Rheinanthrone, a metabolite of sennoside A, triggers macrophage activation to decrease aquaporin-3 expression in the colon, causing the laxative effect of rhubarb extract

The application of rhubarb concoctions in traditional Chinese medicine and its compounds, processing methods, pharmacology, toxicology and clinical research

Objective

This study reviews the development of rhubarb processing and the current status of pharmacological research. We summarized the effects of different processing methods on the active compounds, pharmacological effects, and toxicity of rhubarb, as well as the clinical application of different concoctions, providing reference for further pharmacological research and clinical application of rhubarb.

Methods

A comprehensive literature review was conducted using databases such as Pubmed, Embase, National Science and Technology Library, Web of science, CNKI, China Science and Technology Journal Database, SinoMed, and the Pharmacopoeia of the People's Republic of China. Search terms included "rhubarb", "raw rhubarb", "wine rhubarb", "cooked rhubarb", "rhubarb charcoal", "herbal processing", "compounds", "pharmacological effects", "inflammation", "gastrointestinal bleeding", and "tumor".

Results

Historical records of rhubarb processing date back to the Han Dynasty, with continual innovations. Currently, the types of rhubarb used in traditional Chinese medicine have stabilized to three species: Rheum palmatum L., Rheum tanguticum Maxim.ex Balf. and Rheum officinale Baill. Common concoctions include raw rhubarb, wine rhubarb, cooked rhubarb and rhubarb charcoal. The active compounds of rhubarb are known to defecation, exhibit antibacterial and anti-inflammatory properties, regulate coagulation, protect the digestive system, and possess anti-tumor activities. Guided by Chinese medicine theory, the use of different rhubarb concoctions can enhance specific effects such as purgation to eliminate accumulation, clearing heat and toxins, cooling blood to stop hemorrhages, activating blood circulation to remove blood stasis, and inducing dampness to descend jaundice, thereby effectively treating various diseases. The therapeutic impact of these concoctions on diseases reflects not only in the changes to the active compounds of rhubarb but also in the formulations of traditional Chinese medicine. Processing has also shown advantages in reducing toxicity.

Conclusion

Different processing methods alter the active compounds of rhubarb, thereby enhancing its various pharmacological effects and meeting the therapeutic needs of diverse diseases. Selecting an appropriate processing method based on the patient's specific conditions can maximize its pharmacological properties and improve clinical outcomes.

The phytochemistry and pharmacology of three Rheum species: A comprehensive review with future perspectives

BACKGROUND

Rheum palmatum, R. tanguticum, and R. officinale, integral species of the genus Rheum, are widely used across global temperate and subtropical regions. These species are incorporated in functional foods, medicines, and cosmetics, recognized for their substantial bioactive components.

PURPOSE

This review aims to synthesize developments from 2014 to 2023 concerning the botanical characteristics, ethnopharmacology, nutritional values, chemical compositions, pharmacological activities, mechanisms of action, and toxicity of these species.

METHODS

Data on the three Rheum species were gathered from a comprehensive review of peer-reviewed articles, patents, and clinical trials accessed through PubMed, Google Scholar, Web of Science, and CNKI.

RESULTS

The aerial parts are nutritionally rich, providing essential amino acids, fatty acids, and minerals, suitable for use as health foods or supplements. Studies have identified 143 chemical compounds, including anthraquinones, anthrones, flavonoids, and chromones, which contribute to their broad pharmacological properties such as laxative, anti-diarrheal, neuroprotective, hepatoprotective, cardiovascular, antidiabetic, antitumor, anti-inflammatory, antiviral, and antibacterial effects. Notably, the materials science approach has enhanced understanding of their medicinal capabilities through the evaluation of bioactive compounds in different therapeutic contexts.

CONCLUSION

As medicinal and economically significant herb species, Rheum species provide both edible aerial parts and medicinal underground components that offer substantial health benefits. These characteristics present new opportunities for developing nutritional ingredients and therapeutic products, bolstering the food and pharmaceutical industries.

Multi-omics combined to explore the purging mechanism of Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex

Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex have been used together to treat constipation in the clinical practices for more than 2000 years. Nonetheless, their compatibility mechanism is still unclear. In this study, the amelioration of Rhei Radix et Rhizoma combined with Magnoliae Officinalis Cortex on constipation was systematically and comprehensively evaluated. The results showed that their compatibility could markedly shorten gastrointestinal transport time, increase fecal water content and frequency of defecation, improve gastrointestinal hormone disorders and protect colon tissue of constipation rats compared with the single drug. Furthermore, according to 16S rRNA sequencing in conjunction with UPLC-Q-TOF/MS, the combination of two herbal medications could greatly raise the number of salutary bacteria (Lachnospiraceae, Romboutsia and Subdoligranulum) while decreasing the abundance of pathogenic bacteria (Erysipelatoclostridiaceae). And two herb drugs could markedly improve the disorder of fecal metabolic profiles. A total of 7 different metabolites associated with constipation were remarkably shifted by the compatibility of two herbs, which were mainly related to arachidonic acid metabolism, alpha-linolenic acid metabolism, unsaturated fatty acid biosynthesis and other metabolic ways. Thus, the regulation of intestinal microbiome and its metabolism could be a potential target for Rhei Radix et Rhizoma and Magnoliae Officinalis Cortex herb pair to treat constipation. Furthermore, the multi-omics approach utilized in this study, which integrated the microbiome and metabolome, had potential for investigating the mechanism of traditional Chinese medicines.

Simultaneous rapid detection of glycyrrhizin and sennoside A in Daiokanzoto samples by lateral flow immunoassay

INTRODUCTION

Glycyrrhizin (GLY) and sennoside A (SA) are characteristic bioactive marker compounds of the Kampo medicine Daiokanzoto. Their accurate detection in blends of Rhei rhizoma and Glycyrrhizae radix of several species (4:1 or 4:2) is essential for quality control and to ensure therapeutic efficacy. A rapid, efficient assay can significantly facilitate their detection.

OBJECTIVE

To establish a rapid qualitative assay for GLY and SA detection, a lateral flow immunoassay (LFA) was developed using specific monoclonal antibody (mAb) nanoparticles.

METHODOLOGY

This assay harnesses the competitive binding of mAb nanoparticles to the immobilized analytes on test strips and free analytes in the samples. Two conjugates for detecting GLY and SA, GLY-bovine serum albumin and SA-human serum albumin, were separately immobilized on the test zones of LFA strips. The detection mechanism is reliant on the visual detection of color changes in the test zones.

RESULTS

When GLY and SA were present in samples, they contended with the immobilized conjugates on the strip to bind with the mAb nanoparticles and produced distinct color patterns in the test zones. The limits of detection of the assay for GLY and SA were both 3.13 μg/mL. The capability of the LFA was substantiated using plant samples and Daiokanzoto, and its alignment with indirect competitive ELISA results was confirmed.

CONCLUSION

The introduced LFA is a groundbreaking procedure that offers a rapid, straightforward, and sensitive method for simultaneously detecting GLY and SA in Daiokanzoto samples. It is instrumental in ensuring product quality.

The rhizomes of Atractylodes macrocephala Koidz improve gastrointestinal health and pregnancy outcomes in pregnant mice via modulating intestinal barrier and water-fluid metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Baizhu (BZ) is the dried rhizome of Atractylodes macrocephala Koidz (Compositae), which invigorates the spleen, improves vital energy, stabilizes the fetus, and is widely used for treating spleen deficiency syndrome. However, the impact of BZ on gastrointestinal function during pregnancy remains unexplored.

AIM OF THE STUDY

This study elucidated the ameliorative effects of BZ on gastrointestinal health and pregnancy outcomes in pregnant mice with spleen deficiency diarrhea (SDD).

METHODS

To simulate an irregular human diet and overconsumption of cold and bitter foods leading to SDD, a model of pregnant mice with SDD was established using an alternate-day fasting and high-fat diet combined with oral administration of Sennae Folium. During the experiment, general indicators and diarrhea-related parameters were measured. Gastric and intestinal motility (small intestinal propulsion and gastric emptying rates) were evaluated. Serum motilin (MTL), ghrelin, growth hormone (GH), gastrin (Gas), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-c), chorionic gonadotropin β (β-CG), progesterone (P), and estradiol (E2) were quantified using an enzyme-linked immunosorbent assay. Pathological changes were examined by hematoxylin and eosin staining (H&E) and alcian blue periodic acid Schiff staining (AB-PAS). Immunohistochemistry and immunofluorescence were used to measure the expression levels of the intestinal barrier and water metabolism-related proteins in colonic tissues. The pregnancy rate, ovarian organ coefficient, uterus with fetus organ coefficient, small size, average fetal weight, and body length of fetal mice were calculated.

