Metabolic fingerprinting by 1HNMR for discrimination of the two species used as Radix Bupleuri

Integrative strategy for quality control of Radix Bupleuri based on non-targeted metabolomic profiling and molecular networking

Quality control of Radix Bupleuri (RB) can be challenging due to the complexity of origin, the similar morphological characteristics, and the diversity of the multiple components. In this study, an integrated strategy for extensive identification of metabolites in plants based on multiple data processing methods was proposed to distinguish four commercially available RB species. First, the pre-processed mass spectrometry data was uploaded to Global Natural Products Social Molecular Networking (GNPS) for spectral library search and molecular network analysis, which can effectively differentiate isomers and reduce molecular redundancy. Second, the possible cleavage mode was summarized from the characteristic MS/MS fragment ions of saikoside standard, and then the possible structure of saikoside in the sample was deduced according to the cleavage patterns. Third, collected all kinds of RB components reported in the literature and matched the information in the samples to obtain more comprehensive information about metabolites. Finally, chemical markers were found employing chemometrics. This strategy not only increases the variety and number of identified components, but also improves the accuracy of the data. Based on this strategy, a total of 132 components were identified from different species of RB, and 14 chemical constituents were considered to be potential chemical markers to distinguish four kinds of RB. Among them, saikogenin a, hydroxy-saikosaponin a, hydroxy-saikosaponin d, and rutinum were of great significance for identification. The method proposed in this study not only successfully identified and distinguished four species of RB, but also laid a good theoretical foundation for regulating the RB market. This strategy provides promising perspectives in the accurate analysis of the ingredients of traditional Chinese medicine.

Transcriptome Level Reveals the Triterpenoid Saponin Biosynthesis Pathway of Bupleurum falcatum L

Bupleurum falcatum L. is frequently used in traditional herbal medicine in Asia. Saikosaponins (SSs) are the main bioactive ingredients of B. falcatum, but the biosynthetic pathway of SSs is unclear, and the biosynthesis of species-specific phytometabolites is little known. Here we resolved the transcriptome profiles of B. falcatum to identify candidate genes that might be involved in the biosynthesis of SSs. By isoform sequencing (Iso-Seq) analyses of the whole plant, a total of 26.98 Gb of nucleotides were obtained and 124,188 unigenes were identified, and 81,594 unigenes were successfully annotated. A total of 1033 unigenes of 20 families related to the mevalonate (MVA) pathway and methylerythritol phosphate (MEP) pathway of the SS biosynthetic pathway were identified. The WGCNA (weighted gene co-expression network analysis) of these unigenes revealed that only the co-expression module of MEmagenta, which contained 343 unigenes, was highly correlated with the biosynthesis of SSs. Comparing differentially expressed gene analysis and the WGCNA indicated that 130 out of 343 genes of the MEmagenta module exhibited differential expression levels, and genes with the most "hubness" within this module were predicted. Manipulation of these genes might improve the biosynthesis of SSs.

Identification of the original plants of cultivated Bupleuri Radix based on DNA barcoding and chloroplast genome analysis

Bupleuri Radix is the dry root of certain species of the genus Bupleurum and is commonly used in traditional Chinese medicine. The increasing global demand for Bupleuri Radix cannot be fulfilled with wild populations only. Therefore, cultivated Bupleurum is now the main commercial source of this medicinal product. Different species of Bupleurum show different medicinal properties and clinical effects, making reliable authentication and assignment of correct botanical origin for medicinal species critical. However, accurate identification of the cultivated Bupleurum species is difficult due to dramatic morphological variations resulting from cultivation. In this study, we sampled 56 cultivated Bupleurum populations of six different morphotypes (Types A-F) from the main production areas of China, and 10 wild populations of four species were used as reference materials. Conventional DNA barcoding was conducted to identify cultivated Bupleurum species. Additionally, verification based on complete chloroplast genomes was performed and new chloroplast markers were developed and evaluated. The combination of these methods resulted in the successful identification of all cultivated Bupleurum individuals. Three chloroplast regions are recommended as additional barcodes for the genus: ycf4_cemA, psaJ_rpl33, and ndhE_ndhG. This is a reliable and promising strategy that can be applied to the authentication of natural products and the identification of other medicinal plant species with similar taxonomic problems.

