The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: the Yin/Yang actions of rhubarb

The safety evaluation of Shenze Shugan capsule and mechanism of apoptosis induced by five potentially nephrotoxic components

ETHNOPHARMACOLOGICAL RELEVANCE

Shenze Shugan capsule is a prescription of traditional Chinese medicine for nonalcoholic steatohepatitis treatment. It includes Rhei Radix et Rhizoma (RR), Cassiae Semen (CS) and Alismatis Rhizoma(AR), which widely contains rhein, emodin, aurantio-obtusin, alisol A and alisol B 23-monoacetate.

AIM OF THE STUDY

In this study, we aimed to explore the safety of the medicine, and further elucidate the mechanism of apoptosis induction in HK-2 cells by five components, including rhein, emodin, aurantio-obtusin, alisol A and alisol B 23-monoacetate.

MATERIALS AND METHODS

We investigated the nephrotoxicity of Shenze Shugan capsule, including RR, CS, AR and mixed herbs given for two months in rats. Superoxide dismutase (SOD) in kidney tissues, urea nitrogen (BUN) and creatinine (CRE) in serum were detected, and renal pathology analysis was performed. In cell experiments, the apoptotic rate and cell cycle distribution of HK-2 cells were tested by flow cytometry. The levels of mitochondrial membrane potential (ΔΨm) and related protein expression in mitochondrial pathway were measured as well.

RESULTS

We confirmed that two months of administering high doses(60 times the dose for clinical use in adults) of RR, CS or mixed herbs upregulated the levels of CRE and RUN, inhibited SOD activity, and increased the degree of tubular degeneration and glomerular dilatation, but Shenze Shugan capsule has no significant differences in renal structure or renal function. In addition, we found that five components all concentration-dependently inhibited HK-2 cells proliferation and induced apoptosis, especially aurantio-obtusin as the novel nephrotoxic component. Rhein and emodin significantly induced S/M accumulation, but aurantio-obtusin, alisol A and alisol B 23-monoacetate significantly induced G1/M accumulation in HK-2 cells. Similarly, they could induce Caspase3 activation, loss of mitochondrial membrane potential (ΔΨm), and down-regulation of Bcl-2 and up-regulation of Bax.

CONCLUSIONS

Through a two-month subchronic toxicity study in rats, our preliminary determination is that this formulation is safe and reliable for long-term use. Interestingly, the potentially toxic herbs such as RR, CS, AR can reduce toxicity by drug compatibility. When further exploring the mechanism of action of toxic herbs, we found that mitochondrial pathway is involved in the apoptosis of HK -2 cells induced by rhein, emodin, aurantio-obtusin, alisol A and alisol B 23-monoacetate. Our findings provide new ideas for safety studies of Shenze Shugan capsule.

Rhein for treating diabetes mellitus: A pharmacological and mechanistic overview

With the extension of life expectancy and changes in lifestyle, the prevalence of diabetes mellitus is increasing worldwide. Rheum palmatum L. a natural botanical medicine, has been used for thousands of years to prevent and treat diabetes mellitus in Eastern countries. Rhein, the main active component of rhubarb, is a 1, 8-dihydroxy anthraquinone derivative. Previous studies have extensively explored the clinical application of rhein. However, a comprehensive review of the antidiabetic effects of rhein has not been conducted. This review summarizes studies published over the past decade on the antidiabetic effects of rhein, covering the biological characteristics of Rheum palmatum L. and the pharmacological effects and pharmacokinetic characteristics of rhein. The review demonstrates that rhein can prevent and treat diabetes mellitus by ameliorating insulin resistance, possess anti-inflammatory and anti-oxidative stress properties, and protect islet cells, thus providing a theoretical basis for the application of rhein as an antidiabetic 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.

