 and Rk3 displayed favorable intravenous pharmacokinetic profiles, further exploration on their medicinal application is warranted.

Studies on the chemical transformation of 20(S)-protopanaxatriol (PPT)-type ginsenosides R(e), R(g2), and R(f) using rapid resolution liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (RRLC-Q-TOF-MS)

A rapid resolution liquid chromatography coupled with quadruple-time-of-flight mass spectrometry (RRLC-Q-TOF-MS) method was developed for analysis of chemical transformation of 20(S)-protopanaxatriol (PPT)-type ginsenosides Re, Rg2, and Rf in acidic conditions. The transformation products were identified by comparing the retention time of the standard compounds, the accurate mass measurement, and the fragment ions obtained from RRLC-Q-TOF-tandem mass spectrometry (MS/MS) analyses. The specific product ions of aglycone PPT (m/z 475), C-24- and C-25-hydrated PPT (m/z 493), and Δ20(21) or Δ20(22) dehydration PPT (m/z 457) by MS/MS were discussed for structural characterization. Experiments demonstrated that chemical transformation mechanisms of 20(S)-PPT-type ginsenosides in acidic conditions include hydrolysis of saccharide substitution, Δ20(21) or Δ20(22) dehydration, and hydration addition reactions at C-24 and C-25. The chemical transformation pathway for 20(S)-PPT-type ginsenosides was summarized. The developed RRLC-Q-TOF-MS method was also applied for comparative analysis of 20(S)-PPT ginsenoside and related chemical transformation products in ginseng products.

Silver (Ι)-assisted enantiomeric analysis of ginsenosides using electrospray ionization tandem mass spectrometry

For identification of ginsenoside enantiomers, electrospray ionization mass spectrometry (ESI-MS) was used to generate silver complexes of the type [ginsenoside + Ag](+). Collision induced dissociation of the silver-ginsenoside complexes produced fragment ions by dehydration, allowing differentiation of ginsenoside enantiomers by the intensity of [M + Ag - H(2)O](+) ion. In the meanwhile, an approach based on the distinct profiles of enantiomer-selective fragment ion intensity varied with collision energy was introduced to refine the identification and quantitation of ginsenoside enantiomers. Five pairs of enantiomeric ginsenosides were distinguished and quantified on the basis of the distribution of fragment ion [M + Ag - H(2)O](+). This method was also extended to the identification of other type of ginsenoside isomers such as ginsenoside Rb2 and Rb3. For demonstrating the practicability of this novel approach, it was utilized to analyze the molar ratio of 20-(S) and 20-(R) type enantiomeric ginsenosides in enantiomer mixture in red ginseng extract. The generation of characteristic fragment ion [M + Ag - H(2)O](+) likely results from the reduction of potential energy barrier of dehydration because of the catalysis of silver ion. The mechanism of enantiomer identification of ginsenosides was discussed from the aspects of computational modeling and internal energy.

Structural characterization and identification of major constituents in Jitai tablets by high-performance liquid chromatography/diode-array detection coupled with electrospray ionization tandem mass spectrometry

In the present study a universally applicable HPLC-DAD/ESI-MS/MS method was developed for carrying out the comprehensive characterization of Jitai tablets (JTT). Based on the ESI-MS(n) fragmentation patterns of the reference standards, a total of 101 components were identified or tentatively characterized by comparing their retention times, UV and MS spectra with those of reference standards or through the matching of empirical information with those of published components in the in-house library. The characteristic fragmentation pattern of alkaloids, phenolic acids, tanshinones, flavonoid glycosides, cyanogenic glycosides, ginsenosides, 2-(2-phenylethyl) chromones, phthalides and gingerol-related compounds were tentatively elucidated using structurally-relevant product ions. It was observed that neutral losses of C(9)H(10)O(3) and C(9)H(8)O(2) were the characteristic product ions of scopola alkaloids. Neutral fragment mandelonitrile was the characteristic ion of cyanogenic glycosides. To our knowledge, tropylium ion and C(4)H(2)O unit were the characteristic ions of 2-(2-phenylethyl) chromone, which resulted from the Retro-Diels-Alder (RDA) cleavage of the C ring. The results indicated that the developed analysis method could be employed as a rapid, effective technique for structural characterization of chemical constituents in TCM. This work is expected to provide comprehensive information for the quality evaluation and pharmacokinetic studies of JTT.

Analysis of the Constituents in Rat Serum after Oral Administration of Fufang Zhenzhu Tiaozhi Capsule by UPLC-Q-TOF-MS/MS

A rapid and sensitive UPLC/Q-TOF-MS method has been established for analysis of the constituents in rat serum after oral administration of Fufang Zhenzhu Tiaozhi (FTZ) capsule, an effective compound prescription for treating hyperlipidemia in the clinic. The UPLC/MS information of samples was obtained first in FTZ preparation and FTZ-treated rat serum. Mass spectra were acquired in both negative and positive ion modes. Thirty-six constituents in rat serum after oral administration of FTZ were detected, including the alkaloids, ginsenosides, pentacyclic triterpenes, and their metabolites. These chemicals were identified based on the retention time and mass spectrometry data with those of authentic standards or comparison of the literatures reports. Twenty-seven prototype components originated from FTZ and nine were the metabolites of the FTZ constituents. These results shed light on the potential active constituents of the complex traditional Chinese medicinal formulas.

