Identification of Species in Tripterygium (Celastraceae) Based on DNA Barcoding

Genetic diversities in wild and cultivated populations of the two closely-related medical plants species, Tripterygium Wilfordii and T. Hypoglaucum (Celastraceae)

BACKGROUND

The sustainable supply of medicinal plants is important, and cultivating and domesticating them has been suggested as an optimal strategy. However, this can lead to a loss of genetic diversity. Tripterygium wilfordii Hook. f. is a medicinal plant commonly used in traditional Chinese medicine, but its wild populations are dwindling due to excessive harvesting. To protect the species and meet the increasing demand, it is urgent to cultivate it on a large scale. However, distinguishing between T. wilfordii and T. hypoglaucum, two similar species with different medicinal properties, is challenging. Therefore, it is crucial to understand the genetic diversity and population structure of these species for their sustainable utilization.

RESULTS

In this study, we investigated the genetic diversity and population structure of the two traditional medicinal semiwoody vines plant species, Tripterygium wilfordii and T. hypoglaucum, including wild and cultivated populations using chloroplast DNA (cpDNA) sequences and microsatellite loci. Our results indicated that the two species maintain a high level of genetic divergence, indicating possible genetic bases for the different contents of bioactive compounds of the two species. T. wilfordii showed lower genetic diversity and less subdivided population structures of both markers than T. hypoglaucum. The potential factors in shaping these interesting differences might be differentiated pollen-to-seed migration rates, interbreeding, and history of population divergence. Analyses of cpDNA and microsatellite loci supported that the two species are genetically distinct entities. In addition, a significant reduction of genetic diversity was observed for cultivated populations of the two species, which mainly resulted from the small initial population size and propagated vegetative practice during their cultivation.

CONCLUSION

Our findings indicate significant genetic divergence between T. wilfordii and T. hypoglaucum. The genetic diversity and population structure analyses provide important insights into the sustainable cultivation and utilization of these medicinal plants. Accurate identification and conservation efforts are necessary for both species to ensure the safety and effectiveness of crude drug use. Our study also highlighted the importance of combined analyses of different DNA markers in addressing population genetics of medicinal plants because of the contrasts of inheritance and rates of gene flow. Large-scale cultivation programs should consider preserving genetic diversity to enhance the long-term sustainability of T. wilfordii and T. hypoglaucum. Our study proposed that some populations showed higher genetic diversity and distinctness, which can be considered with priority for conservation and as the sources for future breeding and genetic improvement.

Subchronic toxicity evaluation of Huobahuagen extract and plasma metabolic profiling analysis combined with conventional pathology methods

Huobahua, namely, Tripterygium hypoglaucum (Levl.) Hutch, known as a traditional Chinese herbal medicine, especially its underground parts, has been widely developed into several Tripterygium agents for the treatment of rheumatoid arthritis and other autoimmune diseases. It has sparked wide public concern about its safety, such as multi-organ toxicity. However, the toxic characteristics and damage mechanism of Huobahuagen extract (HBHGE) remain unclear. In the present study, subchronic oral toxicity study of HBHGE (10.0 g crude drug/kg/day for 12 weeks) was performed in male rats. Hematological, serum biochemical, and histopathological parameters, urinalysis, and plasma metabolic profiling were assessed. The single-dose subchronic toxicity results related to HBHGE exhibited obvious toxicity to the testis and epididymis of male rats. Furthermore, plasma metabolomics analysis suggested that a series of metabolic disorders were induced by oral administration of HBHGE, mainly focusing on amino acid (glutamate, phenylalanine, and tryptophan) metabolisms, pyrimidine metabolism, glutathione metabolism, and steroid hormone biosynthesis. Moreover, it appeared that serum testosterone in male rats treated with HBHGE for 12 weeks, decreased significantly, and was susceptible to the toxic effects of HBHGE. Taken together, conventional pathology and plasma metabolomics for preliminarily exploring subchronic toxicity and underlying mechanism can provide useful information about the reduction of toxic risks from HBHGE and new insights into the development of detoxification preparations.