Mechanisms and Efficacy of Chinese Herbal Medicines in Chronic Kidney Disease

As the current treatment of chronic kidney disease (CKD) is limited, it is necessary to seek more effective and safer treatment methods, such as Chinese herbal medicines (CHMs). In order to clarify the modern theoretical basis and molecular mechanisms of CHMs, we reviewed the knowledge based on publications in peer-reviewed English-language journals, focusing on the anti-inflammatory, antioxidative, anti-apoptotic, autophagy-mediated and antifibrotic effects of CHMs commonly used in kidney disease. We also discussed recently published clinical trials and meta-analyses in this field. Based on recent studies regarding the mechanisms of kidney disease in vivo and in vitro, CHMs have anti-inflammatory, antioxidative, anti-apoptotic, autophagy-mediated, and antifibrotic effects. Several well-designed randomized controlled trials (RCTs) and meta-analyses demonstrated that the use of CHMs as an adjuvant to conventional medicines may benefit patients with CKD. Unknown active ingredients, low quality and small sample sizes of some clinical trials, and the safety of CHMs have restricted the development of CHMs. CHMs is a potential method in the treatment of CKD. Further study on the mechanism and well-conducted RCTs are urgently needed to evaluate the efficacy and safety of CHMs.

Ethnobotanical Uses, Phytochemistry and Pharmacology of Different Rheum Species (Polygonaceae): A Review

Today, there is an increased tendency to use herbal remedies. Rhubarb refers to several species of the genus Rheum L. in the Polygonaceae family. This species-rich genus is mainly distributed in Asian countries. Several medicinal effects have been attributed to the Rheum spp. in the traditional and modern medicine such as healing lungs, liver, kidney, womb and bladder diseases, cancer, diabetes, insect bites, relapsing fevers, diarrhea and constipation. Various in vitro, in vivo and clinical studies have investigated the therapeutic effect of extracts, fractions and pure compounds isolated from different species of this genus. Considering the positive findings, several pharmaceutical formulations containing rhubarb extract like capsules, drops, mouthwashes and different topical formulations are now present in the market. However, there are other traditional therapeutic effects of rhubarb that have not been studied yet and it is of great importance to perform confirmatory experiments or clinical investigations. The current review summarizes general information regarding botany, phytochemistry, ethnobotany and pharmacological aspects of Rheum spp. It is hoped that the present review could motivate subsequent research on the other medicinal properties of these plants that have been neglected until today.

Attenuation of potassium dichromate and sodium arsenite toxicities by methanol extract of Rauvolfia vomitoria in mice

OBJECTIVES

Exposure to arsenic and hexavalent chromium is a major public health concern especially in the developing part of the world and there is paucity of information on reliable treatment modalilities. It is in this regard that this study evaluates the efficacy of methanol leaf extract of Rauvolfia vomitoria (MRV) when used as pretreatment agent against potassium dichromate (K₂Cr₂O₇) and sodium arsenite (NaAsO₂) exposure.

METHODS

Swiss albino mice between 7 and 10 weeks old were divided into eight cohorts of five animals each. Treatment groups consisted of a distilled water control, MRV alone (275 mg/kg po daily), K₂Cr₂O₇ (12.0 mg/kg, single ip injection) +/- MRV pretreatment, NaAsO₂ (2.5 mg/kg, single ip injection) +/- MRV pretreatment, Na₂AsO₂ + K₂Cr₂O₇ +/- MRV pretreatment. MRV was given for seven consecutive days, while K₂Cr₂O₇ and NaAsO₂ were injected on day seven of the experiment. The frequency of micronucleated polychromatic erythrocytes (mPCEs) was determined in bone marrow cells, while aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were assessed in the plasma. Hepatic glutathione (GSH), malondialdehyde (MDA), catalase (CAT) and glutathione-S-transferase (GST) levels were also determined.

RESULTS

The NaAsO₂ and K₂Cr₂O₇ significantly (p<0.05) increased mPCE formation, AST, ALT, and CAT when compared with the control. Simultaneous exposure to NaAsO₂ and K₂Cr₂O₇ further increased the levels of the markers. Furthermore, GSH and GST were significantly reduced by NaAsO₂ or K₂Cr₂O₇ or their combination. Pretreatment with MRV reversed the markers towards that of control.

CONCLUSIONS

Methanol extract of Rauvolfia vomitoria may therefore ameliorate NaAsO₂ and K₂Cr₂O₇-induced toxicities via reduction of oxidative stress and fortification of anti-oxidant system.

