A chromosome-level genome reveals genome evolution and molecular basis of anthraquinone biosynthesis in Rheum palmatum.

BACKGROUND: Rhubarb is one of common traditional Chinese medicine with a diverse array of therapeutic efficacies. Despite its widespread use, molecular research into rhubarb remains limited, constraining our comprehension of the geoherbalism. RESULTS: We assembled the genome of Rheum palmatum L., one of the source plants of rhubarb, to elucidate its genome evolution and unpack the biosynthetic pathways of its bioactive compounds using a combination of PacBio HiFi, Oxford Nanopore, Illumina, and Hi-C scaffolding approaches. Around 2.8 Gb genome was obtained after assembly with more than 99.9% sequences anchored to 11 pseudochromosomes (scaffold N50 = 259.19 Mb). Transposable elements (TE) with a continuous expansion of long terminal repeat retrotransposons (LTRs) is predominant in genome size, contributing to the genome expansion of R. palmatum. Totally 30,480 genes were predicted to be protein-coding genes with 473 significantly expanded gene families enriched in diverse pathways associated with high-altitude adaptation for this species. Two successive rounds of whole genome duplication event (WGD) shared by Fagopyrum tataricum and R. palmatum were confirmed. We also identified 54 genes involved in anthraquinone biosynthesis and other 97 genes entangled in flavonoid biosynthesis. Notably, RpALS emerged as a compelling candidate gene for the octaketide biosynthesis after the key residual screening. CONCLUSION: Overall, our findings offer not only an enhanced understanding of this remarkable medicinal plant but also pave the way for future innovations in its genetic breeding, molecular design, and functional genomic studies.

Mid-infrared spectroscopic identification of the right-baked rhubarb for ulcerative colitis therapy.

Clinical and experimental evidences have confirmed the significant therapeutic effects of rhubarb on ulcerative colitis (UC), but the strong purgative function of rhubarb also aggravates UC symptoms such as bloody diarrhea. Stir-baking to scorch is a traditional Chinese medicinal processing method that can eliminate the adverse purgative function while keep or even enhance the UC therapeutic function of rhubarb. However, the under-baked rhubarb still have the undesirable purgative function, but the over-baked rhubarb may lose the required medicinal functions. Therefore, the determination of the right endpoint is the primary quality concern about the baking process of rhubarb. In this research, typical anthraquinone compounds and mid-infrared (MIR) spectra were recruited to determine the best baking degree of rhubarb for UC therapy. Raw rhubarb slices were baked at 180 °C with rotation to prepare the rhubarbs with different baking degrees. The right-baked rhubarb was defined according to the UC therapeutic responses as well as the traditional color criterion. Referring to the typical anthraquinone compounds in rhubarb slices and extracts, the baking degree of rhubarb may be assessed by the conversion ratio of anthraquinone glycosides to anthraquinone aglycones. MIR spectra showed the gradual decompositions of organic compounds including anthraquinone glycosides and tannins during the baking process. Rhubarbs with different baking degrees can be distinguished clearly by MIR-based principal component analysis. In conclusion, the ratio of anthraquinone glycosides to anthraquinone aglycones may be a reasonable chemical indicator of the right-baked rhubarb. Meanwhile, MIR spectroscopy can identify the right-baked rhubarb simply and rapidly.

Optimized therapeutic potential of Yinchenhao decoction for cholestatic hepatitis by combined network meta-analysis and network pharmacology.

