Antiplasmodial, Antioxidant, and Cytotoxic Activity of Bridelia micrantha a Cameroonian Medicinal Plant Used for the Treatment of Malaria

Abstract

Introduction. Resistance to common antimalarial drugs and persistence of the endemicity of malaria constitute a major public health problem in Cameroon. The aim of this study was to evaluate the in vitro antiplasmodial, antioxidant, and cytotoxic activities of aqueous and ethanol extracts of Bridelia micrantha used by Cameroonian traditional healers for the treatment of malaria. Methods. Aqueous and ethanolic stem bark extracts were prepared according to standard procedures. The SYBR Green method was used for antiplasmodial activity on strains of Plasmodium falciparum sensitive to chloroquine (3D7) and resistant (Dd2). In vitro antioxidant activities of B. micrantha were determined using the scavenging activity of 2,2 $\prime$ -diphenyl-1-picrylhydrazyl, nitric oxide, ferric reducing power, and hydrogen peroxide as well as their cytotoxicity on RAW 264.7 macrophage cells and red blood cells (RBC). Results. The aqueous and ethanol extracts of Bridelia micrantha showed antiplasmodial activity on the 3D7 strain with $\text{I}{\text{C}}_{50}$ of $31.65\pm 0.79$  μg/ml and $19.41\pm 2.93$  μg/ml, respectively, as well as $37.64\pm 0.77$  μg/ml and $36.22\pm 1.04$  μg/ml for the Dd2 strain, respectively. The aqueous and ethanol extracts showed free radical scavenging properties. The ${\text{IC}}_{50}$ aqueous and ethanol extract was approximately 0.0001737 μg/ml, 42.92 μg/ml, 1197 μg/ml, 63.78 μg/ml and 4.617 μg/ml, 429.9 μg/ml, 511 μg/ml, and 69.32 μg/ml for DPPH, NO, H2O2, and FRAP, respectively, which were compared to ascorbic acid ( $8.610e-005$  μg/ml, 2901 μg/ml, 3237 μg/ml, and 18.57 μg/ml). The aqueous and ethanol extracts of B. micrantha were found to be nontoxic with ${\text{CC}}_{50}$ values of $950\pm 6.6$  μg/ml and $308.3\pm 45.4$  μg/ml, respectively. Haemolysis test showed that the two extracts were not toxic. Conclusion. These results suggest that B. micrantha can serve as an antimalarial agent. However, further studies are needed to validate the use of B. micrantha as an antimalarial.