Abstract:
Landolphia owariensis P. Beauv (Apocynaceae) is a woody liane commonly used in Africa for the treatment of gonorrhea, worm infestation and malaria. The methanol leaf extract (ME) of L. owariensis was obtained by cold maceration and then fractionated into nhexane (nHF), ethylacetate (EF) and methanol (MF) fractions. The methanol extract and fractions were tested against chloroquine-sensitive Plasmodium berghei berghei in early, established and repository models of infection using Peter’s 4-day suppressive model, Rane’s curative model and Peters prophylactic model respectively. The antiplasmodial activity was evaluated by determining the parasitemia, body weight and survival time of each of the eighty-four mice comprising six mice per group. Groups 1-12 were given graded doses of 200, 400 and 800 mg/kg body weight of extract or fractions respectively while group 13 and 14 received 5 mg/kg/day of chloroquine and 3% Tween 80 respectively. All administration was orally. Acute toxicity was studied using modified Lorke’s method. Phytochemistry of extract and fractions as well as HPLC fingerprinting of ME, EF and MF were also carried out. The methanol extract and all the fractions exhibited significant (P<0.05) but varying levels of antiplasmodial activity comparable to the group treated with chloroquine. MF elicited the highest chemosuppression of 96.04% at 800 mg/kg with the prophylactic model while nHF elicited the least activity with chemosuppression of 29.38-58.75% at 200 -800 mg/kg respectively. The phytochemical screening of the extract and fractions revealed the presence of secondary metabolites. The LD50 was estimated to be greater than 5000 mg/kg p.o in mice. HPLC analysis of ME, EF and MF showed different peaks representing different components. The results of this study suggest that the leaf extract and fractions pose significant antiplasmodial activity.
