Evaluation of Medicinal Plants from Nupeland for Their in vivo Antitrypanosomal Activity

Over 25% of our common medicines contain at least some compounds obtained from plants. Nupeland located on the coastal basins of Rivers Niger and Kaduna in North Central Nigeria is greatly influenced by the savannah-forest vegetations with biodiversity rich in medicinal plants. This type of vegetation also harbours tsetsefly which are the vector of trypanosomes, thus making the area highly endemic to sleeping sickness. Trypanosomiasis is a tropical disease threatening human health and economical development and is responsible for the death of about half a million patients per year. Nupeland inhabited predominantly by Nupe tribe are traditionally noted for generations of using medicinal plants in curing human trypanosomal infections; many of which have not been scientifically proved. Natural products derived from plants offer novel possibilities to obtain new drugs that are active against trypanosomes. In furtherance to the earlier in vitro trypanocidal activity evaluation of some Nupeland medicinal plants; six medicinal plants traditionally used for treatment of sleeping sickness in Nupeland namely: Acacia nilotica, Bombax buonopozense, Heterotis rotundifolia, Pterocarpus erinaceus, Terminalia avicennioides and Zanthoxylum zanthoxyloides were investigated for in vivo antitrypanosomal activity. The solvent soluble extracts obtained by standard methods from various plant parts (stem barks and fruits) of Nupeland medicinal plants were evaluated for their in vivo antitrypanosomal activities against Trypanosoma brucei brucei as well as their phytochemical screening were performed by standard procedures. The extracts of A. nilotica (stem bark), B. buonopozense (stem bark), H. rotundifolia (whole plant), T. avicennioides (round fruit) and Z. zanthoxyloides (stem bark) were effective on trypanosomes. The extracts of A. nilotica, B. buonopozense and H. rotundifolia exhibited antitrypanosomal effects at 200, 300 and 800 mg/kg body weight respectively and cleared the parasites from circulation with prolonging survival period of up to 30 days. The stem bark extracts of P. erinaceus, T. avicennioides and Z. zanthoxyloides showed only trypanostatic effects and could not clear the parasites completely. These extracts contain metabolites that are associated antitrypanosomal effects; hence these medicinal plants may be sources of new antitrypanosomal compounds that may be active against T. b. brucei. The discovery of these potent antitrypanosomal extracts from these plants has increased their potentials to provide lead compounds for the development of new natural drugs for effective treatment of sleeping sickness. It has also justified the claim that some medicinal plants of Nupeland possess antitrypanosomal activity and could be useful in the management of trypanosomiasis. The isolation of trypanocidal compounds from these extracts will require State-Art-Instrumentation particularly for further bioactive fractionation and characterization using chromatographic and spectroscopic techniques.