In vitro and in vivo Antitrypanosomal Activities of Annona muricata Leaf Extracts in Trypanosoma brucei brucei Experimentally Infected Albino Rats

Abstract

Aims: Trypanosomiasis is an important protozoan disease that affects domestic and wild animals as well as man. It is caused by the tsetse fly-transmitted extracellular hemo-flagellates that belong to the genus, Trypanosoma. In East and Southern Africa, Human African Trypanosomiasis (HAT) is caused by Trypanosoma brucei rhodesiense while in West and Central Africa, it is caused by T. b. gambiense. Animal trypanosomiasis on the other hand is caused by T. b. brucei, T. vivax, and T. congolense. In sub-Saharan Africa, about sixty million people are at risk of infection. This current study evaluates the antitrypanosomal efficacy of extracts of Annona muricata leaf in Trypanosoma brucei brucei infected albino rats. Place and Duration of Study: Animal Parasitology and Microbiology Research Unit, Department of Animal Production and Health, Federal University of Technology, Akure, Nigeria, between February and June, 2021. Methodology: In vitro antitrypanosomal analysis was done in varied concentrations of 2.5mg/ml, 5mg/ml and 10mg/ml using various solvent extracts (ethanolic, ethyl acetate, n-hexane, chloroform and aqueous). Diminazine aceturate and normal saline were used as positive and negative controls respectively. The In vivo assay was carried out through intraperitoneal administration of graded doses (200, 400 and 600mg/kg) of ethyl acetate and chloroform extracts of the plant for three consecutive days. Results: The n-hexane, chloroform and ethyl acetate extracts yielded high percentage DPPH free radical scavenging activity of 85.52, 80.00 and 78.49% respectively. Decrease in motility of the parasites at different times were observed in all extracts tested invitro. These responses were positively concentration-dependent. 10mg/ml concentration of chloroform and ethyl acetate showed complete cessation of parasite motility at 35 and 45 minutes respectively. These two extracts (ethyl acetate and chloroform extracts) which showed the best invitro responses, were subjected to invivo analysis. Both extracts caused decrease in trypanosome parasitemia and prolongation of mean survival days of the rats to 14.67days as compared with 6.83days in the negative control group. The extracts displayed dose-dependent significant (p ≤ 0.05) antitrypanosomal activities when compared with the negative and positive controls. Conclusion: The chloroform and ethyl acetate extracts of Annona muricata showed a relatively higher antitrypanosomal activity over other solvent extracts used in this study. Further fractionation, purification and isolation should be done to confirm the active components in this plant that is responsible for the antitrypanosomal activities recorded.