Screening of Bletilla striata, Bletilla ochracea, and Oreorchis foliosa differential metabolites based on metabolomics

As a representative medicinal plant in Orchidaceae, Bletilla striata plays a variety of pharmacological roles in the clinic. However, the emergence of counterfeit species affects the basic medicinal materials source identification process, of which Bletilla ochracea and Oreorchis foliosa of Orchidaceae are two representative species. For this study, 13 representative B. striata samples, 3 B. ochracea samples and 3 O. foliosa samples were selected for the systematic determination of polysaccharide yields and monosaccharide composition, and further detection of secondary metabolites by HPLC-MS. The results revealed that there was a significant difference in the yields of polysaccharides between B. striata and B. ochracea (P = 0.006). Although the polysaccharides of both species were composed of glucose and mannose, the molar ratio of the two monosaccharides was different suggested that the structures of the polysaccharide were different. The metabolomics results showed that there were no differences in the types of metabolites between B. striata and B. ochracea; however, there were differences in the content of these metabolites. Although there was no significant difference in the polysaccharide yields of B. striata and O. foliosa (P = 0.074) and the monosaccharide composition was the same (glucose and mannose), many different metabolites were screened out between them: 6 compounds such as C₃₆ H₃₄ O₁₁ existed only in B. striata, while substance C₃₉ H₅₄ O₂₂ was unique to O. foliosa. Therefore, based on the analysis of the polysaccharide content and monosaccharide composition, combined with phase metabolomics research, a preliminary distinction between B. striata, B. ochracea, and O. foliosa was achieved.

NMR technique and methodology in botanical health product analysis and quality control

Botanicals have played an important role in maintaining human health and well-being throughout history. During the past few decades in particular, the use of botanical health products has gained more popularity. Whereas, quality, safety and efficacy concerns have continuously been critical issues due to the intrinsic chemical complexity of botanicals. Chemical analytical technologies play an imperative role in addressing these issues. Nuclear magnetic resonance (NMR) spectroscopy has proven to be a powerful and useful tool for the investigation of botanical health products. In this review, NMR techniques and methodologies that have been successfully applied to the research and development of botanical health products in all stages, from plants to products, are discussed and summarized. Furthermore, applications of NMR together with other analytical techniques in a variety of domains of botanical health products investigation, such as plant species differentiation, adulteration detection, and bio-activity evaluation, are discussed and illustrated with typical examples. This article provides an overview of the potential uses of NMR techniques and methodologies in an attempt to further promote their recognition and utilization in the field of botanical health products analysis and quality control.

Quantitative 1H NMR for the Direct Quantification of Saikosaponins in Bupleurum chinense DC

Saikosaponin a and saikosaponin d are used as chemical standards for the quality evaluation of Bupleurum chinense DC. by the high-performance liquid chromatography method in current Chinese Pharmacopoeia. However, other saikosaponins, such as saikosaponin c and saikosaponin b₂, also possess pharmaceutical activity, but are not used as chemical standards. In this study, a quantitative proton nuclear magnetic resonance (¹H NMR) method was developed to determine the total mass percentage (mg/g) of SSa, SSb₁, SSb₂ and SSd in B. chinense DC., using the H-24 (δ_H 0.71) signal. Furthermore, the molality (mol/kg) of type I saikosaponins (epoxy-ether structure) was also determined by quantitative ¹H NMR in the area of H-11 (δ_H 5.95) for a more accurate quality evaluation. Validation of the method confirmed that it has acceptable selectivity, precision, stability, and repeatability. The results indicated that this method has the potential to be a reliable method for the quantification of saikosaponins in Bupleurum scorzonerifolium Willd., vinegar baked B. chinense DC. and B. scorzonerifolium Willd., Chaihu Koufuye (oral liquid of Chaihu).

Recent Progress in Saikosaponin Biosynthesis in Bupleurum

BACKGROUND

Chaihu is a popular traditional Chinese medicine that has been used for centuries. It is traditionally used to treat cold fever and liver-related diseases. Saikosaponins (SSs) are one of the main active components of chaihu, in addition to essential oils, flavonoids, and polysaccharides. Considerable effort is needed to reveal the biosynthesis and regulation of SSs on the basis of current progress.

