A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL, FEDERAL UNIVERSITY OF TECHNOLOGY, MINNA, NIGERIA IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF MASTER OF TECHNOLOGY IN ANIMAL BIOLOGY (APPLIED ENTOMOLOGY AND PARASITOLOGY)

Abstract

African trypanosomiasis, a vector-borne parasitic infection, remains a major parasitic disease of the developing nations, causing a significant health threat and risk to lives. The current study elucidated the in vivo curative efficacy of crude toad venom extract against Trypanosoma brucei brucei-infected wistar rats. The toad venom was extracted by pressing the paratoid glands and characterization was carried out to ascertain its bioactive components. The acute toxicity of the venom was determined using a slightly modified Lorke’s method and the LD50 was computed. To establish the anti-trypanosomal effect of the venom, 28 male and female wistar rats were randomly split into seven groups of 4 rats each. Rats in group 1 to 6 were infected with 106 cells of trypanosomes per ml of blood intraperitoneally. Rats in group 1 to 4 were treated with the extract at 5, 10, 20 and 30 mg/kg body weight (b. wt.), respectively; while rats in group 5 and 6 were treated with diminazene aceturate at 5mg/kg b. wt. and normal saline at 2 ml/kg b. wt., respectively. Four rats (group 7) were neither infected nor treated and served as Normal control. The experimental animals were sacrificed and liver and kidney were obtained for histological evaluation. Zoochemical analysis showed the presence of phenols, flavonoids and terpenoids while results of acute toxicity showed the LD50 to be 141.42 mg/kg b. wt. The extract at 10 and 20 mg/kg b. wt. reduced parasitaemia levels significantly (p<0.05), prevented body weight loss and reduced the observed parasite-induced decline in packed cell volume, in comparison to Negative control. The group treated with 20 mg/kg b. wt. showed the highest anti-trypanosomal efficacy with 10 counts/ml on the 5th day of treatment. This is not significantly different from the group treated with standard drug. The haemoglobin concentration (12.17±0.79 g/dL) and red blood cell count (9.88±0.68 × 1012/L) showed a significant (p<0.05) decrease in the negative group compared to control (19.51±0.83 g/dL for haemoglobin and 18.76±0.39 × 1012/L for red blood cell count) and groups treated with 20 mg/kg b. wt. of the extract (18.81±0.94 g/dL for haemoglobin and 14.65±0.40 × 1012/L for red blood cell count). The survival time of rats treated with 20 mg/kg b. wt. of the extract was higher than the rats in the negative control group. GCMS revealed the presence of bioactive components including oleic acid and 9-Octadecenoic acid, methyl ester. Liver and kidney induced damage was ameliorated with the toad venom. This study, thus, established that the toad crude venom possess a promising anti-trypanosomal agent and could be developed into an alternative drug to complement treatment of trypanosomiasis.