A Comparative Metabolomics Analysis Reveals the Tissue-Specific Phenolic Profiling in Two Acanthopanax Species

Recent advances in methods of extraction, pre-concentration, purification, identification, and quantification of kaempferol

As a naturally widely-occurring dietary, cosmetic, and therapeutic flavonoid, kaempferol has gained much consideration for its nutritional and pharmaceutical properties in recent years. Although there have been performed a high number of studies associated with different aspects of kaempferol's analytical investigations, the lack of a comprehensive summary of the various methods and other plant sources that have been reported for this compound is being felt, especially for many biological applications. This study, aimed to provide a detailed compilation consisting of sources (plant species) and analytical information that was precisely related to the natural flavonoid (kaempferol). There is a trend in analytical research that supports the application of modern eco-friendly instruments and methods. In conclusion, ultrasound-assisted extraction (UAE) is the most general advanced method used widely today for the extraction of kaempferol. During recent years, there is an increasing tendency towards the identification of kaempferol by different methods.

Identification of Eleutherococcus senticosus NAC transcription factors and their mechanisms in mediating DNA methylation of EsFPS, EsSS, and EsSE promoters to regulate saponin synthesis

BACKGROUND

The formation of pharmacologically active components in medicinal plants is significantly impacted by DNA methylation. However, the exact mechanisms through which DNA methylation regulates secondary metabolism remain incompletely understood. Research in model species has demonstrated that DNA methylation at the transcription factor binding site within functional gene promoters can impact the binding of transcription factors to target DNA, subsequently influencing gene expression. These findings suggest that the interaction between transcription factors and target DNA could be a significant mechanism through which DNA methylation regulates secondary metabolism in medicinal plants.

RESULTS

This research conducted a comprehensive analysis of the NAC family in E. senticosus, encompassing genome-wide characterization and functional analysis. A total of 117 EsNAC genes were identified and phylogenetically divided into 15 subfamilies. Tandem duplications and chromosome segment duplications were found to be the primary replication modes of these genes. Motif 2 was identified as the core conserved motif of the genes, and the cis-acting elements, gene structures, and expression patterns of each EsNAC gene were different. EsJUB1, EsNAC047, EsNAC098, and EsNAC005 were significantly associated with the DNA methylation ratio in E. senticosus. These four genes were located in the nucleus or cytoplasm and exhibited transcriptional self-activation activity. DNA methylation in EsFPS, EsSS, and EsSE promoters significantly reduced their activity. The methyl groups added to cytosine directly hindered the binding of the promoters to EsJUB1, EsNAC047, EsNAC098, and EsNAC005 and altered the expression of EsFPS, EsSS, and EsSE genes, eventually leading to changes in saponin synthesis in E. senticosus.

CONCLUSIONS

NAC transcription factors that are hindered from binding by methylated DNA are found in E. senticosus. The incapacity of these NACs to bind to the promoter of the methylated saponin synthase gene leads to subsequent alterations in gene expression and saponin synthesis. This research is the initial evidence showcasing the involvement of EsNAC in governing the impact of DNA methylation on saponin production in E. senticosus.

Phytochemistry and Pharmacology of Eleutherococcus sessiliflorus (Rupr. & Maxim.) S.Y.Hu: A Review

Eleutherococcus sessiliflorus (Rupr. & Maxim.) S.Y.Hu (E. sessiliflorus), a member of the Araliaceae family, is a valuable plant widely used for medicinal and dietary purposes. The tender shoots of E. sessiliflorus are commonly consumed as a staple wild vegetable. The fruits of E. sessiliflorus, known for their rich flavor, play a crucial role in the production of beverages and fruit wines. The root barks of E. sessiliflorus are renowned for their therapeutic effects, including dispelling wind and dampness, strengthening tendons and bones, promoting blood circulation, and removing stasis. To compile a comprehensive collection of information on E. sessiliflorus, extensive searches were conducted in databases such as Web of Science, PubMed, ProQuest, and CNKI. This review aims to provide a detailed exposition of E. sessiliflorus from various perspectives, including phytochemistry and pharmacological effects, to lay a solid foundation for further investigations into its potential uses. Moreover, this review aims to introduce innovative ideas for the rational utilization of E. sessiliflorus resources and the efficient development of related products. To date, a total of 314 compounds have been isolated and identified from E. sessiliflorus, encompassing terpenoids, phenylpropanoids, flavonoids, volatile oils, organic acids and their esters, nitrogenous compounds, quinones, phenolics, and carbohydrates. Among these, triterpenoids and phenylpropanoids are the primary bioactive components, with E. sessiliflorus containing unique 3,4-seco-lupane triterpenoids. These compounds have demonstrated promising properties such as anti-oxidative stress, anti-aging, antiplatelet aggregation, and antitumor effects. Additionally, they show potential in improving glucose metabolism, cardiovascular systems, and immune systems. Despite some existing basic research on E. sessiliflorus, further investigations are required to enhance our understanding of its mechanisms of action, quality assessment, and formulation studies. A more comprehensive investigation into E. sessiliflorus is warranted to delve deeper into its mechanisms of action and potentially expand its pharmaceutical resources, thus facilitating its development and utilization.

