Background:  Nigella sativa (N. sativa) has a special place in herbal medicines that are used in plant – based treatment of different ailments.

Aim: The aim of this study was to evaluate the antidiarrheal activity of methanolic extract of seeds of N. sativa.

Methodology: The seeds of N. sativa were collected, identified, and authenticated with the help of a plant taxonomist. The seeds were dried at room temperature, grounded, passed through a 60-mesh sieves, and extracted with hydroalcoholic solvent. Adult albino rats weigh between 150 and 200 gm of both sexes were used for experimental procedure. At the time of experiment, rats were randomly divided into five groups with six rats per group. Group 1 (negative control) received 10ml/kg in distilled water. Group 2 (positive control) received 1mg/kg Loperamide. Group 3, Group 4, Group 5 (test groups) received four different doses respectively such as (100, 200, 300 and 400 mg/kg) of the crude extract and solvent fractions.

Results: N. sativa extract significantly reduced GIT motility, number of defecations and water content in the feces when compared with the standard drug Loperamide (1mg/kg) in a dose dependent manner. N. sativa extract at 300mg/kg extract showed significant results as compared to 100, 200 and 400 mg/kg.

Conclusion: The study concludes with the validation of anti-diarrheal effects of N. sativa seeds provided that the GIT motility decreases in a dose dependent manner. The results also pave way for more study on the chemical constituents (flavonoids, alkaloids, and tannins) present in N. sativa seeds as a possible reason for this medicinal property.

Keywords: Nigella sativa, Loperamide, GIT motility, tannins, flavonoids, anti-diarrheal.