Toxicity and potential anti-trypanosomal activity of ethanolic extract of Azadirachta indica (Maliacea) stem bark: An in vivo and in vitro approach using Trypanosoma brucei

Abstract

To determine the toxicity and anti-trypanosomal activity of the ethanolic extract of Azadirachta indica (Maliacea) stem bark, through in vivo and in vitro approach using Trypanosoma brucei brucei. Graded concentrations (100, 200, 400, 800, 1600 and 3200 mg/kg) of the crude stem bark ethanolic extract of Azadirachta indica, Hochst ex. A. Dc. (Maliacea) was tested for acute toxicity in 35 out bred Swiss (Wister) adult albino rats of both sexes. Secondly, the in vitro activity in test tubes and in vivo activity of the extract in 30 out bred Swiss (Wister) adult albino rats against Trypanosoma brucei brucei strain NITR/14 (Federe) was evaluated in a graded dose manner. The calculated intra-peritoneal LD(50) of the extract was 870 mg/kg and produced toxicity at high doses (>800 mg/kg). Graded concentrations of the ethanolic extract produced remarkable in vitro activity against Trypanosoma brucei brucei within seconds of inoculation. It also suppressed the establishment of parasitaemia at 100mg/kg when administered simultaneously with infection in vivo. Similarly, at 200 and 400mg/kg, the extract administered at the onset of parasitaemia for 4 consecutive days reduced parasitaemia, modulated declined packed volume (PCV) changes by day 48 post-infection in vivo. The results confirm that the folkloric medicinal application of the extract of Azadirachta indica (Maliacea) has a pharmacological basis. Further investigation is however, needed to optimize the effectiveness of the extract.