A Study on Tissue-Specific Metabolite Variations in Polygonum cuspidatum by High-Resolution Mass Spectrometry-Based Metabolic Profiling

Screening and characterization of potential anti-gout components from Polygonum cuspidatum by integration off-line two-dimensional liquid chromatography-mass spectrometry with affinity ultrafiltration and on-line HPLC-ABTS

Polygonum cuspidatum (P. cuspidatum) is a traditional herbal medicine with a long history and proven efficacy in treating gout. However, due to the complexity of composition and extensive content distribution, the substance basis of its anti-gout effectiveness is still unclear. A strategy was proposed via integrating off-line two-dimensional liquid chromatography (2D-LC) and targeted rapid screening technology based on ultrafiltration-liquid chromatography-mass spectrometry (UF-LC/MS) and on-line high-performance liquid chromatography-2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (HPLC-ABTS) to accomplish high coverage and high throughput screening of anti-gout components from P. cuspidatum. As a result, twenty components were screened from P. cuspidatum extract with both xanthine oxidase (XOD) inhibitory activity and free radical scavenging activity, then were preliminarily identified by high-resolution electrospray ionization-quadrupole-time-of-flight mass spectrometer (ESI-Q-TOF/MS). The screened results were verified by the in vitro assays. Meanwhile, molecular docking further elucidated that the screened bioactive ingredients had favourable binding capabilities with XOD. The performance of this study can achieve high efficiency and high coverage screening of the anti-gout components from P. cuspidatum, which provides methodology and strategy support for the rapid screening of bioactive ingredients from complex medicinal plants.

Comparative metabolite analysis of Piper sarmentosum organs approached by LC-MS-based metabolic profiling

Piper sarmentosum Roxb. (Piperaceae) is a traditional medicinal and food plant widely distributed in the tropical and subtropical regions of Asia, offering both health and culinary benefits. In this study the secondary metabolites in different organs of P. sarmentosum were identified and their relative abundances were characterized. The metabolic profiles of leaves, roots, stems and fruits were comprehensively investigated by liquid chromatography high-resolution mass spectrometry (LC-HR-MS) and the data subsequently analyzed using multivariate statistical methods. Manual interpretation of the tandem mass spectrometric (MS/MS) fragmentation patterns revealed the presence of 154 tentatively identified metabolites, mostly represented by alkaloids and flavonoids. Principle component analysis and hierarchical clustering indicated the predominant occurrence of flavonoids, lignans and phenyl propanoids in leaves, aporphines in stems, piperamides in fruits and lignan-amides in roots. Overall, this study provides extensive data on the metabolite composition of P. sarmentosum, supplying useful information for bioactive compounds discovery and patterns of their preferential biosynthesis or storage in specific organs. This can be used to optimize production and harvesting as well as to maximize the plant's economic value as herbal medicine or in food applications.

Metabolomic analysis revealed the edible and extended-application potential of specific Polygonum multiflorum tissues

The diverse applications of various tissues of Polygonum Multiflorum (PM) encompass the use of its leaf and bud as tea and vegetables, as well as the utilization of its expanded root tubers and caulis as medicinal substances. However, previous studies in the field of metabolomics have primarily focused on the medicinal properties of PM. In order to investigate the potential for broader applications of other tissues within PM, a metabolomic analysis was conducted for the first time using UPLC-Q-TOF-MS/MS on 15 fresh PM tissues. A total of 231 compounds, including newly discovered compounds such as torosachrysone and dihydro-trihydroxystilbene acid derivatives, were identified within PM. Through clustering analysis, the PM tissues were categorized into edible and medicinal parts, with edible tissues exhibiting higher levels of phenolic acids, organic acids, and flavonoids, while the accumulation of quinones, dianthrones, stilbenes, and xanthones was observed in medicinal tissues. Comparative analysis demonstrated the potential application of discarded tissues, such as unexpanded root tuber (an industrial alternative to expanded root tuber) and young caulis (with edible potential). Moreover, the quantification of representative metabolites indicated that flowers and buds contained significant amounts of flavonoids or phenolic acids, suggesting their potential as functional food. Additionally, the edible portion of PM exhibited a high content of quercitrin, ranging from 0.59 to 10.37 mg/g. These findings serve as a valuable point of reference for the expanded utilization of PM tissues, thereby mitigating resource waste in this plant.

