Investigation of the "dose-time-response" relationships of rhubarb on carbon tetrachloride-induced liver injury in rats

Research Progress on the Anti-Liver Cancer Mechanism and Toxicity of Rhubarb Anthraquinone

Ethnopharmacological Relevance

Rhubarb has the effect of breaking blood stasis and abnormal mass, and was often used to treat various tumor diseases including liver cancer in ancient China. Recipes containing rhubarb have anti-liver cancer properties and are still used today. However, the main components and mechanism of action of rhubarb against liver cancer are still unclear.

Aim of the Review

To conduct a review of the anti-liver cancer effects and toxicity of rhubarb anthraquinones (AQs).

Materials and Methods

This article reviewed the effects of rhubarb AQs in the treatment of liver cancer and the signaling pathways involved, and discussed the toxicity and pharmacokinetics of rhubarb AQs by searching the Web of Science, PubMed and CNKI databases.

Results

Rhubarb (Rhei Radix et Rhizoma) is a traditional Chinese medicine that has been existed for thousands of years and is used as an anti-cancer drug. Modern pharmacological research shows that rhubarb AQs, as the main component of rhubarb, contains emodin, rhein, chrysophanol, physcione and aloe-emodin, which has anti-liver cancer effects and can be considered as a potential therapeutic drug for liver cancer. However, many modern studies have shown that rhubarb AQs have certain toxicity, which hinders in-depth research on rhubarb AQs.

Conclusion

Rhubarb AQs can be used as a potential anti-liver cancer drug, but its research still has many limitations. Strengthening research on related experiments and finding a balance between toxicity and efficacy are all directions worth studying in the future.

Bidirectional regulation effect of rhubarb as laxative and astringent by metabolomics studies

ETHNOPHARMACOLOGICAL RELEVANCE

Rhubarb, a prominent traditional Chinese medicine, has been employed as a potent laxative for centuries and garnered particular popularity among the youth owing to its notable efficacy in weight management. Historical records indicated that rhubarb initially exhibited robust laxative properties, but extended and consistent usage may lead to an astringent response in the later stage of long-term use. In contrast, steamed pieces of rhubarb (SR), preparing through the process of steaming with wine, have demonstrated a gentle laxative effect with no reported adverse effects.

AIM OF THE STUDY

Our study was designed to explore the intricate mechanisms underlying laxative and astringent properties of rhubarb through metabolomics research.

MATERIALS AND METHODS

In this investigation, we employed a serum metabolomics approach utilizing the UPLC-Q-Extractive-Orbitrap-MS method to delve into the contrasting laxative and astringent effects of rhubarb, as well as to unravel the mechanisms of underpinning its bidirectional regulatory influence. To commence, we assessed alterations in Evacuation Index (EI) values, intestinal hormone levels, and colon histopathology in mice to gauge rhubarb's laxative and astringent effects. Subsequently, metabolomics methodology was employed for cluster analysis through Principal Component Analysis (PCA) and biomarker identification via Orthogonal Partial Least Squares-Discriminant Analysis (OPLS-DA). Then, we delved into the distinctions in characteristic biomarkers, metabolic pathways, their association with pathological changes, and correlation heatmap for biomarkers between raw pieces of rhubarb (RR) and SR to gain insights into the potential mechanisms behind rhubarb's bidirectional regulatory effects.

RESULTS

Our findings revealed that RR exhibited a laxative effect in the early stage and transitioned to an astringent effect in the later stage, as indicated by the EI values. In contrast, SR consistently demonstrated a mild laxative effect. Biochemical indexes and histopathological assessments unveiled that RR triggered its astringent effect by inhibiting secretion of motilin (MTL), promoting secretion of vasoactive intestinal peptide (VIP) and epinephrine (EPI), and inducing onset of inflammation. Furthermore, serum metabolomics analysis identified 59 discriminative biomarkers modulated by RR and SR. Through comprehensive analysis, we elucidated the in vivo transformation relationships among multiple endogenous metabolites. Notably, our results underscored the down-regulation of certain phosphatidylcholines (PCs), amino acids, acylcarnitines, and up-regulation of lysophosphatidylcholines (LysoPCs) played pivotal roles in the onset of gut dysfunction, intestinal inflammation, gut barrier damage, and gastrointestinal motility disorder upon prolonging RR administration, ultimately contributing to its astringent effect. Additionally, our correlation analysis elucidated that anthraquinones, stilbenes, and phenylbutanones were the pharmacodynamic material basis responsible for inducing the astringent effect of RR.