BACKGROUND: Cholestatic hepatitis is recognized as a significant contributor to the development of liver fibrosis and cirrhosis. As a well-known classic formula for the treatment of cholestatic hepatitis, Yinchenhao decoction (YCHD) is widely used in countries in Asia, including China, Japan, and Korea. However, in recent years, a risk of liver injury has been reported from Rheum palmatum L. and Gardenia jasmonoides J.Ellis which are the main ingredients of YCHD. Therefore, the question arises whether YCHD is still safe enough for the treatment of cholestatic hepatitis or whether an optimized ratio of ingredients should be applied. These is inevitable questions for the clinical application of YCHD. PURPOSE: To provide a scientific basis for the clinical application of YCHD through a combination of meta-analysis and network pharmacology and to find the best ratio of components to ensure optimal therapeutic efficacy and safety. At the same time, a deeper understanding of the mechanisms of YCHD was explored. METHODS: We retrieved relevant trials from various databases including PubMed, Web of Science, EMBASE, Cochrane Library, China National Knowledge Infrastructure (CNKI), VIP and Wanfang databases up to August 2023. After screening for inclusion and exclusion criteria, we assessed efficiency, ALT, AST, and TBIL as outcome parameters. The relevant data underwent a network meta-analysis using STATA 16.0 software. Based on network pharmacology, we screened the disease targets, active ingredients, and targets related to YCHD. The targets were visualized using Cytoscape 3.9.1. Then, potential mechanisms were explored based on bioinformatic techniques. RESULTS: Twenty eligible studies were finally screened and a total of 1,591 patients who fulfilled the inclusion criteria were enrolled in the study. The meta-analysis results indicated that TG-c (treatment group c) [(Artemisia capillaris Thunb. : Gardenia jasminoides J.Ellis : Rheum palmatum L. = 10:5:2-10:5:3) + CT] was the most promising therapeutic approach, demonstrating superior efficacy and notable improvements in both AST and TBIL levels. For ALT, TG-d [(Artemisia capillaris : Gardenia jasminoides : Rheum palmatum = 5:1:1-5:2:1) + CT] exhibited the greatest potential as optimal therapy option. Based on the surface under the cumulative ranking curve (SUCRA) values, TG-c was the best therapy in terms of efficiency and improvement in TBIL levels, while TG-d was the most effective in reducing ALT levels. For AST levels, TG-e [(Artemisia capillaris : Gardenia jasminoides : Rheum palmatum = 5:2:2-5:3:3) + CT] was the most effective therapy. The comprehensive analysis revealed that TG-c exhibited the most pronounced efficacy. Combined network pharmacology, GO enrichment analysis and KEGG pathway enrichment analysis displayed that the key target genes of Artemisia capillaris, Rheum palmatum, and Gardenia jasminoides were closely involved in inflammation response, bile transport, apoptosis, oxidative stress, and regulation of leukocyte migration. Notably, bile secretion dominated the common pathway of the three herbs. On the other hand, Artemisia capillaris exhibited a unique mode of action by regulating the IL-17 signaling pathway, which may play a crucial role in its effectiveness. CONCLUSION: Based on our findings, the optimal TG-C demonstrated the most favorable overall therapeutic efficacy by increasing the dosage of Artemisia capillaris while reducing the dosage of Gardenia jasminoides and Rheum palmatum. This is attributed to the potent ability of Artemisia capillaris. to effectively modulate the IL-17 signaling pathway, thereby exerting a beneficial therapeutic effect. Conversely, Gardenia jasminoides and Rheum palmatum may potentially enhance the activation of the NF-кB signaling pathway, thereby elevating the risk of hepatotoxicity.

Network analysis of microbiome and metabolome to explore the mechanism of raw rhubarb in the protection against ischemic stroke via microbiota-gut-brain axis.

Ischemic stroke (IS) has attracted worldwide attention due to the high mortality and disability rate. Raw rhubarb (RR) is a traditional medicinal plant and whole-food that has been used in China for its various pharmacological activities, such as antioxidant and anti-inflammatory properties. Recent pharmacological research has shown the role of RR against IS, but its mechanism of action remains unclear, particularly in the context of the brain-gut axis. To address this gap in knowledge, the present study was conducted in the middle cerebral artery occlusion/reperfusion (MCAO/R) model with the aim of investigating the effects of RR on regulating the intestinal microbiota barrier and metabolism and thereby reducing inflammatory response so as to improve the IS. The results showed that pre-treatment of RR attenuated cerebral infarct area and inflammation response in MCAO rats. Furthermore, RR also improved intestinal barrier function, including the integrity and permeability of the intestinal barrier. Additionally, RR intervention significantly attenuated gut microbiota dysbiosis caused by ischemic stroke, especially the increased Firmicutes. Notably, the pseudo-germ-free (PGF) rats further demonstrated that the anti-stroke effect of RR might rely on intestinal microbiota. In addition, the UPLC/Q-Orbitrap-MS-Based metabolomics revealed the disrupted metabolic profiles caused by MCAO/R, and a total of 11 differential metabolites were modulated by RR administration, especially bile acids. Further correlation analysis and network pharmacology analysis also demonstrated a strong association between specific bacteria, such as Firmicutes and bile acids. In conclusion, our work demonstrated that RR could effectively ameliorate ischemic stroke by modulating the microbiota and metabolic disorders.

Prediction of potential mechanisms of rhubarb therapy for colorectal cancer based on network pharmacological analysis and molecular docking.

