Rhus tripartita (Anacardiacae) is a plant which is traditionally used for the treatment of ulcer and diarrhea in Tunisia. However, the scientific basis for this usage has not been well established. The core aim of the present study is to evaluate the antidiarrheal activity of Rhus tripartita root methanolic extract (RRE).

The antidiarrheal activity of RRE oral doses (50, 100, 200 and 300mg/kg) was evaluated using the castor oil-induced diarrhea, the intestinal fluid emptying method and the normal intestinal transit test. The antibacterial activity was tested against four pathogenic bacteria using two methods. The RRE was also phytochemical studied.

Diarrhea experiments showed a protective effect of the RRE which produced a significant (p<0.05) and dose-dependent reduction of all the diarrhea parameters. It delayed the onset of diarrhea, produced a significant decrease in the frequency of defecation and the diarrhea score severity and decreased the volume of intestinal fluid induced by castor oil as well as the propulsion intestinal transit. The effect of the extract at the highest dose (300mg/kg) was similar to that of loperamide, the standard anti-diarrheal drug (10mg/kg).

The anti-bacterial activity test showed that RRE exhibited a great inhibition activity against four pathogenic bacteria strains (Esherichia coli, Salmonella typhimurium, Salmonella argenosa, Staphylococcus aureus). Oral administration of the extract up to 3g/kg did not produce any acute toxicity in rats. The preliminary phytochemical screening of the RRE revealed the presence of flavonoids, tannins, and polyphenols.

Results showed that RRE at 300mg/kg possesses the highest anti-diarrheal activity possibly mediated by the inhibitory effects on gastrointestinal propulsion and intestinal fluid accumulation.