Safety and Efficacy of Prosopis juliflora Leaf Extract as a Potential Treatment against Visceral Leishmaniasis in Balb/c Mice

Background: Visceral Leishmaniasis caused by Leishmania donovani is a major health problem in the tropics and sub-tropic regions where it is endemic. We aimed in testing the leishmanicidal activity and toxicity of Prosopis juliflora leaf extract in BALB/c mice and in vitro test systems respectively. Methods: In the year 2017 until 2019, BALB/c mice of mixed sexes aged between 6 and 8 weeks in groups of 8 were used. Group I treated with 100 mg/kg of P. juliflora extract, Group II -1 mg/kg of Sodium stibogluconate (SSG) and Group III treated with normal saline. All mice were anaesthized and sacrificed to obtain blood, spleen samples for antibody measurements, and determination of parasite loads. Results: There was significant inhibitory effect (P<0.05) exhibited by P. juliflora leaf extract on promastigote growth during the in vitro test whereby up to 98% parasites were killed at the highest concentrations of 100 μg/Ml of the extract as compared to SSG, which showed less inhibitory effect on promastigotes. P. juliflora exhibited a higher splenic antiamastigote effect after 21 days of administration as compared to SSG. P. juliflora methanolic leaf extract induced a higher total IgG level as compared to the reference drug which could be attributed to higher titer in IgG2a subtype in mice treated with the extract, which was not induced in mice, treated with SSG. Conclusion: P. juliflora exhibited higher inhibitory effects against L. donovani promastigotes as well as amastigotes and induced significantly higher IgG antibody levels as compared to SSG (P<0.05). Furthermore, it was safer than SSG on Vero E6 cells.