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.

Acute and sub-acute toxicity evaluation of the root extract of Rheum turkestanicum Janisch.

Despite the widespread use of Rheum turkestanicum in herbal medicine, no study has yet examined its in vivo toxicity. The aim of this study is to evaluate the acute and sub-acute toxicity of hydroalcoholic extract of R. turkestanicum root. In acute toxicity experiment, female and male mice (n = 5/group/sex) were orally administrated with the extract at single doses of 300, 2000 and 3000 mg/kg and observed for 14 days. In the sub-acute study, the extract was orally administered daily at doses of 100 and 400 mg/kg to male rats (n = 8) for 4 weeks. During the acute toxicity test, there were no deaths or any signs of toxicity observed after administration of the R. turkestanicum extract at 300 mg/kg, which was the no-observed-adverse-effect level (NOAEL). The extract at a dose of 3000 mg/kg led to the death of one female and one male mouse (LD50 > 3000 mg/kg). In sub-acute toxicity experiment, the extract induced no mortality or significant changes in body weight, general behaviors, hematological parameters, serum biochemical factors (related to the kidney and liver function), and histopathology of the heart, liver, kidney, and brain up to the highest dose tested of 400 mg/kg (NOAEL). High-performance liquid chromatography-mass spectrometry revealed the presence of phenolic compounds, flavonoids, alkanes, and anthraquinones in the extract. In conclusion, short-term use of R. turkestanicum root does not appear to produce significant toxicity up to a dose of 400 mg/kg.

An experimental study on providing a scientific evidence for seven-time alcohol-steaming of Rhei Rhizoma when clinically used.

BACKGROUND: Rhei Rhizoma (RR) has been widely used as laxative and processed to alter its therapeutic actions or reduce its side effects. In this study, we evaluated experimentally the clinical application guideline that RR should be alcohol-steamed seven times before being used in elderly patients, as described in Dongeuibogam, the most famous book on Korean traditional medicine. METHODS: Unprocessed RR (RR-U) was soaked in rice wine, steamed and then fully dried (RR-P1). The process was repeated four (RR-P4) or seven times (RR-P7). Reversed-phase high-performance liquid chromatography was used to determine the RR-U, RR-P1, RR-P4 and RR-P7 (RRs) constituents. To evaluate the effect of RRs on liver toxicity, human hepatoma cells (HepG2) were treated with RRs at 100 µg/mL for 4 h and then cell viabilities were measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide method. To confirm the effects in vivo, 5-week-old male Sprague-Dawley rats were treated with RRs at 3 g/kg/day for 21 days. Body weight and serum biochemical parameters were measured and liver histology was assessed. RESULTS: The levels of sennosides decreased in processed RRs in an iteration-dependent manner, while the emodin level was unaffected. In HepG2 cells, cell viability was reduced with RR-U, while the toxicity decreased according to the number of processing cycles. The changes in body weight, relative liver weight and liver enzymes of RR-U-treated rats were reduced in processed RRs-treated rats. Histopathological analysis indicated swelling and cholestasis improved following seven times alcohol-steaming cycles. CONCLUSIONS: These results provide experimental evidence that RR-P7 almost completely reduces RR hepatotoxicity.

THIN-LAYER CHROMATOGRAPHY IDENTIFICATION FOR RHUBARB AND PHELLODENDRI AMURENSIS CORTEX IN SHUANG-BAI CATAPLASM AND STUDY OF SKIN IRRITATION ASSAY.

