Antidiarrheal activity of 80 % methanol extract of the aerial part of Ajuga remota Benth (Lamiaceae) in mice

BACKGROUND In the Ethiopian traditional medicine, the aerial part of Ajuga remota Benth is used in the treatment of diarrhea. There are different mechanisms by which Ajuga remota may have antidiarrheal effect. Some of the possible mechanisms are through its anthelmintic and antibacterial activity. The present study aimed to evaluate whether the antidiarrheal effect of the plant also include antimotility and antisecretory effect using 80 % methanol extract of A. remota (MEAR). METHODS The MEAR was administered at doses of 200, 400, 600 and 800 mg/kg to four groups of mice (six animals per group) orally in castor oil diarrhea model. The effect of the extract on enteropooling and gastrointestinal transit model was also evaluated using the same grouping and dosing. Two other groups, one as control and the other as standard (loperamide 5 mg/kg) were used for comparison with the treatment groups. RESULTS The extract at the doses of 400, 600, and 800 mg/kg produced a dose-dependent and significant inhibition both on the frequency and onset of diarrhea. The percentage purging frequency was 53.4, 66.7, 79.6, and 66.7 % (p < 0.001) at three doses of MEAR (400, 600, and 800 mg/kg) and with loperamide (5 mg/kg), respectively. The percentage inhibition in intestinal fluid accumulation was 42.5, 62.1, and 74.2 % (p < 0.001) at the doses of 400, 600 and 800 mg/kg of MEAR, respectively. The MEAR also inhibited the intestinal transit of charcoal meal in a dose dependent manner both in the normal and castor oil induced intestinal transit. CONCLUSION This study has shown that the 80 % methanol extract of A. remota contains pharmacologically active substances with significant antimotility and antisecretory effect contributing for its antidiarrheal activity.