OBJECTIVE

The aim of this study is to provide a reference for further studies and arouse attention by summarizing the recent achievements of SS biosynthesis.

METHODS

All the data compiled and presented here were obtained from various online resources, such as PubMed Scopus and Baidu Scholar in Chinese, up to October 2019.

RESULTS

A few genes of the enzymes of SSs participating in the biosynthesis of SSs were isolated. Among these genes, only the P450 gene was verified to catalyze the SS skeleton β-amyrin synthase. Several UDP-glycosyltransferase genes were predicted to be involved in the biosynthesis of SSs. SSs could be largely biosynthesized in the phloem and then transported from the protoplasm, which is the biosynthetic site, to the vacuoles to avoid self-poisoning. As for the other secondary metabolites, the biosynthesis of SSs was strongly affected by environmental factors and the different species belonging to the genus of Bupleurum. Transcriptional regulation was studied at the molecular level.

CONCLUSION

Profound discoveries in SSs may elucidate the mechanism of diverse the monomer formation of SSs and provide a reference for maintaining the stability of SS content in Radix Bupleuri.

Comparison of chemical constituents of Bupleurum marginatum var. stenophyllum and Bupleurum chinense DC. using UHPLC-Q-TOF-MS based on a metabonomics approach

The overall chemical composition of Bupleurum marginatum var. stenophyllum and Bupleurum chinense DC. was compared in this study. Metabolites were identified using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Multivariate statistical analysis techniques such as principal component analysis were used to conduct metabonomics analysis and study the correlation between different components. Principal component analysis results showed a clear distinction among medicinal materials of different origins and divided them into different categories, consistent with the results of hierarchical cluster analysis. Both partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA) showed that the two materials could be distinguished clearly. Using PLS-DA and OPLS-DA combined with the S-plot and a variable importance in the projection (VIP) score >1, 24 differential metabolites were screened and identified; all of the metabolites were triterpenoid saponins. In addition, SPSS 25.0 and Metabo Analyst 4.0 were used to analyze significant differences in the relative contents of different compounds in the two materials. This study has successfully provided not only a new direction for research based on the chemical substances identified and the quality evaluation of Bupleuri Radix but also a better theoretical basis for the expansion of medicinal sources and their clinical application.

Botany, traditional uses, phytochemistry, analytical methods, processing, pharmacology and pharmacokinetics of Bupleuri Radix: A systematic review

Bupleuri Radix (BR) is the dry root of Bupleurum chinense DC. and Bupleurum scorzonerifolium Willd. It has the functions of evacuation and antipyretic, soothing liver and relieving depression and often used to treat cold fever, chest and rib swelling pain, irregular menstruation, uterine prolapse, rectocele and other diseases. In this paper, the botany, traditional application, phytochemistry, pharmacology and toxicity of BR were reviewed. On the basis of limited literature, the analytical method, quality control, processing method, processing effect and pharmacokinetics of BR were summarized and analyzed for the first time. This review makes an in-depth discussion on the shortcomings of the current research on BR, and puts forward its own views and solutions. This has never been summarized in the previous review of BR. It is of great practical significance for future scholars to find a breakthrough point in the study of BR. So far, its mechanism has not been satisfactorily explained. Moreover, the comprehensive quality evaluation and multi-target network pharmacology of BR need to be further studied. In the future, more in vitro and in vivo experiments are needed to give full play to the therapeutic potential of BR.

Improving the Concentrations of the Active Components in the Herbal Tea Ingredient, Uraria crinita: The Effect of Post-harvest Oven-drying Processing

Uraria crinita is widely used as a popular folk drink; however, little is known about how the post-harvest operations affect the chemical composition and bioactivity of UC. We assessed three drying methods (Oven-drying, Air-drying, Sun-drying), as well as the Oven-drying temperature using metabolomics approaches and bioactivity assays. The samples processed at 40 degree show a greater effect on the levels of estrogen receptor-alpha activity and nuclear factor erythroid 2-related factor 2 activity, anti-oxidative activity, and cyclooxygenase-2 inhibition compared with the other samples. A multivariate analysis showed a clear separation between the 40 degree Oven-dried samples and the other samples, which is consistent with the results of bioactivity assay. These results are ascribed to at least two-fold increase in the concentrations of flavonoids, spatholosineside A and triterpenoids in the oven-dried samples compared with the other groups. The proposed Oven-drying method at 40 degree results in an improved quality of UC.