RESULTS

The results showed that BZ significantly improved general indicators and diarrhea in pregnant mice with SDD, increased gastric emptying rate and small intestinal propulsion rate, elevated the levels of gastrointestinal hormones (AMS, ghrelin, GH, and Gas) in the serum, and reduced lipid levels (TC and LDL-c). It also improved colonic tissue morphology, increased the number of goblet cells, and promoted the mRNA and protein expression of occludin, claudin-1, ZO-1, AQP3, AQP4, and AQP8 in colonic tissues, downregulating the mRNA and protein expression levels of claudin-2, thereby alleviating intestinal barrier damage and regulating the balance of water and fluid metabolism. BZ also held the levels of pregnancy hormones (β-CG, P, and E2) in the serum of pregnant mice with SDD. Moreover, it increased the pregnancy rate, ovarian organ coefficient, uterus with fetus organ coefficient, litter size, average fetal weight, and body length of fetal mice. These findings indicate that BZ can improve spleen deficiency-related symptoms in pregnant mice before and during pregnancy, regulate pregnancy-related hormones, and improve pregnancy outcomes.

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.

Time-dependent laxative effect of sennoside A, the core functional component of rhubarb, is attributed to gut microbiota and aquaporins

ETHNOPHARMACOLOGICAL RELEVANCE

Sennoside A is a natural anthraquinone component mainly derived from rhubarb and has been routinely used as a clinical stimulant laxative. However, long-term application of sennoside A may lead to drug resistance and even adverse reactions, thus limiting its clinical use. Therefore, to reveal the time-dependent laxative effect and potential mechanism of sennoside A is of critical importance.

AIM OF THE STUDY

This study was conducted to investigate the time-dependent laxative effect of sennoside A and unveil its underlying mechanism from the perspective of gut microbiota and aquaporins (AQPs).

MATERIALS AND METHODS

Based on a mouse constipation model, 2.6 mg/kg sennoside A was administered orally for 1, 3, 7, 14 and 21 days, respectively. The laxative effect was assessed by the fecal index and fecal water content, the histopathology of the small intestine and colon was evaluated by hematoxylin-eosin staining. Gut microbiota changes was observed by 16S rDNA sequencing, and colonic AQPs expression was analyzed by quantitative real-time polymerase chain reaction and western blotting. Partial least-squares regression (PLSR) was used to screen out the effective indicators contributing to the laxative effect of sennoside A. The effective indicators were then fitted to time by a drug-time curve model to analyze the trend of efficacy of sennoside A, and the optimal time of administration was derived by comprehensive analysis with a three-dimensional (3D) time-effect image.

RESULTS

Sennoside A had a significant laxative effect at 7 days of administration with no pathological changes in the small intestine or colon; however, at 14 or 21 days of administration, the laxative effect diminished and slight damage to the colon was observed. Sennoside A affects the structure and function of gut microbes. The alpha diversity showed that the abundance and diversity of gut microorganisms reached the highest value after 7 days of administration. Partial least squares discriminant analysis showed that the composition of the flora was close to normal when administered for less than 7 days, but was closest to the composition of constipation over 7 days. The expression of aquaporin 3 (AQP3) and aquaporin 7 (AQP7) decreased gradually after the administration of sennoside A, with the lowest expression at 7 days, and then increased gradually afterwards, while the expression of aquaporin 1 (AQP1) was the opposite. The PLSR results showed that AQP1, AQP3, Lactobacillus, Romboutsia, Akkermansia and UCG_005 contributed more to the laxative effect of the fecal index, and after fitting with the drug-time curve model, each index showed a trend of increasing and then decreasing. The comprehensive evaluation of the 3D time-effect image concluded that the laxative effect of sennoside A reached its best after 7 days of administration.

CONCLUSION

Sennoside A should be used in regular dosages for less than one week, as it provides significant relief of constipation and exhibits no colonic damage within 7 days of administration. In addition, Sennoside A exerts its laxative effect by regulating gut microbiota of Lactobacillus Romboutsia, Akkermansia and UCG_005 and water channels of AQP1 and AQP3.

Protective effects of Liupao tea against high-fat diet/cold exposure-induced irritable bowel syndrome in rats

Liupao tea as a type of dark tea can relieve irritable bowel syndrome by regulating gut microbiota, but the mechanism has not been fully explained. An ultra-high performance liquid chromatography along with quadrupole time of flight tandem mass spectrometry was used to analyze the phytochemicals in Liupao tea. Then, we explored the effects of Liupao tea against IBS. From the results of chemical analysis, we identified catechins, polyphenols, amino acids, caffeine, polysaccharides and other components in Liupao tea. The open-field test, gastrointestinal function-related indexes, histochemical assays, measurements of cytokine and aquaporin 3 (AQP3), and determination of serum metabolites were utilized to monitor the physiological consequences of Liupao tea administration in rats with irritable bowel syndrome. The results showed that Liupao tea had a significant protective effect on irritable bowel syndrome. Liupao tea increased locomotive velocity while reducing interleukin-6, interleukin-1β, and tumor necrosis factor-α levels, as well as gastrointestinal injury. Moreover, Liupao tea increased the AQP3 levels of renal tissues but reduced the AQP3 levels of gastrointestinal tissues. Liupao tea reduced the Firmicutes/Bacteroides ratio and significantly reconstructed the microbial pattern. Liupao tea relieved irritable bowel syndrome by repairing gastrointestinal dysfunction, regulating the secretion of pro-inflammatory cytokines, modulating water metabolism, and restoring microbial homeostasis.

Comparative LC-ESIMS-Based Metabolite Profiling of Senna italica with Senna alexandrina and Evaluating Their Hepatotoxicity

Senna Mill. (Fabaceae) is an important medicinal plant distributed worldwide. Senna alexandrina (S. alexandrina), the officinal species of the genus, is one of the most well-known herbal medicines traditionally used to treat constipation and digestive diseases. Senna italica (S. italica), another species of the genus, is native to an area ranging from Africa to the Indian subcontinent, including Iran. In Iran, this plant has been used traditionally as a laxative. However, very little phytochemical information and pharmacological reports investigating its safety of use are available. In the current study, we compared LC-ESIMS metabolite profiles of the methanol extract of S. italica with that of S. alexandrina and measured the content of sennosides A and B as the biomarkers in this genus. By this, we were able to examine the feasibility of using S. italica as a laxative agent like S. alexandrina. In addition, the hepatotoxicity of both species was evaluated against HepG2 cancer cell lines using HPLC-based activity profiling to localize the hepatotoxic components and evaluate their safety of use. Interestingly, the results showed that the phytochemical profiles of the plants were similar but with some differences, particularly in their relative contents. Glycosylated flavonoids, anthraquinones, dianthrones, benzochromenones, and benzophenones constituted the main components in both species. Nevertheless, some differences, particularly in the relative amount of some compounds, were observed. According to the LC-MS results, the amounts of sennoside A in S. alexandrina and S. italica were 1.85 ± 0.095% and 1.00 ± 0.38%, respectively. Moreover, the amounts of sennoside B in S. alexandrina and S. italica were 0.41 ± 0.12 % and 0.32 ± 0.17%, respectively. Furthermore, although both extracts showed significant hepatotoxicity at concentrations of 50 and 100 µg/mL, they were almost non-toxic at lower concentrations. Taken together, according to the results, the metabolite profiles of S. italica and S. alexandrina showed many compounds in common. However, further phytochemical, pharmacological, and clinical studies are necessary to examine the efficacy and safety of S. italica as a laxative agent.

Evaluation and Management of Postsurgical Patient With Hirschsprung Disease Neurogastroenterology & Motility Committee: Position Paper of North American Society of Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN)

Children with Hirschsprung disease have postoperative long-term sequelae in defecation that contribute to morbidity and mortality and significantly impact their quality of life. Pediatric patients experience ongoing long-term defecation concerns, which can include fecal incontinence (FI) and postoperative obstructive symptoms, such as constipation and Hirschsprung-associated enterocolitis. The American Pediatric Surgical Association has developed guidelines for management of these postoperative obstructive symptoms and FI. However, the evaluation and management of patients with postoperative defecation problems varies among different pediatric gastroenterology centers. This position paper from the Neurogastroenterology & Motility Committee of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition reviews the current evidence and provides suggestions for the evaluation and management of postoperative patients with Hirschsprung disease who present with persistent defecation problems.

Recent advances in the identification of biosynthetic genes and gene clusters of the polyketide-derived pathways for anthraquinone biosynthesis and biotechnological applications

Natural anthraquinones are represented by a large group of compounds. Some of them are widespread across the kingdoms, especially in bacteria, fungi and plants, while the others are restricted to certain groups of organisms. Despite the significant pharmacological potential of several anthraquinones (hypericin, skyrin and emodin), their biosynthetic pathways and candidate genes coding for key enzymes have not been experimentally validated. Understanding the genetic and epigenetic regulation of the anthraquinone biosynthetic gene clusters in fungal endophytes would help not only understand their pathways in plants, which ensure their commercial availability, but also favor them as promising systems for prospective biotechnological production.

Evolving interplay between natural products and gut microbiota

Growing evidence suggests gut microbiota status affects human health, and microbiota imbalance will induce multiple disorders. Natural products are gaining increasing attention for their therapeutical effects and less side effects. The emerging studies support that the activities of many natural products are dependent on gut microbiota, meanwhile gut microbiota is modulated by natural products. In this review, we summarized the interplay between the gut microbiota and host disease, and the emerging molecular mechanisms of the interaction between natural products and gut microbiota. Focusing on gut microbiota metabolite of various natural products, and the effects of natural products on gut microbiota, we summarized the biotransformation pathways of natural products, and discussed the effect of natural products on the composition modulation of gut microbiota, protection of gut mucosal barrier and modulation of the gut microbiota metabolites. Dissecting the interplay between gut microbiota and natural products will help elucidate the therapeutic mechanisms of natural products.

