Assessment of Antidiarrheal, Antispasmodic and Antimicrobial Activities of Methanolic Seeds Extract of Peganum harmala L. (Nitrariaceae)

Background: Many plants and herbs have been shown to possess antidiarrheal, antispasmodic, and antimicrobial activities. The present study was developed to determine the possible antidiarrheal and antispasmodic effects of methanolic extract of Peganum harmala L. (MEPH) in diarrhea and hyperactive gut.

Methodology: The crude MEPH was studied using the in-vivo castor oil-induced diarrhea model in mice, while isolated rat ileum was used in the in-vitro studies. Antimicrobial efficacy of MEPH was tested against different bacterial strains (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia), Yeast (Candida albicans) and Fungus (Aspergillus niger) using in-vitro assays.

Results: In the castor oil-induced diarrhea, MEPH at 100 and 200 mg/kg showed 40% and 80% protection in mice while positive control drug, loperamide showed 100% protection. In the in-vitro experiments, MEPH dose-dependently (0.01 to 0.3 mg/mL) inhibited carbachol and high K+-induced contractions at comparable EC50 values similar to papaverine, a phosphodiesterase (PDE) inhibitor. The PDE inhibitory like effect was further confirmed when pre-incubated ileum tissues with MEPH (0.1 and 0.3 mg/mL) shift the isoprenaline-mediated inhibitory CRCs against carbachol to the left, similar to papaverine. In antibacterial assay, MEPH showed efficacy against two Gram positive bacteria (S. aureus, and B. subtilis) and one Gram negative bacteria (E. coli). But extract didn’t show any effect against K. pneumoniae. The MEPH also showed efficacy against fungal strain (A. niger) and yeast strain (C. albicans).

Conclusions: MEPH shows antidiarrheal and antispasmodic effects because of its antimotility effect which were possibly due to the inhibition of PDE enzyme. The study has shown an optimal antimicrobial activity of MEPH as all bacteria, yeast and fungal strains were found sensitive except K. pneumoniae. MEPH proved efficacy against both enteric and non-enteric pathogens causing diarrhea, thus confirming its role in both the infectious and non-infectious diarrhea.