Metabolic characterization of natural and cultured Ophicordyceps sinensis from different origins by 1H NMR spectroscopy

Ophicordyceps sinensis is a well-known traditional Chinese medicine and cultured mycelium is a substitute for wild O. sinensis. Metabolic profiles of wild O. sinensis from three geographical locations and cultivated mycelia derived from three origins were investigated using (1)H nuclear magnetic resonance (NMR) analysis combined with multivariate statistical analysis. A total of 56 primary metabolites were identified and quantified from O. sinensis samples. The principle component analysis (PCA) showed significant differences between natural O. sinensis and fermentation mycelia. Seven metabolites responsible for differentiation were screened out by orthogonal partial least squares discriminant analysis (OPLS-DA). The concentrations of mannitol, trehalose, arginine, trans-4-hydroxyproline, alanine and glucitol were significantly different between wild and cultured groups. The variation in metabolic profiling among artificial mycelia was greater than that among wild O. sinensis. Furthermore, wild samples from different origins were clearly distinguished by the levels of mannitol, trehalose and some amino acids. This study indicates that (1)H NMR-based metabolomics is useful for fingerprinting and discriminating O. sinensis of different geographical regions and cultivated mycelia of different strains. The present study provided an efficient approach for investigating chemical compositions and evaluating the quality of medicine and health food derived from O. sinensis.

Chemical and biological comparison of raw and vinegar-baked Radix Bupleuri

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Bupleuri (RB) is a commonly used herbal drug in Traditional Chinese Medicine (TCM), and it can be baked with vinegar to afford vinegar-baked Radix Bupleuri (VBRB), which is used in TCM for liver diseases treatment. In this study, the chemical compositions and biological effects between raw and two processed RBs by different vinegars were systematically compared.

MATERIALS AND METHODS

The chemical compositions of raw and two processed RBs were analyzed by (1)H NMR spectroscopy coupled with multivariate analysis. Two different extraction procedures were used, including direct extraction and liquid-liquid partition. Then HPLC was applied to determine the changes of saikosaponin contents. In addition, their liver protective effects against CCl4 induced liver injury were also investigated, and the biochemical parameters and histopathology were measured after treatment of mice with raw RB and two processed RBs (5 g/kg/day) for 14 days.

RESULTS

Multivariate analysis showed clear differences between the raw and the two processed RBs, and the vinegar-baking process induced elevated contents of ssb1, ssb2, acetic acid, malic acid, citric acid, 5-HMF, and ligustrazine, as well as the decreased contents of ssa, ssd, sucrose, glycine, succinic acid etc. In addition, both raw and processed RBs showed liver protective effects against CCl4 induced liver injury, and the vinegar-baked RBs showed better effects than that of raw RB.

CONCLUSIONS

The raw and vinegar-baked RBs differed not only in the chemical compositions but also in the pharmacological effects. And two processed RBs also showed chemical differences, suggesting that the type of vinegar had an important effect on vinegar baking. In order to ensure the therapeutic effect and safety of TCM, the effect of different vinegars on processing of herbal drugs should be further studied.

Metabolomics coupled with pattern recognition and pathway analysis on potential biomarkers in liver injury and hepatoprotective effects of yinchenhao