Xuanhuang Runtong Tablets Relieve Slow Transit Constipation in Mice by Regulating TLR5/IL-17A Signaling Mediated by Gut Microbes

This study aims to investigate the regulation effects of Xuanhuang Runtong tablets (XHRTs) on intestinal microbes and inflammatory signal toll receptor 5 (TLR5)/interleukin-17A (IL-17A) in STC mice. First, high-performance liquid chromatography (HPLC) was used to verify the composition of XHRT and quality control. Then, the defecation ability of STC mice was evaluated by measuring fecal water content and intestinal transit function. The pathological examination of colonic mucosa was observed by Alcian Blue and periodic acid Schiff (AB-PAS) staining. 16S ribosomal DNA (16S rDNA) genes were sequenced to detect the fecal microbiota. Western blotting, immunofluorescence, and real-time fluorescence quantitative PCR (qRT-PCR) were applied to detect the expression of aquaporin 3 (AQP3), connexin 43 (Cx43), TLR5, and IL-17A. The defecation function of the STC mice was significantly decreased. The amount of mucus secretion and the thickness of the colonic mucus layer were decreased, and the number of microbial species in the intestinal wall, such as Firmicutes/Bacteroidetes, anaerobic bacteria, and Alistipes, were also decreased. In addition, the expression of AQP3 and Cx43 was disordered, and the inflammatory factorsTLR5 and IL-17A were activated in the colon. The changes in the above indicators were significantly reversed by XHRT. This study demonstrates that XHRT provides a new strategy for the treatment of slow transit constipation by regulating the activation of the intestinal inflammatory signal TLR5/IL-17A mediated by gut microbes.

Aquaporins: A new target for traditional Chinese medicine in the treatment of digestive system diseases

Aquaporins (AQPs) are a family of transmembrane proteins expressed in various organ systems. Many studies have shown that the abnormal expression of AQPs is associated with gastrointestinal, skin, liver, kidneys, edema, cancer, and other diseases. The majority of AQPs are expressed in the digestive system and have important implications for the physiopathology of the gastrointestinal tract as well as other tissues and organs. AQP regulators can prevent and treat most gastrointestinal-related diseases, such as colorectal cancer, gastric ulcer, and gastric cancer. Although recent studies have proposed clinically relevant AQP-targeted therapies, such as the development of AQP inhibitors, clinical trials are still lacking and there are many difficulties. Traditional Chinese medicine (TCM) has been used in China for thousands of years to prevent, treat and diagnose diseases, and is under the guidance of Chinese medicine (CM) theory. Herein, we review the latest research on the regulation of AQPs by TCMs and their active components, including Rhei Radix et Rhizoma, Atractylodis macrocephalae Rhizoma, Salviae miltiorrhizae Radix et Rhizoma, Poria, Astragali radix, and another 26 TCMs, as well as active components, which include the active components include anthraquinones, saponins, polysaccharides, and flavonoid glycosides. Through our review and discussion of numerous studies, we attempt to explore the regulatory effects of TCMs and their active components on AQP expression in the corresponding parts of the body in terms of the Triple Energizer concept in Chinese medicine defined as "upper energizer, middle energizer, and lower energizer,"so as to offer unique opportunities for the development of AQP-related therapeutic drugs for digestive system diseases.

Constipation Mitigation by Rhubarb Extract in Middle-Aged Adults Is Linked to Gut Microbiome Modulation: A Double-Blind Randomized Placebo-Controlled Trial

Gut microbiota alterations are intimately linked to chronic constipation upon aging. We investigated the role of targeted changes in the gut microbiota composition in the relief of constipation symptoms after rhubarb extract (RE) supplementation in middle-aged volunteers. Subjects (95% women, average 58 years old) were randomized to three groups treated with RE at two different doses determined by its content of rhein (supplementation of 12.5 mg and 25 mg per day) vs. placebo (maltodextrin) for 30 days. We demonstrated that daily oral supplementation of RE for 30 days was safe even at the higher dose. Stool frequency and consistency, and perceived change in transit problem, transit speed and difficulty in evacuating, investigated by validated questionnaires, were improved in both groups of RE-treated volunteers compared to placebo. Higher abundance of Lachnospiraceae (mainly Roseburia and Agathobacter) only occurred after RE treatment when present at low levels at baseline, whereas an opposite shift in short-chain fatty acid (SCFA) levels was observed in both RE-treated groups (increase) and placebo (decrease). Fecal Lachnospiraceae and SCFA were positively correlated with stool consistency. This study demonstrates that RE supplementation promotes butyrate-producing bacteria and SCFA, an effect that could contribute to relieving chronic constipation in middle-aged persons.

Bidirectional effects and mechanisms of traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

The bidirectional property of traditional Chinese medicines (TCMs) was recorded in the classic work Medicine Origin (Yi Xue Qi Yuan) as early as the Jin and Yuan dynasties of ancient China. Since then, this imperative theory has been applied to guide the clinical application of TCMs. Studies have been performed to investigate this phenomenon only over the last three decades. A limited number of reviews on the bidirectional role of TCMs have been published, and almost all current studies are published in the Chinese language.

AIM OF THE REVIEW

The aim of this review is to provide the first comprehensive evidence regarding the bidirectional effects and the underlying mechanisms of TCMs and their active compounds.

MATERIALS AND METHODS

Information relevant to opposing pharmacological activities or opposing properties exerted by TCM prescriptions, herbal medicines, and their active compound, as well as their mechanisms was summarized by searching Chinese and English databases, including the Chinese National Knowledge Infrastructure (CNKI), Wan Fang Data, Chinese Scientific Journal Database (VIP), Google Scholar, PubMed, Web of Science, Science Direct, and Wiley Online Library.

RESULTS

Although the bidirectional regulation of TCMs has been applied in the clinic since ancient times in China, only limited reviews have been published in Chinese. The existing data showed that bidirectional effects can be found in TCM prescriptions, herbal medicines, and pure active compounds. Additionally, the bidirectional role of TCMs was primarily reported in the modulation of immune function, blood circulation and hemostasis, gastrointestinal motility, the central nervous system and blood pressure. This may because the therapeutic outcomes of these disorders are more obvious than those of other complicated diseases. Intriguingly, some herbal medicines have multiple bidirectional activities; for instance, Panax ginseng C. A. Meyer showed bidirectional regulation of immune function and the central nervous system; Astragalus membranaceus can bidirectionally regulate blood pressure and immune function; and Rheum officinale Baill exerts bidirectional effects on blood circulation and hemostasis, gastrointestinal motility and immune function. The mechanisms underlying the bidirectional effects of TCMs are largely attributed to the complexity of herbal constituents, dosage differences, the processing of herbal medicine, and compatibility of medicines, the physiological conditions of patients and adaptogenic effects.

CONCLUSION

Uncovering the bidirectional effects and mechanisms of TCMs is of great importance for both scientific research and clinical applications. This review may help to facilitate the recognition of the bidirectional role of TCMs, to explain some seemingly-opposite phenomena in the pharmacological study of herbal medicines and to provide guidance for TCM practitioners.

Study on chronic toxicity of rhubarb extract in Sprague-Dawley rats

Objective

The purpose of this study was to evaluate the safety of rhubarb extract.

Methods

SD rats were treated with rhubarb extract at 0, 101, 405 and 1620 mg/kg/day for 52 weeks. food consumption and body weights were recorded. Blood and urine samples were collected for serum biochemical evaluation and urinalysis, and organ tissues were collected for histopathological examination.

Results

The rats of 1620 mg/kg group developed diarrhea symptoms with dark brown loose stool after exposure; decreased body weight and increased food consumption were observed in the 1620 mg/kg and 405 mg/kg groups; urine WBC and NIT was significantly increased in the male and female rats of 1620 mg/kg group, and the urine pH was decreased in male rats of 1620 mg/kg group; renal tubular pigmentation was observed in the 1620 mg/kg group.

Conclusion

The NOAEL of rhubarb extract on chronic toxicity (52 weeks) of Sprague-Dawley rats was 101 mg/kg in female and 94 mg/kg in male, and the LOAEL was 408 mg/kg in female and 381 mg/kg in male. The target organ of toxicity was the kidney, and the target cells was tubular epithelial cells.

Understanding the tonifying and the detoxifying properties of Chinese medicines from their impacts on gut microbiota and host metabolism: a case study with four medicinal herbs in experimental colitis rat model

BACKGROUND

Chinese medicines (CMs) have emerged as an alternative therapy for ulcerative colitis through reinforcing the vital qi and/or eliminating the pathogenic factors according to the traditional Chinese medicinal theory. Presystemic interactions of CMs with gut microbiota and the associated metabolic network shift are believed to be essential to achieve their holistic health benefits in traditional oral application.

