Abstract :

This study aimed to investigate the in vitro antiprotozoal effects of methanolic seed extracts of the Ruta graveolens, Peganumharmala, and Citrullus colocynthis against Giardia lamblia and Entamoeba histolytica using the trypan blue staining methodand MTT Assay. Cultured trophozoites of G. lamblia and E. histolytica were treated with 20 µg/mL of Metronidazole (MTZ)and 40 mg/mL of R. graveolens, P. harmala, and C. colocynthis seed extracts. Metronidazole significantly reduced thenumber of living G. lamblia and E. histolytica trophozoites (P < 0.05) as compared to the negative control (normal saline).R. graveolens significantly showed better effects on the mortality rate of both G. lamblia, and E. histolytica trophozoites incomparison to P. harmala (P < 0.05) followed by C. colocynthis (P < 0.05) by using both colorimetric and trypan bluemethods, whereas IC50 in all plants extracts was >40 mg/mL. Among the tested plant extracts, R. graveolens showed significantantiprotozoal activity against G. lamblia and E. histolytica trophozoite in vitro but far less than metronidazole, a drug usedas a positive control. The results of the antiprotozoal screening support the possible use of R. graveolens for the treatmentof diarrhea and dysentery in the traditional medicine.