Partial compression increases acidity, but decreases phenolics in jujube fruit: Evidence from targeted metabolomics

Jujube fruit (Ziziphus jujuba Mill.) is extremely susceptible to mechanical injury by extrusion and collision during storage, transportation and processing. In this study, we examined the morphology and endogenous metabolism of jujubes at three developmental stages after applying partial compression (PC) to mimic mechanical injury. Generally, PC did not affect the total soluble solids content, but increased the acidity and decreased the amount of phenolics in the jujube fruit. Targeted metabolomics analysis further confirmed that acid and phenolics content were differentially altered in response to PC. To our knowledge, this is the first study to characterize metabolic variations in ready-to-eat fruit that occur in response to physical damage. The results will provide insight into the understanding the consequences of mechanical injury on fruit nutrition and health benefits.

Chemical profile and antioxidant activity of bidirectional metabolites from Tremella fuciformis and Acanthopanax trifoliatus as assessed using response surface methodology

This study aimed to establish a bidirectional fermentation system using Tremella fuciformis and Acanthopanax trifoliatus to promote the transformation and utilization of the synthesized antioxidant metabolites from fermentation supernatant. The effect of fermentation conditions on the total phenolic content was investigated using response surface methodology in terms of three factors, including temperature (22–28°C), pH (6–8), and inoculum size (2–8%, v/v). The optimized fermentation parameters were: 28°C, pH 8, and an inoculum size of 2%, which led to a maximum total phenolic content of 314.79 ± 6.89 μg/mL in the fermentation supernatant after 24 h culture. The content of total flavonoids and polysaccharides reached 78.65 ± 0.82 μg/mL and 9358.08 ± 122.96 μg/mL, respectively. In addition, ABTS+, DPPH⋅, and ⋅OH clearance rates reached 95.09, 88.85, and 85.36% at 24 h under optimized conditions, respectively. The content of total phenolics, flavonoids and polysaccharides in the optimized fermentation supernatant of T. fuciformis–Acanthopanax trifoliatus increased by 0.88 ± 0.04, 0.09 ± 0.02, and 33.84 ± 1.85 times that of aqueous extracts from A. trifoliatus, respectively. Simultaneously, 0.30 ± 0.00, 0.26 ± 0.01, and 1.19 ± 0.12 times increase of antioxidant activity against ABTS+, DPPH⋅, and ⋅OH clearance rates were observed, respectively. Additionally, the metabolite composition changes caused by fermentation were analyzed using ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) based on untargeted metabolomics and the phytochemical profile of fermentation supernatant differentiated significantly based on unsupervised principal component analysis (PCA) during fermentation from 24 to 96 h. Furthermore, a significant increase in antioxidant phenolic and flavonoid compounds, such as ellagic acid, vanillin, luteolin, kaempferol, myricetin, isorhamnetin, and (+)-gallocatechin, was observed after fermentation. Thus, these results indicated that the fermentation broth of T. fuciformis and A. trifoliatus had significant antioxidant activity, and may have potential application for health products such as functional beverages, cosmetics, and pharmaceutical raw materials.

Metabolome and transcriptome analysis of eleutheroside B biosynthesis pathway in Eleutherococcus senticosus

Eleutheroside B (syringin) is a medicinal active ingredient extracted from Eleutherococcus senticosus (Ruper. et Maxim.) Maxim with high clinical application value. However, its synthesis pathway remains unknown. Here, we analyzed the eleutheroside B biosynthesis pathway in E. senticosus. Consequently, metabolomic and transcriptomic analyses identified 461 differentially expressed genes (DEGs) and 425 metabolites. Further, we identified 7 DEGs and 67 metabolites involved in the eleutheroside B biosynthetic pathway in the eleutheroside B high and low plants. The correlation between the gene and metabolites was explored using the pearson correlation coefficient (PCC) analysis. Caffeoyl-CoA O-methyltransferase, caffeic acid-O-methyltransferase, β-amyrin synthase (β-AS) genes, NAC5, and HB5 transcription factors were identified as candidate genes and transcription factors related to the eleutheroside B synthesis. Eleutheroside B content was the highest at the young stage of the leaves both in the high and low eleutheroside B plants. Quantitative real-time polymerase chain reaction revealed that phenylalanine ammonia-lyase1, cinnamate 4-hydroxylase, β-AS, and leucoanthocyanidin reductase gene had higher expression levels at the young stage of the leaves in the low eleutheroside B plants but lower expression levels in the high eleutheroside B plants. In the present study, we complemented the eleutheroside B biosynthetic pathway by analyzing the expression levels of relevant genes and metabolite accumulation patterns.