The objective of this study was to investigate the potential targets and mechanism of Rheum palmatum L in the treatment of colorectal cancer based on the network pharmacology and molecular docking, which could provide the theoretical basis for clinical applications. The potential components were screened using TCMSP database and articles. The gene targets of colorectal cancer were screened through the Genecards database and Online Mendelian Inheritance in Man database. Then, the common targets of components and colorectal cancer were used to construct the network diagram of active components and targets in Cytoscape 3.7.0. The protein-protein interaction (PPI) diagram was generated using String database, and the targets were further analyzed by gene ontology and Kyoto Encyclopedia of Genes and Genomes. Molecular docking between gene targets and active components was analyzed via AutoDock, and visualized through PyMol. Among this study, main targets might be TP53, EGF, MYC, CASP3, JUN, PTGS2, HSP90AA1, MMP9, ESR1, PPARG. And 10 key elements might associate with them, such as aloe-emodin, beta-sitosterol, gallic acid, eupatin, emodin, physcion, cis-resveratrol, rhein, crysophanol, catechin. The treatment process was found to involve nitrogen metabolism, p53 signaling pathway, and various cancer related pathway, as well as the AGE-RAGE signaling pathway, estrogen signaling pathway, interleukin-17 signaling pathway and thyroid hormone signaling pathway. The molecular docking was verified the combination between key components and their respective target proteins. Network pharmacological analysis demonstrated that R palmatum was could regulated p53, AGE-RAGE, interleukin-17 and related signaling pathway in colorectal cancer, which might provide a scientific basis of mechanism.

Metabolomics analysis reveals the metabolite profiles of Rheum tanguticum grown under different altitudinal gradients.

BACKGROUND: Plant growth and quality are often affected by environmental factors, including geographical location, climate, and soil. In this study, we describe the effect of altitudinal differences on the growth and active ingredients in Rheum tanguticum Maxim. ex Balf. (R. tanguticum), a traditional Chinese medicinal herb known for its laxative properties. RESULTS: The results showed that plants grown at lower altitudes had better growth performances than those in higher altitude areas. The yield varied by 2.45-23.68 times with altitude, reaching a maximum of 102.01 t/ha. In addition, total anthraquinone and total sennoside contents decreased with increasing altitude, whereas total tannins increased with increasing altitude. The total anthraquinone content of the indicator compound reached 5.15% at five experimental sites, which exceeded the Chinese Pharmacopoeia standard by 70.87%. The content of the other two categories of active ingredients reached a maximum value of 0.94% (total sennosides) and 2.65% (total tannins). Redundancy analysis revealed that annual rainfall, annual average temperature, annual sunshine hours, and pH significantly affected growth and active ingredients. Moreover, key metabolites, such as flavonoids, amino acids and their derivatives, phenolic acids, lipids, and terpenes, were differentially expressed between samples from low- and high-altitude cultivation areas. These metabolites were enriched in the flavonoid and flavonol biosynthetic pathway and the monoterpene biosynthetic pathway. CONCLUSIONS: These results suggest that high anthraquinone content was observed in the lowest-latitude cultivation area due to low rainfall and alkaline soil pH. Key metabolites were significantly upregulated in high-latitude cultivation areas. These results provide a scientific basis for quality control and the systematic cultivation of R. tanguticum.

Distinguishment of different varieties of rhubarb based on UPLC fingerprints and chemometrics.

Rhubarb, a widely used traditional Chinese medicine (TCM), is primarily used for purging in practice. It is derived from the dried roots and rhizomes of R. tanguticum Maxim. ex Balf. (RT), Rheum officinale Baill. (RO) and R. palmatum L. (RP). To date, although the three varieties of rhubarb have been used as the same medicine in clinical, studies have found that they have different chemical compositions and pharmacological effects. To ensure the stability of rhubarb for clinical use, a simple and effective method should be built to compare and discriminate three varieties of rhubarb. Here, ultra-performance liquid chromatography-diode array detection (UPLC-DAD) fingerprints combined with chemometric methods were developed to evaluate and discriminate 29 batches of rhubarb. Similarity evaluation, hierarchical cluster analysis (HCA) and principal component analysis (PCA) showed that the chemical constituents of the three varieties of rhubarb were significantly different, and the three varieties could be effectively distinguished. Finally, all the 14 common peaks were identified by ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In this research, the developed UPLC fingerprints offer a simple, reliable and specific approach for distinguishing different varieties of rhubarb. This research aims to promote the scientific and appropriate clinical application of rhubarb from three varieties.

Application of two-dimensional reversed phase countercurrent chromatography × high-performance liquid chromatography to bioactivity-guided screening and isolation of α-glucosidase inhibitors from Rheum palmatum L.

