Rapid characterization of chlorogenic acids in Duhaldea nervosa based on ultra-high-performance liquid chromatography-linear trap quadropole-Orbitrap-mass spectrometry and mass spectral trees similarity filter technique

Polyphenols of the Inuleae-Inulinae and Their Biological Activities: A Review

Polyphenols are ubiquitous plant metabolites that demonstrate biological activities essential to plant-environment interactions. They are of interest to plant food consumers, as well as to the food, pharmaceutical and cosmetic industry. The class of the plant metabolites comprises both widespread (chlorogenic acids, luteolin, quercetin) and unique compounds of diverse chemical structures but of the common biosynthetic origin. Polyphenols next to sesquiterpenoids are regarded as the major class of the Inuleae-Inulinae metabolites responsible for the pharmacological activity of medicinal plants from the subtribe (Blumea spp., Dittrichia spp., Inula spp., Pulicaria spp. and others). Recent decades have brought a rapid development of molecular and analytical techniques which resulted in better understanding of the taxonomic relationships within the Inuleae tribe and in a plethora of data concerning the chemical constituents of the Inuleae-Inulinae. The current taxonomical classification has introduced changes in the well-established botanical names and rearranged the genera based on molecular plant genetic studies. The newly created chemical data together with the earlier phytochemical studies may provide some complementary information on biochemical relationships within the subtribe. Moreover, they may at least partly explain pharmacological activities of the plant preparations traditionally used in therapy. The current review aimed to systematize the knowledge on the polyphenols of the Inulae-Inulinae.

Characterisation and identification of chemical constituents in aqueous extract of Fomes officinalis Ames based on ultrahigh-performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometry

INTRODUCTION

Fungal species are an attractive resource for physiologically functional food and drug precursor. Fomes officinalis Ames, a medicinal fungus, is traditionally used as a folk medicine in traditional Chinese medicine prescription for the therapy of cough and asthma. The water-soluble substances in Chinese herbal medicines are likely to play an important physiological function. However, information on probing and identifying chemical components of the aqueous extract of Fomes officinalis Ames (AFO) remains unknown.

OBJECTIVE

This study was conducted to screen and characterise the chemical components of AFO.

MATERIAL AND METHODS

An effective and sensitive ultrahigh-performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS) method with the Full MS/PIL/dd-MS2 acquisition approach was applied for the profiling of chemical components in AFO. An HSS T3 column was used for component separation, and a strategy of simultaneous targeted and untargeted multicomponent characterisation was implemented. Multiple identification approaches were used, including accurate molecular mass and elemental composition matching, literature and database searching, and fragmentation rules elucidation.

RESULTS

A total of 115 components, including 20 amino acids and derivatives, six nucleobases, nine nucleosides, 75 dipeptides, two tripeptides, and three other components, were tentatively identified. Among them, the targeted exploring method screened six nucleobases and nine nucleosides including modified nucleosides. To our best knowledge, this is the first time a report has been done on the presence of the 115 compounds in AFO.

CONCLUSION

Profiling and characterisation compounds of AFO enriched its material basis, which would lay the foundation for improving potential medicinal and nutritional values and effecting comprehensive quality control of Fomes officinalis Ames.

Comparative bioactivity evaluation and metabolic profiling of different parts of Duhaldea nervosa based on GC-MS and LC-MS

Duhaldea nervosa (Wallich ex Candolle) Anderberg has been widely used as medicine and food additive in China for a long history. Its roots, known as Xiaoheiyao, are the mainly used medicinal part, while the other tissues of D. nervosa are ignored as non-medicinal parts despite their high biomass, resulting in a huge waste of resources. To mine and expand the medicinal values of different parts of D. nervosa, metabolic analysis by GC/LC-MS and bioactivity evaluation were performed. Based on the antioxidant activity and correlation analysis, a metabolite-related network was constructed. A total of 45 volatile and 174 non-volatile compounds were identified. Among them, caffeoylquinic acids and derivatives were more abundant in roots and flowers, while coumaroyltartaric acids and derivatives were mainly present in stems and leaves. By multivariate analysis, 13 volatile and 37 non-volatile differential metabolites were found, respectively. In the bioactivity evaluation of different parts, the order of antioxidant capacity was flowers > roots > leaves or stems. The flowers showed the highest FRAP value (354.47 μM TE/g DW) and the lowest IC50 values in the DPPH (0.06 mg/mL) and ABTS (0.19 mg/mL) assay, while higher inhibitory activity against α-glucosidase was exhibited by flowers and leaves. This study first established the similarities and differences of phytochemicals and bioactivities in D. nervosa, providing a scientific basis for developing non-medicinal parts and guiding the clinical application of this medicinal and edible herb.