Ionomic and Metabolomic Analyses Reveal Different Response Mechanisms to Saline-Alkali Stress Between Suaeda salsa Community and Puccinellia tenuiflora Community

Soil salinization imposes severe stress to plants, inhibits plant growth, and severely limits agricultural productivity and land utilization. The response of a single plant to saline-alkali stress has been well investigated. However, the plant community that usually works as a group to defend against saline-alkali stress was neglected. To determine the functions of plant community, in our current work, Suaeda salsa (S. salsa) community and Puccinellia tenuiflora (P. tenuiflora) community, two communities that are widely distributed in Hulun Buir Grassland in Northeastern China, were selected as research objects. Ionomic and metabolomic were applied to compare the differences between S. salsa community and P. tenuiflora community from the aspects of ion transport and phenolic compound accumulation, respectively. Ionomic studies demonstrated that many macroelements, including potassium (K) and calcium (Ca), were highly accumulated in S. salsa community whereas microelement manganese (Mn) was highly accumulated in P. tenuiflora community. In S. salsa community, transportation of K to aboveground parts of plants helps to maintain high K+ and low Na+ concentrations whereas the accumulation of Ca triggers the salt overly sensitive (SOS)-Na+ system to efflux Na+. In P. tenuiflora community, enrichment of Mn in roots elevates the level of Mn-superoxide dismutase (SOD) and increases the resistance to saline-alkali stress. Metabolomic studies revealed the high levels of C6C1-compounds and C6C3C6-compounds in S. salsa community and also the high levels of C6C3-compounds in P. tenuiflora community. C6C1-compounds function as signaling molecules to defend against stress and may stimulate the accumulation of C6C3C6-compounds. C6C3-compounds contribute to the elimination of free radicals and the maintenance of cell morphology. Collectively, our findings determine the abundance of phenolic compounds and various elements in S. salsa community and P. tenuiflora community in Hulun Buir Grassland and we explored different responses of S. salsa community and P. tenuiflora community to cope with saline-alkali stress. Understanding of plant response strategies from the perspective of community teamwork may provide a feasible and novel way to transform salinization land.

Phenolics from Medicinal and Aromatic Plants: Characterisation and Potential as Biostimulants and Bioprotectants

Biostimulants and bioprotectants are derived from natural sources and can enhance crop growth and protect crops from pests and pathogens, respectively. They have attracted much attention in the past few decades and contribute to a more sustainable and eco-friendly agricultural system. Despite not having been explored extensively, plant extracts and their component secondary metabolites, including phenolic compounds have been shown to have biostimulant effects on plants, including enhancement of growth attributes and yield, as well as bioprotectant effects, including antimicrobial, insecticidal, herbicidal and nematicidal effects. Medicinal and aromatic plants are widely distributed all over the world and are abundant sources of phenolic compounds. This paper reviews the characterisation of phenolic compounds and extracts from medicinal and aromatic plants, including a brief overview of their extraction, phytochemical screening and methods of analysis. The second part of the review highlights the potential for use of phenolic compounds and extracts as biostimulants and bioprotectants in agriculture as well as some of the challenges related to their use.

A comprehensive analysis of transcriptome and phenolic compound profiles suggests the role of flavonoids in cotyledon greening in Catharanthus roseus seedling

