A bioactivity-guided study on the anti-diarrheal activity of Polygonum chinense Linn

Ethnopharmacological relevance: Polygonum chinense Linn., a folk medicine, has long been used for the treatment of diarrhea and enteritis in southwestern China. However, the components responsible for its anti-diarrheal activity are still poorly understood.

Aim of the study: To determine anti-diarrheal activities of Polygonum chinense L. and to identify its active components through bioactivity-guided isolation technique.

Materials and methods: Animals were orally administered with the extract of Polygonum chinense L. The anti-diarrheal effects of 75% ethanol extract, four fractions with different polarities from 75% ethanol extract, different eluates collected from Diaion HP-20 macroporous resin chromatography, ellagic acid and corilagin, were examined based on mouse models of castor oil- and magnesium sulfate-induced diarrhea.

Results: The results showed that the 75% ethanol extract of Polygonum chinense L. exhibited significant anti-diarrheal activities in a dose-dependent manner in two mouse models. Through in vivo bioactivity-guided fractionation processes, n-butanol and aqueous fractions were found to exhibit prominent anti-diarrheal activities, and two major compounds, ellagic acid and corilagin, from these active fractions were found to possess anti-diarrheal effects.

Conclusion: Present study provides evidence of the utilization of Polygonum chinense L. for diarrhea, and ellagic acid and corilagin are two components contributing to the anti-diarrheal effect.