Risk Assessment of Chlorogenic and Isochlorogenic Acids in Coffee By-Products

Chlorogenic and isochlorogenic acids are naturally occurring antioxidant dietary polyphenolic compounds found in high concentrations in plants, fruits, vegetables, coffee, and coffee by-products. The objective of this review was to assess the potential health risks associated with the oral consumption of coffee by-products containing chlorogenic and isochlorogenic acids, considering both acute and chronic exposure. An electronic literature search was conducted, revealing that 5-caffeoylquinic acid (5-CQA) and 3,5-dicaffeoylquinic acid (3,5-DCQA) are the major chlorogenic acids found in coffee by-products. Toxicological, pharmacokinetic, and clinical data from animal and human studies were available for the assessment, which indicated no significant evidence of toxic or adverse effects following acute oral exposure. The current state of knowledge suggests that long-term exposure to chlorogenic and isochlorogenic acids by daily consumption does not appear to pose a risk to human health when observed at doses within the normal range of dietary exposure. As a result, the intake of CQAs from coffee by-products can be considered reasonably safe.

Structural Characterization and Anti-Inflammatory Activity of a Novel Polysaccharide from Duhaldea nervosa

In the present study, a novel water-soluble polysaccharide (DNP-1) was isolated and purified from the root of Duhaldea nervosa via column chromatography. Structural analyses indicated that DNP-1 had a linear backbone consisting of (2→1)-linked β-D- fructofuranosyl residues, ending with a (2→1) bonded α-D-glucopyranose. DNP-1 was a homogeneous polysaccharide with an average molecular weight of 3.7 kDa. Furthermore, the anti-inflammatory activity of DNP-1 was investigated in vitro. The concentration of pro-inflammatory cytokines, including NO, TNF-α, MCP-1, IL-2, and IL-6, in the DNP-1 treatment group was suppressed in LPS-induced RAW 264.7 cells. DNP-1 was able to improve inflammatory injury by inhibiting the secretion of pro-inflammatory cytokines. These investigations into this polysaccharide from the root of Duhaldea nervosa provide a scientific basis for the further development of this plant. The results indicate that this Duhaldea nervosa polysaccharide could be used as a potential natural source for the treatment of inflammatory injury.

A Systematic Method for the Identification of Aporphine Alkaloid Constituents in Sabia schumanniana Diels Using UHPLC-Q-Exactive Orbitrap/Mass Spectrometry

Sabia schumanniana Diels (SSD) is a plant whose stems are used in traditional folk medicine for the treatment of lumbago and arthralgia. Previous studies have revealed chemical constituents of SSD, including triterpenoids and aporphine alkaloids. Aporphine alkaloids contain a variety of active components, which might facilitate the effective treatment of lumbago and arthralgia. However, only 5-oxoaporphine (fuseine) has been discovered in SSD to date. In this study, we sought to systematically identify the aporphine alkaloids in SSD. We established a fast and reliable method for the detection and identification of these aporphine alkaloids based on ultra-high-performance liquid chromatography (UHPLC)-Q-Exactive-Orbitrap/mass spectrometry combined with parallel reaction monitoring (PRM). We separated all of the analyzed samples using a Thermo Scientific Hypersil GOLD™ aQ C18 column (100 mm × 2.1 mm, 1.9 μm). Finally, we identified a total of 70 compounds by using data such as retention times and diagnostic ions. No fewer than 69 of these SSD aporphine alkaloids have been reported here for the first time. These findings may assist in future studies concerning this plant and will ultimately contribute to the research and development of new drugs.