During seedling photo-morphogenesis, cotyledon greening is a vital developmental process and a moment of responding to light stress. An increasing number of reports suggest the function of natural antioxidant protection of phenolic compounds in plant growth and development processes. Due to the antioxidant functions, flavonoids allow plants to respond to abiotic or biotic stresses. As one of the plants rich in secondary metabolites, Catharanthus roseus has drawn great academic interest due to its richness of diverse secondary metabolites with medicinal values. To assess the distribution and function of phenolic compounds during cotyledon greening, combined phenolic profiling and transcriptome were applied in C. roseus seedling through ultra-high performance liquid chromatography quadrupole time-of-flight mass spectrometer (UPLC-Q-TOF/MS) and high throughput RNA sequencing, respectively. Results herein showed that light-exposed greening cotyledon accumulated large amounts of C6C3C6-type flavonoids, suggesting the function in repressing reactive oxygen species (ROS) generation to improve light adaptation and seedling survival. Moreover, synergistic up-regulation of relevant genes involved in flavonoids pathway, including PAL, C4H, CHS, FLS, and F3'H, was monitored in response to light. Several crucial candidate transcription factors including bHLH, MYB, and B-box families were likely to function, and thereinto, CrHY5 (CRO_T122304) and CRO_T137938 revealed a prompt response to light, supposing to induce flavonoids accumulation by targeting CHS and FLS. Therefore, this study provided new insight into the potential regulation and underlying roles of flavonoids to improve light acclimation during cotyledon greening.

Different Metabolites in the Roots, Seeds, and Leaves of Acanthopanax senticosus and Their Role in Alleviating Oxidative Stress

In this study, we examined the metabolites from different parts of Acanthopanax senticosus and their role in alleviating damage caused by oxidative stress. We used UHPLC-QTOF-MS to analyze the chemical components in the root, seed, and leaf extracts of A. senticosus. Two multivariate statistical analysis methods-namely, principal component analysis and partial least square discriminant analysis-were used to distinguish the samples obtained from different parts of the plant. Using univariate statistics, 130 different metabolites were screened out. Among these, the relative content of flavonoids and terpenoids was found to be highest in the leaves, the lignin and phenolic acid content was highest in the roots, and the amino acid and phenolic acid levels were highest in seeds. An MTT assay was used to test the anti-H₂O₂ oxidative damage to PC12 cells in different parts of the sample. Lastly, using Pearson's correlation analysis, various metabolites from different parts of A. senticosus were correlated with their antioxidant effects from the corresponding parts. Fifty-two related different metabolites were found, of which 20 metabolites that were positively correlated to oxidative stress were present at a relatively higher level in the roots, whereas 32 metabolites that were negatively correlated were present at relatively higher levels in the seeds and leaves. The results of this study reveal the distribution characteristics and the antioxidant activity of different metabolites of A. senticosus and provide a reference for the rational development of its medicinal parts.

Comprehensive phytochemical analysis and sedative-hypnotic activity of two Acanthopanax species leaves

Acanthopanax senticosus leaves (SCL) and Acanthopanax sessiliflorus leaves (SFL), which are usually made into functional teas, possess similar pharmacological activities. With the aim of revealing their chemical compositions and evaluating their sedative-hypnotic effects, comprehensive metabolite profiling analysis based on ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UPLC-Q/TOF-MS) and high-performance liquid chromatography with evaporative light scattering detection (HPLC-ELSD) as well as bioassay studies in mice were performed for the first time. Firstly, a total of 75 compounds (including 69 shared components) were identified or briefly characterized. Results indicated that the leaves of the two species were both rich in phytochemicals and contained similar structural types. Secondly, 20 and 7 chemical markers were identified from SCL and SFL, respectively. Five oleanane-type triterpene saponins (ciwujianoside C1, C3, D2, E and saniculoside N) and two lupine-type triterpene saponins (1-deoxychiisanoside and 24-hydroxychiisanoside) may be used for rapid identification of SCL and SFL. Thirdly, the contents of rutin, hederacoside D, ciwujianoside B, -C3, -E and ursolic acid in SCL (0.308%, 0.024%, 0.042%, 0.131%, 0.038%, and 0.255%, respectively) were higher than in SFL (0.067%, 0.005%, 0.012%, 0.015%, 0.002%, and 0.087%, respectively). Fourthly, an in vivo bioassay verified that both SCL and SFL could inhibit autonomous activity, shorten sleep latency and prolong sleep duration in a dose-dependent manner. To a certain degree, SCL showed a higher and more stable effect. The hypnotic effect could be inhibited by flumazenil (FLU). The two leaves not only had an obvious antagonism action of p-chlorophenoxyacetic acid (pCPA) but also showed a synergistic hypnotic effect with 5-hydroxytryptophan (5-HTP). The beneficial bioactivity may be mediated by 5-hydroxytryptamine (5-HT) and γ-aminobutyric acid (GABA). Finally, network pharmacology analysis showed that the undifferentiated and differentiated compounds were the material basis for the similar and the different activities of two leaves. Some typical chemical markers (such as saniculoside N, hederacoside D, ciwujianoside C3, -E and ursolic acid, 24-hydroxychiisanoside and 1-deoxyisochiisanoside) were the potential active compounds and could be used as quality markers in the future. The present study furnished a basis for the further development and utilization of the leaves of these two Acanthopanax species.

