In vitro reduction of rhein anthraquinone to rhein anthrone by rat cecal microflora and some intestinal bacterial strains.

After in vitro incubation of cecal content from CVL or gnotobiotic rats with rhein anthraquinone (1 mg g-1) for 18 h at 37 degrees, the anthraquinone was converted to rhein anthrone for 23.5 (SD +/- 3.4) per cent and 19.

The effect of rhein and rhein anthrone on intestinal fluid transport and on large intestine transit in germ-free rats.

The effect of rhein and rhein anthrone on the transit and the transport of water and electrolytes in the large intestine was investigated in germ-free rats. After intracaecal administration, neither of the two compounds was found to accelerate the transit of a colour marker through the large intestine. Both drugs reduced the net absorption of sodium and chloride in the colon and enhanced net potassium secretion.

Direct and indirect evidence for the involvement of prostaglandins in the secretagogue action of rhein anthrone in the small intestine.

The present study was undertaken to investigate the involvement of prostaglandins in the secretagogue action, observed after intraduodenal administration of rhein anthrone and rhein in rats. After intraduodenal administration of rhein anthrone (50 mg/kg), the active metabolite of sennosides, a very marked increase of secretion was observed compared to control. The amount of secretion was calculated by dividing the total weight of the small intestine, obtained 30 minutes after administration of the drug, by the total length.