In the present work, comprehensive two-dimensional reversed-phase countercurrent chromatography × reversed-phase liquid chromatography combined (2D RPCCC × RPLC) with 2D microfraction bioactive evaluation was employed to screen and isolate α-glucosidase inhibitors from Rheum palmatum L. Countercurrent chromatography was employed to improve 2D analysis and preparative separation. A selected biphasic solvent system composed of petroleum ether/ethyl acetate/methanol/water with gradient elution mode was used for the first dimension RPCCC separation (1D RPCCC). Solid-phase extraction was applied to eliminate interfering polar compounds before the second dimension analysis (2D RPLC). 76 components were shown in 2D contour plot in UV 280 nm. 11 Candidates were separated by a scaled-up CCC and identified by 1H NMR and 13C NMR, including anthraquinones, flavonoids, stilbenes, phenols, and glucoside derivatives. In addition, it was found that two components, resveratrol-4'-O-(6″-galloyl)glucoside (36) and lyciumaside (43) were identified as natural α-glucosidase inhibitors in Rheum palmatum L. for the first time.

Free total rhubarb anthraquinones protect intestinal mucosal barrier of SAP rats via inhibiting the NLRP3/caspase-1/GSDMD pyroptotic pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhubarb is the peeled and dried roots of Rheum palmatum L. and Rheum tanguticum Maxim. ex Balf. or Rheum officinale Baill. Free total rhubarb anthraquinones (FTRAs) were isolated and extracted from rhubarb. Previous studies have revealed that the early administration of FTRAs protects the intestinal mucosal barrier in rats with severe acute pancreatitis (SAP), the mechanism of which is not yet clear. However, we observed an enhanced expression of intestinal pyroptotic factors in rats treated with SAP, which may be related to the mechanism of intestinal barrier protection by FTRAs. AIM OF THE STUDY: The main objective of this study was to investigate the mechanism by which FTRAs protect the intestinal mucosal barrier in SAP rats, focusing on the classical pyroptosis pathway. MATERIALS AND METHODS: SAP was induced in rats through retrograde injection of sodium taurocholate via the pancreaticobiliary duct. Subsequently, FTRAs (22.5, 45, and 90 mg/kg), rhubarb (900 mg/kg, positive control), and saline (control) were administered at 0 h (immediately), 12 h, and 24 h post-surgery. Pancreatic and intestinal tissue injury, positive PI staining rate, and expression levels of various factors in intestinal tissues were compared across different groups. These factors include diamine oxidase (DAO), lactate dehydrogenase (LDH), high mobility group box chromosomal protein 1(HMGB1) and pro-inflammatory factors in intestinal and serum, pyroptosis-associated factors, toll-like receptor 4 (TLR-4), nuclear factor kappa-B (NF-kB), apoptosis-associated speck-like protein (ASC), NOD-like receptor protein 3 (NLRP3), cysteine protease-1 (caspase-1) and Gasdermin (GSDMD). RESULTS: The findings indicated that FTRAs protected the damaged intestine and pancreas and restored the expression of intestinal epithelial junction proteins in SAP rats. Additionally, it reduced intestinal and serum levels of DAO, interleukin 1, interleukin 18, HMGB1, and LDH, attenuated intestinal Positive PI staining rate, and significantly decreased the expressions of TLR-4, NF-kB, ASC, NLRP3, caspase-1 and GSDMD in SAP rats. CONCLUSIONS: The results suggest that FTRAs inhibited pyroptosis through down-regulation of the NLRP3-Caspase-1-GSDMD and TLR-4- NF-kB signaling pathways of intestinal tissues., thereby protecting the intestinal barrier of SAP rats.

Revealing the anti-inflammatory ingredients in wine-processed Radix et Rhizoma Rhei using immobilized cysteinyl leukotriene receptor type 1 as the stationary phase.

Despite the tremendous progress of wine-processed Radix et Rhizoma Rhei (Jiudahuang, JDH) in removing toxic heat from the blood in the upper portion of the body for hundreds of years, the deep understanding of its functional material basis of the anti-inflammatory ingredients remains unclear due to the lack of high specific and efficient methods. Herein, taking Cysteinyl leukotriene receptor type 1(CysLT1R) as the target protein, we established a chromatographic method based on the immobilized CysLT1R using haloalkane dehalogenases (Halo) at the C-terminus of the receptor in one step. After careful characterization by X-ray photoelectronic spectroscopy, immune-fluorometric analysis, and chromatographic investigations, the immobilized receptor was used to screen the anti-inflammatory ingredients in JDH. Aloe-emodin, rhein, emodin, chrysophanol, and physcion were identified as the main anthraquinone exerting anti-inflammatory effects in the drug. The association constants for the five compounds to bind with the receptor were calculated as (0.30 ± 0.06)× 105, (0.35 ± 0.03)× 105, (0.46 ± 0.05)× 105, (1.05 ± 0.14)× 105, and (1.66 ± 0.17)× 105 M-1 by injection amount-dependent method. Meanwhile, hydrogen bonds were identified as the main driving force for the five compounds to bind with CysLT1R by molecular docking. Based on these results, we believe that the immobilized receptor chromatography preserves historic significance in revealing the functional material basis of the complex matrices.