This paper aimed to raise a thin-layer chromatography (TLC) identification method for rhubarb and Phellodendri Amurensis Cortex and inspected skin irritation induced by them. It applied the TLC identification for Rhubarb and Phellodendri Amurensis Cortex in Shuang-bai cataplasm prescription. In this study six rabbits were divided into two groups to observe the skin irritation from Shuang-bai cataplasm on intact and defected skin. Another 36 were randomly divided into 6 groups to observe the acute toxicity from Shuang-bai cataplasm on intact and defected skin. Also 30 guinea pigs were divided into 3 groups to observe skin allergy to Shuang-bai cataplasm. The results showed that the average weight of the group of intact-skin rabbits was 2.026±0.10 kg and 2.427±0.023 kg after medication; the average weight of the group of defected-skin rabbits was 2.170±0.05 kg and 2.540±0.15 kg after medication; Shuang-bai cataplasm produced no irritation on intact or defected rabbit skin, no acute toxicity in rabbits and no allergy on the skin of guinea pigs. The skin allergy rate on guinea pigs of the medication group was 0 at each time quantum. Therefore, it can be concluded that this preparation produces no extreme skin irritation for rabbits, guinea pigs or human beings, and it can be safely put into practice.

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

Chromium nephrotoxicity (CrNT) is thought to occur through the oxidant lesion mechanism. There is still a lack of specific remedies against CrNT. We primarily screened Chinese herbal medicines with a potential protective effect against CrNT, e.g., rhubarb (Rheum palmatum L.). However, the active constituents in rhubarb and its mechanisms remain unclear. In this study, the total rhubarb extract (TR) was successively separated into three parts: total anthraquinone extract (TA), total tannin extract (TT) and remaining component extract (RC). The effects of each extract on the potassium dichromate (K(2)Cr(2)O(7))-induced nephrotoxicity in rats were comparatively assessed. The results showed that only the administration of TT protected the kidney function in K(2)Cr(2)O(7)-injured rats. Besides, TT showed significant activity to scavenge hydroxyl radicals, which is considered to be the dominant lesion product generated by hexavalent chromium. TT also showed a reduced ability to transform toxic high valence chromium ions into non-toxic low valence ions. And TT was able to further precipitate chromium ions. These results suggested that rhubarb tannins treat CrNT as a free radical scavenger, reductant, and metal precipitant. The multiple protective routes of the plant tannins reveal a superior option for development into a promising natural remedy against CrNT. In addition, the opposite effects of rhubarb anthraquinones in treating CrNT were observed compared to rhubarb tannins, which suggested the duo-directional effects (Yin and Yang) of herbal medicines should be addressed.

Toxic effects caused by rhubarb (Rheum palmatum L.) are reversed on immature and aged rats.

AIM OF THE STUDY: Rhubarb is generally used to people of broad age, but diverse responses of people at different age to rhubarb have been little clarified. In this study, an attempt was made to access the safety of rhubarb to both immature and aged rats to provide some references for its clinical usage. MATERIALS AND METHODS: The total extract of rhubarb was administered intragastricly to both immature and aged rats once a day and lasted for 5 weeks. Then histopathologic and biochemical examinations were performed. RESULTS: No death was observed in immature rat groups, while 23.3% (21/90) subjects in aged rat groups died and most of the death cases were observed in the high-dosage (40 gkg(-1) of body weight per day od, counted on the quantity of crude material) group. The death rate between aged and immature rats was found of significantly statistical difference. Dosage-dependent histopathologic changes in kidney were observed in all the rhubarb-treated rats, principally involving the proximal tubules. Kidney changes in aged rats were severer than those observed in immature ones. Hepatic cells necrosis was occasionally observed in the middle- and high-dosage aged rat groups and minimal biliary hyperplasia was found in all the rhubarb-treated aged rats. Increased incidences of activated Kupffer cells and lymphocytic infiltration were found in all the rhubarb-treated rats. And dosage-dependent increase of interleukin 6 (IL-6) and notable increase of IL-8 was found in aged rat groups. CONCLUSIONS: The immature and aged rats showed reversed responses to the toxic potential of rhubarb extract. Elderly subjects were susceptible to the toxicity of high-dosage rhubarb, which drove rigorous consideration on rational use of rhubarb to aged people.

Oral dose-ranging developmental toxicity study of an herbal supplement (NT) and gallic acid in rats.

