Polygonum tinctorium leaves suppress sodium dextran sulfate-induced colitis through interleukin-10-related pathway.

Indigo naturalis, a herbal medicine purified from indigo-containing plants, such as Strobilanthes cusia, Isatis tinctoria, and Polygonum tinctorium, has been reported to be useful in the treatment of ulcerative colitis by activating the aryl hydrocarbon receptor. However, the aryl hydrocarbon receptor pathway causes crucial side effects, such as pulmonary arterial hypertension. Although P. tinctorium is one of the plant derivatives of indigo naturalis, it is not identical to it. To date, the pure leaves of P. tinctorium have not been reported to ameliorate ulcerative colitis. Therefore, we investigated the effect of pure P. tinctorium leaves, which are consumed in some regions, on experimental colitis induced in mice using sodium dextran sulfate. We found that P. tinctorium leaves ameliorated weight loss (P < 0.01) and pathological inflammatory changes in the colon (P < 0.05), enhanced mRNA expression of interleukin-10 (P < 0.05), and decreased expression of tumor necrosis factor-in colonic tissues (P < 0.05), as determined using quantitative real-time reverse transcription polymerase chain reaction. The intraperitoneal administration of an aryl hydrocarbon receptor antagonist did not antagonize the inhibition of mucosal destruction, whereas an anti-interleukin-10 receptor antibody did. These results suggest that P. tinctorium ameliorate sodium dextran sulfate-induced intestinal inflammation via interleukin-10-related pathway, independent of the aryl hydrocarbon receptor pathway. P. tinctorium leaves have the potential to be a new, safe treatment for ulcerative colitis.

Daidzein Intake Is Associated with Equol Producing Status through an Increase in the Intestinal Bacteria Responsible for Equol Production.

Equol is a metabolite of isoflavone daidzein and has an affinity to estrogen receptors. Although equol is produced by intestinal bacteria, the association between the status of equol production and the gut microbiota has not been fully investigated. The aim of this study was to compare the intestinal bacteria responsible for equol production in gut microbiota between equol producer and non-producer subjects regarding the intake of daidzein. A total of 1044 adult subjects who participated in a health survey in Hirosaki city were examined. The concentration of equol in urine was measured by high-performance liquid chromatography. The relative abundances of 8 bacterial species responsible for equol production in the gut microbiota was assessed using 16S rRNA amplification. There were 458 subjects identified as equol producers. The proportion of equol production status and the intake of daidzein increased with age. Daily intake of daidzein was larger in equol-producer. The intestinal bacteria, which convert daidzein to equol were present in both equol producers and non-producers. However, the relative abundance and the prevalence of Asaccharobacter celatus and Slackia isoflavoniconvertens were significantly higher in equol producers than those in equol non-producers. The intestinal bacteria that convert daidzein to equol are present in not only the equol producers but also in the non-producers. The daidzein intake is associated with the equol production status through an increase of A. celatus and S. isoflavoniconvertens in the gut microbiota.