Rhubarb Enema Improved Colon Mucosal Barrier Injury in 5/6 Nephrectomy Rats May Associate With Gut Microbiota Modification

Chronic kidney disease (CKD) is often accompanied with colon mucosal barrier damage and gut microbiota disturbance, which strongly associate with up-regulated inflammation and kidney tubulointerstitial fibrosis. However, few interventions could protect the damaged barrier effectively. Rheum palmatum L or rhubarb is a common herbal medicine which is widely used to protect the colon mucosal barrier. In previous studies, we found that rhubarb intervention may reduce renal inflammation and tubulointerstitial fibrosis, via gut microbiota modification. However, whether intestinal barrier function could be improved by rhubarb intervention and the relationship with intestinal flora are still unknown. Therefore, we investigated the effects of rhubarb enema on intestinal barrier, and further analyzed the relationship with gut microbiota in 5/6 nephrectomy rats. Results indicated that rhubarb enema improved the intestinal barrier, regulated gut microbiota dysbiosis, suppressed systemic inflammation, and alleviated renal fibrosis. More specifically, rhubarb enema treatment inhibited the overgrowth of conditional pathogenic gut bacteria, including Akkermansia, Methanosphaera, and Clostridiaceae in CKD. The modification of gut microbiota with rhubarb intervention displayed significant correlation to intestinal barrier markers, TLR4–MyD88–NF-κB inflammatory response, and systemic inflammation. These results revealed that rhubarb enema could restore intestinal barrier by modifying several functional enteric bacteria, which may further explain the renal protection mechanism of the rhubarb enema.

Metabolic Profiling Analysis of the Alleviation Effect of the Fractions of Niuhuang Jiedu Tablet on Realgar Induced Toxicity in Rats

Niuhuang Jiedu Tablet (NJT) is a classical formula in treating acute tonsillitis, pharyngitis, and so on. In the formula, significant level of Realgar as a potentially toxic element is contained. Our previous experiments revealed that it was less toxic for combined Realgar in NJT. However, the active fraction of this prescription with toxicity alleviation effect on Realgar was still obscure. NJT was divided into five different polar fractions (NJT-PET, NJT-25, NJT-50, NJT-75, and NJT-95), and we explored the toxicity alleviation effect on Realgar. Based on 1H NMR spectra of urine and serum from rats, PCA and PLS-DA were performed to identify different metabolic profiles. Liver and kidney histopathology examinations and serum clinical chemistry analysis were also performed. With pattern recognition analysis of metabolites in urine and serum, Realgar group showed a clear separation from control group, while the metabolic profiles of NJT-PET, NJT-25, NJT-50, and NJT-95 groups were similar to Realgar group, and the metabolic profiles of NJT and NJT-75 groups were very close to control group. Statistics results were confirmed by the histopathological examination and biochemical assay. The present work indicated that 75% EtOH fraction of NJT was the most valid fraction with the toxicity alleviation effect on Realgar.

Advances in bio-active constituents, pharmacology and clinical applications of rhubarb

Rhubarb is one of the most ancient, commonly used and important herbs in Chinese medicine. The modern researches of rhubarb clarified the efficacies, ingredients and mechanisms in a more scientific and rigorous way. The main chemical compositions of rhubarb include anthraquinones, anthrones, stilbenes, tannins, polysaccharides etc. These compositions show extensive pharmacological activities including regulating gastrointestinal, anticancer, antimicrobial, hepatoprotective, anti-inflammatory, protecting cardiovascular, cerebrovascular and so on. This paper reviews the recent studies on the active ingredients, pharmacological effects, clinical application and functional mechanism.

Potassium Dichromate Toxicities: Protective Effect of Methanol Extract of Corchorus olitorius in Albino Rats

Exposure to hexavalent chromate compounds such as other human carcinogens is unavoidable in the developing countries of the world. Research efforts are being directed toward minimizing exposure to them, intercepting their activity in vivo, and/or prophylaxis. The present study therefore evaluates the effect of methanol extract of the leafy vegetable, Corchorus olitorius (MECO), against potassium dichromate (K2Cr2O7)-induced toxicities. Negative control animals were fed distilled water, while the positive control rats received 12 mg/kg body weight K2Cr2O7 once a week for 6 weeks. Test rats were exposed daily to 25, 50, and 100 mg/kg body weight MECO alone for 6 weeks and 12 mg/kg body weight of K2Cr2O7 once a week for 6 weeks before sacrifice. The frequency of micronucleated polychromatic erythrocytes (mPCEs) was monitored in bone marrow cells, while induction of aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine levels, and hematological parameters were assessed in the plasma. The phytochemical analysis of MECO was also carried out. K2Cr2O7 significantly (P < .05) increased the levels of mPCEs, AST, ALT, creatinine, total white blood cells, and lymphocytes compared with the control. The percentage pack cell volume and neutrophils were, however, reduced. In contrast, MECO at different doses restored the markers toward the levels of the negative control. MECO is rich in flavonoids, saponins, anthraquinones, terpenoids, and phenols, and they might be responsible for the protective effect observed in this study. Our results suggest that MECO has a promising potential in the treatment/management of chromate-induced toxicities.