Transcriptomic divergence of the Rheum palmatum complex derived from top-geoherb and non-geoherb areas provides the insights into geoherbalism properties of rhubarb.

Geoherb usually represents high-quality medicinal herbs with better clinical therapeutic effects, and elucidating the geoherbalism is essential for the quality improvement of traditional Chinese Medicine. However, few researches were conducted to clarify the geoherbalism based on a large scale of transcriptomics. In the present study, we compared the transcriptomes of Rheum palmatum complex derived from top-geoherb and non-geoherb areas to show the geoherbalism properties of rhubarb. A total of 412.32 Gb clean reads were obtained with unigene numbers of 100,615 after assembly. Based on the obtained transcriptome datasets, key enzyme-encoding genes involved in the anthraquinones biosynthesis were also obtained. We also found that 21 anthraquinone-related unigenes were differentially expressed between two different groups, and some of these DEGs were correlated to the content accumulation of five free anthraquinones, indicating that the gene expression profiles may promote the geoherbalism formation of rhubarb. In addition, the selective pressure analyses indicated that most paired orthologous genes between these two groups were subject to negative selection, and only a low proportion of orthologs under positive selection were detected. Functional annotation analyses indicated that these positive-selected genes related to the functions such as gene expression, substance transport, stress response and metabolism, indicating that discrepant environment also enhanced the formation of geoherbalism. Our study not only provided insights for the genetic mechanism of geoherbalism of rhubarb, but also laid more genetic cues for the future rhubarb germplasms improvement and utilization.

Integration of pharmacodynamics and metabolomics to reveal rhubarb anthraquinone protection against nonalcoholic fatty liver disease rat model.

OBJECTIVES: The objective of the present study was to investigate the effect of Rhubarb anthraquinone (RA) on a high-fat diet (HFD)-induced nonalcoholic fatty liver disease (NAFLD) rat model, and explore potential biomarker and metabolic pathways by using the metabolomics method. MATERIALS AND METHODS: We established HFD rats as the NAFLD model. Forty Sprague-Dawley rats were randomly divided into a control group, model group, RA low-dose group, RA medium-dose group, and RA high-dose group, and evaluated the protective effect of RA on NAFLD by detecting biochemical indicators of serum and pathological changes of liver tissue. Investigating potential biomarkers and metabolic pathways connected with RA's protective effects against NAFLD by UHPLC-Q-TOF-MS untargeted metabolomics. RESULTS: The results showed that RA significantly reversed the increase of TG, TC, ALT, AST, and ALP (P < .05), the decrease of HDL-C (P < .05), and alleviated pathological conditions in NAFLD rats. Based on potential biomarker analysis, RA affected metabolic pathways such as fatty acids biosynthesis, bile acids biosynthesis, and pentose phosphate pathway, delaying the progression of NAFLD. CONCLUSION: RA improved blood lipid levels, liver function, and pathological conditions of NAFLD rats. Meanwhile, affected the metabolic pathways and regulated the synthesis of fatty acids and bile acids in NAFLD rats.

Neuroprotection of rhubarb extract against cerebral ischaemia-reperfusion injury via the gut-brain axis pathway.