Comparative analyses of complete chloroplast genomes reveal interspecific difference and intraspecific variation of Tripterygium genus

The genus Tripterygium was of great medicinal value and attracted much attention on the taxonomic study using morphological and molecular methods. In this study, we assembled 12 chloroplast genomes of Tripterygium to reveal interspecific difference and intraspecific variation. The sequence length (156,692-157,061 bp) and structure of Tripterygium were conserved. Comparative analyses presented abundant variable regions for further study. Meanwhile, we determined the ndhB gene under positive selection through adaptive evolution analysis. And the phylogenetic analyses based on 15 chloroplast genomes supported the monophyly of Tripterygium hypoglaucum and the potential sister relationship between Tripterygium wilfordii and Tripterygium regelii. Molecular dating analysis indicated that the divergence time within Tripterygium was approximately 5.99 Ma (95% HPD = 3.11-8.68 Ma). The results in our study provided new insights into the taxonomy, evolution process, and phylogenetic construction of Tripterygium using complete plastid genomes.

Network Pharmacology and Experimental Validation to Explore That Celastrol Targeting PTEN is the Potential Mechanism of Tripterygium wilfordii (Lév.) Hutch Against IgA Nephropathy

Purpose

Accumulating clinical evidence showed that Tripterygium hypoglaucum (Lév.) Hutch (THH) is effective against IgA nephropathy (IgAN), but the mechanism is still unclear. This study is to evaluate the renal protective effect and molecular mechanism of THH against IgAN via network pharmacology, molecular docking strategy and experimental validation.

Methods

Several databases were used for obtaining the active ingredients of THH, the corresponding targets, as well as the IgAN-related genes. The critical active ingredients, functional pathways, and potential for the combination of the hub genes and their corresponding active components were determined through bioinformatics analysis and molecular docking. The IgAN mouse model was treated with celastrol (1 mg/kg/d) for 21 days, and the aggregated IgA1-induced human mesangial cell (HMC) was treated with various concentrations of celastrol (25, 50 or 75 nM) for 48 h. The immunohistochemistry and Western blot techniques were applied to evaluate the protein expression of the predicted target. The cell counting kit 8 (CCK8) was used to detect HMC proliferation.

Results

A total of 17 active ingredients from THH were screened, covering 165 IgAN-related targets. The PPI network identified ten hub targets, including PTEN. The binding affinity between the celastrol and PTEN was the highest (-8.69 kJ/mol). The immunohistochemistry showed that celastrol promoted the expression of PTEN in the glomerulus of IgAN mice. Furthermore, the Western blot techniques showed that celastrol significantly elevated the expression of PTEN and inhibited PCNA and Cyclin D1 in vitro and in vivo. The CCK8 assay determined that celastrol decreased HMC proliferation in a concentration-dependent manner.

Conclusion

This study suggests that activating PTEN by celastrol may play a pivotal role in THH alleviating IgAN renal injury.

Applications and Mechanisms of Tripterygium Wilfordii Hook. F. and its Preparations in Kidney Diseases

Tripterygium wilfordii Hook. f. (TwHF) is a Chinese botanical drug containing a large number of metabolites. The discovered and recognized anti-inflammatory and immune-regulating effects have made it attract more and more attentions in trials and clinical researches. The extraction and processing of TwHF for pharmaceuticals is a manifestation of the role of traditional Chinese medicine. However, TwHF is toxic. Optimization of TwHF preparations has become a requirement for the development of TwHF pharmaceuticals. Our article introduces the main preparations of TwHF on the Chinese market and their characteristics. In particular, we summarize the clinical applications and influential mechanisms of TwHF and its preparations in kidney diseases. Considering that nephropathy is closely related to immune inflammation and TwHF is a botanical drug with a high number of metabolites, the application of TwHF in kidney diseases may be much more complicated. By revealing the role and mechanisms of TwHF in kidney diseases, this study aims to provide more insights to basic and clinical studies about nephropathy.

Role of Glutamine-Glutamate/GABA cycle and potential target GLUD2 in alleviation of rheumatoid arthritis by Tripterygium hypoglaucum (levl.) Hutch based on metabolomics and molecular pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium hypoglaucum (levl.) Hutch (Celastraceae) (THH), as a traditional Chinese medicine, was clinically exploited to treat rheumatoid arthritis (RA), yet the underlying mechanism for this effect remains largely unclear.

