Rhubarb is one of the most well-known herbal medicines that constitute daiokanzoto (DKT), which is clinically effective for constipation. Sennoside A is transformed into an active metabolite, rheinanthrone, by intestinal bacteria. Sennoside A in rhubarb showed significantly accelerated metabolic activity in intestinal bacteria in comparison with sennoside A alone. In this study, we investigated the influence of rhubarb constituents on the metabolism and purgative activity of sennoside A. The 20% MeOH-eluted fraction separated by MCI-gel CHP-20P column chromatography from the water extract of rhubarb showed sennoside A metabolic activity similar to that of rhubarb extract. The 20% MeOH elute was further purified and rhein 8-O-β-D-glucopyranoside (RG) was isolated. The metabolic activity of sennoside A was significantly accelerated by increasing the level of RG. Moreover, rhein, emodin and aloe-emodin also accelerated sennoside A metabolism. The purgative activity of sennoside A was significantly accelerated when RG or rhein was concomitantly given with sennoside A in a dose-dependent manner. These results suggest that anthraquinones contribute to the purgative action of sennoside A in rhubarb. Therefore, it is assumed that the influence of anthraquinones on the fate of rheinanthrone transformed from sennoside A may promote the purgative action of sennoside A. Key words rhubarb; sennoside A; rhein 8-O-β-D-glucopyranoside; anthraquinone; daiokanzotoKampo is traditional Japanese medicine that was developed from traditional medicine originating in ancient China. Kampo medicine involves drugs based on multiple constituents, for which prescriptions are based on the combination of two or more herbal medicines. It is thought that the interaction between each herbal medicine is important for their activity, such as by reinforcing the effect of a medicine and relieving side effects, by pharmacologic or pharmacokinetic action. For example, calcium sulfate from gypsum raises ephedrine alkaloid dissolution in makyokansekito decoction.1,2) A lower glycyrrhizin content in shoseiryuto decoction is attributable to the pH of organic acids in schisandra fruit.3) In addition, the purgative activity increases 1.7-fold compared with that with each medication alone when the mixture ratio of sennosides A and C is 7 : 3. 4)Rhubarb is one of the most well-known herbal medicines that constitute daiokanzoto (DKT), which was demonstrated to be useful for constipation in a clinical double-blind study. 5)The purgative effect of rhubarb is due to sennoside A as the main laxative constituent. Sennoside A is an inactive glycoside, and is transformed to an active metabolite, rheinanthrone, by intestinal bacteria. [6][7][8] We have reported an HPLC method for the determination of sennoside A.9) This method is applicable for determination of the activity of sennoside A metabolism by anaerobic incubation of DKT with mouse feces. By using this method, we found that the activity of sennoside A metabolism in intestinal bacteria was significantly acceler...

Kampo medicine is Japanese traditional medicine originating from ancient China. It is produced by combining multiple crude drugs and includes many constituents. This makes it extremely difficult to identify the active constituents and to reveal the mechanism of the pharmacological action. An exception to this is daiokanzoto (DKT), a simple formulation that consists of two kinds of crude drugs, Rhei Rhizoma (rhubarb) and Glycyrrhizae Radix (glycyrrhiza). It is the most well-known Kampo medicine and was demonstrated to be applicable for constipation in a clinical double-blind study.1) The purgative effect of DKT is due to rhubarb, which is considered to promote the secretion of water and electrolytes into the colon and bowel movement.2) Sennoside A, which is a well-known diarrheal constituent of rhubarb, is an inactive glycoside, and is transformed to an active metabolite, rheinanthrone, by intestinal bacteria.3-5) Therefore, investigation of the purgative action and metabolism of sennoside A is important in order to understand the character of DKT.Glycyrrhiza is a crude drug contained in more than 70% of Kampo medicines certified by the Japanese Ministry of Health and Welfare. 6) Unlike rhubarb, glycyrrhiza does not induce diarrhea directly. Glycyrrhiza has been considered to moderate the effects of other crude drugs in Kampo medicine. In DKT, glycyrrhizin and liquiritin, the main constituents of glycyrrhiza, cooperatively prevent the rhubarb-induced strong spiking activity of colonic circular muscle.7) Interestingly, it has been reported that glycyrrhiza shows a significant potentiating effect on the purgative action of rhubarb in rats when DKT is prepared at a ratio (4 : 1) of rhubarb to glycyrrhiza that is used for the traditional formulation. 8)However, it is not clear how glycyrrhiza potentiates the purgative action of rhubarb. Recently, we found that the activity of sennoside A metabolism in intestinal bacteria was significantly accelerated when glycyrrhiza, liquiritin, or liquiritin apioside coexisted with sennoside A. 9) In this study, we investigated whether glycyrrhiza, liquiritin, or liquiritin apioside actually potentiates the purgative action of sennoside A in mice. Since the bioavailability of felodipine was shown to be improved with grapefruit juice in a clinical study, 10) a number of the studies have been published on interactions between Western drugs and herbal medicines as medicinal topics.11,12) Kampo medicine is clinically used for the treatment of a wide variety of diseases in Japan. Since 86.3% of physicians have been reported to use Kampo medicines in Japan, 13) Kampo medicines are frequently prescribed with Western drugs for the treatment of various chronic diseases. The possibilities of interaction between Kampo medicines and Western drugs in experimental studies have been reported in recent years. [14][15][16][17] Combinational use of Kampo medicines and antibiotics was observed in 7% of cases of Kampo prescription.18) Because most glycosides are transformed by intestinal bacteria befo...