CONCLUSION

This study provides valuable insights into the bidirectional regulatory effects of rhubarb and sheds light on its underlying mechanisms through a comprehensive metabolomics approach.

Investigation of therapeutic effects of rhubarb decoction retention enema on minimal hepatic encephalopathy in rats based on 16S rDNA gene sequencing and bile acid metabolomics

Minimal hepatic encephalopathy (MHE) is an early stage of hepatic encephalopathy (HE), with high incidence and a high rate of clinically missed diagnosis. Early diagnosis of MHE and effective clinical intervention are of great importance. Rhubarb decoction (RD)-induced retention enema can effectively improve the cognitive function of patients with MHE, whereas disturbances in the enterohepatic circulation of bile acid (BAs) can induce MHE. However, the molecular mechanisms underlying the therapeutic effects of RD have not been examined from the perspective of intestinal microbiota and bile metabolomics. In this study, we investigated the effects of RD-induced retention enema on intestinal microbiota and bile metabolites in rats with CCl₄- and TAA-induced MHE. RD-induced retention enema significantly improved liver function, reduced blood ammonia levels, alleviated cerebral oedema and restored cognitive function in rats with MHE. In addition, it increased the abundance of intestinal microbes; partially reversed the disorder in the composition of intestinal microbiota, including the Bifidobacterium and Bacteroides genera; and regulated BA metabolism, such as taurine combined with increased BA synthesis. In conclusion, this study highlights the potential importance of BA enterohepatic circulation for RD to improve cognitive function in MHE rats, providing a new perspective on the mechanism of this herb. The findings of this study will facilitate experimental research on RD and help to develop RD-based strategies for clinical application.

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.

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.

Aloe-emodin induces hepatotoxicity by the inhibition of multidrug resistance protein 2

BACKGROUND

Aloe-emodin (AE) is among the primary bioactive anthraquinones present in traditional Chinese medicinal plants such as Rheum palmatum L. Multidrug resistance protein 2 (ABCC2/ MRP2) is an important efflux transporter of substances associated with cellular oxidative stress. However, the effects of traditional Chinese medicine on this protein remain unclear.

PURPOSE

The aim of this research is to study the role of ABCC2 in AE-induced hepatotoxicity.

METHODS

The expression of ABCC2 protein and mRNA levels were analyzed by Western-Blotting and qRT-PCR, respectively. The intracellular oxidative stress caused by AE was evaluated by quantifying the levels of intracellular reactive oxygen species, malondialdehyde, glutathione reduced and oxidized glutathione. The levels of adenosine triphosphate, mitochondrial membrane potential and mitochondrial DNA were explored to evaluate the effects of AE on mitochondrial function. The effects of AE on cell apoptosis and cell cycle were detected by flow cytometry. To further clarify the key role of ABCC2 in AE induced cytotoxicity, we used pCI-neo-ABCC2 plasmid to over express ABCC2 protein, and small interfering RNA was used to knockdown ABCC2 in HepG2 cells. Additionally, we investigated the impact of AE on ABCC2 degradation pathway and the hepatotoxic effects of AE in mice.

RESULTS

AE was found to inhibit ABCC2 transport activity, downregulate ABCC2 expression and altered intracellular redox balance. Induction of oxidative stress resulted in depletion of intracellular glutathione reduced, mitochondria dysfunction and activation of apoptosis. ABCC2 overexpression significantly reduced AE-induced intracellular oxidative stress and cell death, which was enhanced by ABCC2 knockdown. Furthermore, AE was observed to promote ABCC2 degradation through induction of autophagy and hepatotoxicity was induced in mice by promoting ABCC2 degradation.

