The anti-diarrheic properties of methanolic leaf extract of P.hirsuta and its fractions were evaluated using castor oil-induced diarrhea model and charcoal meal to evaluate small intestinal transit. The extract yielded seven fractions after column chromatography. The extract (100 mg/kg) significantly (P<0.05) decreased total number of fecal output 3 h postadministration of castor oil compared with 10 ml/kg distilled water and caused 46% inhibition of diarrhea compared with diphenoxylate (5 mg/kg). Comparing the ratio of solid to watery stools showed that the extract (100 mg/kg) produced 61:39% against 41:59% by diphenoxylate (5 mg/kg). The small intestinal transit was significantly (P<0.05) decreased by all doses of extract used (50, 100, 150 mg/kg) when compared with distilled water and caused 4% inhibition of intestinal fluid accumulation at 50 mg/kg compared with diphenoxylate. Fraction 2 (50 mg/kg) caused significant (P<0.05) decrease in small intestinal transit compared with distilled water and caused 2% inhibition of intestinal fluid accumulation compared with diphenoxylate. The major phytochemical constituents of fraction 2 were tannins. The extract of P. hirsuta showed promising anti-diarrheic properties, possibly through retardation of gastrointestinal motility and mediated by tannins, justifying its traditional use for treatment of diarrhea among the Igbo tribe of Eastern Nigeria.