METHODS

This study first employed 16S rDNA-based microbial profiling and mass spectrometry-based urinary metabolomics to simultaneously evaluate four single CMs frequently prescribed as main constituent herbs for alleviating UC, the tonic ginseng and Astragali Radix (AR) and the detoxifying Scutellaria Radix (SR) and Rhubarb, on a dextran sodium sulfate (DSS)-induced colitis rat model, with aims to understanding the tonifying or detoxifying properties of CMs through clinical phenotypes, the common features and herb-specific signatures in gut microbial alterations and the associated host metabolic shifts. Colitis was induced in rats receiving 5% DSS for consecutive 7 days. Control group received water alone. Herbal groups received 5% DSS and respective herbal preparation by gavage once daily. Body weight, stool consistency, and rectal bleeding were recorded daily. Feces and urine were freshly collected at multiple time points. On day 7, blood and colon tissues were collected to determine anti-/pro-inflammatory cytokines levels, colonic myeloperoxidase activity, and histopathologic alterations.

RESULTS

Gut microbiome was more prone to herb intervention than metabolome and displayed increasing associations with metabolic dynamics. Although both the tonic and the detoxifying herbs alleviated colitis and caused some similar changes in DSS-induced microbiome and metabolome disturbance, the tonic herbs were more effective and shared more common microbial and metabolic signatures. The detoxifying herbs elicited herb-specific changes. Rhubarb uniquely affected phenylalanine metabolism and established high correlations between Akkermansia muciniphila and Parasutterella and hydroxyphenylacetylglycine and phenylbutyrylglycine, while SR caused significant elevation of steroidal glucuronides dehydropregnenolone glucuronide and estriol glucuronide, both displaying exclusive correlations with genus Acetatifactor.

CONCLUSION

Both tonic and detoxifying herbs tested ameliorated experimental colitis and elicited alternative microbial and host metabolic reprogramming. The findings highlight the importance of presystemic interactions with gut microbiota to host metabolic shifts and promote modern translation of tonic and detoxifying properties of CMs.

Potential roles of gut microbes in biotransformation of natural products: An overview

Natural products have been extensively applied in clinical practice, characterized by multi-component and multi-target, many pharmacodynamic substances, complex action mechanisms, and various physiological activities. For the oral administration of natural products, the gut microbiota and clinical efficacy are closely related, but this relationship remains unclear. Gut microbes play an important role in the transformation and utilization of natural products caused by the diversity of enzyme systems. Effective components such as flavonoids, alkaloids, lignans, and phenols cannot be metabolized directly through human digestive enzymes but can be transformed by enzymes produced by gut microorganisms and then utilized. Therefore, the focus is paid to the metabolism of natural products through the gut microbiota. In the present study, we systematically reviewed the studies about gut microbiota and their effect on the biotransformation of various components of natural products and highlighted the involved common bacteria, reaction types, pharmacological actions, and research methods. This study aims to provide theoretical support for the clinical application in the prevention and treatment of diseases and provide new ideas for studying natural products based on gut biotransformation.

Natural phenylethanoid glycosides diuretics derived from Lagopsis supina: Biological activity, mechanism, molecular docking, and structure-activity relationship

Aquaporins (AQPs) and vasopressin type 2 receptor (V2R) play a crucial role in urine excretion and are widely used to explore novel diuretics. In this study, three phenylpropanoids including stachysoside A (L1), acteoside (L2), and glucopyranosyl (1 → 6) martynoside (L3) were isolated from Lagopsis supina (Steph. ex Willd.) lk. -Gal. ex Knorr. Their diuretic activity, mechanism, molecular docking, and structure-activity relationships were explored. The results suggest that L1, L2, and L3 exhibit acute (6 h) and prolonged (6 d) activities including increased urinary excretion volume, diuretic action, and diuretic activity, without affecting the urinary pH and minor altering the electrolyte balance in saline-loaded rats. Further, L1, L2, and L3 significantly reduced the levels of angiotensin II (Ang II), anti-diuretic hormone (ADH), and aldosterone (ALD), AQPs 1-4 and 7, and V2R, and remarkably elevated the atriopeptin (ANP) level. Besides, L1, L2, and L3 obviously suppressed mRNA and protein levels of AQPs 1-4 and 7, and V2R. The hypothetical binding modes of L1, L2, and L3 with these proteins were determined by molecular docking, and a tight structure-activity relationship was also proposed. Collectively, L1, L2, and L3 represent three natively novel phenylethanoid glycoside diuretics, which inhibit AQP and V2R-mediated molecular mechanisms. They are superior to furosemide as long-term diuretics.

Associations between intestinal microbiota, fecal properties, and dietary fiber conditions: The Japanese traditional medicine Junchoto ameliorates dietary fiber deficit-induced constipation with F/B ratio alteration in rats

Changes in the intestinal microbiota are known to occur in constipated patients. Dietary fiber restriction presents obstacles to appropriate defecation and affects fecal properties, but the relationship between fecal microbiota and fecal morphological properties remains obscure. Therefore, we examined the influence of fiber diets on the fecal microbiome and properties in rats, and the effectiveness of the Japanese traditional medicine Junchoto (JCT) in rats with fiber deficit-induced constipation. Rats were fed three different fiber diets with varying cellulose contents (0 %, FFD; 5 %, ND; 15 %, HFD), respectively, as follows: study 1: 21 days of feeding; study 2: 14 days of feeding followed by 7 days of ND (fiber normalization in all groups); study 3: FFD for 21 days, followed by JCT administration from 14 days. Fecal properties and 16S rRNA amplicon sequencing results were examined. We observed that the fecal frequency, dry weight, and length were increased, and water ratio were decreased in a cellulose dose-dependent manner. The difference in several kinds of fecal microbiota, but not the α-diversity Chao1 index and the Firmicutes/Bacteroidetes ratio (F/B ratio), between groups were observed. The change in fecal property in both the HFD and FFD groups was ameliorated with fiber normalization, accompanied by alteration of the Chao1 index and/or F/B ratio. JCT administration reversed the fecal morphological changes in FFD group, accompanied by F/B ratio increasing. In conclusion, short-term dietary changes modulated microbial homeostasis, which is linked to fecal property. JCT may alter the F/B ratio and improve fecal properties to facilitate easier excretion.

[A Randomized, Double-blind, Active-controlled Exploratory Clinical Trial for the Evaluation of the Efficacy and Safety of Goodmorning S Granule® on Constipation]

BACKGROUND/AIMS

Constipation is a common gastrointestinal disease that reduces the quality of life and incurs considerable medical expenses. Bisacodyl and sodium docusate are generally used to treat constipation. This study assessed the effectiveness and safety of Goodmorning S Granule^® (Hanpoong Pharm. Co., Ltd., Wanju, Korea) in functional constipation by a comparison with bisacodyl.

METHODS

A 2-week randomized, double-blind, active-controlled exploratory clinical trial was conducted to compare the treatment (Goodmorning S Granule^®) with the control (bisacodyl). The efficacy was measured by the changes in transition, Bristol stool type, stomachache, clinical manifestation, defecation time after drug consumption, 36-item short-form survey (SF-36), and the results of improvement evaluation. The safety was evaluated by the incidence of adverse drug events and vital signs. Additional analyses were conducted by dividing the severity according to the proportion of Bristol Stool Scale types 1 and 2.

RESULTS

Subjects were randomized to the treatment (n=24) or control (n=26) groups. No significant differences were observed in demographics. After 2 weeks from the baseline, the changes in the complete spontaneous bowel movement (CSBM) were higher in the treatment (4.00±2.62) group than in the control group (1.40±2.34) (p<0.05). The treatment group exhibited significant improvement in the score on the SF-36 questionnaire. The clinical side effects, such as stomachache and borborygmus, were reduced in the moderate constipation patients in the treatment group, according to additional analyses.

CONCLUSIONS

Goodmorning S Granule^®, a herbal medicine, was more effective in improving quality of life and CSBM per week and safer in the moderate constipation groups because of the reduced clinical side effects.

Research progress in the treatment of slow transit constipation by traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Slow transit constipation (STC) is a common gastrointestinal disorder seriously impacting patients' quality of life. At present, although conventional chemical drugs effectively control STC symptoms in the short term, the long-term effects are poor, and the side effects are significant. In this regard, traditional Chinese medicine (TCM) offers an opportunity for STC treatment. Many pharmacological and clinical studies have confirmed this efficacy of TCM with multiple targets and mechanisms.

AIM OF THE STUDY

This review attempted to summarize the characteristics of TCM (compound prescriptions, single Chinese herbs, and active ingredients) for STC treatment and discussed their efficacy based on analyzing the pathogenesis of STC.

MATERIALS AND METHODS

The information was acquired from different databases, including PubMed, Web of Science, China National Knowledge Infrastructure, and Wanfang databases. We then focused on the recent research progress in STC treatment by TCM. Finally, the future challenges and trends are proposed.