OBJECTIVE: To evaluate the combination of rhubarb, astragalus, red sage, ginger, and turmeric (mixture referred to as "NT") together with gallic acid for evidence of reproductive toxicity in rats. METHODS: Fifty virgin female rats were cohabited with male rats. Day 0 of potential pregnancy was evidence of spermatozoa on vaginal smear. The presumably pregnant rats were randomized to five groups of 10 individuals and were fed by daily gavage on days 6-20 of presumed gestation with one of the following: deionized water placebo, 21.6 mg/kg per day, 215 mg/kg per day, 430 mg/kg per day, or 860 mg/kg per day of a mixture of NT (20%) and gallic acid (80%). Cesarean section was performed on day 21. RESULTS: All 50 rats had one or more live fetuses and survived until they were killed. Body weight was reduced in the 860 mg/kg per day group compared with placebo: mean (SD), 406.8 (23.0) vs. 430.1 (27.7) g, P<0.05. There were no dose-related adverse events or differences between groups in uterine size, food intake, corpora lutea, implantations, litter size, number of live fetuses, and gender distribution of fetuses or fetal resorptions. There were no dead fetuses, and all placentae appeared normal. All rats and tissues were normal at necropsy. Fetal weights did not differ between groups, and there were no fetal abnormalities. CONCLUSION: The combination of NT and gallic acid gave no evidence of reproductive toxicity at 430 mg/kg per day or below, which is reassuring should this combination be used in the future as a dietary herbal supplement for the treatment of obesity.

[Effect of processing on the chemical contents and hepatic and renal toxicity of rhubarb studied by canonical correlation analysis].

In this article, canonical correlation analysis was used to explore the relationship between the toxicity-attenuating effect and the variation of chemical contents in rhubarb caused by processing. With quasi-acute toxicity test, the difference of hepatic and renal toxicity to mice with the processed materials of rhubarb was researched. The chemical contents of anthraquinones and tannins in rhubarb were measured by UV-vis spectrophotometry and high performance liquid chromatography. The results showed that there were toxic effects to liver and kidney in mice after repeated intragastric administration of rhubarb and its processed materials for 14 days at a dosage of 76 g x kg(-1). The toxic effect of processed materials was much lower than crude drug. With canonical correlation analysis, the sequence of the hepatic and renal toxicity of chemical contents in rhubarb were found as follows: total anthraquinone glycosides (AQGs) > tannins (Tns) > total anthraquinones (AQs); aloe-emodin (AE) > physcione (Ph) > rhein (Rn) > emodin (Ed) > chrysophanol (Ch) and AEG > PhG > ChG > EdG > RnG of glycosyl-anthraquinone. It could be concluded that processing would attenuate the toxicity of crude drug of rhubarb. The toxicity-attenuating effect might be correlated to the decline of the contents of both anthraquinone glycosides and tannins, especially the aloe-emodin glycoside and physcione glycoside. The results also suggested that the serum alanine aminotransferase (ALT) and creatine (CREA) would be useful to monitor the hepatic and renal toxicity of rhubarb.

Nephrotoxicity study of total rhubarb anthraquinones on Sprague Dawley rats using DNA microarrays.

Total rhubarb anthraquinones (TRAs) are the active therapeutic components from the rhizomes of Rheum palmatum L. (Polygonaceae), which are widely used in traditional Chinese medicines (TCMs) and have been reported to have cell toxicity recently. This study focuses on the toxicity of TRAs on Sprague Dawley (S.D.) rats. TRAs administrated per os for 13 weeks induced nephrotoxicity on S.D. rats as renal tubule epithelial cells swelled and denatured in tissue slice examination. After high-density oligonucleotide microarrays scanning, we have identified mitogen-activated protein kinase (MAPK) kinase 6 to be the target gene which causes cell cycle arrest and proliferation inhibition and contributes to nephrotoxicity on S.D. rats.