Effects of Fermented Polygonum cuspidatum on the Skeletal Muscle Functions

Plant extract fermentation is widely employed to enhance the nutritional and pharmaceutical value of functional foods. Polygonum cuspidatum (Pc) contains flavonoids, anthraquinones, and stilbenes, imparting protective effects against inflammatory diseases, cancer, diabetes, and cardiovascular diseases. However, the effects of fermented Pc on skeletal muscle strength remain unexplored. In this study, we generated fermented Pc using a complex of microorganisms containing Lactobacillus spp. (McPc) and assessed its effects on muscle strength and motor function in mice. Compared to unfermented Pc water extract, elevated levels of emodin and resveratrol were noted in McPc. This was identified and quantified using UPLC-QTOF/MS and HPLC techniques. Gene expression profiling through RNA-seq and quantitative RT-PCR revealed that McPc administration upregulated the expression of genes associated with antioxidants, glycolysis, oxidative phosphorylation, fatty acid oxidation, and mitochondrial biogenesis in cultured C2C12 myotubes and the gastrocnemius muscle in mice. McPc significantly improved skeletal muscle strength, motor coordination, and traction force in mice subjected to sciatic neurectomy and high-fat diet (HFD). McPc administration exhibited more pronounced improvement of obesity, hyperglycemia, fatty liver, and hyperlipidemia in HFD mice compared to control group. These findings support the notion that emodin and resveratrol-enriched McPc may offer health benefits for addressing skeletal muscle weakness.

Longitudinal Distribution Map of the Active Components and Endophytic Fungi in Angelica sinensis (Oliv.) Diels Root and Their Potential Correlations

The three distinct medicinal parts of Angelica sinensis (Oliv.) Diels (Ang) roots are the head, body, and tail (ARH, ARB, and ART, respectively). How endophytic fungi shape the differences in metabolic components among these parts remains unclear. We quantified the distribution of active components and endophytic fungi along the ARH, ARB, and ART and their relationships. Based on the metabolic components and their abundances detected via non-target metabolism, the different medicinal parts were distinguishable. The largest number of dominant metabolic components was present in ART. The difference between ART and ARH was the greatest, and ARB was in a transitional state. The dominant active molecules in ART highlight their effects in haemodynamics improvement, antibacterial, anti-inflammatory, and hormone regulation, while ARH and ARB indicated more haemostasis, blood enrichment, neuromodulation, neuroprotection and tranquilisation, hepatoprotection, and antitumour activities than that of ART. The ARHs, ARBs, and ARTs can also be distinguished from each other based on the endophytic fungi at the microbiome level. The most dominant endophytic fungi were distributed in ART; the differences between ART and ARH were the largest, and ARB was in a transition state, which is consistent with the metabolite distributions. Structural equation modelling showed that the endophytic fungi were highly indicative of the metabolic components. Correlation analysis further identified the endophytic fungi significantly positively correlated with important active components, including Condenascus tortuosus, Sodiomyces alcalophilus, and Pleotrichocladium opacum. The bidirectional multivariate interactions between endophytic fungi and the metabolic components shape their spatial variations along the longitudinal direction in the Ang root.

Advances for pharmacological activities of Polygonum cuspidatum - A review

CONTEXT

Polygonum cuspidatum Sieb. et Zucc (Polygonaceae), the root of which is included in the Chinese Pharmcopoeia under the name 'Huzhang', has a long history as a medicinal plant and vegetable. Polygonum cuspidatum has been used in traditional Chinese medicine for the treatment of inflammation, hyperlipemia, etc.

OBJECTIVE

This article reviews the pharmacological action and the clinical applications of Polygonum cuspidatum and its extracts, whether in vivo or in vitro. We also summarized the main phytochemical constituents and pharmacokinetics of Polygonum cuspidatum and its extracts.

METHODS

The data were retrieved from major medical databases, such as CNKI, PubMed, and SinoMed, from 2014 to 2022. Polygonum cuspidatum, pharmacology, toxicity, clinical application, and pharmacokinetics were used as keywords.

