Evaluation of the antidiarrheal activity of the leaf extracts of Myrtus communis Linn (Myrtaceae) in mice model

Background: Myrtus communis L. has a folkloric repute for the management of diarrhea and dysentery in different parts of the world. However, the safety and efficacy of the leaf extract have not been scientifically validated in animal model. This study was, therefore, aimed to investigate the antidiarrheal effect of 80% methanol extract (80ME) and solvent fractions of the leaves of Myrtus communis L. in mice. Methods: The antidiarrheal activity of the 80ME and solvent fractions was evaluated against castor oil induced diarrheal model, charcoal meal and enteropooling tests. For the 80% ME, the test groups received 100, 200 and 400 mg/kg of the extract. In case of fractions, the test groups received various doses of fractions (200, 300, 400 mg/kg and an additional dose of 800 mg/kg for the aqueous fraction (AF)), where as negative controls received the vehicle (10 ml/kg) and positive controls received loperamide (3 mg/kg). Results: The 80ME at 200 mg/kg (p < 0.05) & 400 mg/kg (p < 0.01) as well as the chloroform fraction (CF) and methanol fraction (MF) at 400 mg/kg (p < 0.05) significantly delayed the onset of diarrhea. Besides, the 80ME (at all tested doses) and both of these fractions (at 300 & 400 mg/kg) significantly decreased the frequency and weight of fecal outputs. Results from the charcoal meal test revealed that the 80ME, at all doses, (p < 0.001) as well as the CF and MF at 300 mg/kg (p < 0.05) & 400 mg/kg (p < 0.001) produced a significant anti-motility effect. Similarly, in the entero-pooling test, the 80ME (at all tested doses) (p < 0.01) as well as the CF and MF (at 300 & 400 mg/kg, p < 0.05) produced a significant decline in the weight and volume of intestinal contents, whereas the AF revealed significant effect (p < 0.05) at dose of 800 mg/kg only. Conclusion: The study demonstrated that the 80ME and solvent fractions contain bioactive constituents that have antidiarrheal activity. Therefore, this study provides a scientific support for the acclaimed traditional use of Myrtus communis L for the treatment of diarrheal diseases.