AIM OF THE STUDY

This study aimed to examine the beneficial effects of THH extract (THHE) against rheumatoid arthritis and its regulating role in differential metabolic pathways and potential targets.

MATERIALS AND METHODS

In the present study, the Lewis rat model with rheumatoid arthritis induced by adjuvant was established and administrated THHE for 14 days. Untargeted/targeted metabolomics analysis were used for determining the changes of differential metabolites, and molecular docking method was further developed to verify predicted targets and investigate the therapeutic mechanism of THH extract on RA.

RESULTS

The results showed that THH extract could obviously improve body weight, significantly decrease the joint index and swelling degree of the RA model rats to reduce damage in the joint. Meanwhile, THHE could significantly suppress the releases of IL-1α, IL-1β and MMP3, but also the expression levels of IL-4 and IL-10 and percentage of Treg cells were significantly improved, a result consistent with inhibitory effects on multiplication of macrophages, inflammatory cell infiltration and fibro genesis in the synovial tissues. Furthermore, 516 differential metabolites were identified by serum metabolic profiles analysis, including vitamin, organic acids and derivatives, lipids and lipid-like molecule, hormone, amino acids and derivatives, and other compounds, which targeted 47 metabolic pathways highly correlated with immunosuppression, such as citrate cycle (TCA cycle), sphingolipid metabolism, urea cycle, arachidonic acid metabolism and amino acid metabolism (such as Glutamine-Glutamate metabolism). Targeted metabolomics was used to verify that L-Glutamate and Glutamine changed significantly after THHE administration for 14 days, and many active ingredients of THHE could be successfully docked with glutamate dehydrogenase 2 (GLUD2).

CONCLUSION

This study indicated that the Glutamine-Glutamate/GABA cycle played essential regulation roles in protective effect of THHE on rat RA following adjuvant-induced damage, and GLUD2 as an attractive target also provides great potential for development of therapy agents for rheumatoid arthritis and autoimmune diseases with less unfavorable tolerability profile.

Development of a Specific Mini-Barcode From Plastome and its Application for Qualitative and Quantitative Identification of Processed Herbal Products Using DNA Metabarcoding Technique: A Case Study on Senna

Herbal products play an important role globally in the pharmaceutical and healthcare industries. However, some specific groups of herbal products are easily adulterated by confused materials on the market, which seriously reduces the products’ quality. Universal conventional DNA barcodes would function poorly since the processed herbal products generally suffer from varying degrees of DNA degradation and DNA mixing during processing or manufacturing. For quality control purposes, an accurate and effective method should be provided for species identification of these herbal products. Here, we provided a strategy of developing the specific mini-barcode using Senna as an example, and by coupling with the metabarcoding technique, it realized the qualitative and quantitative identification of processed herbal products. The plastomes of Senna obtusifolia (L.) H.S.Irwin & Barneby and Senna occidentalis (L.) Link were newly assembled, and the hypervariable coding-regions were identified by comparing their genomes. Then, the specific mini-barcodes were developed based on the identified hypervariable regions. Finally, we applied the DNA metabarcoding technique to the developed mini-barcodes. Results showed that the lengths of plastomes of S. obtusifolia and S. occidentalis were 162,426 and 159,993 bp, respectively. Four hypervariable coding-regions ycf1, rpl23, petL, and matK were identified. Two specific mini-barcodes were successfully developed from matK, and the mini-barcode of primer 647F-847R was proved to be able to qualitatively and quantitatively identify these two processed Senna seeds. Overall, our study established a valuable way to develop the specific mini-barcode, which may provide a new idea for the quality control of processed herbal products.

Triptolide: reflections on two decades of research and prospects for the future

Covering: 2000 to 2020 Triptolide is a bioactive diterpene triepoxide isolated from Tripterygium wilfordii Hook F, a traditional Chinese medicinal plant whose extracts have been used as anti-inflammatory and immunosuppressive remedies for centuries. Although triptolide and its analogs exhibit potent bioactivities against various cancers, and inflammatory and autoimmune diseases, none of them has been approved to be used in the clinic. This review highlights advances in material sourcing, molecular mechanisms, clinical progress and new drug design strategies for triptolide over the past two decades, along with some prospects for the future course of development of triptolide.