BACKGROUND: The gut-brain axis (GBA) plays a central role in cerebral ischaemia-reperfusion injury (CIRI). Rhubarb, known for its purgative properties, has demonstrated protective effects against CIRI. However, it remains unclear whether this protective effect is achieved through the regulation of the GBA. AIM: This study aims to investigate the mechanism by which rhubarb extract improves CIRI by modulating the GBA pathway. METHODS: We identified the active components of rhubarb extract using LC-MS/MS. The model of middle cerebral artery occlusion (MCAO) was established to evaluate the effect of rhubarb extract. We conducted 16S rDNA sequencing and untargeted metabolomics to analyze intestinal contents. Additionally, we employed HE staining, TUNEL staining, western blot, and ELISA to assess intestinal barrier integrity. We measured the levels of inflammatory cytokines in serum via ELISA. We also examined blood-brain barrier (BBB) integrity using Evans blue (EB) penetration, transmission electron microscopy (TEM), western blot, and ELISA. Neurological function scores and TTC staining were utilized to evaluate neurological outcomes. RESULTS: We identified twenty-six active components in rhubarb. Rhubarb extract enhanced α-diversity, reduced the abundance of Enterobacteriaceae, and partially rectified metabolic disorders in CIRI rats. It also ameliorated pathological changes, increased the expressions of ZO-1, Occludin, and Claudin 1 in the colon, and reduced levels of LPS and d-lac in serum. Furthermore, it lowered the levels of IL-1ß, IL-6, IL-10, IL-17, and TNF-α in serum. Rhubarb extract mitigated BBB dysfunction, as evidenced by reduced EB penetration and improved hippocampal microstructure. It upregulated the expressions of ZO-1, Occludin, Claudin 1, while downregulating the expressions of TLR4, MyD88, and NF-κB. Similarly, rhubarb extract decreased the levels of IL-1ß, IL-6, and TNF-α in the hippocampus. Ultimately, it reduced neurological function scores and cerebral infarct volume. CONCLUSION: Rhubarb effectively treats CIRI, potentially by inhibiting harmful bacteria, correcting metabolic disorders, repairing intestinal barrier function, alleviating BBB dysfunction, and ultimately improving neurological outcomes.

Rheum khorasanicum. Hydroalcoholic root extract induces cell death in human colorectal adenocarcinoma: An in vitro and in silico study.

Colorectal cancer (CRC) is the second greatest cause of cancer-related death in the world and chemotherapy, as an important part of CRC treatment, has some drawbacks, including systemic toxicity. Therefore, it is crucial to discover new and more effective CRC treatment plans. Rheum khorasanicum (R. khorasanicum) is a medicinal plant with high flavonoids, stilbenes, and anthraquinone contents, so it can be a potential source of antioxidants and can be used for therapeutic purposes and trigger apoptosis in cancer cells. In this study, we investigated the effects of hydroalcoholic root extract of R. khorasanicum treatment on inducing mitochondrial apoptosis of HT-29 and Caco-2 human colorectal adenocarcinoma cells. Firstly, the total phenolic and flavonoid content was determined. Then, the cytotoxic effects of R. khorasanicum on cells of three different types, including HT-29 and Caco-2 colon cancer cells as well as normal 3T3 cells were assessed using the MTT assay. To investigate the characteristics of cellular death, flow cytometry, and western blotting were performed. The results of this study indicated considerable phenolic (356.4±9.4 GAE/gDW) and flavonoid (934.55±17.1 QE/gDW) contents in R. khorasanicum. MTT assay's finding indicated that 100, 60, and 30µg/mL concentrations of R. khorasanicum reduce cell viability in HT-29 and Caco-2 cell lines significantly (P<0.05). It has been also revealed that R. khorasanicum extract induces apoptosis rather than necrosis in these cell lines. Moreover, Bcl-2 expression was significantly reduced in both HT-29 and Caco-2 cell lines, while Bax and cleaved caspase-3 expression soared considerably in the groups under R. khorasanicum treatment (P<0.05). In conclusion, our findings have suggested that high phenol and flavonoid contents of R. khorasanicum root extract possibly play an important role in cell cytotoxicity and apoptosis induction in HT-29 and Caco-2 colon cancer cells.

The haplotype-resolved genome assembly of autotetraploid rhubarb Rheum officinale provides insights into its genome evolution and massive accumulation of anthraquinones.

Rheum officinale, a member of the Polygonaceae family, is an important medicinal plant that is widely used in traditional Chinese medicine. Here, we report a 7.68-Gb chromosome-scale assembly of R. officinale with a contig N50 of 3.47 Mb, which was clustered into 44 chromosomes across four homologous groups. Comparative genomics analysis revealed that transposable elements have made a significant contribution to its genome evolution, gene copy number variation, and gene regulation and expression, particularly of genes involved in metabolite biosynthesis, stress resistance, and root development. We placed the recent autotetraploidization of R. officinale at ∼0.58 mya and analyzed the genomic features of its homologous chromosomes. Although no dominant monoploid genomes were observed at the overall expression level, numerous allele-differentially-expressed genes were identified, mainly with different transposable element insertions in their regulatory regions, suggesting that they functionally diverged after polyploidization. Combining genomics, transcriptomics, and metabolomics, we explored the contributions of gene family amplification and tetraploidization to the abundant anthraquinone production of R. officinale, as well as gene expression patterns and differences in anthraquinone content among tissues. Our report offers unprecedented genomic resources for fundamental research on the autopolyploid herb R. officinale and guidance for polyploid breeding of herbs.

Comparative Pharmacokinetic Study of Rhubarb Anthraquinones in Normal and Nonalcoholic Fatty Liver Disease Rats.