CONCLUSIONS

The inhibition of ABCC2 is a novel effect of AE that triggers oxidative stress and apoptosis. These findings are helpful in understanding the toxicological effects of AE-containing medicinal plants.

In Vitro Anticancer MCF-7, Anti-Inflammatory, and Brine Shrimp Lethality Assay (BSLA) and GC-MS Analysis of Whole Plant Butanol Fraction of Rheum ribes (WBFRR)

In this study, GC-MS analysis has shown that whole plant butanol fraction of rheum ribes (WBFRR) comprises of 21 compounds which exhibited anticancer (MCF-7) activity having IC50 value of 36.01± 0.26. MTT assay (MCF-7), Oxidative Burst assay using chemiluminescence technique, and B-Hatching techniques were the methods used for anticancer MCF-7, anti-inflammatory, and Brine Shrimp Lethality Assay (BSLA). GC-MS was used for structural elucidation. Whole plant methanol extract of rheum ribes (WMERR), whole plant n-hexane fraction of rheum ribes (WHFRR), and whole plant aqueous fraction of rheum ribes (WAFRR) were inactive against anticancer (MCF-7) cell line. Whole plant methanol extract of rheum ribes (WMERR), whole plant aqueous fraction of rheum ribes (WAFRR) and whole plant butanol fraction of rheum ribes (WBFRR) showed anti-inflammatory activity on ROS having IC50 value of 23.2±1.9, 24.2±2.7 and 12.0±0.6. Whole plant butanol fraction of rheum ribes (WBFRR) showed Brine Shrimp Lethality with LD50 693.302 while whole plant methanol extract of rheum ribes (WMERR) and whole plant aqueous fraction of rheum ribes (WAFRR) showed high lethality at highest concentration. This study revealed that whole plant butanol fraction of rheum ribes (WBFRR) exhibited significant anticancer (MCF-7) activity. In the near future, the constituent of whole plant butanol fraction of rheum ribes (WBFRR) can be the alternative drug against MCF-7 cell line with least toxicity and side effects.

Crude extract of Rheum palmatum L. Induces cell cycle arrest S phase and apoptosis through mitochondrial-dependent pathways in U-2 OS human osteosarcoma cells

Cancer is the second cause of death in children. Osteosarcoma is the most common primary malignancy of solid bone cancer primarily affecting adolescents and young adults. In the Chinese population, the crude extract of Rheum palmatum L. (CERP) has been used for treating different diseases, including SARS, rheumatoid arthritis, coxsackievirus B3, and human colon cancer cell, pancreatic cancer. There are no reports on CERP and human osteosarcoma cells. The present study examined effects of CERP on cytotoxicity including cell cycle distribution and cell death (apoptosis) in U-2 OS human osteosarcoma cells. CERP significantly induced S phase arrest in U-2 OS cells in a dose-dependent. CERP produced DNA damage and DNA condensation. Other effects of CERP were stimulation of ROS and Ca(2+) , mitochondria impairment, and activation of caspase-3, -8, and -9. CERP increased the levels of Bax, Bak, Bad, cyclin B, Fas, PARP, GRP78, GADD153, AIF, Endo G, Calpain-2, p21, and p27, but decreased the levels of Bcl-2, BCL-X, XIAP, Akt, CDC25A, CDK2, Cyclin A, and Cyclin E of U-2 OS cells. It was also observed that CERP promoted the expression of AIF, Endo G, GADD153, and cytochrome c. These results indicate that CERP has anticancer effects in vitro and provide the foundation for in vivo studies of animal models of osteosarcoma. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 957-969, 2016.

Influence of wine-processing on the pharmacokinetics of anthraquinone aglycones and glycosides from rhubarb in hyperlipidemic hamsters

A high performance liquid chromatography-tandem mass spectrometry method was developed to investigate the influence of wine-processing on pharmacokinetics of anthraquinones from rhubarb in hyperlipidemic hamsters.