Molecular Identification of Three Aquilaria (Thymelaeaceae) Species through DNA Barcoding

Aquilaria LAM. is an endangered tropical tree that produces agarwood, a common ingredient in medicine, perfumes and incense. The species endemic to China, Aquilaria yunnanensis, is often misidentified as the two valuable species, Aquilaria sinensis and Aquilaria crassna. In present study, three DNA barcodes (internal transcribed spacer (ITS), maturase K gene (matK) and trnL-trnF) were used to evaluate whether these genes can be used to discriminate the three species, and evaluate the phylogenetic relationship between the three Aquilaria species. For accurate identification of the three Aquilaria species, a total of 26 nucleotide variations were detected when comparing the three DNA barcodes. We found that A. sinensis is closely related to A. crassna based on combination of nuclear and chloroplast DNA barcodes, and is closely related to A. yunnanensis based on chloroplast DNA barcodes. Taken together, we suggest that the combination of ITS+matK and ITS+trnL-trnF are suitable for identifying these three Aquilaria species.

Investigation on Species Authenticity for Herbal Products of Celastrus Orbiculatus and Tripterygum Wilfordii from Markets Using ITS2 Barcoding

Herbal material is both a medicine and a commodity. Accurate identification of herbal materials is necessary to ensure the safety and effectiveness of medication. With this work, we initiated an identification method to investigate the species authenticity for herbal products of Celastrus orbiculatus and Tripterygum wilfordii utilizing DNA barcoding technology. An ITS2 (internal transcribed spacer two) barcode database including 59 sequences was successfully established to estimate the reliability of species-level identification for Celastrus and Tripterygium. Our findings showed that ITS2 can effectively and clearly distinguish C. orbiculatus, T. wilfordii and its congeners. Then, we investigated the proportions and varieties of adulterant species in the herbal markets. The data from ITS2 region indicated that 13 (62%) of the 21 samples labeled as “Nan-she-teng” and eight (31%) of the 26 samples labeled as “Lei-gong-teng” were authentic; the remaining were adulterants. Of the 47 herbal products, approximately 55% of the product identity were not in accordance with the label. In summary, we support the efficacy of the ITS2 barcode for the traceability of C. orbiculatus and T. wilfordii, and the present study provides one method and reference for the identification of the herbal materials and adulterants in the medicinal markets.

Phylogeographic and phylogenetic analysis for Tripterygium species delimitation

Tripterygium wilfordii (Celastraceae) is a traditional Chinese medicine; and the dried root and rhizome constitute the main officinal parts. Tripterygium wilfordii has been identified as a potential candidate for the treatment of systemic lupus erythematosus, rheumatoid arthritis, nephritis, asthma, leprosy, and cancer. The phylogenetic relationships within the Tripterygium genus are ambiguous; thus, our aim is to clarify the relationships within this genus using phylogeographic and phylogenetic analyses. Here, we first sequenced three plastid DNA regions (i.e., psbA‐trnH, rpl32‐trnL, and trnL‐trnF) and found that Tripterygium hypoglaucum and T. wilfordii were clustered together based on the strength of the topology in the phylogenetic analysis: T. hypoglaucum is polyphyletic, and T. wilfordii is paraphyletic. A spatial analysis of molecular variance showed that the best group value is 4, and the groups were almost consistent with the topology of in the phylogenetic analysis. The Mantel analyses of Tripterygium using IBD web showed statistically significant relationships between genetic and geographical distance distributions (r = .3479, p < .0001). The molecular dating using Fossil calibration indicated that the divergence in Tripterygium was approximately 8.13 Ma. Furthermore, we also analyzed four DNA regions (i.e., ITS2, psbA‐trnH, matK, and rbcL) that were obtained from the NCBI nucleotide database; these results showed that T. wilfordii and T. hypoglaucum clustered together, while Tripterygium regelii represented a separate cluster. Tripterygium hypoglaucum and T. wilfordii were never distinct lineages, and the species circumscriptions are artificial. We propose that T. wilfordii and T. hypoglaucum are conspecific, while T. regelii likely constitutes a separate species.