BACKGROUND AND OBJECTIVES: Rhubarb anthraquinones contain five main components, that is, rhein, emodin, aloe-emodin, chrysophanol, and physcion, which demonstrate good therapeutic effects on nonalcoholic fatty liver disease (NAFLD). However, research on its pharmacokinetics in NAFLD remains lacking. This study aimed to investigate the pharmacokinetic differences of rhubarb anthraquinones in normal and NAFLD rats. METHODS: This study developed an NAFLD rat model by high-fat diet feeding for 6 weeks. Normal and NAFLD groups were orally administered different rhubarb anthraquinones doses (37.5, 75, and 150 mg/kg). The concentration of the rhein, emodin, aloe-emodin, chrysophanol, and physcion in plasma was determined by high-performance liquid chromatography-ultraviolet. RESULTS: The results revealed significant differences in pharmacokinetic behavior between normal and NAFLD rats. Compared with normal rats, NAFLD rats demonstrated significantly increased maximum plasma concentration (Cmax) and area under the plasma concentration-time curve (AUC0 → ∞) of rhubarb anthraquinones (P < 0.05), as well as significantly prolonged time to reach maximum plasma concentration (Tmax), terminal elimination half-life (t1/2), and mean residence time (MRT) of rhubarb anthraquinones (P < 0.05). CONCLUSIONS: This study indicates significant differences in the pharmacokinetics of rhubarb anthraquinones between the physiological and NAFLD states of rats. Rhubarb anthraquinone demonstrated a longer retention time and slower absorption rate in NAFLD rats and exhibited higher bioavailability and peak concentration. This finding provides important information for guiding the clinical use of rhubarb anthraquinones under pathological conditions.

Stool-softening effect and action mechanism of free anthraquinones extracted from Rheum palmatum L. on water deficit-induced constipation in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: In traditional Chinese herbal medicine, rhubarb is said to remove accumulation with purgation, clearing heat, and discharging fire. Modern pharmacology has shown that rhubarb extract has a purgative effect when given to experimental animals in an appropriate dose. However, the active components and their mechanism of action are still not clearly defined. AIM OF THE STUDY: The current research aimed to evaluate the synergistic stool-softening effects and explore the action mechanism of rhubarb free anthraquinones (RhA) and their monomers on constipation in rats. MATERIALS AND METHODS: A rat model of water deficit-induced constipation was established to induce constipation, and these rats were treated with RhA and its monomers. ELISA, histopathology, immunohistochemistry, qPCR and Western blotting based on network pharmacology and molecular docking were conducted to explore the possible mechanism of action of RhA and its monomers. RESULTS: RhA, aloe-emodin, rhein, and chrysophanol showed stool-softening activity, and the combination of aloe-emodin and rhein had the strongest softening effect on faecal pellets. Aloe-emodin, rhein, and chrysophanol significantly increased the serum levels of vasoactive intestinal peptide (VIP), motilin (MTL), and substance P (SP), upregulated the expression of VIP, cyclase-associated protein 1 (CAP1), protein kinase A (PKA), cystic fibrosis transmembrane conductance regulator (CFTR), aquaporin 3 (AQP3), aquaporin 4 (AQP4), and aquaporin 8 (AQP8), decreased the expression of epithelial sodium channel (ENaC) and Na+/H+ exchanger 3 (NHE3), and reduced the colonic tissue concentration of Na+-K+-ATPase in the constipated rats. Osmolality of colonic fluid in model rats treated by RhA, aloe-emodin, rhein, and chrysophanol was increased. CONCLUSION: Aloe-emodin, rhein, and chrysophanol were the stool-softening components of the RhA extract, and there were certain drug-interactions between the components. RhA upregulated VIP expression, activated the cyclic adenosine monophosphate protein kinase A (cAMP/PKA) pathway, and further stimulated CFTR expression while inhibiting NHE3 and ENaC expression, resulting in a hypertonic state in the colonic lumen. Water transport could then be driven by an osmotic gradient, which in turn led to the upregulation of AQP3, AQP4, and AQP8 expression. In addition, RhA likely improved gastrointestinal motility by increasing serum VIP, SP, and MTL concentrations, thus promoting faecal excretion.

The response of rhubarb to smut infection is revealed through a comparative transcriptome and metabolome study.

