Antiplasmodial Activity and Hematological Recovery Effects of Ethanol Leaf Extract of Solenostemon monostachyus in Plasmodium berghei-Infected Mice

Abstract

Background: The increasing prevalence of antimalarial drug resistance necessitates the identification of effective and affordable alternative therapies derived from medicinal plants. Solenostemon monostachyus P. Beauv. (Lamiaceae) is used traditionally in West Africa for the treatment of malaria, although its pharmacological efficacy requires further validation. Purpose: This study evaluated the in vitro antiplasmodial activity and the in vivo antimalarial and haematological recovery effects of the ethanol leaf extract of S. monostachyus. Methods: In vitro antiplasmodial activity was assessed against the chloroquine-sensitive Plasmodium falciparum 3D7 strain. Curative antimalarial efficacy was investigated in Swiss albino mice infected with Plasmodium berghei ANKA and treated orally with the extract at 100, 200, or 400 mg/kg for four consecutive days; artemether/lumefantrine served as the reference drug. Parasitaemia, body temperature, and haematological parameters were determined. Statistical significance was evaluated using one-way analysis of variance followed by Fisher's least significant difference post hoc test, with significance levels ranging from p < 0.05 to p < 0.001. Results: The extract completely inhibited P. falciparum growth at concentrations from 100 to 0.1 µg/mL, with a minimum inhibitory concentration of 0.1 µg/mL comparable to that of chloroquine. In vivo, the extract significantly suppressed parasitaemia; the 200 mg/kg dose reduced the parasite burden to 44.00 ± 9.45%, compared with 89.00 ± 8.20% in untreated infected mice, whereas artemether/lumefantrine achieved 34.20 ± 7.09%. Treatment also reduced malaria-associated pyrexia and improved haematological indices, including erythrocyte count, haemoglobin concentration, haematocrit, and platelet count, while normalising elevated leukocyte levels. Conclusion: The ethanol leaf extract of S. monostachyus demonstrated antiplasmodial, antipyretic, and haematoprotective activities in experimental malaria. These findings support its ethnomedicinal use and justify further phytochemical, toxicological, and mechanistic investigation.