Evaluation of Sorghum bicolor leaf base extract for gastrointestinal effects

The leaf base of Sorghum bicolor (Family: Gramineae, Poaceae) was cold-macerated with 70% v/v methanol. The aqueous methanolic extract was further fractionated into non-polar, medium polar and very polar components using hexane, ethylacetate and water (aqueous), respectively. The gastrointestinal effects of these extracts were tested on intestinal motility (transit) in mice, castor oilinduced diarrhoeal model in rats, isolated rabbit jejunum, guinea pig ileum and rat stomach fundus strip. The oral and intraperitoneal LD50 values for the extracts were determined in mice and rats. The aqueous methanolic extract (100 – 400 mg/kg i.p) significantly (P < 0.05) and dose-dependently decreased the intestinal motility, inhibited castor oil-induced diarrhoea, produced concentrationdependent relaxation of rabbit jejunum with half maximal effective concentration (EC50) of 0.21 mg/ml. This extract also produced both non-myogenic and slight relaxation effects on guinea pig ileum and a contraction on rat stomach fundus strips. Both aqueous and ethylacetate fractions also reduced intestinal motility. However, ethylacetate fraction caused greater reduction than the aqueous fraction. The oral LD50 value for the aqueous methanolic extact in both rats and mice was found to be 2000 mg/kg while the intraperitoneal values are 1414.2 mg/kg in rats and 1341.6 mg/kg in mice. The intrapertoneal value for both aqueous and ethylacetate fractions is 2000 mg/kg in mice. The study provided scientific bases for the traditional use of S. bicolor for treatment of gastrointestinal related problems such as diarrhoea.