RESULTS

The rhizomes, leaves, and flowers of Polygonum cuspidatum have different phytochemical constituents. The plant contains flavonoids, anthraquinones, and stilbenes. Polygonum cuspidatum and the extracts have anti-inflammatory, antioxidation, anticancer, heart protection, and other pharmacological effects. It is used in the clinics to treat dizziness, headaches, traumatic injuries, and water and fire burns.

CONCLUSIONS

Polygonum cuspidatum has the potential to treat many diseases, such as arthritis, ulcerative colitis, asthma, and cardiac hypertrophy. It has a broad range of medicinal applications, but mainly focused on root medication; its aerial parts should receive more attention. Pharmacokinetics also need to be further investigated.

In vivo recognition of bioactive substances of Polygonum multiflorum for protecting mitochondria against metabolic dysfunction-associated fatty liver disease

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a severe threat to human health. Polygonum multiflorum (PM) has been proven to remedy mitochondria and relieve MAFLD, but the main pharmacodynamic ingredients for mitigating MAFLD remain unclear.

AIM

To research the active ingredients of PM adjusting mitochondria to relieve high-fat diet (HFD)-induced MAFLD in rats.

METHODS

Fat emulsion-induced L02 adipocyte model and HFD-induced MAFLD rat model were used to investigate the anti-MAFLD ability of PM and explore their action mechanisms. The adipocyte model was also applied to evaluate the activities of PM-derived constituents in liver mitochondria from HFD-fed rats (mitochondrial pharmacology). PM-derived constituents in liver mitochondria were confirmed by ultra-high-performance liquid chromatography/mass spectrometry (mitochondrial pharmacochemistry). The abilities of PM-derived monomer and monomer groups were evaluated by the adipocyte model and MAFLD mouse model, respectively.

RESULTS

PM repaired mitochondrial ultrastructure and prevented oxidative stress and energy production disorder of liver mitochondria to mitigate fat emulsion-induced cellular steatosis and HFD-induced MAFLD. PM-derived constituents that entered the liver mitochondria inhibited oxidative stress damage and improved energy production against cellular steatosis. Eight chemicals were found in the liver mitochondria of PM-administrated rats. The anti-steatosis ability of one monomer and the anti-MAFLD activity of the monomer group were validated.

CONCLUSION

PM restored mitochondrial structure and function and alleviated MAFLD, which may be associated with the remedy of oxidative stress and energy production. The identified eight chemicals may be the main bioactive ingredients in PM that adjusted mitochondria to prevent MAFLD. Thus, PM provides a new approach to prevent MAFLD-related mitochondrial dysfunction. Mitochondrial pharmacology and pharmacochemistry further showed efficient strategies for determining the bioactive ingredients of Chinese medicines that adjust mitochondria to prevent diseases.

Characterization of the chemical constituents and metabolic profile of Polygonum cuspidatum Sieb. et Zucc. in rat plasma, urine, and feces by ultra-high performance liquid chromatography coupled with Quadrupole-Exactive Orbitrap mass spectrometry

Polygonum cuspidatum Sieb. et Zucc. is a traditional and popular Chinese medicine with a wide spectrum of pharmacological effects such as anti-bacterial, anti-inflammatory, and anti-tumor activities together with other health effects like lowering lipids, preventing diabetes, and regulating the immune system. It is of great significance to explore the complex chemical constituents and metabolic process of Polygonum cuspidatum in vivo to further clarify the effective substances. However, studies on its metabolism in vivo were not comprehensive in previous literature. In this study, ultra-high performance liquid chromatography coupled with Quadrupole-Exactive Orbitrap mass spectrometry was used to comprehensively identify the chemical constituents in Polygonum cuspidatum and further analyze its metabolic profile in rats. Compared with reference substances, various databases, and literature retrieval, 62 compounds were inferred from the Polygonum cuspidatum extract. Furthermore, a total of 119 compounds, including 44 prototype compounds and 75 metabolites, were annotated in rat plasma, urine, and feces. The main metabolic pathways of Polygonum cuspidatum in rats included hydrogenation reduction, hydroxylation, dehydration, methylation, sulfation, and glucuronidation. This is the first systematic study on the chemical constituents of Polygonum cuspidatum and its metabolic profile in vivo, which contributes to finding its bioactive components and seeking its therapeutic targets.

