ABSTRACT
OBJECTIVES: Mentha longifolia L. (Lamiaceae) is an annual herb that is used in the Iranian traditional medicine for treating stomach and intestinal disorders. The purpose of this study was to determine the protective effect of M. longifolia on experimental diarrhea in a rat model. MATERIALS AND METHODS: The antidiarrheal activity of essential oil of M. longifolia (20-80 mg/kg) was investigated against castor oil-induced diarrhea in rats using loperamide as the standard reference drug. In acute toxicity evaluation, rats were orally administrated with single dose of EOML at doses ranging from 10 to 1000 mg/kg. RESULTS: EOML caused a significant (p<0.05) and dose-dependent decrease of gastrointestinal transit, nevertheless, it could not block the inhibitory effect of atropine (0.1 mg/kg). EOML at oral doses of 20 and 80 mg/kg protected the animals against castor oil-induced diarrhea significantly (p<0.05). EOML decreased the intestinal fluid accumulation as indicated by the significantly (p<0.05 to p<0.001) decrease compared to control. The oral LD50 of EOML was found to be 470 mg/kg in rat. CONCLUSION: Since the inhibition of intestinal hyperactivity and hypersecretory are the bases of the treatment of diarrhea, results obtained in the present study suggest that EOML is endowed with antidiarrheal activity. EOML is moderately toxic for oral medication.
ABSTRACT
CONTEXT: 1,8-Cineole, a terpene, characterized as a major constituent occurring in the essential oils of several aromatic plants. It is widely used in pharmaceutical industry, as a food additive and for culinary purposes. OBJECTIVE: This study investigates the inhibitory effect of 1,8-cineole on transit time and diarrhea in animal models. MATERIALS AND METHODS: Acute toxicity and lethality of 1-8-cineole was determined by Lork's guidelines. The antidiarrheal effect of 1,8-cineole was investigated by determining the intestinal transit and enterpooling in rats. In all experiments, different doses of 1,8-cineole (20-120 mg/kg), atropine, and loperamide were administered orally. RESULTS: The LD50 of 1,8-cineole for oral administration was estimated to be 1280 mg/kg. 1,8-Cineole (20-120 mg/kg) did not show a significant decrease in small intestine transit (p > 0.05); however, the highest dose displayed a significant decrease in comparison with atropine (p < 0.05). This substance decreased the peristaltic index value to 68 ± 0.36% at a dose of 120 mg/kg compared with the control group (85.22 ± 4.31%) in the castor oil transit test. 1,8-Cineole significantly delayed the onset of diarrhea to -142.33 ± 6.08 min at 120 mg/kg, while the time was 103.66 ± 20.73 min for the control and >240 min for the loperamide. Moreover, 1,8-cineole significantly decreased intestinal fluid accumulation (p < 0.05). CONCLUSIONS: This study demonstrated antispasmodic and antisecretory activities of 1,8-cineole and rationalized the traditional use of the plant containing various levels of this terpene in the treatment of gastrointestinal complains such as diarrhea.
