Antiplasmodial and Antipyretic Activity and Safety Evaluation of the Methanolic Leaf Extract of Murraya exotica (L.)

Abstract

Background: The increasing mortality and morbidity of malaria in Africa coupled with the recent reports of antimalarial drug resistance reinforces the need for novel antimalarial agents from natural plant products with folkloric use for the disease. Murraya exotica (L.) (Rutaceae) is widely used as an ornamental plant used indigenously to treat fever, cough, and infectious wounds and eliminate pain from injury and trauma. This study was conducted to evaluate extracts of the leaves of Murraya exotica (L.) (Rutaceae) for its safety and antipyretic and antimalarial activity in rodent models.

Method: In this study, the Peters 4-day suppressive and curative test in Plasmodium berghei-infected mice was used to demonstrate the antiplasmodial activity of the methanolic leaf extract of Murraya exotica (L.) (MEE). The study also evaluated the subacute toxicity study and the antipyretic activity of MEE on baker's yeast-induced hyperthermia in rodent models.

Results: Murraya exotica (L.) extract demonstrated curative antimalarial activity, with a percentage suppression of 45.84, 64.32 ± 0.33, 56.74 ± 2.16, and 64.61 ± 0.67 at doses of 50, 100, 300, and 600 mg/kg, respectively. In the Peters 4-day suppressive test, MEE at dose 600 mg/kg had the highest chemosuppression (76.02 ± 1.38%) compared with artesunate (2 mg/kg, p.o.) (82.56 ± 0.97%). Subacute oral toxicity studies in Sprague-Dawley rats documented no deaths, with no significant changes in clinical signs, organ weights, and hematological and biochemical parameters. The LD₅₀ of MEE was estimated to be above 1000 mg/kg in Sprague-Dawley rats. All doses of MEE and paracetamol reduced pyrexia in 1 h and 2 h after their administration. The percentage reduction of rectal temperature (T _R ) for the positive control (paracetamol, 150 mg/kg, p.o.) was 44.36% while the Murraya exotica extract at doses 50 mg/kg, 100 mg/kg, 300 mg/kg, and 600 mg/kg recorded 67.74%, 40.78%, 66.42%, and 59.42%, respectively. Murraya exotica at dose 100 mg/kg exhibited significant reduction (p < 0.05) in baker's yeast-induced pyrexia.

Conclusions: The findings in this study show the antipyretic, curative, and suppressive antiplasmodial activity as well as the safety of the methanolic leaf extract of Murraya exotica (L.) supporting its traditional use for malaria and fever.

Figure 1

Effect of MEE 50-600 mg/kg, p.o., and paracetamol (150 mg/kg, p.o.) on time-course curve (a) and the total increase in temperature (calculated as AUCs (b)) on baker's yeast-induced changes of rectal temperatures in rats. Naive represents animals with no treatment with yeast. Values are expressed as mean ± SEM (n = 5). ^∗∗∗∗p < 0.001 compared to vehicle-treated group (control) (ordinary one-way ANOVA comparison test with descriptive statistics).