A Comparative Phylogenetic Analysis on the Chloroplast Genome in Different Reynoutria japonica Populations

Reynoutria japonica Houtt., a traditional medicine herb of the Polygonaceae family, has been used since ancient times in China due to its various pharmacological effects. Chloroplast genomes are conservative and play an essential role in population diversity analysis. However, there are few studies on the chloroplast genome of R. japonica. In this study, the complete chloroplast genomes of three R. japonica from different regions were performed by next-generation sequencing technology. The results revealed that the lengths of the three chloroplast genomes are between 163,371~163,372 bp, and they have a highly conserved structure with a pair of inverted repeat (IR) regions (31,121 bp), a large single-copy (LSC) region (87,571~87,572 bp), and a small single-copy (SSC) region (13,558 bp). In total, 132 genes were annotated, including 8 rRNA genes, 37 tRNA genes, and 87 protein-coding genes. The phylogenetic analysis strongly revealed that 13 populations of R. japonica form a monophyly, and Fallopia multiflora (Polygonaceae) is its closest species. The two species diverged at ~20.47 million years ago, and R. japonica in China could be further divided into two major groups based on genetic structure analysis. In addition, several potential loci with suitable polymorphism were identified as molecular markers. Our study provides important genetic resources for further development and utilization of R. japonica germplasm, as well as some new insights into the evolutionary characteristics of this medicinal plant.

Arbuscular mycorrhizal fungi and phosphorus supply accelerate main medicinal component production of Polygonum cuspidatum

The medicinal plant Polygonum cuspidatum Sieb. Et Zucc is rich in stilbenes (e.g., polygonin and resveratrol) and anthraquinones (e.g., emodin) for the therapy of human diseases, while how to increase the growth and medicinal composition concentrations of P. cuspidatum has become an urgent issue. The aim of the present study was to evaluate the effects of inoculation with an arbuscular mycorrhizal (AM) fungus, Funneliformis mosseae, on plant growth, phosphorus (P) acquisition, medicinal component concentrations, and expressions of resveratrol synthesis-associated enzyme genes of P. cuspidatum at two P levels (0 M and 0.2 M). P supply (0.2 M) stimulated root AM fungal colonization rate. F. mosseae inoculation significantly improved growth performance (height, diameter, and biomass) and root morphology (diameter, length, and projected area), irrespectively of substrate P levels. P supply and F. mosseae distinctly increased soil acid and neutral phosphatase activities, as well as root P concentrations. P supply increased root physcion and resveratrol concentrations in inoculated and uninoculated plants, along with up-regulated expressions of PcCHS1, PcCRS1, PcRS11, and PcSTS. AM plants represented significantly higher root aloe-emodin, chrysophanol, emodin, physcion, polydatin, and resveratrol concentrations than non-AM plants irrespective of P levels, coupled with up-regulated expressions of PcCHS1, PcCHS2, PcRS11, PcRS, and PcSTS. It is concluded that 0.2 M P supply and F. mosseae inoculation promoted chrysophanol, physcion, polydatin, and resveratrol concentrations of P. cuspidatum, with the increase in resveratrol associated with up-regulated expressions of related genes.

An affinity interaction guided two-dimensional separation system for the screening of neuraminidase inhibitors from Reynoutria japonica Houtt. roots

Discovering bioactive compounds from medicinal herbs is crucial for drug discovery. Ultrafiltration is often used in the screening of bioactive compounds from natural herbs because of its simple and rapid operations. However, the ultrafiltration results are often disturbed by the undissolved compounds and the non-target compounds, which reduces the accuracy of the results. Herein, an affinity interaction guided two-dimensional (2D) separation system was developed. Discovery of the potential neuraminidase (NA) inhibitors from the dried roots of Reynoutria japonica Houtt. (RRJ) was used as an example. Only the small molecules showing affinity interaction with NA could be screened by the affinity interaction guided 2D separation system. Firstly, the NA and crude extract were incubated to form a sample solution (containing NA-inhibitor complexes, NA, and three types of small molecules with different polarities) by affinity interaction. Then the sample solution was separated and detected by the 2D separation system. This aimed to reduce the interference of the undissolved compounds and non-target compounds, and pick out the NA-inhibitor complexes (NA-Is). The collected NA-Is were denatured to release small molecular inhibitors (Is) for LC-MS/MS analysis. Compared with the ultrafiltration, more obvious peak area differences were observed in the results, and four potential NA inhibitors were successfully identified. In all, we provided a simple strategy with better performance in the screening of natural bioactive compounds.