Diverse chemical modifications of the chlorogenic acid composition of Viscum combreticola Engl.: A premise for the state of readiness against excessive sunlight exposure

Mistletoe plants that are positioned on the canopy of their hosts are more susceptible to UV radiation exposure. These aerial plants are resistant to damage by UV radiation due the presence of epidermal constituents such as the cuticle, cork layer, trichomes and antioxidant secondary metabolites. In response to the photo-oxidative stress associated with UV exposure, plants generally deploy photo-protective responsive mechanisms that involve the biosynthesis of UV absorbing phenolic compounds such as chlorogenic acids (CGAs). The hydroxycinnamic acid moieties of these CGAs are predominantly in the trans configuration, naturally. However, excessive sunlight exposure of plants containing these compounds can result in geometrical isomerisation, characterized by the formation of cis isomers. Therefore, in this study, the effect of UV light radiation on the CGA composition of Viscum combreticola Engl. (Santalacaeae) plants using an in vitro model was unravelled through UHPLC-q-TOF-MS-based metabolic profiling. Interestingly, the findings of this study revealed that this plant has a diverse chemical composition of CGAs that is characterized by epimerization, monoacylation, homodiacylation and heterodiacylation of the quinic acid (QA), thereby, contributing to the state of readiness in these plants against sunlight or UV exposure. In addition to the commonly reported cinnamoyl containing heterodiacylated CGAs, hydroxybenzoyl containing heterodiacylated CGAs were also reported in this study. Moreover, cis isomers (24 in total) of some CGAs were identified in the non-irradiated samples and the formation of these compounds has been reported to help plants in the mitigation of photo-oxidative stress. An additional 28 cis isomers of CGAs and HCA derivatives were observed in the UV-irradiated samples, hence, further increasing the complexity of the metabolome of this plant, with a total of 108 compounds identified in this study. The presence of epimers, positional and geometrical isomers of these compounds could be a biochemical strategy to maximize the chemical arsenal of this plant to withstand the photo-oxidative stress posed by UV radiation from the sunlight. Due to purported pharmacological properties associated with the identified compounds these parasitic plants can be a rich source of prospective therapeutic compounds that can be employed as drug discovery leads. Moreover, UV radiation might be essential in future to produce potent drugs since plants naturally produce these compounds in low quantities.

Hu’po Anshen Decoction Accelerated Fracture-Healing in a Rat Model of Traumatic Brain Injury Through Activation of PI3K/AKT Pathway

Hu’po Anshen decoction (HPASD) is a traditional Chinese medicine formula comprising five herbal medicines for the treatment of concussion and fracture healing, but its pharmacological mechanism is still unclear. Ultra-performance liquid chromatography coupled with quadrupole time of flight mass spectrometry (UPLC/Q-TOF MS) was used to analyze the main active components of HPASD. Rats were randomly assigned to fracture group, fracture combined with traumatic brain injury (TBI) group (FBI) and FBI combined with HPASD treatment group (FBIH). Rats in the FBIH group were given oral doses of HPASD (2.4 g/kg, 4.8 g/kg and 9.6 g/kg) for 14 or 21 consecutive days. The fracture callus formation and fracture sites were determined by radiographic analysis and micron-scale computed tomography (micro-CT) analysis. Hematoxylin and eosin (H&E) staining and a three-point bending test were applied to assess histological lesions and biomechanical properties, respectively. The levels of cytokines-/protein-related to bone formation and differentiation as well as PI3K/AKT pathway-related proteins were determined by Enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription-polymerase chain reaction (qRT-PCR), or western blot assays, respectively. UPLC-Q/TOF-MS-based serum metabolomic analysis was also performed to investigate the therapeutic effects of HPASD in the treatment of FBI. UPLC/Q-TOF MS analysis showed the chemical components in HPASD, including flavonoids, amino acids, saponins, and phenylpropanoid constituents, etc. HPASD dose-dependently promoted callus formation, increased bone density, improved mechanical parameters and morphological scores, and facilitated the expressions of VEGF, PDGF, bFGF, VEGFA, CoL1A1, RUNX2, BMP2, and Aggrecan, inhibited the expression of MMP13, and activated PI3K/AKT pathway. Metabolomics analysis revealed abnormalities of malate-aspartate shuttle and glucose-alanine. HPASD accelerates fracture healing by promoting bone formation and regulating the malate-aspartate shuttle and glucose-alanine cycle, which might be associated with the activation of the PI3K/AKT pathway.