MAIN CONCLUSION: Integrated transcriptome and metabolome analysis have unveiled the physiological and molecular responses of rhubarb to infection by smut fungi. Rhubarb is an important medicinal plant that is easily infected by smut fungi during its growth. Thus far, no research on the influence of smut fungi on the growth of rhubarb and its secondary metabolism has been conducted. In this study, petioles of Chinese rhubarb (Rheum officinale) [healthy or infected with smut fungus (Thecaphora schwarzmaniana)] were characterized. Microscopic structure, global gene expression profiling, global metabolic profiling, and key enzyme activity and metabolite levels in infected plants were analyzed. Infection by smut fungi resulted in numerous holes inside the petiole tissue and led to visible tumors on the external surface of the petiole. Through metabolic changes, T. schwarzmaniana induced the production of specific sugars, lipids, and amino acids, and inhibited the metabolism of phenolics and flavonoids in R. officinale. The concentrations of key medicinal compounds (anthraquinones) were decreased because of smut fungus infection. In terms of gene expression, the presence of T. schwarzmaniana led to upregulation of the genes associated with nutrient (sugar, amino acid, etc.) transport and metabolism. The gene expression profiling showed a stimulated cell division activity (the basis of tumor formation). Although plant antioxidative response was enhanced, the plant defense response against pathogen was suppressed by T. schwarzmaniana, as indicated by the expression profiling of genes involved in biotic and abiotic stress-related hormone signaling and the synthesis of plant disease resistance proteins. This study demonstrated physiological and molecular changes in R. officinale under T. schwarzmaniana infection, reflecting the survival tactics employed by smut fungus for parasitizing rhubarb.

Therapeutic Potential of 1,8-Dihydroanthraquinone Derivatives for Breast Cancer.

Breast cancer (BC) is the most common malignancy among women worldwide. In recent years, significant progress has been made in BC therapy. However, serious side effects resulting from the use of standard chemotherapeutic drugs, as well as the phenomenon of multidrug resistance (MDR), limit the effectiveness of approved therapies. Advanced research in the BC area is necessary to create more effective and safer forms of therapy to improve the outlook for individuals diagnosed with this aggressive neoplasm. For decades, plants and natural products with anticancer properties have been successfully utilized in treating various medical conditions. Anthraquinone derivatives are tricyclic secondary metabolites of natural origin that have been identified in plants, lichens, and fungi. They represent a few botanical families, e.g., Rhamnaceae, Rubiaceae, Fabaceae, Polygonaceae, and others. The review comprehensively covers and analyzes the most recent advances in the anticancer activity of 1,8-dihydroanthraquinone derivatives (emodin, aloe-emodin, hypericin, chrysophanol, rhein, and physcion) applied both individually, or in combination with other chemotherapeutic agents, in in vitro and in vivo BC models. The application of nanoparticles for in vitro and in vivo evidence in the context of 1,8-dihydroanthraquinone derivatives was also described.

Novel acaricidal and growth-regulating activity of Aloe vera and Rheum rhabarbarum extracts and their oil/water nanoemulsions against the camel tick, Hyalomma dromedarii.

Hyalomma dromedarii is an important tick species infesting livestock. This work evaluated the novel adulticidal, insect growth-regulating, and enzymatic efficacy of ethanol plant extracts of Aloe vera and Rheum rhabarbarum and their nanoemulsions against males and engorged females of the camel tick, H. dromedarii. The physicochemical properties of nanoemulsions were evaluated. The High-Performance Liquid Chromatography (HPLC) analyses indicated that the extracts contained polyphenols and flavonoids, which could enhance their acaricidal effect. Dynamic light scattering (DLS) of the nanoemulsions of A. vera and R. rhabarbarum were 196.7 and 291 nm, whereas their zeta potentials were - 29.1 and - 53.1 mV, respectively. Transmission electron microscope (TEM) indicated that nanoemulsions showed a regular spherical shape (less than 100 nm). Fifteen days post-treatment (PT) with 25%, the mortality% of A. vera and R. rhabarbarum were 88.5 and 96.2%, respectively. Five days PT, the median lethal concentration values of A. vera, R. rhabarbarum, and their nanoemulsions were 7.8, 7.1, 2.8, and 1.02%, respectively, and their toxicity indices were 91.02, 100, 36.4, and 100%, respectively. Their median lethal time values PT with 3.5% were 6.09, 5.09, 1.75, and 1.34 days, respectively. Nanoemulsions enhanced the efficacy of the crude extract 1-7 folds, 5 days PT, and accelerated their speed of killing ticks 2-4 times. The total protein and carbohydrates, Acetylcholinesterase, Alpha esterase, and Amylase were affected PT. The reproductive potential of engorged females was adversely impacted. In conclusion, the novel A. vera and R. rhabarbarum extracts were promising acaricides, and their nanoformulations enhanced their efficacies.