Tanzanian Botanical Derivatives in the Control of Malaria Vectors: Opportunities and Challenges

This paper report on assessment of the chemicals derived from Tanzanian botanical resource as a viable source of safe, environmentally friendly and low cost mosquitocidal agents, but has yet to be developed into simple blends and formulations to be used in malaria control campaigns. Selection of bioactive plant species were based on random screening, phytochemical targeting, ethnobotanical survey, chemotaxonomic approach and targeted screening approach. The crude extracts from leaves, stem and root barks, and pure isolated compounds from over 20 different Tanzania plant species have been established to possess antimosquito activities. The bioassay experiments were based on cytotoxicity screening in BST followed by mosquitocidal assays of larvicidal, tarsal contact and repellency bioassays. The activities were characterized to be larvicidal, growth disruptors, insecticidal and repellents. Seasonal variations, geographical locations, isolation of small amounts of pure compounds, limits in the availability of essential facilities such as NMR spectroscopy, MS and X-ray diffraction analysis for structural elucidation, stereochemical and conformational assignments, have been realised to be among the impediments in the search and establishment of new and biodegradable botanical natural products. The results suggest that the investigated plant species are promising as mosquitocidal agents and could be useful leads for the development of new insecticide products.