Sequential abundant ion fragmentation analysis (SAIFA): an alternative approach for phosphopeptide identification using an ion trap mass spectrometer

Phosphorylation has been the most studied of all the posttranslational modifications of proteins. Mass spectrometry has emerged as a powerful tool for phosphomapping on proteins/peptides. Collision-induced dissociation (CID) of phosphopeptides leads to the loss of phosphoric or metaphosphoric acid as a neutral molecule, giving an intense neutral loss product ion in the mass spectrum. Dissociation of the neutral loss product ion identifies peptide sequence. This method of data-dependent constant neutral loss (DDNL) scanning analysis has been commonly used for mapping phosphopeptides. However, preferential losses of groups other than phosphate are frequently observed during CID of phosphopeptides. Ions that result from such losses are not identified during DDNL analysis due to predetermined scanning for phosphate loss. In this study, we describe an alternative approach for improved identification of phosphopeptides by sequential abundant ion fragmentation analysis (SAIFA). In this approach, there is no predetermined neutral loss molecule, thereby undergoing sequential fragmentation of abundant peak, irrespective of the moiety lost during CID. In addition to improved phosphomapping, the method increases the sequence coverage of the proteins identified, thereby increasing the confidence of protein identification. To the best of our knowledge, this is the first report to use SAIFA for phosphopeptide identification.

Rapid and global detection and characterization of the constituents in ShengMai San by ultra-performance liquid chromatography-high-definition mass spectrometry

An ultra-performance liquid chromatography-high definition mass spectrometry (UPLC-HDMS) method was developed for detection and characterization of the chemical constituents in ShengMai San (SMS), a traditional Chinese medical formula (TCMF). The full-scan LC-MS/MS data sets combined with extra mass were acquired within 14 min using UPLC-HDMS in the MS(E) mode in a single injection. As a result, 92 compounds were identified by comparing the accurate mass and fragments information with that of the authentic standards as well as by MS analysis and the correlative references data. These constituents included ginsenosides, lignans, steroidal saponins and homoisoflavanones. Among them, 25-hydroxyginsenosides were discovered in SMS for the first time. Compare with the previous studies, our research detected more compounds and presented more rapid by applying UPLC-HDMS. It is concluded that a rapid and effective method has been established based on UPLC-HDMS with the utilization of MS(E) , which shows high sensitivity and resolution that is suitable for identifying the constituents of SMS, and this method could be applied to other TCMF.

Metabolite profiling of triterpene saponins in Medicago truncatula hairy roots by liquid chromatography Fourier transform ion cyclotron resonance mass spectrometry

Triterpenes are one of the largest classes of plant natural products, with an enormous variety in structure and bioactivities. Here, triterpene saponins from hairy roots of the model legume Medicago truncatula were profiled with reversed-phase liquid chromatography coupled to negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (LC ESI FT-ICR MS). Owing to the accuracy of the FT-ICR MS, reliable molecular formulas of the detected compounds could be predicted, which, together with the generated MS(n) spectra, allowed the tentative identification of 79 different saponins, of which 61 had not been detected previously in M. truncatula. Upon collision-induced dissociation of saponins that contain a uronic acid residue in the sugar chain, fragment ions resulting from cross-ring cleavages of the uronic acid residues were observed. The identified saponins are glycosides of 10 different sapogenins, of which three were not detected before in M. truncatula. Zanhic acid glycosides, which are prevalent in the aerial parts of M. truncatula, were absent in the hairy root extracts. This metabolite compendium will facilitate future functional genomic studies of triterpene saponin biosynthesis in M. truncatula.

Isolation and analysis of ginseng: advances and challenges

Ginseng occupies a prominent position in the list of best-selling natural products in the world. Because of its complex constituents, multidisciplinary techniques are needed to validate the analytical methods that support ginseng's use worldwide. In the past decade, rapid development of technology has advanced many aspects of ginseng research. The aim of this review is to illustrate the recent advances in the isolation and analysis of ginseng, and to highlight new applications and challenges. Emphasis is placed on recent trends and emerging techniques.

Rapid characterization of triterpene saponins from Conyza blinii by liquid chromatography coupled with mass spectrometry

Conyza blinii Le'vl is a medicinal herb used for the treatment of inflammation in Chinese folk medicine. Its major bioactive constituents are triterpene saponins, most of which contain 6-8 sugar residues. In this report, electrospray ionization tandem mass spectrometry fragmentation behaviors of bisdesmosidic triterpene saponins (conyzasaponin A, B, and C) were studied in both positive and negative ion modes with an ion-trap mass spectrometer. In full scan mass spectrometry, these saponins gave predominant [M-H](-) and [M+Na](+) ions, which determined the molecular weights. In tandem mass spectrometry (MS(n), n = 2-4), the [M-H](-) and [M+Na](+) ions yielded fragments [Y(0α)-H](-) and [B(α)+Na](+), which were diagnostic for the structures of the triterpene skeleton and sugar chains. The structural elucidation was approved by accurate mass data using IT-TOF-MS. An interpretation guideline based on MS(n) (n = 2-4) diagnostic ions was proposed in order to elucidate the chemical structures of unknown triterpene saponins in C. blinii extract. The saponins in C. blinii were separated by liquid chromatography with a methanol/acetonitrile/water solvent system, and then analyzed by ion-trap and IT-TOF mass spectrometers. Based on the interpretation guideline, a total of 35 triterpenoid saponins were tentatively identified. Among them, 15 saponins had been previously reported, and the other 20 saponins were reported from Conyza species for the first time. This study indicates that LC/MS is a powerful technology for the rapid characterization of complicated saponins in herbal extracts.