Herbal formula, Scutellariae radix and Rhei rhizoma attenuate dimethylnitrosamine-induced liver fibrosis in a rat model

The bioactive components extracted from Scutellariae radix and Rhei rhizoma (SR) have been commonly used to treat liver diseases. The aim of this study was to verify the underlying mechanisms and antifibrotic effects of ethanol extract from the herbal combinatorial formula (SRE) in a dimethylnitrosamine (DMN)-administered rat model, with functional proteome tools. Our results indicated that the hepatic collagen content and alpha-smooth muscle actin expression were obviously alleviated by treatment with SRE. Comprehensive proteomics revealed global protein changes, and the network analysis implied that SRE application would attenuate oxidative stress and cytoskeleton dysregulation caused by DMN exposure. Next, marked downregulation of antioxidant enzymes mediated by DMN treatment was restored in the presence of SRE, while SRE treatment contributed to decreased MDA content. Moreover, protein carbonylation and DNA adduction induced by oxidative stress finally leading to liver injury were also reduced under SRE administration. These findings demonstrate that SRE could effectively prevent hepatic fibrosis mainly through regulating the redox status, and subsequently modulating the modification of intracellular molecules. Our experiments might help in developing novel therapeutic strategies against oxidation-caused liver diseases.

Large dose means significant effect--dose and effect relationship of Chi-Dan-Tui-Huang decoction on alpha-naphthylisothiocyanate-induced cholestatic hepatitis in rats

Background

Large dose application of traditional Chinese medicines has attracted more and more attentions in recent years. However, the scientific connotation of large dose application has not been clarified so far. The present study was designed to investigate the protective effects of Chi-Dan-Tui-Huang decoction (CDTHD) against Alpha-naphthylisothiocyanate (ANIT) induced acute cholestatic hepatitis in rats and explore the dose-effect relationship of CDTHD as a reference for clinical application.

Methods

The administration of CDTHD at a series of doses was performed twice each day for 5 days. The acute cholestasic hepatitis models were induced by intragastric administration of ANIT on the third day of CDTHD administration. Then, the protective effects on cholestatic hepatitis were investigated by examining the following parameters: body weights of rats, morphological and histopathological liver changes, the levels of serum biomarkers including alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total bilirubin, direct bilirubin and γ-glutamyltranspeptidase. Furthermore, the dose-effect relationship was investigated with the application of correspondence analysis.

Result

In the tested range of doses, CDTHD at the maximum tolerance dose did not show any toxicity as time went on. The efficacy result showed that CDTHD from 21.6 g/kg⋅d to 86.4 g/kg⋅d exhibited significant hepatoprotective effect against ANIT-induced acute cholestatic hepatitis. It alleviated liver injury and reversed adverse biochemical and histopathological changes in a dose-dependent manner. Correspondence analysis showed that Radix Paeoniae Rubra in CDTHD was the main effective component and CDTHD could enhance the integrated efficacy in dose-dependent manner.

Conclusions

CDTHD is beneficial to liver protection in a dose-dependent manner. Especially large dose demonstrates potent efficacy and Radix Paeoniae Rubra in the formula contributes the main effect on ANIT-induced acute cholestatic hepatitis without toxicity.

Persistent fibrosis in the liver of choline-deficient and iron-supplemented L-amino acid-defined diet-induced nonalcoholic steatohepatitis rat due to continuing oxidative stress after choline supplementation

Nonalcoholic steatohepatitis (NASH) is characterized by combined pathology of steatosis, lobular inflammation, fibrosis, and hepatocellular degeneration, with systemic symptoms of diabetes or hyperlipidemia, all in the absence of alcohol abuse. Given the therapeutic importance and conflicting findings regarding the potential for healing the histopathologic features of NASH in humans, particularly fibrosis, we investigated the reversibility of NASH-related findings in Wistar rats fed a choline-deficient and iron-supplemented l-amino acid-defined (CDAA) diet for 12weeks, with a recovery period of 7weeks, during which the diets were switched to a choline-sufficient and iron-supplemented l-amino acid-defined (CSAA) one. Analysis showed that steatosis and inflammation were significantly resolved by the end of the recovery period, along with decreases in AST and ALT activities within 4weeks. In contrast, fibrosis remained even after the recovery period, to an extent similar to that in continuously CDAA-fed animals. Real-time reverse transcriptase-polymerase chain reaction, Western blot, and immunohistochemical investigations revealed that expression of some factors indicating oxidative stress (CYP2E1, 4-HNE, and iNOS) were elevated, whereas catalase and SOD1 were decreased, and a hypoxic state and CD34-positive neovascularization were evident even after the recovery period, although the fibrogenesis pathway by activated α-SMA-positive hepatic stellate cells via TGF-β and TIMPs decreased to the CSAA group level. In conclusion, persistent fibrosis was noted after the recovery period of 7weeks, possibly due to sustained hypoxia and oxidative stress supposedly caused by capillarization. Otherwise, histopathological features of steatosis and inflammation, as well as serum AST and ALT activities, were recovered.

