The prophylactic effect of ethanolic leaf extract of Nauclea latifolia, widely used in herbal malarial treatment, against the widely used drug Coartem® (Artemether/Lumefantrine) in Plasmodium-infected mice was investigated, and thereafter analysed for organosomatic index, parasitemia, histomorphological and immunohistochemical changes in the hippocampus. Twenty male mice about 6 to 8 weeks weighing 20 to 24 g were randomized into four groups of five mice each. Group 1 served as control received placebo; group 2 received 500 mg/kg of the extract; group 3 received 1000 mg/kg of extract; and group received 5 mg/kg of Artemether/Lumefantrine. Administration extract and drug was done for 3 days and thereafter mice were infected with 106 of Plasmodium berghei parasites, and monitored for 4 days, after which the experiment was terminated. Thick blood smear were prepared from lateral tail vein, then under anesthesia via a cocktail of xylaxine and ketamine, intracardiac perfusion was performed first with phosphate buffered saline to clear systemic blood, and then 4% paraformaldehyde to fixed brain for routine histology and immunohistochemistry. Result indicates organosomatic index was not statistically significant, parasitemia in the treated groups were significantly (p<0.05) decreased compared to control and were corroborated in the photomicrographs of respective blood morphology, however, histologically there was moderate to severe distortion of the hippocampus across the groups, but glial fibrillary acidic protein expression, a marker for neurotoxicity indicated that group 4 had the most immunolabelling intensity compared to other test groups. In conclusion, the prophylactic ethanolic extract of N. latifolia and Artemether/Lumefantrine cleared parasitemia seen also in blood morphology, with the presence of hemozoin in hippocampus of infected-treated groups and other cytoarchitectural distortions, and up-regulated glial fibrillary acidic protein expression.

Keywords: Malaria, hippocampus, neuron damage, Artemether/Lumefantrine, Nauclea latifolia.