Rapid Identification of Constituents in Cephalanthus tetrandrus (Roxb.) Ridsd. et Badh. F. Using UHPLC-Q-Exactive Orbitrap Mass Spectrometry

Cephalanthus tetrandrus (Roxb.) Ridsd. et Badh. F. (CT) belongs to the Rubiaceae family. Its dried leaves are widely used in traditional Chinese medicine to treat enteritis, dysentery, toothache, furuncles, swelling, traumatic injury, fracture, bleeding, and scalding. In order to further clarify the unknown chemical composition of CT, a rapid strategy based on UHPLC-Q-exactive orbitrap was established for this analysis using a Thermo Scientific Hypersil GOLD^TM aQ (100 mm × 2.1 mm, 1.9 µm) chromatographic column. The mobile phase was 0.1% formic acid water–acetonitrile, with a flow rate of 0.3 mL/min and injection volume of 2 µL; for mass spectrometry, an ESI ion source in positive and negative ion monitoring modes was adopted. A total of 135 chemicals comprising 67 chlorogenic acid derivatives, 48 flavonoids, and 20 anthocyanin derivatives were identified by comparing the mass spectrum information with standard substances, public databases, and the literature, which were all discovered for the first time in this plant. This result broadly expands the chemical composition of CT, which will contribute to understanding of its effectiveness and enable quality control.

LC-MS Characterization and Quantification of Known and Unknown (Poly)phenol Metabolites-Possible Pitfalls and Their Avoidance

This review focuses on the LC-MS characterization and quantification of dietary (poly)phenols and their metabolites. It draws attention to errors, omissions, and misunderstandings that appear frequently in published papers, and suggests strategies for their avoidance. Aspects covered include the use of authentic standards and surrogate reference materials, the importance of collecting and archiving Total Ion Current MS data, the limitations of using on-line compilations of accurate mass MS data to assign unknown components when multiple isomers are possible, and the often understated magnitude of person-to-person variation that may significantly impact at population level any potential health benefit.

Caffeoylquinic acids: chemistry, biosynthesis, occurrence, analytical challenges, and bioactivity

Caffeoylquinic acids (CQAs) are specialized plant metabolites we encounter in our daily life. Humans consume CQAs in mg-to-gram quantities through dietary consumption of plant products. CQAs are considered beneficial for human health, mainly due to their anti-inflammatory and antioxidant properties. Recently, new biosynthetic pathways via a peroxidase-type p-coumaric acid 3-hydroxylase enzyme were discovered. More recently, a new GDSL lipase-like enzyme able to transform monoCQAs into diCQA was identified in Ipomoea batatas. CQAs were recently linked to memory improvement; they seem to be strong indirect antioxidants via Nrf2 activation. However, there is a prevalent confusion in the designation and nomenclature of different CQA isomers. Such inconsistencies are critical and complicate bioactivity assessment since different isomers differ in bioactivity and potency. A detailed explanation regarding the origin of such confusion is provided, and a recommendation to unify nomenclature is suggested. Furthermore, for studies on CQA bioactivity, plant-based laboratory animal diets contain CQAs, which makes it difficult to include proper control groups for comparison. Therefore, a synthetic diet free of CQAs is advised to avoid interferences since some CQAs may produce bioactivity even at nanomolar levels. Biotransformation of CQAs by gut microbiota, the discovery of new enzymatic biosynthetic and metabolic pathways, dietary assessment, and assessment of biological properties with potential for drug development are areas of active, ongoing research. This review is focused on the chemistry, biosynthesis, occurrence, analytical challenges, and bioactivity recently reported for mono-, di-, tri-, and tetraCQAs.

Diagnostic Fragment-Ion-Based for Rapid Identification of Chlorogenic Acids Derivatives in Inula cappa Using UHPLC-Q-Exactive Orbitrap Mass Spectrometry

Inula cappa (Buch.-Ham. ex D. Don) DC has been used in traditional Chinese medicine to treat malaria, dysentery, and hepatitis. Previous studies have shown that chlorogenic acid is the effective ingredient of plants in this family. And the research of the chlorogenic acid in Inula cappa will help to further improve the effective resource utilization rate of this plant. Therefore, it is necessary to establish an accurate method to characterize the chlorogenic acid components in Inula cappa. In this study, a simple, fast, and sensitive UHPLC-Q-Exactive Orbitrap mass spectrometry method was established, which can simultaneously analyze known and unknown ingredients in a short time (within 30 minutes) in Inula cappa. According to the diagnosis fragmentation ions, retention time, and bibliography, 68 chlorogenic acid derivatives were identified in Inula cappa. The results of this experiment lay the foundation for the active substances and quality control of Inula cappa and provide a theoretical basis for whether Inula cappa can be an alternative to the endangered wild medicinal materials of the same family.