Targeted Development-Dependent Metabolomics Profiling of Bioactive Compounds in Acanthopanax senticosus by UPLC-ESI-MS

An ultra-performance liquid chromatography-electrospray ionization-mass spectrometry targeted metabolomics strategy was applied to analyze protocatechuate, syringin, eleutheroside E, isofraxidin, hyperoside, kaempferol, and oleanolic acid, the active compounds in 3-year-old, 5-year-old, and 9-year-old Acanthopanax senticosus. Then, targeted metabolomics was conducted with 3 growth year plants to identify 19 phenolic metabolites related to the above-mentioned active compounds, including 9 C6C3C6-type, 6 C6C3-type, and 4 C6C1-type. Multivariate statistical analysis was applied to the bioactive metabolite data, and targeted metabolic profiling was used for marker compound classification and characterization. The results showed that 7 active compounds in the roots and stems in the 3 growth year plants differed. The principal component “Q” values showed that the total contents of 7 active compounds in 5-year-old roots and stems were higher than in other growth years. Results of targeted metabolomics profiling of 19 phenolic metabolites showed that the C6C1-type compounds accumulated in 9-year-old plants, the C6C3-type in 3-year-old plants, and the C6C3C6-type in 5-year-old plants. The stems had the greatest accumulations of the phenolic metabolites. C6C1 and C6C3-type metabolites are the most abundant in both roots and stems. In conclusion, the active compounds and pharmacological effects of A. senticosus in different growth years are different. The best harvest age for A. senticosus roots and stems was 5 years. The accumulation of 19 phenolic metabolites in different growth years also showed significant differences.

A comparative metabolomics analysis of the components of heartwood and sapwood in Taxus chinensis (Pilger) Rehd

Taxus chinensis is a well-known gymnosperm with great ornamental and medicinal value. Its purple red brown heartwood (HW) has many attributes such as straight texture, high density, mechanical strength, rich elasticity and corrosion resistance that is highly prized commercially. T. chinensis sapwood (SW), in comparison, lacks these important traits. At present, little is known about the differences of metabolites between the SW and HW in T. chinensis. Widely targeted metabolic profiling was performed to analyze the metabolic profiles of HW and SW in T. chinensis using Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-EI-MS). A total of 607 metabolites were detected in HW and SW. Among them, 146 metabolites were significantly higher, and 167 metabolites significantly lower, in HW as compared to SW. These differential metabolites were mainly involved in metabolic pathways and biosynthesis of secondary metabolites, such as flavonoids, flavone and flavonol, phenylpropanoids and antibiotics. Moreover, 71 flavonoids and isoflavones were found to be significantly different between HW and SW. Our results show the difference of components between the HW and SW, which has potential significance to further elucidate the mechanism of HW color formation. The results will provide insight into the metabolites associated with wood color formation and useful information for understanding the metabolites associated with wood quality.

Geographical Distribution and Environmental Correlates of Eleutherosides and Isofraxidin in Eleutherococcus senticosus from Natural Populations in Forests at Northeast China

Non-wood forest products (NWFPs) derived from understory plants are attracting attention about sustainable forestry development. Geographical distribution and climate correlates of bioactive compounds are important to the regional management for the natural reserves of medical plants in forests. In this study, we collected Eleutherococcus senticosus individuals from 27 plots to map the special distribution of concentrations of eleutheroside B, eleutheroside E, and isofraxidin in forests of Northeast China. Compound concentrations in both aerial and underground organs were further detected for relationships with the average of 20-year records of temperature, precipitation, and relative humidity (RH). We found higher shoot eleutheroside B concentration in populations in northern and low-temperature regions (R = −0.4394; P = 0.0218) and in eastern and high-RH montane forests (R = 0.5003; P = 0.0079). The maximum-likelihood regression indicated that both RH (Pr > Chi-square, 0.0201) and longitude (Pr > Chi-square, 0.0026) had positive contributions to eleutheroside B concentration in roots, but precipitation had strongly negative contributions to the concentrations of eleutheroside E (Pr > Chi-square, 0.0309) and isofraxidin (Pr > Chi-square, 0.0014) in roots. Both geography and climate factors had effects on the special distribution of medical compounds in E. senticosus plants in natural populations in Northeast China. The management of NWFP plants at the regional scale should consider effects from climatic geography.