Organ specific differences in alteration of aquaporin expression in rats treated with sennoside A,senna anthraquinones and rhubarb anthraquinones

OBJECTIVE Senna and rhubarb are classified as stimulative laxatives,and known to have similar effective constituents,the anthraquinones.Being protected by theβ-glucoside bond,the anthraquinones can reach the intestines where they are degraded into complex metabolites by enzymes secreted from the intestinal microbiome.It is these complex metabolites that produce the laxative effects.Then the similarities and differences of action between the anthraquinones require further elucidation.METHODS Here,we studied metabolites of senna anthraquinones(SAQ),rhubarb anthraquinones(RAQ)and their chemical marker,sennoside A(SA),in a rat diarrhea model.In the in vitro biotransformation experiments,SAQ,RAQ and SA were incubated with rat fecal flora solution and the metabolites produced were analyzed using HPLC.In the in vivo studies,the same compounds were investigated for purgation induction,with measurement of histopathology and multiple aquaporins(Aqps)gene expression in six organs.RESULTS SAQ and RAQ had similar principal constituents but could be degraded into different metabolites.A similar profile of Aqps down-regulation for all compounds was seen in the colon,suggesting a similar mechanism of action for purgation.However,in the kidneys and livers of the diarrhea-rats,down-regulation of Aqps was found in the RAQ-rats whereas up-regulation of Aqps was seen in the SAQ-rats.Furthermore,the RAQ-rats showed lower aquaporin 2(Aqp2)protein expression in the kidneys,whilst the SA-rats and SAQ-rats had higher Aqp2 protein expression in the kidneys.This may have implications for side effects of SAQ or RAQ in patients with chronic kidney or liver diseases.CONCLUSION SAQ and RAQ showed similar laxative actions with a similar mechanism,they could display different actions in rat kidneys and livers.We suggest that the clinical usage of senna or rhubarb products should be clarified for patients having chronic kidney or liver diseases.

Comparison of intestinal absorption characteristics between rhubarb traditional Chinese medicine preparation and activity ingredients using in situ and in vitro model

Objective: The intestinal absorption characteristics of active ingredients are very important for oral administration of traditional Chinese medicine(TCM) to achieve the desired therapeutic effect.However, a deeper understanding about active ingredients absorption characteristics is still lack. The aim of this study was to investigate the absorption properties and mechanism of rhubarb active ingredients in TCM preparation and pure form.Methods: The intestinal absorption behavior of active ingredients in Shenkang extract(SKE) and rhubarb anthraquinone ingredients(RAI) were investigated by in situ single-pass intestinal perfusion model. And the bidirectional transport characteristics of these active ingredients were assessed by in vitro Caco-2 cell monolayer model.Results: In situ experiment on Sprague-Dawley rats, the effective permeability coefficient values of aloeemodin, emodin and chrysophanol in RAI were higher than those in SKE, and the value of rhein in RAI was lower than that in SKE. But the easily absorbed segments of intestine were consistent for all ingredients,whether in SKE or in RAI. In vitro experiment, the apparent permeability coefficient values of rhein, emodin and chrysophanol in RAI were higher than those in SKE, and this value of aloe-emodin in RAI was lower than that in SKE. But their efflux ratio(ER) values in SKE and RAI were all similar.Conclusion: Four rhubarb anthraquinone ingredients in SKE and RAI have similar absorption mechanism and different absorption behavior, and the microenvironment of the study models influenced their absorption behavior. The results may provide an aid for understanding of the absorption characteristics of the TCM active ingredients in complex environments and the complementarities of different research models.

Simultaneous Determination of 10 Anthraquinones in Rhubarb Based on HPLC-Q-HR/MS

Objective To develop a simple, sensitive, and precise method for simultaneous determination of 10 anthraquinones in Rhubarb. Methods HPLC-Q-HR/MS was employed for simultaneous quantification of free anthraquinones（aloe-emodin, emodin, chrysophanol, physcion, and rhein） and their glycosides. Chromatographic analysis was performed on an XBridge^（TM） C_（18） column（2.1 mm × 150 mm, 5 μm） with mobile phases consisting of 3 mmol/L ammonium acetate（A） and methanol（B） at a flow rate of 0.3 mL/min. Results All calibration curves exhibited good linear relationship（R^2 〉 0.999）. The limits of detection（LOD） and quantification（LOQ） were in the range of0.39-2.97 ng/mL and 0.56-8.90 ng/mL, respectively. The overall intra-and inter-day precisions of analytes presented as relative standard deviations（RSDs） were less than 2.79%. Relative recoveries varied between 97.83% and 104.28%. The validated method was applied to assess the quality of Rhubarb collected from different regions of China. Results showed that chrysophanol and rhein-8-O-β-D-glucoside was the largest portion of free anthraquinones and anthraquinone glycosides in Rhubarb, respectively. The total content of anthraquinones was higher in Rhubarbs from Sichuan, Qinghai, Yunnan, and Gansu provinces than that in those from Shandong and Henan provinces, while no significant variability existed in different regions of the same province.Conclusion HPLC-Q-HR/MS method is accurate and reliable for simultaneous quantification of above free anthraquinones and their glycosides in Rhubarb and can be applied to standardize the quality of Rhubarb and its quality control in different regions.