Insight into chemical basis of traditional Chinese medicine based on the state-of-the-art techniques of liquid chromatography-mass spectrometry

Traditional Chinese medicine (TCM) has been an indispensable source of drugs for curing various human diseases. However, the inherent chemical diversity and complexity of TCM restricted the safety and efficacy of its usage. Over the past few decades, the combination of liquid chromatography with mass spectrometry has contributed greatly to the TCM qualitative analysis. And novel approaches have been continuously introduced to improve the analytical performance, including both the data acquisition methods to generate a large and informative dataset, and the data post-processing tools to extract the structure-related MS information. Furthermore, the fast-developing computer techniques and big data analytics have markedly enriched the data processing tools, bringing benefits of high efficiency and accuracy. To provide an up-to-date review of the latest techniques on the TCM qualitative analysis, multiple data-independent acquisition methods and data-dependent acquisition methods (precursor ion list, dynamic exclusion, mass tag, precursor ion scan, neutral loss scan, and multiple reaction monitoring) and post-processing techniques (mass defect filtering, diagnostic ion filtering, neutral loss filtering, mass spectral trees similarity filter, molecular networking, statistical analysis, database matching, etc.) were summarized and categorized. Applications of each technique and integrated analytical strategies were highlighted, discussion and future perspectives were proposed as well.

Shotgun chemome characterization of Artemisia rupestris L. Using direct infusion-MS/MSALL

In comparison of liquid chromatography, direct infusion is a superior choice to achieve high-throughput measurements. The specificity and selectivity of tandem mass spectrometry (MS/MS) actually result in a so-called MS separation potential when chemical characterization of herbal medicines. Here, a MS/MS^ALL program was introduced to promote DI-MS/MS to be an eligible tool for shotgun chemome characterization of Artemisia rupestris L. that is currently drawing worldwide interests because of the promising antiviral activity. After MS¹ spectral acquisition for the crude extract, the gas phase fractionation concept enabled the precursor ion cohort sequentially entered the collision cell with a stepped unit mass window (step-size as 1 Da) to generate MS² spectra, thus generating a unique property integrating the advantages of both data-dependent and data-independent acquisition manners. Even though being free of chromatographic separation, spectrometric separations were accomplished for by MS/MS^ALL program unless the components shared identical nominal molecular weights. Extensive efforts such as the correlations of MS¹ signals with MS² spectra, structural annotations of fragment ion species, information retrieval in some accessible databases, and referring to the literature data, were devoted for chemical characterization, and as a result, 44 compounds, in total, were structurally identified from 50% aqueous methanol exact of A. rupestris, including 8 caffeoyl quinic acid derivatives, 13 flavonoids, 15 monomeric and dimeric sesquiterpenoids, 4 fatty acids, 2 penylpropanoids, along with 2 other compounds. However, isomers were assigned as an isomeric mixture because their precursor ions always co-existed in a single mass window. Above all, DI-MS/MS^ALL provides an alternative tool for chemome characterization of herbal medicines, in particular when the great measurement workload for a large sample cohort, attributing to the high-throughput advantage.

Rapid Identification and Systematic Mechanism of Flavonoids from Potentilla freyniana Bornm. Based on UHPLC-Q-Exactive Orbitrap Mass Spectrometry and Network Pharmacology

Potentilla freyniana Bornm. (P. freyniana), belonging to the family Rosaceae, has been used as a folk medicine in China. However, as we know, the constituents and the systematic elucidation of the mechanism were not fully investigated. Therefore, it is necessary to develop a rapid method using LC-MS and network pharmacology for the detection and identification of constituents and the systematic mechanism of P. freyniana. Firstly, the flavonoids were detected and identified based on ultra-high-performance liquid chromatography coupled with Quadrupole-Exactive Focus Orbitrap MS (UHPLC-Q-Exactive Orbitrap MS). After that, the potential targets of those constituents were obtained by database mining. Then, the core targets were predicted by protein-protein interaction network and network analysis. Finally, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were carried out via DAVID. This finding revealed that P. freyniana possessed 43 flavonoids (40 of them were first reported) with 23 core target genes, which are associated with PI3K-Akt, MAPK, TNF signaling pathway, and pathway in cancer. This study demonstrated the multicompound, multitarget, and multimechanism of P. freyniana, which are very beneficial to develop the further study and utilization of this plant including the material basis and quality control research.