Evaluation of the protective effect of Rhei Radix et Rhizoma against α-naphthylisothiocyanate induced liver injury based on metabolic profile of bile acids

ETHNOPHARMACOLOGICAL RELEVANCE

To evaluate the hepatoprotective effect of the root and rhizome of Rhubarb (Rhei Radix et Rhizoma) against α-naphthylisothiocyanate (ANIT)-induced liver injury using metabolic profile of bile acids (BAs) along with biochemical parameters and histological alterations.

MATERIALS AND METHODS

Ultra-performance liquid chromatography coupled with quadrupole mass spectrometry (UPLC-MS) was applied to determinate the concentration of BAs, which was followed by multivariate statistical analysis of Principal Component Analysis (PCA) and Partial Least Squares Discriminate Analysis (PLS-DA).

RESULTS

Based on PCA results, three groups (Vehicle group, ANIT group and RhO+ANIT group) were clearly distinguished. Tauro-cholic acid (TCA), tauro-hyodesoxycholic acid (THDCA), glyco-cholic acid (GCA), and glyco-chenodeoxycholic acid (GCDCA) were proved to be the most important markers corresponding to ANIT-induced liver injury and protection provided by Rhubarb, which is further confirmed by PLS-DA. A correlation was found between the foregoing BAs and biochemical parameters including serum aspartate aminotransferase (ALT) and aspartate aminotransferase (AST), which confirmed that TCA, THDAC, GCA, and GCDCA could be considered as sensitive biomarkers.

CONCLUSION

The variance of the BAs contents can be used to evaluate ANIT-induced hepatotoxicity caused by ANIT and protective effects of Rhubarb. It also lays the foundation for the further research on the mechanisms of cholestasis as well as the therapeutic effect of Rhubarb.

A comparative study on the tissue distributions of rhubarb anthraquinones in normal and CCl4-injured rats orally administered rhubarb extract

AIM OF THE STUDY

The present study comparatively investigated the tissue distributions of rhubarb anthraquinone derivatives (AQs) to examine whether they undergo different uptakes in normal or CCl(4)-induced liver-damaged rats, to explore possible reasons for the different toxicities of AQs in pathological model rats and normal rats at the tissue distribution level.

MATERIALS AND METHODS

The total rhubarb extract (14.49 g kg(-1) of body weight per day based on the quantity of crude material) was administrated orally to normal and model rats for 12 weeks. The concentrations of free AQs in tissues were quantitated by liquid chromatography-tandem mass spectrometry (LC-MS). After drug withdrawal for 4 weeks, tissue distributions were again determined.

RESULTS

The five free AQs-aloe-emodin, rhein, emodin, chrysophanol and physcion--were detected in the liver, kidney and spleen, while only rhein, aloe-emodin and emodin reached the quantitative limit. The tissue distributions of rhein (p < 0.001), aloe-emodin (p < 0.001) and emodin (p < 0.05) in normal rats were higher than those in model rats with rhein>aloe-emodin>emodin in kidney and spleen tissues and aloe-emodin > rhein > emodin in liver tissues. Free AQs were not detected in the tissues after drug withdrawal for 4 weeks.

CONCLUSIONS

These results suggest that the tissue toxicity of AQs in normal animals is higher than that in pathological model animals with little accumulative toxicity of rhubarb. The results are concordant with the traditional Chinese theory of You Gu Wu Yun recorded first in Su Wen, a classical Chinese medical treatise.