Efficacy of Chinese Herbal Medicine as an Adjunctive Therapy on in-Hospital Mortality in Patients with Acute Kidney Injury: A Systematic Review and Meta-Analysis

Objective. We aimed to systematically assess the efficacy of Chinese herbal medicine (CHM) as an adjunctive therapy on in-hospital mortality in patients with acute kidney injury (AKI). Methods. We did a systematic review of articles published in any language up until Jun 23, 2015, by searching PubMed, Embase, the Cochrane Library, CBM, and CNKI. We included all RCTs that compared outcomes of patients with AKI taking CHM plus Western treatment (WT) with those taking WT alone. We applied Cochrane risk-of-bias tool to assess the methodological quality of the included trials. Results. Of 832 citations, 15 studies involving 966 patients met inclusion criteria. The methodological quality was assessed with unclear risk of bias. In the primary outcome of meta-analysis, pooled outcome of in-hospital mortality showed that patients randomly assigned to CHM treatment group were associated with low risk of in-hospital mortality compared with those randomly assigned to WT alone (RR = 0.41; 95% CI = 0.24 to 0.71; P = 0.001). Conclusions. CHM as an adjunctive therapy is associated with a decreased risk of in-hospital mortality compared with WT in patients with AKI. Further studies with high quality and large sample size are needed to verify our conclusions.

Rhubarb Anthraquinones Protect Rats against Mercuric Chloride (HgCl₂)-Induced Acute Renal Failure

Mercury (Hg) causes severe nephrotoxicity in subjects with excess exposure. This work attempted to identify whether a natural medicine—rhubarb—has protective effects against mercuric chloride (HgCl₂)-induced acute renal failure (ARF), and which of its components contributed most to the treatment. Total rhubarb extract (TR) were separated to the total anthraquinones (TA), the total tannins (TT) and remaining component extract (RC). Each extract was orally pre-administered to rats for five successive days followed by HgCl₂ injection to induce kidney injury. Subsequently, renal histopathology and biochemical examinations were performed in vitro to evaluate the protective effects. Pharmacological studies showed that TR and TA, but not TT or RC manifested significant protection activity against HgCl₂-induced ARF. There were also significant declines of serum creatine, urea nitrogen values and increases of total protein albumin levels in TR and TA treated groups compared to HgCl₂ alone (p < 0.05). At last, the major components in TA extract were further identified as anthraquinones by liquid chromatography coupled mass spectroscopy. This study thus provides observational evidences that rhubarb could ameliorate HgCl₂-induced ARF and its anthraquinones in particular are the effective components responsible for this activity in rhubarb extract.

Inflammatory stress potentiates emodin-induced liver injury in rats

Herbal medicines containing emodin, widely used for the treatment of hepatitis in clinic, have been reported with hepatotoxicity in individuals. A modest inflammatory stress potentiating liver injury has been linked to the idiosyncratic drug-induced liver injury (IDILI). In this study, we investigated the hypothesis that lipopolysaccharide (LPS) interacts with emodin could synergize to cause liver injury in rats. Emodin (ranging from 20, 40, to 80 mg/kg), which is in the range of liver protection, was administered to rats, before LPS (2.8 mg/kg) or saline vehicle treatment. The biochemical tests showed that non-toxic dosage of LPS coupled with emodin caused significant increases of plasma ALT and AST activities as compared to emodin alone treated groups (P < 0.05). In addition, with LPS or emodin alone could not induce any changes in ALT and AST activity, as compared with the control group (0.5% CMC-Na treatment). Meanwhile, the plasma proinflammatory cytokines, TNF-α, IL-1β, and IL-6 increased significantly in the emodin/LPS groups compared to either emodin groups or the LPS (P < 0.05). Histological analysis showed that liver damage was only found in emodin/LPS cotreatmented rat livers samples. These results indicate that non-toxic dosage of LPS potentiates the hepatotoxicity of emodin. This discovery raises the possibility that emodin and herbal medicines containing it may induce liver injury in the inflammatory stress even in their therapeutic dosages.