Antitrypanosomal activity of Khaya senegalensis and Anogeissus leiocarpus stem bark on Trypanosoma brucei brucei infected rats
Trypanosoma brucei brucei, a haemo-protozoan parasite causes African Animal Trypanosomiasis (AAT). Khaya senegalensis (KS) and Anogeissus leiocarpus (AL) are medicinal plants used either individually or in combination by local farmers in Northern Nigeria in the treatment of many diseases including trypanosomiasis. There is however, no information on the efficacy of the plants used in combination. In this study, the antitrypanosomal activity of combined methanolic stem bark extracts of K. senegalensis and A. leiocarpus were determined in vivo using suppressive and repository tests. The combined extracts were administered at 250 mg/kg to T. b. brucei infected rats in ratios 1:4, 2:3, 1:1, 3:2 and 4:1 (K. senegalensis to A. leiocarpus). Diminor® (3.5 mg/kg) was positive control and Tween-80 the negative control. Trypanocidal activity was recorded in all four ratios with the highest in the 4:1 ratio for both tests. All ratios in repository test had varying levels of prophylactic activity which were significantly higher (p<0.05) than the negative control group. Chemo-prophylactic activity in the 4:1 ratio compared (p>0.05) favorably with the positive control. The extracts however had significantly lower (p<0.05) parasite suppressive activity compared to Diminor® (100%). The 1:4 combinations had the lowest activity (4.35%). In the repository test, packed cell volume (PCV) levels varied in the groups with an increase as the quantity of K. senegalensis in the dose increased. The results therefore show that the antitrypanosomal activity and haemolytic effects of the extracts was dependent on the ratio of K. senegalensis to A. leiocarpus. A higher quantity of K. senegalensis provided a more effective prophylaxis and normal PCV. The use of a threefold quantity of K. senegalensis to A. leiocarpus in the local management of animal trypanosomiasis is therefore suggested.
Key words: Antitrypanosoma, suppressive test, repository test, Khaya senegalensis, Anogeissus leiocarpus.