Aloe-Emodin Induces Mitochondrial Dysfunction and Pyroptosis by Activation of the Caspase-9/3/Gasdermin E Axis in HeLa Cells

Aloe-emodin (1,8-dihydroxy-3-hydroxymethyl-anthraquinone), derived from some Chinese edible medicinal herbs, exerts a potential anticancer activity on various cancer cells, making it a drug candidate for cancer therapy. Yet, the role of aloe-emodin in pyroptosis, a new type of cell death, is uncharacterized. In this study, we explored the molecular mechanisms of aloe-emodin-triggered pyroptosis. Aloe-emodin inhibited proliferation and migration and triggered caspase-dependent cell death of HeLa cells in a dose-dependent manner. Aloe-emodin caused mitochondrial dysfunction and induced pyroptosis by activating the caspase-9/3/GSDME axis. Transcriptional analysis showed extensive changes in gene expressions in cellular pathways, including MAPK, p53, and PI3K-Akt pathways when treated with aloe-emodin. This study not only identified a novel role of aloe-emodin in pyroptotic cell death, but also performed a systematical genome-wide analysis of cellular pathways responding to aloe-emodin, providing a theoretical basis for applying anthraquinone derivatives in the treatment of GSDME-expressing cancers.

Novel Functional Food from an invasive species Polygonum cuspidatum: Safety evaluation, Chemical Composition, and Hepatoprotective Effects

Accidentally, we found that the shoots of Polygonum cuspidatum (SPC) have been consumed for centuries as a traditional vegetable in the Shennongjia region of China. Local residents believe that SPC has biological effects such as antibacterial, anti-aging, and antioxidant. To provide scientific support for the use of SPC as a functional food, SPC was evaluated in terms of safety, chemical composition, antioxidant activity both in vivo and in vitro. In the first, SPC exhibited no adverse cytotoxic effects or acute toxicity in mice. Then the chemical composition of SPC was determined by UHPLC-ESI-QTOF-MS/MS. 22 compounds were identified from the SPC extracts, including phenolic, flavonoid, stilbene, and anthraquinone. Finally, an acute ethanol-induced oxidative stress model in mice showed hepatoprotective effects. In brief, our study indicated that SPC is a safe, multi-functional food with antioxidant and hepatoprotective activities. Importantly, the consumption of SPC as a functional food provides a novel strategy of efficient utilization of the invasive plant.

Proteomics and metabolomics reveal the mechanism underlying differential antioxidant activity among the organs of two base plants of Shiliang tea (Chimonanthus salicifolius and Chimonanthus zhejiangensis)

The leaves and branches of Chimonanthus salicifolius and Chimonanthus zhejiangensis are the base ingredients of Shiliang tea. In this study, proteomics and metabolomics were performed to understand the molecular mechanisms underlying antioxidant activity (AA) in the leaves and branches of the two species. Stress and redox related proteins are differentially expressed among organs. The abundance of isoprenoid pathway-related proteins is higher in leaves while the abundance of phenylpropanoid and flavonoid pathway-related proteins is higher in branches in both species. Metabolomics revealed the flavonoid composition and demonstrated that procyanidins are more abundant in branches. Superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), and AA are stronger in branches than leaves. Overall, branches might contribute to redox homeostasis through SOD/GSH-PX and flavonoids. Furthermore, the high level of AA of branches might be largely due to their increased accumulation of procyanidins.

Expression, purification and structural characterization of resveratrol synthase from Polygonum cuspidatum

