Neurobehavioural and repeated-dose toxicity studies on the extractive from the decoction of a mixture of Alstonia boonei and Picralima nitida in mice

Safety of natural products is a priority before they are acceptable for consumption. Alstonia boonei De Wild (Apocynaceae) stem-bark and Picralima nitida (Stapf) T. & H. Dur. (Apocynaceae) seed are combined into a powder dosage form for the treatment of malaria fever. This study evaluated the central nervous system effects and the toxicity of the remedy on acute and repeated doses with a view to providing information on its safety. The powder mixture (ratio 1:2) of A. boonei stem-bark and P. nitida seed was extracted with water by the decoction method, concentrated in vacuo and freeze-dried. The acute toxicity of the extractive was determined by Lorke’s method. For the novelty-induced behaviour tests, 24 mice (18–22 g) of four groups (six mice per group) were orally given the aqueous solution of the extractive at 12.5, 25 and 50 mg/kg while the control group was given distilled water once daily for 30 days, after which the liver, kidney, brain, spleen and testes of each animal were humanely harvested for histopathological examination. At 25 mg/kg, a significant increase (P < 0.05) was observed in the grooming activity of the mice on acute and repeated doses. Histopathological analysis revealed that all the organs were essentially normal when compared with the control. The repeated oral administration of the extractive was relatively safe at each of the doses tested.