Identification of Metabolites of Aurantio-Obtusin in Rats Using Ultra-High-Performance Liquid Chromatography-Q-Exactive Orbitrap Mass Spectrometry with Parallel Reaction Monitoring

Aurantio-obtusin (AO) is a major anthraquinone compound isolated from Cassiae Semen or Duhaldea nervosa, which possesses diverse pharmacological effects. Previous studies have shown that it has a good effect on lowering blood lipids and treating various diseases. A few studies have also reported about its metabolites. A rapid and reliable method using ultra-high-performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry and multiple data-processing technologies was established to investigate the metabolites of AO in the plasma and various tissues of rats, including the heart, liver, spleen, lung, kidneys, and brain. Finally, a total of 36 metabolites were identified in the plasma of rats, which could be very beneficial for understanding the effective form of AO metabolites leading to new drug discovery. The result demonstrated that this strategy, especially parallel reaction monitoring, has shown a wide range of applications in the identification of metabolites.

Identification of the metabolites of isochlorogenic acid A in rats by UHPLC-Q-Exactive Orbitrap MS

CONTENT

Isochlorogenic acid A, one of the main components of Duhaldea nervosa (Wallich ex Candolle) A. Anderberg (Asteraceae), is a folk medicine used to treat a variety of diseases including fracture and rheumatoid arthritis. Despite its widespread use, the metabolism of isochlorogenic acid A in vivo has not been fully studied.

OBJECTIVE

An analytical strategy based on UHPLC-Q-Exactive Orbitrap MS is proposed for the detection and identification of the metabolites of isochlorogenic acid A in rats.

MATERIALS AND METHODS

Six male Sprague-Dawley rats (180 ± 20 g) were randomly divided into two groups. Then, blood and tissue samples were obtained after oral administration of isochlorogenic acid A (200 mg/kg). All the samples were pre-treated by the Solid Phase Extraction (SPE) method. Next, the samples were analysed by UHPLC-Q-Exactive Orbitrap MS. Finally, the metabolites were identified based on the metabolomic workflow template.

RESULTS

A total of 33 metabolites were identified in rat plasma, with 30 of them being reported for the first time. The distribution of all metabolites in tissues was first investigated, three of them were widely distributed in liver, lungs, and kidneys. The corresponding reactions including methylation, hydrolysis, sulphate conjugation, glucuronide conjugation, as well as their composite reactions, are reported in this study.

DISCUSSION AND CONCLUSIONS

This method has wide-scale application prospects in the identification of metabolites. Considering that limited research has been conducted in this area, this study proposes metabolic pathways to further understand mechanisms of isochlorogenic acid A and the forms that are truly effective in vivo.

Current Advances in Naturally Occurring Caffeoylquinic Acids: Structure, Bioactivity, and Synthesis

Caffeoylquinic acids (CQAs) are a broad class of secondary metabolites that have been found in edible and medicinal plants from various families. It has been 100 years since the discovery of chlorogenic acid in 1920. In recent years, a number of naturally derived CQAs have been isolated and structurally elucidated. Accumulated evidence demonstrate that CQAs have a wide range of biological activities, such as antioxidation, antibacterial, antiparasitic, neuroprotective, anti-inflammatory, anticancer, antiviral, and antidiabetic effects. Up to date, some meaningful progresses on the biosynthesis and total synthesis of CQAs have also been made. Therefore, it is necessary to comprehensively summarize the structure, biological activity, biosynthesis, and chemical synthesis of CQAs. This review provides extensive coverage of naturally occurring CQAs discovered from 1990 until 2020. Modern isolation techniques, chemical data (including structure, biosynthesis, and total synthesis), and bioactivity are summarized. This would be helpful for further research of CQAs as potential pharmaceutical agents.