Polygonum cuspidatum, an important medicinal plant in China, is a rich source of resveratrol compounds, and its synthesis related resveratrol synthase (RS) gene is highly expressed in stems. The sequence of the resveratrol synthase was amplified with specific primers. Sequence comparison showed that it was highly homologous to the STSs. The RS gene of Polygonum cuspidatum encodes 389 amino acids and has a theoretical molecular weight of 42.4 kDa, which is called PcRS1. To reveal the molecular basis of the synthesized resveratrol activity of PcRS1, we expressed the recombinant protein of full-length PcRS1 in Escherichia coli, and soluble protein products were produced. The collected products were purified by Ni-NTA chelation chromatography and appeared as a single band on SDS-PAGE. In order to obtain higher purity PcRS1, SEC was used to purify the protein and sharp single peak, and DLS detected that the aggregation state of protein molecules was homogeneous and stable. In order to verify the enzyme activity of the high-purity PcRS1, the reaction product was detected at 303 nm. By predicting the structural information of monomer PcRS1 and PcRS1 ligand complexes, we analyzed the ligand binding pocket and protein surface electrostatic potential of the complex, and compared it with the highly homologous STSs protein structures of the iso-ligand. New structural features of protein evolution are proposed. PcRS1 obtained a more complete configuration and the optimal orientation of the active site residues, thus improving its catalytic capacity in resveratrol synthesis.

Polyphenol oxidase (PPO) arm of catecholamine pathway catalyzes the conversion of L-tyrosine to L-DOPA in Mucuna pruriens (L.) DC var. pruriens: An integrated pathway analysis using field grown and in vitro callus cultures

Mucuna pruriens (L.) DC var. pruriens is the natural source for _L-DOPA, precursor of the neurotransmitter dopamine, used widely in the treatment of Parkinson's disease. However, _L-DOPA synthesis in plants is mediated either by Catecholamine (CA) pathway or alternate pathway catalyzed by Cytochrome P450 (CYP450) class of enzymes. Interestingly, the CA pathway itself can be initiated either by tyrosine hydroxylase (TH) or polyphenol oxidase (PPO). The CA pathway mediated synthesis of _L-DOPA has not yet been proved in M. pruriens albeit strong indications. Therefore, the present investigation is focused on metabolite analysis of major intermediates of CA pathway up to the formation of dopamine and expression analysis of the selected genes, in different tissues and callus cultures. The four major intermediates, _L-tyrosine, tyramine, _L-DOPA and dopamine, were detected using NMR spectroscopy and quantified by HPLC in the callus cultures and in different tissues of the field plant, respectively. The various stages of leaf tissue were also analyzed for metabolite profiling. The relative amount of intermediates detected during the ontogeny of leaf indicates that PPO mediated conversion of _L-tyrosine to dopamine through _L-DOPA is relatively higher compared to dopamine production from tyramine. Among the two possible enzymes, activity of PPO was 6.5-fold more than TH in metabolically active young leaves compared to intermediate leaves. The gene expression profiles comprising upstream genes of _L-tyrosine synthesis and downstream up to dopamine synthesis shows strong correlation with _L-DOPA synthesis. The study validates CA pathway mediated synthesis of _L-DOPA with PPO as candidate enzyme, in M. pruriens.

Comparative metabolomics analysis of different sesame (Sesamum indicum L.) tissues reveals a tissue-specific accumulation of metabolites

BACKGROUND

Sesame (Sesamum indicum L.) leaves, flowers, especially seeds are used in traditional medicine to prevent or cure various diseases. Its seed's market is expanding. However, the other tissues are still underexploited due to the lack of information related to metabolites distribution and variability in the plant. Herein, the metabolite profiles of five sesame tissues (leaves, fresh seeds, white and purple flowers, and fresh carpels) have been investigated using ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS/MS)-based widely targeted metabolomics analysis platform.

RESULTS

In total, 776 metabolites belonging to diverse classes were qualitatively and quantitatively identified. The different tissues exhibited obvious differences in metabolites composition. The majority of flavonoids predominantly accumulated in flowers. Amino acids and derivatives, and lipids were identified predominantly in fresh seeds followed by flowers. Many metabolites, including quinones, coumarins, tannins, vitamins, terpenoids and some bioactive phenolic acids (acteoside, isoacteoside, verbascoside, plantamajoside, etc.) accumulated mostly in leaves. Lignans were principally detected in seeds. 238 key significantly differential metabolites were filtered out. KEGG annotation and enrichment analyses of the differential metabolites revealed that flavonoid biosynthesis, amino acids biosynthesis, and phenylpropanoid biosynthesis were the main differently regulated pathways. In addition to the tissue-specific accumulation of metabolites, we noticed a cooperative relationship between leaves, fresh carpels, and developing seeds in terms of metabolites transfer. Delphinidin-3-O-(6"-O-p-coumaroyl)glucoside and most of the flavonols were up-regulated in the purple flowers indicating they might be responsible for the purple coloration.