RESULTS

TCM has good clinical efficacy in the treatment of STC with multi-mechanisms. Based on the theory of syndrome differentiation, five kinds of dialectical treatment for STC by compound TCM prescriptions were introduced, namely: Nourishing Yin and moistening the intestines; Promoting blood circulation and removing blood stasis; Warming Yang and benefiting Qi; Soothing the liver and regulating Qi; and Benefiting Qi and strengthening the spleen. In addition, six single Chinese herbs and eight active ingredients also show good efficacy in STC treatment.

CONCLUSIONS

TCM, especially compound prescriptions, has bright prospects in treating STC attributed to its various holistic effects.

Treatment of Gastrointestinal Disorders-Plants and Potential Mechanisms of Action of Their Constituents

The worldwide prevalence of gastrointestinal diseases is about 40%, with standard pharmacotherapy being long-lasting and economically challenging. Of the dozens of diseases listed by the Rome IV Foundation criteria, for five of them (heartburn, dyspepsia, nausea and vomiting disorder, constipation, and diarrhoea), treatment with herbals is an official alternative, legislatively supported by the European Medicines Agency (EMA). However, for most plants, the Directive does not require a description of the mechanisms of action, which should be related to the therapeutic effect of the European plant in question. This review article, therefore, summarizes the basic pharmacological knowledge of synthetic drugs used in selected functional gastrointestinal disorders (FGIDs) and correlates them with the constituents of medicinal plants. Therefore, the information presented here is intended as a starting point to support the claim that both empirical folk medicine and current and decades-old treatments with official herbal remedies have a rational basis in modern pharmacology.

Targeting intestinal flora and its metabolism to explore the laxative effects of rhubarb

Rhubarb, a traditional herb, has been used in clinical practice for hundreds of years to cure constipation, but its mechanism is still not clear enough. Currently, growing evidence suggests that intestinal flora might be a potential target for the treatment of constipation. Thus, the aim of this study was to clarify the laxative effect of rhubarb via systematically analyzing the metagenome and metabolome of the gut microbiota. In this study, the laxative effects of rhubarb were investigated by loperamide-induced constipation in rats. The gut microbiota was determined by high-throughput sequencing of 16S rRNA gene. Ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry was used for fecal metabolomics analysis. The data showed that rhubarb could significantly shorten gastrointestinal transit time, increase fecal water content and defecation frequency, improve gastrointestinal hormone disruption, and protect the colon mucus layer. Analysis of 16S rRNA gene sequencing indicated that rhubarb could improve the disorder of intestinal microbiota in constipated rats. For example, beneficial bacteria such as Ligilactobacillus, Limosilalactobacillus, and Prevotellaceae UCG-001 were remarkably increased, and pathogens such as Escherichia-Shigella were significantly decreased after rhubarb treatment. Additionally, the fecal metabolic profiles of constipated rats were improved by rhubarb. After rhubarb treatment, metabolites such as chenodeoxycholic acid, cholic acid, prostaglandin F2α, and α-linolenic acid were markedly increased in constipation rats; in contrast, the metabolites such as lithocholic acid, calcidiol, and 10-hydroxystearic acid were notably reduced in constipation rats. Moreover, correlation analysis indicated a close relationship between intestinal flora, fecal metabolites, and biochemical indices associated with constipation. In conclusion, the amelioration of rhubarb in constipation might modulate the intestinal microflora and its metabolism. Moreover, the application of fecal metabolomics could provide a new strategy to uncover the mechanism of herbal medicines.Key points• Rhubarb could significantly improve gut microbiota disorder in constipation rats.• Rhubarb could markedly modulate the fecal metabolite profile of constipated rats.

Biochemical Screening of Potent Zika Virus Protease Inhibitors

As the Zika virus protease is an essential and well-established target for the development of antiviral agents, we here have biochemically screened for inhibitors using a purified recombinantly expressed form of this enzyme. As a result, we were able to identify 10 new Zika virus protease inhibitors. These compounds are natural products and showed strong inhibition in the biochemical assays. Inhibitory constants values for the compounds ranged from 5 nM to 8 μM. Among the most potent inhibitors are flavonoids like irigenol hexa-acetate (K i = 0.28 μM), katacine (K i = 0.26 μM), theaflavin gallate (K i = 0.40 μM) and hematein (K i = 0.33 μM). Inhibitors from other groups of natural products include sennoside A (K i = 0.19 μM) and gossypol (K i = 0.70 μM). Several of the obtained compounds are known for their beneficial health effects and have acceptable pharmacokinetic characteristics. Thus, they could be of interest as lead compounds for the development of important and essential Zika antiviral drugs.

Rhubarb granule promotes diethylnitrosamine-induced liver tumorigenesis by activating the oxidative branch of pentose phosphate pathway via G6PD in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb is a natural herbal medicine widely used clinically with numerous pharmacological activities including anti-cancer. Specifically, several studies reported that free anthraquinones from Rhubarb suppressed the proliferation of hepatoma cells. Nonetheless, recent studies revealed that Rhubarb caused hepatotoxicity in vivo, confirming its "two-way" effect on the liver. Therefore, the efficacy and safety of Rhubarb in the in vivo treatment of liver cancer should be further elucidated.

AIM OF THE STUDY

This study investigated the presence of hepatoprotection or hepatotoxicity of Rhubarb in diethylnitrosamine (DEN)-induced hepatocarcinogenesis.

MATERIAL AND METHODS

A total of 112 male Sprague-Dawley rats weighing 190-250 g were enrolled. The rats were induced hepatocarcinogenesis using diethylnitrosamine (0.002 g/rat) until 17 weeks. Starting at week 11, Rhubarb granules (4 g/kg and 8 g/kg) were intragastrically administered daily for 7 weeks. All rats were euthanized at week 20 and the livers were analyzed via non-targeted metabolomics analysis. We established hepatic glucose 6 phosphate (6PG) levels and glucose 6 phosphate dehydrogenase (G6PD) activities to assess the pentose phosphate pathway (PPP). And the liver injuries of rats were analyzed via histological changes, hepatic function, as well as hepatic protein levels of alpha-fetoprotein (AFP), pyruvate kinase isozyme type M2 (PKM2), and proliferating cell nuclear antigen (PCNA). Furthermore, polydatin (0.1 g/kg/d) as a specific inhibitor of G6PD was used to treat rats. Notably, their histological changes, hepatic function, hepatic 6PG levels, hepatic G6PD activities, PCNA levels, and PKM2 levels were recorded.

RESULTS

Non-targeted metabolomics revealed that Rhubarb regulated the PPP in the liver of Rhubarb-DEN-treated rats. Besides, Rhubarb activated the oxidative branch of the PPP by activating G6PD (a rate-limiting enzyme in the oxidative PPP) in the liver of Rhubarb-DEN-treated rats. Meanwhile, Rhubarb promoted DEN-induced hepatocarcinogenesis. Moreover, polydatin attenuated the promoting effect of Rhubarb on DEN-induced hepatocarcinogenesis.

CONCLUSIONS

Rhubarb promoted DEN-induced hepatocarcinogenesis by activating the PPP, indicating that the efficacy and safety of Rhubarb in the treatment of liver cancer deserve to be deliberated.

Pharmacology, Toxicology, and Metabolism of Sennoside A, A Medicinal Plant-Derived Natural Compound

Sennoside A (SA) is a natural dianthrone glycoside mainly from medicinal plants of Senna and Rhubarb, and used as a folk traditional irritant laxative and slimming health food. Accumulating evidences suggest that SA possesses numerous pharmacological properties, such as laxative, anti-obesity, hypoglycemic, hepatoprotective, anti-fibrotic, anti-inflammatory, anti-tumor, anti-bacterial, anti-fungal, anti-viral, and anti-neurodegenerative activities. These pharmacological effects lay the foundation for its potential application in treating a variety of diseases. However, numerous published studies suggest that a long-term use of SA in large doses may have some adverse effects, including the occurrence of melanosis coli and carcinogenesis of colon cancer, thereby limiting its clinical use. It remains to be established whether SA or its metabolites are responsible for the pharmacological and toxicity effects. In this review, the latest advances in the pharmacology, toxicology, and metabolism of SA were summarizedbased on its biological characteristics and mechanism.

Advances in the study of emodin: an update on pharmacological properties and mechanistic basis

Rhei Radix et Rhizoma, also known as rhubarb or Da Huang, has been widely used as a spice and as traditional herbal medicine for centuries, and is currently marketed in China as the principal herbs in various prescriptions, such as Da-Huang-Zhe-Chong pills and Da-Huang-Qing-Wei pills. Emodin, a major bioactive anthraquinone derivative extracted from rhubarb, represents multiple health benefits in the treatment of a host of diseases, such as immune-inflammatory abnormality, tumor progression, bacterial or viral infections, and metabolic syndrome. Emerging evidence has made great strides in clarifying the multi-targeting therapeutic mechanisms underlying the efficacious therapeutic potential of emodin, including anti-inflammatory, immunomodulatory, anti-fibrosis, anti-tumor, anti-viral, anti-bacterial, and anti-diabetic properties. This comprehensive review aims to provide an updated summary of recent developments on these pharmacological efficacies and molecular mechanisms of emodin, with a focus on the underlying molecular targets and signaling networks. We also reviewed recent attempts to improve the pharmacokinetic properties and biological activities of emodin by structural modification and novel material-based targeted delivery. In conclusion, emodin still has great potential to become promising therapeutic options to immune and inflammation abnormality, organ fibrosis, common malignancy, pathogenic bacteria or virus infections, and endocrine disease or disorder. Scientifically addressing concerns regarding the poor bioavailability and vague molecular targets would significantly contribute to the widespread acceptance of rhubarb not only as a dietary supplement in food flavorings and colorings but also as a health-promoting TCM in the coming years.