Metabolomics can provide an opportunity to develop the systematic analysis of the metabolites in biological samples and has been increasingly applied to discovering and identifying biomarkers and perturbed pathways. It enables us to better understand the metabolic pathways which can clarify the mechanism of traditional Chinese medicines (TCM). Yinchenhao (YCH, Artemisia annua L), a famous TCM plant, has been used clinically for more than a thousand years to relieve liver diseases in Asia, and its mechanisms are not still completely clear. Here, metabolomic techniques may provide additional insight, and our investigation was designed to assess the effects and possible mechanisms of YCH on α-naphthylisothiocyanate (ANIT)-induced liver injury. Metabolite profiling was performed by ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry (UPLC/ESI-Q-TOF/MS) combined with pathway analysis and pattern recognition approaches including independent component analysis (ICA) and partial least squares-discriminant analysis (PLS-DA). Biochemistry test was also performed for the liver tissue and plasma samples. The changes in metabolic profiling were restored to their baseline values after YCH treatment according to the ICA score plots. Of note, YCH has a potential pharmacological effect through regulating multiple perturbed pathways to normal state, correlating well to the assessment of biochemistry test. Five different potential biomarkers in the positive mode contributing to the treatment of YCH were discovered. Pathway analysis showed that these metabolites were associated with perturbations in pyrimidine metabolism, primary bile acid biosynthesis, and propanoate metabolism, which may be helpful to further understand the action mechanisms of YCH. It showed that changed biomarkers and pathways may provide evidence to insight into drug action mechanisms and drug discovery.

Effect of saikosaponins and extracts of vinegar-baked Bupleuri Radix on the activity of β-glucuronidase

In Traditional Chinese Medicine, liver targeting is usually achieved by coadministration with Vinegar-baked Radix Bupleuri (VBRB), but the mechanism is unclear. In this paper, the influence of VBRB on the activity of β-glucuronidase was investigated and compared with that of saikosaponins. The activity of β-glucuronidase was measured by microplate reader using a 4-nitrophenyl-β-d-glucuronide substrate. The change of 4-nitrophenol content was used to characterize the activity of β-glucuronidase. Bupleurum chinenes were found to be the inhibitor of β-glucuronidase. The inhibition rate of Bupleurum chinenes extracts BC1 (high molecular weight polysaccharides), BC2 (ethanol soluble/water insoluble component), BC3 (extracted by n-butanol, soluble in water), and BC4 (low molecular weight water soluble parts) on the activity of β-glucuronidase was found to be 45.15%, 33.94%, 24.94%, and 34.54%, respectively, after 1 h incubation, with BC1 showing the highest inhibition rate. In contrast, the saikosaponins were demonstrated to be the promoter of β-glucuronidase, with promotion rates of 333.56%, 217.04%, 247.87%, 149.75%, and 92.50% for saikosaponin standard samples A, B, B2, C, and D, respectively, (p<0.05). In conclusion, inhibiting the activity of β-glucuronidase might be one of the reasons why VBRB could influence drug distribution upon its coadministration with other drugs. Since saikosaponins and VBRB extracts have opposite effect, more attention should be paid to the content of saikosaponins in the extracts upon its application.

Metabolomic-based study of the leafy gall, the ecological niche of the phytopathogen Rhodococcus fascians, as a potential source of bioactive compounds

Leafy gall is a plant hyperplasia induced upon Rhodococcus fascians infection. Previously, by genomic and transcriptomic analysis, it has been reported that, at the early stage of symptom development, both primary and secondary metabolisms are modified. The present study is based on the hypothesis that fully developed leafy gall, could represent a potential source of new bioactive compounds. Therefore, non-targeted metabolomic analysis of aqueous and chloroform extracts of leafy gall and non-infected tobacco was carried out by 1H-NMR coupled to principal component analysis (PCA) and orthogonal projections to latent structures-discriminant analysis (OPLS-DA). Polar metabolite profiling reflects modifications mainly in the primary metabolites and in some polyphenolics. In contrast, main modifications occurring in non-polar metabolites concern secondary metabolites, and gas chromatography and mass spectrometry (GC-MS) evidenced alterations in diterpenoids family. Analysis of crude extracts of leafy galls and non-infected tobacco leaves exhibited a distinct antiproliferative activity against all four tested human cancer cell lines. A bio-guided fractionation of chloroformic crude extract yield to semi-purified fractions, which inhibited proliferation of glioblastoma U373 cells with IC50 between 14.0 and 2.4 µg/mL. Discussion is focused on the consequence of these metabolic changes, with respect to plant defense mechanisms following infection. Considering the promising role of diterpenoid family as bioactive compounds, leafy gall may rather be a propitious source for drug discovery.