Abstract
Background: Toxoplasmosis is a serious zoonotic protozoal disease that is distributed worldwide and can infect almost all warm-blooded animals, including humans. In most cases, it is asymptomatic, but in immunocompromised individuals, it is associated with severe neurological and gastrointestinal disorders. A previous serological prevalence investigation in Saudi Arabia indicated that the disease prevalence ranged between 25% and 51% in various areas. Recommended commercial drugs cannot achieve 100% clearance due to side effects. Hence, the development of new safe and affordable drugs is an important goal. Aim: In the present study, extracts from the leaves and fruit of Azadirachta indica A. Juss. collected from different areas, along with two other medicinal plants (Argemone mexicana L. and Xanthium brasilicum Vell.) with established antiprotozoal activity, will be evaluated for antitoxoplasmal activity using an in vitro technique. Materials and Methods: All plants were extracted with 100% methanol and examined for activity against the Toxoplasma gondii RH strain via an intracellularly invaded Vero cell line with calculated inhibition percentages. The 3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide colorimetric assay against the Vero cell line was used for cytotoxic evaluation, followed by selectivity index (SI) calculation. Results: X. brasilicum exhibited the best antitoxoplasmal activity with an IC50 of 7.19 mu g/ml, followed by the A. indica fruits collected from Qassim, Kingdom of Saudi Arabia, and leaves collected from Central Sudan with an IC50 of 17.26 and 18.43 mu g/ml, respectively. The best SI was obtained from the leaves of A. indica (6.28) collected from Sudan. Conclusion: Although X. brasilicum proved to have very potent antitoxoplasmal activity, the cytotoxicity was also very high, so the isolation of active compounds is highly recommended.