Action Mode of Gut Motility, Fluid and Electrolyte Transport in Chronic Constipation

Chronic constipation is a common gastrointestinal disorder, with a worldwide incidence of 14–30%. It negatively affects quality of life and is associated with a considerable economic burden. As a disease with multiple etiologies and risk factors, it is important to understand the pathophysiology of chronic constipation. The purpose of this review is to discuss latest findings on the roles of gut motility, fluid, and electrolyte transport that contribute to chronic constipation, and the main drugs available for treating patients. We conducted searches on PubMed and Google Scholar up to 9 February 2021. MeSH keywords “constipation”, “gastrointestinal motility”, “peristalsis”, “electrolytes”, “fluid”, “aquaporins”, and “medicine” were included. The reference lists of searched articles were reviewed to identify further eligible articles. Studies focusing on opioid-induced constipation, evaluation, and clinic management of constipation were excluded. The occurrence of constipation is inherently connected to disorders of gut motility as well as fluid and electrolyte transport, which involve the nervous system, endocrine signaling, the gastrointestinal microbiota, ion channels, and aquaporins. The mechanisms of action and application of the main drugs are summarized; a better understanding of ion channels and aquaporins may be helpful for new drug development. This review aims to provide a scientific basis that can guide future research on the etiology and treatment of constipation.

Diuretic effect of Lagopsis supina fraction in saline-loaded rats is mediated through inhibition of aquaporin and renin-angiotensin-aldosterone systems and up-regulation of atriopeptin

Lagopsis supina (Steph. ex Willd.) lk. -Gal. ex Knorr. has been used as a diuretic agent in China for centuries with limited scientific evidence. This study investigated the diuretic efficacy and underlying mechanism of a macroporous adsorption resin with 30% ethanol elution fraction from L. supina (LSC) in saline-loaded rats and to identify its phytochemicals by ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UHPLC-qTOF-MS/MS). As a result, 18 phenylpropanoids, 14 flavonoids and 15 others were identified in LSC, among which stachysoside A and acteoside could be the main bio-active constituents responsible for the diuretic effect. In parallel, the daily administration of LSC (16, 32 and 64 mg/kg) markedly promoted urinary excretion after 2 h of treatment. Moreover, LSC had no effect on urinary Na+ and K+ concentrations, as well as on serum Na+-K+-ATPase activity. Meanwhile, LSC significantly decreased the serum levels of angiotensin II (Ang II), anti-diuretic hormone (ADH), aldosterone (ALD), aquaporin (AQP) 1, AQP2 and AQP3, suppressed renal AQP1, AQP2, and AQP3 mRNA expressions, down-regulated AQP1, AQP2 and AQP3 protein levels, and up-regulated serum atriopeptin (ANP) level in a dose-dependent manner. These findings suggest that LSC has acute and prolonged diuretic effects by inhibiting the AQPs, RAAS, and upregulation of atriopeptin in saline-loaded rats, and this finding support LSC as a novel diuretic agent.

Subchronic oral toxicity study of rhubarb extract in Sprague-Dawley rats

OBJECTIVE

The study was primarily used to evaluate subchronic oral toxicity of rhubarb extract.

METHODS

The rhubarb extract was orally administered to rats at doses of 0.00, 0.65, 1.62 and 4.05 g/kg BW/day for 13 weeks with a recovery period of 4 weeks. The weight and the relative organ weight of the kidney in the 0.65 g/kg BW group were significantly increased but no significant changes were seen in renal histopathology. When the rats received rhubarb extract at 1.62 g/kg BW or above, the relative weight of the spleen and kidney were significantly increased; the kidney was also swollen and black with hydronephrosis. Histologic examination showed that there was an obvious increase in pigment deposition in renal tubular epithelial cells. No toxic related changes were observed in the 0.65 g/kg BW group, even though organ weight was increased and relative ratio to body weight of kidney were observed at 0.65 g/kg BW dosage, no significant renal histopathologic changes were detected at this dose. Based on the current study conditions and results, the no observed adverse effect level (NOAEL) of rhubarb extract in rats is 0.65 g/kg BW/day.

Aquaporin: targets for dietary nutrients to regulate intestinal health

Aquaporins (AQP) are a class of water channel membrane proteins that are widely expressed in the gut. The biological functions of aquaporins, which regulate the absorption and secretion of water molecules and small solutes, maintain the stable state of the intestine, regulate cell proliferation and migration, participate in the process of intestinal inflammation, and mediate tumorigenesis, demonstrate the physiological significance of these channels in intestinal health. The pathology of many intestinal diseases is associated with changes in the location and expression of aquaporins, such as intestinal infection, which can change the expression and distribution of AQPs in intestinal tissues/cells by affecting cytokines and chemokines. This can lead to various intestinal diseases such as diarrhoea, which also suggests the importance of aquaporins in the prevention and treatment of intestinal diseases. This review summarizes the relationship between aquaporins and intestinal physiology and diseases and focuses on drugs (such as plant extracts) or diets that can regulate intestinal health by regulating aquaporins. It provides a basis for establishing aquaporins as biomarkers and therapeutic targets for intestinal health.

Comparison of content-toxicity-activity of six ingenane-type diterpenoids between Euphorbia kansui before and after stir-fried with vinegar by using UFLC-MS/MS, zebrafish embryos and HT-29 cells

The dried roots of Euphorbia kansui (EK) are especially beneficial for the treatment of edema, but the severe toxicity limits their clinical applications. Euphorbia kansui stir-fried with vinegar (VEK) is traditionally employed to reduce the toxicity of EK. However, the material basis for the toxicity reduction with effectivity conservation is still unclear. Therefore, in this study, a rapid, sensitive, and reliable ultra-fast liquid chromatography tandem mass spectrometry (UFLC-MS/MS) method was firstly established to simultaneously determine six ingenane-type diterpenoids, i.e. kansuiphorin C (1), 5-O-benzoyl-20-deoxyingenol (2), 20-deoxyingenol (3), 3-O-(2'E,4'E-decadienoyl)-20-O-acetylingenol (4), 20-O-(2'E,4'Z-decadienoyl)ingenol (5), and ingenol (6), in EK and VEK based on the processing conversion. Then, the toxicity evaluation on zebrafish embryos and modulation of the expression of aquaporin-3 (AQP3) proteins in HT-29 cells were employed to investigate the toxicity-activity of six compounds. Chromatographic separation was obtained on Waters BEH RP18 column (2.1 mm × 100 mm, 2.5 μm) with the mobile phase composed of 0.1 % formic acid in acetonitrile and water, respectively. The column temperature was 35 ℃ at a flow rate of 0.4 mL min^-1. Multiple reaction monitoring was conducted in both positive and negative modes for quantitative analysis. The method was then successfully used for the determination of six compounds in EK and VEK. In addition, 1, 2, 4, and 5 had evident cardiotoxicity, intestinal irritation and nutrient absorption disorders on zebrafish larvae, while no in-vivo toxicity was seen for groups given 3 and 6 (LC₅₀ > 200 μM). Meanwhile, 1, 2, 4, 5, and 6 significantly increased the expression of AQP3 protein (p < 0.05) to promote the excretion of water in the colon. This study demonstrated that toxic ingenane-type diterpenoids converted into the less toxic compounds with the same core structure through the breakage of multiple ester bonds in the side chain. At the same time, the laxative effect was retained, providing useful information for the optimization of the process of EK and quality evaluation of other similar toxic Chinese herbal medicines.

Influence of Decoction Duration of FDY2004 on Its Physicochemical Components and Antioxidant and Antiproliferative Activities

FDY2004 (Medicinal herbs: Rheum palmatum, Paeonia suffruticosa Andrews, and Prunus davidiana), an herbal drug composition with an antiproliferative effect, is prepared by boiling, which is the most common herbal extraction method in traditional Korean medicine. Several parameters are considered in the process, including herb-to-solvent ratio, extraction temperature and pressure, and total decoction time. The aim of this study was to examine the physicochemical changes, index compound analysis results, antioxidant activity, and antiproliferative activity of FDY2004 according to the decoction duration to establish the conditions that ensure efficacy while minimizing side effects. Different samples of FDY2004 were obtained by decocting for 30, 60, 90, 120, 180, and 240 minutes. Each sample was evaluated for hydrogen ion concentration (pH), total soluble solid content (TSSC), index compound profiles, and antioxidative and antiproliferative activity. pH was found to decrease, while TSSC increased with an increase in decoction duration. Index compound contents for FDY2004 (aloe emodin, emodin, rhein, chrysophanol, physcion, and sennoside A for R. palmatum, paeonol for P. suffruticosa Andrews, and amygdalin for P. davidiana) increased when the decoction duration was 120 minutes or more, while the content of sennoside A did not increase. The total d-glucose amount increased with an increase in boiling duration. Antioxidant activity of FDY2004 increased when the decoction duration was 120 minutes or more, and the antiproliferative activity of FDY2004 was concentration dependent. The decoction duration for FDY2004 needs to be carefully determined so as to maintain efficacy while reducing side effects related to digestive absorption.

