Trypanocidal Activity of Aqueous and Ethanolic Extracts of Leptadenia hastata on White Mice Infected with Trypanosoma congolense

Aims: The aim of this study is to evaluate the trypanocidal activity of the plant extracts on mice infected with the trypanosome strain.

Study Design: The retrospective study was conducted from June to November 2020 at the laboratory of animal Biology, Department of Biological Sciences, and University of Ngaoundéré, Cameroon.

Methodology: The trypanocidal activity of Leptadenia hastata aqueous and ethanolic extracts on Trypanosoma congolense was evaluated during ten days of treatment. Thus, the smear was used to monitor the parasites density and its mortality rate in mice treated with Leptadenia hastata aqueous and ethanolic extracts by gavage at doses of 250, 500, 1000 mg/kg (test groups); with 10 ml/kg of distilled water (negative control) and 1mg/kg of isometamidium chloride (positive control). The lethal dose 50 (LD50) was evaluated using the equation of the linear regression line obtained with the mortality probits at day 10 of treatment.

Results: Phytochemical analysis showed the presence of steroid, Alkaloids, Saponosides, Flavonoids, tannins and triterpene. The 1000 mg/kg dose of the aqueous extract on day six (D6) right up to day eight (D8), induced a statistically decrease in parasites density which is similar to that of isometamiduim chloride. At day 0 (D0) the parasite density was 500 parasites/µl and at day 10 (D10) it was reduced to 250 parasites/µl with the 1000 mg/kg dose of the ethanolic extract. Parasite mortality was induced by 35 % by the 250 mg/kg dose, 60 % by the 500 mg/kg dose and 41 % by the 1000 mg/kg dose of the aqueous extract on day ten (D10) of treatment. With the ethanolic extract, parasite mortality on day 10 day of treatment was induced by 48 % by the 250 mg/kg dose, 68.75 % by the 500 mg/kg dose and 59.18 % by the 1000 mg/kg dose. Isometamidium chloride, a positive control, induced a parasite mortality rate of 85 %. The LD50 was 229.07 mg/kg for the aqueous extract and 271.37 mg/kg for the ethanolic extract.

Conclusion: All these results justify at least in part the use of this plant in traditional medicine for the treatment of trypanosomiasis.