Evaluation of the Antimalarial Activity of the Hydroalcoholic Extract of Leaf of Leonotis ocymifolia (Burm. f.) Iwarsson (Lamiaceae) against Plasmodium berghei in Mice

Malaria's global impact, fueled by resistance to several antimalarial drugs, has necessitated a quest to new antimalarial drugs from several sources with traditional medicinal plants being one of them. This study was conducted to assess the antimalarial activity of a traditionally used medicinal plant, Leonotis ocymifolia, against Plasmodium berghei. The plant has been extracted using maceration technique, and doses ranging from 100–800 mg/kg of Leonotis ocymifolia were used to test its antimalarial activity. Tween 80 (2% in water) and chloroquine 25 mg/kg were used as negative and positive controls, respectively. The antimalarial activities of the plant were determined by measuring parasitemia, survival time, packed cell volume, temperature, and weight. The plant's hydroalcoholic extract, as compared to negative control, maximally decreased parasite load by 41.4% at 800 mg/kg (p < 0.001). This parasite suppression was followed by longer survival time in the groups taking 400 mg/kg (p < 0.05) and 800 mg/kg (p < 0.05) in a four-day suppressive test and in those taking 800 mg/kg (p < 0.05) in Rane's test. The plant did not prevent weight and PCV reduction but prevented temperature reduction at 400 mg/kg (p < 0.05) and 800 mg/kg (p < 0.05) in a four-day suppressive model, and at 800 mg/kg (p < 0.05) in Rane's model. The average but consistent antimalarial activity of the plant across the test models corroborates the folkloric antimalarial use of the plant. The study recommends further pharmacological screenings, isolation, and identification of active compound(s) of the plant Leonotis ocymifolia.