Sennoside A drug capped biogenic fabrication of silver nanoparticles and their antibacterial and antifungal activities

Sennoside A (dianthrone glycoside) shows laxative properties and used as a folk traditional medicine. Sennoside A capped silver nanoparticles (Ag/sennoside A) were synthesized at room temperature for the first time by using sennoside A as reducing and capping agent. UV-visible spectroscopic data reveals that the absorption peaks of pure sennoside A was appeared at 266, and 340 nm, which red shifted to 304, and 354 nm at higher sennoside A concentration. Upon addition of the Ag+ ions, an additional peak also observed at 398 nm, indicating the formation of spherical sennoside A capped silver nanoparticles (Ag/sennoside A). Cetyltrimethylammonium bromide (CTAB) was used a stabilizing agent to determine the role of cationic micelles on the nucleation and growth processes of Ag/sennoside A NPs formation. The 2,2-diphenyl-1-picrylhydrazyl nitrogen radical (DPPH · ), two bacteria strains (Staphylococcus aureus and Escherichia coli) and two yeast strains (Candida albicans ATCC 10231 and Candida parapsilosis ATCC 22019) were used to determine the antioxidant and antimicrobial properties of Ag/sennoside A NPs. In addition, Rhein-9-anthrone (4,5-dihydroxy-10-oxo-9H-anthracene-2-carboxylate) was isolated from the acidic hydrolysis of glycoside linkage of sennoside A and characterized. The antioxidant and antimicrobial activities of rhein-9-anthrone were also determined against DPPH radical, antibacterial and antifungal strains. The minimum inhibitory concentration was determined and discussed.

Hepatoprotection and hepatotoxicity of Chinese herb Rhubarb (Dahuang): How to properly control the "General (Jiang Jun)" in Chinese medical herb

Chinese herb Rhubarb (Dahuang), one of the most widely used traditional Chinese medicine in clinical application for over a thousand years and known as the "General (Jiang Jun)" in Chinese medical herb, currently used clinically for long-term treatment of gastrointestinal diseases and chronic liver diseases. Through previous researches, it has been identified that Rhubarb possessed a good hepatoprotective effect, which primarily protected liver from oxidation, fibrosis and cirrhosis, liver failure, hepatocellular carcinoma and various types of hepatitis. Meanwhile, it has been recently reported that long-term administration of Rhubarb preparation may undertake the risk of liver damage, which has aroused worldwide doubts about the safety of Rhubarb. Therefore, how to correctly understand the "two-way" effect of Rhubarb on liver protection and liver toxicity provides a basis for scientific evaluation of Rhubarb's efficacy on liver and side effects, as well as guiding clinical rational drug use. In this review, the mechanisms of Rhubarb how to play a role in hepatoprotection and why it causes hepatotoxic potential will be elaborated in detail and critically. In addition, some positive clinical guidances are also advised on how to reduce its hepatotoxicity in medical treatment.

Morning glory seed keeps laxative effect while retains less subchronic toxicity after being fried

ETHNOPHARMACOLOGICAL RELEVANCE

Morning glory seed (MGS), has been widely used in treating constipation especially towards children. Clinically, people usually take fried MGS (MGSF) in formulas to reduce its side effect. However, the safety of MGSF other than MGS has yet to be explored.

OBJECTIVE

The study aimed to reveal the potential mechanisms of using MGSF instead of MGS basing on chemistry, pharmacodynamics and toxicology.

METHODS

The chemical compositions of the extracts of MGS and MGSF were compared using UPLC-Q-TOF/MS method. Simultaneously, to prove the availability and safety of MGSF, we investigated the laxative effect and subchronic toxicity of MGS and MGSF and addressed the mechanism of laxative effect of them.

RESULTS

In this study, less phenolic acids and more fatty acids were detected in MGSF compared with the compounds in MGS. Moreover, we found that MGS group had stronger laxative effect than MGSF group via downregulating the expression of AQP3 protein. As for subchronic toxicity test, the body weights of MGS group were lower than MGSF group. In serum biochemistry and histopathological examinations, MGS group could cause more serious toxicity in liver, kidney and colon than MGSF group with higher values of BUN, Cr, AST and ALP.

CONCLUSION

Based on the findings in this study, MGSF with varied compounds contents could still keep the laxative effect while retain less subchronic toxicity, which emphasized the necessity of processing and provided an insight into the rational use of MGSF in clinical practice.

Enhancing our understanding of small bowel function using modern imaging techniques

Small intestinal function is critical to digestive health and patients believe an abnormal reaction to food is responsible for many of their symptoms. Despite this, our ability to assess disturbed function in clinical practice has been limited, particularly after ingestion of the complex nutrients which make up normal food. Recent advances in both wireless capsules and magnetic resonance imaging have provided new insights. This review will briefly describe the limitations of past techniques and focus on how these newer techniques are changing our understanding, particularly of how patients' gastrointestinal tracts respond to food.

Gut microbiota: a new angle for traditional herbal medicine research

Traditional Herbal Medicine (THM) has been used for thousands of years, and is popular worldwide due to its effectiveness in a variety of diseases. THM has also formed the basis of the discovery of modern drugs like artemisinin and paclitaxel. However, at present, studies that focus on development in the field of THM are stagnant because currently, the effective ingredients in the herbal formulations and the ambiguity of the underlying mechanisms of action are unknown. In this review, we have investigated the studies available that focused on the efficacy, active ingredients and bioavailability of THM, and the function of gut microbiota in THM-mediated treatment of disease. We hypothesized that most THMs treat diseases via three mechanisms: (1) metabolizing into active metabolites by the action of gut microbiota, (2) regulation of gut microbiota balance, and (3) regulating the fermentation products of the gut microbes. Therefore, focusing on these aspects can help elucidate the pharmacodynamic constituents of THM preparations, and their therapeutic mechanisms of action.

Intraluminal Impact of Food: New Insights from MRI

Understanding how the gut responds to food has always been limited by the available investigatory techniques. Previous methods involving intubation and aspiration are largely limited to liquid-only meals. The aim of this review is to describe how MRI has allowed analysis of the processing of complex multiphase meals. This has demonstrated the role of physical factors such as viscosity, fat and fibre content in controlling gastric secretion and motility. It has also allowed the description of changes induced in small bowel water content and the role of osmotic effects of poorly absorbed carbohydrates such as fructose, sorbitol and mannitol. Intestinal secretions can be shown to be stimulated by a range of fruit and vegetables and the effect of this on colonic water content can also be measured. This has been used to demonstrate the mode of action of commonly used laxatives including bran and psyllium. The wealth of data which can be obtained together with its non-invasive nature and safety makes the technique ideal for the serial evaluation of the impact of different nutrients and drugs in both health and disease.

Fructus Gardeniae-induced gastrointestinal injury was associated with the inflammatory response mediated by the disturbance of vitamin B6, phenylalanine, arachidonic acid, taurine and hypotaurine metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Gardenia (FG) is a widely used bitter and cold herb for clearing heat and detoxicating. Currently, toxicity of FG and its relative formula has been reported in many clinical and animal studies. However, no systematic research has been carried out on FG-related gastrointestinal (GI) injury which has been emphasized in China since the Ming Dynasty.

AIM OF THE STUDY

The purpose of this article is to investigate whether FG could damage GI and explore the mechanisms involved.

MATERIAL AND METHODS

FG was given to male mice by 7-day intragastric administration at average doses of 0.90 g (L group), 1.50 g (M group), and 3.00 g (H group) crude drug/kg FG. Comprehensive understanding of changes in weight, diarrhea degree, stool routine, histomorphology and inflammatory factors of stomach, small intestine, and colon for evaluating the effect of different doses of FG on GI injury. Moreover, metabolomics-based mechanisms exploration of FG on GI injury was carried out via HPLC-Q-TOF/MS analysis on mice urine.

RESULTS

High dose FG caused GI injury with serious diarrhea, decreased weight, abnormal stool routine, sever alteration in histomorphology of small intestine and colon (mild change in stomach), and significant change in inflammatory factors. The results of metabolomics suggested that 55 endogenous metabolites dispersed in 21 significantly altered metabolic pathways in 3.00 g/kg crude FG treated mice. The hub metabolites of GI injury were mainly related with vitamin B6 metabolism, phenylalanine metabolism, arachidonic acid metabolism, and taurine and hypotaurine metabolism via correlated network analysis.

CONCLUSION

FG affected the normal functions of GI via the regulating a variety of metabolic pathways to an abnormal state, and our results provided a research paradigm for the GI-injury of the relative bitter and cold traditional Chinese medicines.

