Evaluation of in Vitro and in Vivo Antitrypanosomal Activity of Aqueous and Methanol Leaf Extracts of Clutia Abyssinica (Euphorbiaceae) and Verbascum Sinaiticum (Scrophulariaceae) Against Trypanosoma Congolense Field Isolate
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Date
2014-01
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Addis Ababa University
Abstract
Aqueous and methanol leaf extracts of C. abyssinica and V. sinaiticum were investigated for the
presence of secondary metabolites, their in vitro and in vivo activity against Trypanosoma
congolence, the main causative agent of African animal trypanosomosis in Sub-Saharan Africa and
Ethiopia. The in vitro assay was carried out by monitoring test concentrations of 4, 2, 1, 0.4 and 0.2
mg/ml for cessation or reduction in motility of trypanosomes followed by monitoring for loss of
infectivity to mice. The in vivo antitrypanosomal efficacy of the extracts was evaluated in Swiss
albino mice infected with T. congolense field isolate. The leaf extracts were administered 12 days
post-infection at peak parasitaemia level of ~108 trypanosomes/ml at doses of 100, 200 and 400
mg/kg by intraperitoneal injection once daily for 7 days. Parasitaemia, packed cell volume (PCV),
mean survival time and change in body weight were used as indices for monitoring the efficacy of
the extracts by comparing with the positive control: 28 mg/kg dose of diminazene aceturate and
negative control: 2% tween 80 treated groups. Phytochemical screening revealed presence of
alkaloids, anthraquinones, flavonoids, glycosides, phenolic compounds, saponins, steroids, terpenes
and tannins. An appreciable in vitro activity was attained by the methanol extract of C. abyssinica at
4 mg/ml concentration which ceased motility of trypanosomes within 30 min and which caused loss
of infectivity of trypanosomes to mice, which remained aparasitaemic for 21 days after the
inoculation of the in vitro mixtures. The extracts had a lethal dose greater than 2000 mg/kg and there
were no evidences of acute toxicity at the doses tested. Highly significant (p<0.001) reduction in
pre-treatment parasitaemia by 3.91% (7.38+0.18) and increase in PCV by 1.12% (48.66+0.20) was
noticed in animals treated by the methanol leaf extract of C. abyssinica at dose of 400 mg/kg; while
body weight improvement by 1.67% (22.54+0.28) and mean survival time of 40.20 ± 0.37 days was
seen in the group treated by 400 mg/kg methanol leaf extract of V. sinaiticum. In general, the results
obtained suggest ethno-pharmacological usefulness of these plants and necessitate further studies to
be carried on isolated active substances from these plants.
Key words: Trypanosomosis, Trypanosoma congolense, Clutia abyssinica, Verbascum
sinaiticum, Parasitaemia, Packed cell volume, Body weight, Mean survival time
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Keywords
Trypanosomosis; Trypanosoma congolense; Clutia abyssinica; Verbascum sinaiticum; Parasitaemia, Packed cell volume; Body weight, Mean survival time