Daiokanzoto (DKT, combination of rhubarb and glycyrrhiza), a Kampo medicine, is clinically effective for constipation. Sennoside A is well known to induce diarrhea. Sennoside A is a prodrug that is transformed into an active metabolite, rheinanthrone, by intestinal bacteria. In this study, we investigated the effects of glycyrrhiza on the activity of sennoside A metabolism in intestinal bacteria using mouse feces. A high-performance liquid chromatography (HPLC) method for the determination of sennoside A in incubation mixture of DKT with mouse feces was established. The retention time of sennoside A was 9.26±0.02 min with a TSKgel ODS-80TsQA column by linear gradient elution using a mobile phase containing aqueous phosphoric acid and acetonitrile and detection at 265 nm. We found that the activity of sennoside A metabolism in intestinal bacteria was significantly accelerated when glycyrrhiza, liquiritin or liquiritin apioside coexisted with sennoside A, whereas that of glycyrrhizin was not altered. This method is applicable for determination of the activity of sennoside A metabolism by anaerobic incubation of DKT with mouse feces.

Interindividual differences affect the purgative activities of sennoside A (SA) and Daiokanzoto (Da-Huang-Gan-Cao-Tang, DKT). In this study, we manipulated gut microbiota in mice to establish laxative responders and non-responders by feeding them a high-carbohydrate, a high-fat or a high-fibre diet. To assess the relationship between laxatives and gut microbiota, we monitored the gut microbiota before and after administering laxatives. Twenty mice per diet were divided into four groups of five mice to evaluate purgative activities of four laxative preparations, DKT, SA, SA plus rhein 8- O - β -D-glucopyranoside (SA + RG), and SA plus liquiritin (SA + LQ). Gut microbiota changes were monitored by next-generation sequencing of 16 S rRNA gene amplicons. In high-carbohydrate and high-fat diet-fed mice, DKT exerted a significantly higher purgative activity than SA alone, and RG contributed to this activity. DKT and SA + RG administration increased the Enterobacteriaceae content of gut microbiota, which was associated with an increased purgative activity. In contrast, DKT activity was significantly suppressed by high-fibre diet. Hence, diet-induced differences in gut microbiota determined the effect of DKT, which is interesting, considering that Oriental medicines are formulated for a specific functional state or “pattern”. These results demonstrated that the purgative activity of anthranoid laxatives is susceptible to diet-induced alterations in gut microbiota.

Goreisan, a well-known hydrostatic modulating formulation, is used clinically in the treatment of edematous disorders. In this study, in order to clarify hydrostatic modulation in the intestine, we analyzed the effect of Goreisan in an experimental diarrhea model created with the single oral pretreatment of magnesium sulfate in mice. Ninjinto (166 mg/kg, p.o.) did not lead to improvements in this model, whereas Goreisan (133 mg/kg, p. o.) significantly abated the diarrhea.The warm Goreisan extraction (at 37 , for 0.5 hr) showed anti-diarrheal activity that was significantly stronger than the decoction. On investigating the anti-diarrheal activity of Goreisan by comparing the difference in crude drugs made from Atractylodis Rhizoma (Byakujutsu) and Atractylodis Lanceae Rhizoma (Sojutsu), no distinction between Byakujutsu-Goreisan and Sojutsu-Goreisan was recognized. Atractylodis Rhizoma, Polyporus, Poria, and Cinnamomi Cortex, which were administered singly, showed anti-diarrheal activities, but these were weak in comparison with Goreisan. Concoctions in which either Atractylodis Rhizoma, Polyporus, Poria, Alismatis Rhizoma, or Cinnamomi Cortex were omitted from Goreisan showed decreased anti-diarrheal activity as compared with Goreisan. The anti-diarrheal activity was clearly lower in the concoctions of warm extractions whereby the five kinds of crude drugs were extracted separately, compared with the warm extraction of Goreisan in which all crude drugs were extracted simultaneously.These findings suggest that the anti-diarrheal activity of Goreisan in this model was not dependent on a specific crude drug, it being optimal to extract the five kinds of crude drug simultaneously.