Evaluation of the Antimalarial Effects of the Leaf Extract and Fruit Juice of Annona muricata against Plasmodium berghei Infection in Mice

Abstract

Background: Inappropriate use of mosquito nets, emergence of insecticides resistant mosquitoes, ineffective vaccines and evolvement of Plasmodium species that are resistant to antimalarial drugs have constituted barriers to the effective prevention and treatment of malaria. Therefore, there is a need to continue research in the development of new antimalarial drugs. Laboratory investigation of antimalarial plants used in herbal medicine could give a lead to discovery of new antimalarial drugs. Many in vitro studies have already shown Annona muricata to possess antiplasmodial effects. The present in vivo animal study was designed to further establish the antimalarial activities of the leaf extract and fruit juice of A. muricata against Chloroquine-sensitive Plasmodium berghei infection in mice.

Objective: To determine the antimalarial activity of the leaf and fruitjuice extracts of A. muricata against Chloroquine-sensitive Plasmodium berghei infection in mice.

Materials and Methods: Two different models (curative and chemoprophylactic)were used to determine the antimalarial effect of A. muricata. Mice infected with Plasmodium berghei parasite were treated separately with extracts fromthe leaf and fruit juice of A. muricata using distilled water and chloroquine as negative and positive controls respectively. After the treatment period, blood films were obtained from the tails of the mice and used to determine the average percentage parasitemia suppression caused by the plant extracts and drugs of the control groups. The results were subjected to statistical analysis using two-way analysis ofvariance (ANOVA).Acute toxicity test was also performed in order to determine the safe doses of the plant as well as its toxic effects after a single exposure.

Results: The results indicated that the leaf extract of A. muricata produced the highest percentage parasitemia suppression at a dose of 150 mglkg for the two models. The fruit juice extract produced significant parasitemia suppression (p<O.05) in the prophylaxis test model at all the three doses (5, 10 and 20 ml/kg), but only the 20 ml/kg dose of the fruit juice extract showed significant parasitemia reduction (p<0.05) in the curative test model when compared to the distilled water control group.

Conclusion: Annona muricata possesses antimalarial effect with the ethanolic leaf extract recording a better antiplasmodial activity than the fruit juice extract. The dose of 150 mglkg of the leaf extract produced the highest efficacy. Even at this dose, a total parasitemia clearance was achieved at a longer period (day 5) than the standard antimalarial drug, chloroquine, which produced total parasitemia clearance as early as the third day. The fruit juice extract may be useful for prophylaxis against malaria but it is relatively ineffective for treating malaria at the doses used in this study.