CONCLUSION

This study revealed that the metabolic processes in the sesame tissues are differently regulated. It offers valuable resources for investigating gene-metabolites interactions in sesame tissues and examining metabolic transports during seed development in sesame. Furthermore, our findings provide crucial knowledge that will facilitate sesame biomass valorization.

Tissue-specific transcriptome analyses reveal candidate genes for stilbene, flavonoid and anthraquinone biosynthesis in the medicinal plant Polygonum cuspidatum

BACKGROUND

Polygonum cuspidatum Sieb. et Zucc. is a well-known medicinal plant whose pharmacological effects derive mainly from its stilbenes, anthraquinones, and flavonoids. These compounds accumulate differentially in the root, stem, and leaf; however, the molecular basis of such tissue-specific accumulation remains poorly understood. Because tissue-specific accumulation of compounds is usually associated with tissue-specific expression of the related biosynthetic enzyme genes and regulators, we aimed to clarify and compare the transcripts expressed in different tissues of P. cuspidatum in this study.

RESULTS

High-throughput RNA sequencing was performed using three different tissues (the leaf, stem, and root) of P. cuspidatum. In total, 80,981 unigenes were obtained, of which 40,729 were annotated, and 21,235 differentially expressed genes were identified. Fifty-four candidate synthetase genes and 12 transcription factors associated with stilbene, flavonoid, and anthraquinone biosynthetic pathways were identified, and their expression levels in the three different tissues were analyzed. Phylogenetic analysis of polyketide synthase gene families revealed two novel CHS genes in P. cuspidatum. Most phenylpropanoid pathway genes were predominantly expressed in the root and stem, while methylerythritol 4-phosphate and isochorismate pathways for anthraquinone biosynthesis were dominant in the leaf. The expression patterns of synthase genes were almost in accordance with metabolite profiling in different tissues of P. cuspidatum as measured by high-performance liquid chromatography or ultraviolet spectrophotometry. All predicted transcription factors associated with regulation of the phenylpropanoid pathway were expressed at lower levels in the stem than in the leaf and root, but no consistent trend in their expression was observed between the leaf and the root.

CONCLUSIONS

The molecular knowledge of key genes involved in the biosynthesis of P. cuspidatum stilbenes, flavonoids, and anthraquinones is poor. This study offers some novel insights into the biosynthetic regulation of bioactive compounds in different P. cuspidatum tissues and provides valuable resources for the potential metabolic engineering of this important medicinal plant.

Orthogonality in the selection of biphasic solvent systems for off-line two-dimensional countercurrent chromatography from Polygonum cuspidatum Sieb. et Zucc

Off-line two-dimensional countercurrent chromatography has been widely applied to the isolation of complex samples, but little research on the investigation of orthogonality in the selection of biphasic solvent systems is available. In the present work, the orthogonality in the selection of a biphasic solvent system for liquid-liquid chromatographic separation of aqueous extract and ether extract from the traditional Chinese medicinal plant Polygonum cuspidatum Sieb. et Zucc was evaluated by the correlation coefficient and space occupancy rate. In total, 25 different biphasic solvent systems were tested, and 313 system combinations were analysed. A convex hull methodology was used to determine the separation space and to optimize separation conditions. The correlation coefficient matrix was transformed into dendrograms and a colour map to visualize the dissimilarity between, and orthogonality for, all solvent systems. The aqueous extracts from Polygonum cuspidatum were separated using selected biphasic solvent systems with high orthogonality: ethyl acetate-ethanol-water (70:1:70, v/v) and petroleum ether-ethyl acetate-water (1:5:5, v/v). The ether extracts from Polygonum cuspidatum were also separated using selected biphasic solvent systems with high orthogonality: petroleum-ethyl acetate-methanol-aqueous 0.25 M NH₃•H₂O (5:5:5:5, v/v) and petroleum-ethyl acetate-methanol-water (5:5:5:5, v/v). Thirteen compounds were successfully obtained. The experimental results demonstrated that the evaluation of orthogonality provided an alternative strategy to select an applicable solvent system for the separation of complex samples using off-line two-dimensional countercurrent chromatography.