Profiling of Chlorogenic Acids from Bidens pilosa and Differentiation of Closely Related Positional Isomers with the Aid of UHPLC-QTOF-MS/MS-Based In-Source Collision-Induced Dissociation

Bidens pilosa is an edible herb from the Asteraceae family which is traditionally consumed as a leafy vegetable. B. pilosa has many bioactivities owing to its diverse phytochemicals, which include aliphatics, terpenoids, tannins, alkaloids, hydroxycinnamic acid (HCA) derivatives and other phenylpropanoids. The later include compounds such as chlorogenic acids (CGAs), which are produced as either regio- or geometrical isomers. To profile the CGA composition of B. pilosa, methanol extracts from tissues, callus and cell suspensions were utilized for liquid chromatography coupled to mass spectrometric detection (UHPLC-QTOF-MS/MS). An optimized in-source collision-induced dissociation (ISCID) method capable of discriminating between closely related HCA derivatives of quinic acids, based on MS-based fragmentation patterns, was applied. Careful control of collision energies resulted in fragment patterns similar to MS² and MS³ fragmentation, obtainable by a typical ion trap MSⁿ approach. For the first time, an ISCID approach was shown to efficiently discriminate between positional isomers of chlorogenic acids containing two different cinnamoyl moieties, such as a mixed di-ester of feruloyl-caffeoylquinic acid (m/z 529) and coumaroyl-caffeoylquinic acid (m/z 499). The results indicate that tissues and cell cultures of B. pilosa contained a combined total of 30 mono-, di-, and tri-substituted chlorogenic acids with positional isomers dominating the composition thereof. In addition, the tartaric acid esters, caftaric- and chicoric acids were also identified. Profiling revealed that these HCA derivatives were differentially distributed across tissues types and cell culture lines derived from leaf and stem explants.

Identification of the Constituents of Percutaneous Absorption from Duhaldea nervosa Based on UHPLC-Q-Exactive Orbitrap MS and Microdialysis Technique

Duhaldea nervosa (D. nervosa) has been used for treatment of bone fracture by external use. Thus, the percutaneous absorption was crucial to the effect of D. nervosa, especially the constituents of percutaneous absorption. However, the constituents in vivo were never investigated to date. In this study, an efficient method was developed for the identification of constituents of percutaneous absorption using UHPLC-Q-Exactive Orbitrap MS and microdialysis technique. A total of 20 constituents including 15 chlorogenic acid analogues, 3 amino acids, and 2 organic acids were unambiguously or tentatively identified based on high-resolution mass data including MS and MS², chromatography retention time, and bibliography data. To the best of our knowledge, this is the first study to report the constituents of percutaneous absorption from D. nervosa, which will be very helpful for understanding the bioactive compounds and quality control.

Liquid chromatography coupled with time-of-flight tandem mass spectrometry for comprehensive phenolic characterization of pomegranate fruit and flower extracts used as ingredients in botanical dietary supplements

Pomegranate (Punica granatum L.) fruit and flower extracts, which are rich sources of bioactive phenolics, are widely utilized as ingredients in botanical dietary supplements. While the phenolic characterization of extracts of pomegranate fruit has been previously studied by liquid chromatography with tandem mass spectrometry, there is lack of similar data for pomegranate flowers. Herein, liquid chromatography with time-of-flight tandem mass spectrometry was utilized to comprehensively characterize the phenolics present in two pomegranate extracts, previously studied for their in vitro and in vivo biological effects, namely, a patented commercial pomegranate fruit extract (Pomella®), and a pomegranate flower extract. Seventy-one phenolics were characterized in the pomegranate fruit extract with the vast majority identified in the flower extract. However, only the pomegranate fruit extract contained tannin-glucuronides and two punicalagin isomers (a characteristic pomegranate phenolic) were identified in this extract while four were identified in the flower extract. The previously reported compounds, pomellatannin and punicatannins A/B, were identified as unique chemical markers in the pomegranate fruit and flower extracts, respectively. This study will aid in the quality control, authentication, and standardization of these botanical ingredients to evaluate their potential health benefits in future planned pre-clinical and clinical studies. Also, this is the first phenolic characterization of a pomegranate flower extract using liquid chromatography with tandem mass spectrometry.