In vivo antiplasmodial and toxicological studies of Dialium angolense Welw. Ex Oliv. (Fabaceae) leaves extracts, a medicinal plant from Eastern Congo

Dialium angolense is used in traditional medicine in Bagira-Bukavu in the management of malaria. In this study, in vivo antiplasmodial and in vitro antioxidant activities, phytochemical screening of secondary metabolic and in vivo toxicological studies where carried out on aqueous and methanolic extracts of its leaves. The plant was selected following an ethnobotanical survey conducted in DR Congo and focusing on antimalarial plants. Extracts’ phytochemical secondary metabolites were determined using standard procedures and the antiplasmodial activity was evaluated using 4-day suppressive test, while antioxidant activity was evaluated by DPPH assay. In acute toxicity, eighteen animal (6/group) were given orally singular 2000 mg of extract/kg body weight (BW) then observed for 14 days. In sub-acute toxicity assay, 150 or 300 mg/kg BW/Day were given orally, and animals (6/group) were observed for 28 days. The total phenolic (0.89 - 0.98 mg GAEg-1), total flavonoid (0.42 - 0.44 mg QEg-1) and total tannin contents (0.080 – 0.098 mg GAEg-1) were in the same rate in the two extracts as well as the antioxidant activity with IC50 value 6.1 and 6.8 μg/mL. At the highest oral dose, 300 mg/kg body weight, all extracts produced 70.4–70.8% chemo-suppression against P. berghei ANKA and 28 survival days. No deaths were recorded during the acute toxicity assay suggesting the LD50 > 2000 mg/kg and no abnormal behavior or variation in toxicity biomarkers were observed during the subacute toxicity assessment. D. angolense leaves extracts showed a great antiplasmodial and a very good antioxidant activity. It can be used to prepare antimalarial recipe or isolate antimalarial compounds in the future.