Aquaporin Expression in Colonic Mucosal Biopsies From Irritable Bowel Syndrome With Diarrhea

INTRODUCTION

Aquaporin (AQP) channels are involved in regulating fluid homeostasis in the colon. Several AQP channels were detected in human colon epithelial cells. In a previous study, rats fed 1% (wt/wt) sodium cholate had increased AQP3, 7, and 8 levels, suggesting AQP involvement in bile acid diarrhea (BAD). Our aim was to compare AQP expressions in rectosigmoid mucosal (RSM) biopsies from patients with irritable bowel syndrome-diarrhea (IBS-D) (divided into those with normal or high fecal BA excretion) and in patients with IBS-constipation (IBS-C) compared with healthy controls.

METHODS

In RSM biopsies from 44 patients with IBS-D (with normal (<) or high (>2,337 μmol/48 hours (BAD)) fecal BA excretion), 10 patients with IBS-C, and 17 healthy controls, we measured expressions of AQP1, 3, 7, and 8, with RT-PCR (housekeeper gene GAPDH). We analyzed RNA for expression by RT-PCR assays, with expression calculated using 2-based fold-change. Comparisons of IBS groups were corrected for false detection rate (Bonferroni correction for 12 comparisons; P < 0.0042). AQP protein measurements on biopsies from 3 healthy controls, 3 patients with IBS-D, and 3 patients with BAD were performed by western blots (GAPDH housekeeping protein).

RESULTS

In RSM from patients with IBS-D (but not IBS-C), mRNA expression of AQP3 was decreased, and AQP7 and 8 were increased relative to controls. Fold differences were not different in IBS-D with or without BAD. Western blots confirmed increased expression of AQP7 and 8 and decreased AQP3 proteins in biopsies from patients with IBS-D compared with controls.

CONCLUSIONS

Increased AQP7 and 8 and decreased AQP3 expressions in RSM suggest that further studies on AQPs' potential role in the pathophysiology of diarrhea in IBS-D are warranted.

Changes in the Expression of Aquaporin-3 in the Gastrointestinal Tract Affect Drug Absorption

Aquaporin-3 (AQP3) plays an important role in water transport in the gastrointestinal (GI) tract. In this study, we conducted a Caco-2 cell permeability assay to examine how changes in the expression and function of AQP3 affect the rate at which a drug is absorbed via passive transport in the GI tract. When the function of AQP3 was inhibited by mercuric chloride or phloretin, there was no change in warfarin permeability. In contrast, when the expression of AQP3 protein was decreased by prostaglandin E₂ (PGE₂) treatment, warfarin permeability increased to approximately twice the control level, and membrane fluidity increased by 15%. In addition, warfarin permeability increased to an extent comparable to that after PGE₂ treatment when cell membrane fluidity was increased by 10% via boric acid/EDTA treatment. These findings suggest the possibility that the increased drug absorption under decreased AQP3 expression was attributable to increased membrane fluidity. The results of this study demonstrate that the rate of water transport has little effect on drug absorption. However, our findings also indicate that although AQP3 and other similar transmembrane proteins do not themselves transport drugs, changes in their expression levels can cause changes in cell membrane fluidity, thus affecting drug absorption rates.

Downregulation of Aquaporin 3 Mediated the Laxative Effect in the Rat Colon by a Purified Resin Glycoside Fraction from Pharbitis Semen

Background

Pharbitis Semen, the seeds of Pharbitis nil, is widely used as a traditional purgative medicine in China, Korea, and Japan. This study investigated the laxative effects of a purified resin glycoside fraction obtained in our previous study from Pharbitis Semen in vivo and in vitro.

Materials and Methods

After orally administering a purified resin glycoside fraction from Pharbitis Semen (RFP) to rats, the content of fecal water, AQP3, NF-κB, COX-2 expression, and the prostaglandin E₂ (PGE₂) concentrations in the colon were examined. Moreover, human intestinal epithelial cells (HT-29) were used to investigate the mechanism of RFP decreasing the AQP3 expression.

Results

Results obtained showed that treatment with RFP increased the feces excretion and fecal water content of rats in a dose-dependent manner. More interestingly, AQP3 expression was suppressed by RFP treatment both in the rat colons and in HT-29 cells, while the NF-κB pathway-mediated PGE₂ production was activated. Interestingly, pretreating rats with BAY-11-7082 (NF-κB inhibitor) or indomethacin (COX-2 inhibitor) and RFP neither induced diarrhea nor decreased the AQP3 expression in the colon.

Conclusions

The purgative property of the purified resin glycoside fraction was attributed to NF-κB activation in the colon, which increased the COX-2-mediated secretion of PGE₂. PGE₂ decreased AQP3 expression which inhibits water absorbed from the intestine to the blood vessel side, resulting in the laxative effect of RFP.

Fluid resuscitation via the rectum ameliorates hemodynamic disorders through adjusting aquaporin expression in an experimental severe acute pancreatitis model

Acute pancreatitis is an acute abdominal disease, with 10-20% of the cases deteriorating rapidly, accompanied by persistent organ failure and further development into severe acute pancreatitis (SAP). The aim of the present study was to investigate the mechanism of fluid resuscitation via the rectum in the early stages of SAP and the role of aquaporins (AQPs). An SAP model was constructed by injection of 5% sterile sodium taurocholate into the biliopancreatic duct of Sprague Dawley rats, and the mean arterial pressure (MAP) was continuously monitored via femoral artery catheterization. At 30 min after the construction of the SAP model, the rats in the fluid resuscitation groups were resuscitated with normal saline at a rate of 4 ml/kg/h through the venous or the rectal route. The AQP and Na⁺-K⁺-ATPase levels, and the correlation of the MAP and colon AQPs at the early stages of SAP were analyzed. The results demonstrated that the mRNA level of AQP-3 and AQP-4 in the distal colon decreased significantly in the group subjected to fluid resuscitation via the rectum, while no significant differences were identified in the Na⁺-K⁺-ATPase levels of the colon in that group. Furthermore, a negative correlation was identified between the expression of AQPs and the MAP (P<0.01). Thus, fluid resuscitation via the rectum appears to ameliorate hemodynamic disorders through adjusting the expression of AQP-3 and AQP-4 in the distal colon in an experimental SAP model.

Identification of active compound combination contributing to anti-inflammatory activity of Xiao-Cheng-Qi Decoction via human intestinal bacterial metabolism

Human intestinal bacteria play an important role in the metabolism of herbal medicines, leading to the variations in their pharmacological profile. The present study aimed to investigate the metabolism of Xiao-Cheng-Qi decoction (XCQD) by human intestinal bacteria and to discover active component combination (ACC) contributing to the anti-inflammatory activity of XCQD. The water extract of XCQD was anaerobically incubated with human intestinal bacteria suspensions for 48 h at 37 °C. A liquid chromatography-hybrid quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) method was performed for identification of the metabolites. In addition, the anti-inflammatory effects of XCQD and biotransformed XCQD (XCQD-BT) were evaluated in vitro with cytokines in RAW264.7 cells induced by lipopolysaccharide (LPS). A total of 51 compounds were identified in XCQD and XCQD-BT. Among them, 20 metabolites were proven to be transformed by human intestinal bacteria. Significantly, a combination of 14 compounds was identified as ACC from XCQD-BT, which was as effective as XCQD in cell models of inflammation. In conclusion, this study provided an applicable method, based on intestinal bacterial metabolism, for identifying combinatory compounds responsible for a certain pharmacological activity of herbal medicines.

A New Model of Diarrhea with Spleen-Kidney Yang Deficiency Syndrome

OBJECTIVE

The aim of this study was to examine a new method to create a rat model of diarrhea with spleen-kidney yang deficiency syndrome.

METHODS

A senna leaf (Folium sennae) decoction was made in 3 concentrations of 1.0, 0.5, and 0.25 g/mL. Rats were randomly divided into 4 groups: the control (C)-, high (H)-, middle (M)-, and low (L)- dose groups. The groups received saline, 1.0, 0.5, or 0.25 g/mL senna leaf decoction, respectively, for 4 weeks. Body weight monitoring, food consumption, water intake, defecation frequency, stool Bristol score, weight-loaded forced swimming test, forelimb grip strength test, D-xylose absorption test, serum cortisone, adrenocorticotropic hormone (ACTH), 24 h urine 17-hydroxycorticosteroid (17-OHCS), and histopathological detection were conducted to assess the success of the senna leaf decoction-induced model.

RESULTS

This study showed that the senna leaf decoction could induce diarrhea and dose-dependently slow body weight growth, reduce food consumption, and increase water intake, stool Bristol score, and defecation frequency. Statistical differences were found between groups H and M in rectal temperature, weight-loaded forced swimming time, forelimb grip strength, and serum cortisone. The D-xylose absorption test also showed dysfunction of intestinal absorption in groups H and M. The serum cortisone and 24 h urine 17-OHCS were significantly reduced in group H.

CONCLUSIONS

Gastric gavage of 10 mL/kg of body weight of a high concentration of a senna leaf decoction (1.0 g/mL) for 4 weeks was used to create a rat model of diarrhea with spleen-kidney yang deficiency syndrome.