Chemistry and pharmacology of three antiplasmodial traditional medicinal plants from tropical Africa – A review

Sterculia tragacantha Lindl., Zanthoxylum gilletii (De Wild.) P. G. Waterman and Annickia polycarpa (DC.) Setten & Maas ex I.M.Turner are commonly used folk medicinal plants, particularly against malaria, in tropical and warm African areas. Besides, S. tragacantha and Z. gilletii are used traditionally to manage rheumatism, boils, ulcer, gonorrhea, and snake bite. On the other hand, A. polycarpa is used for the treatment of Trypanosoma, and stomach ulcer. Some pharmacological studies have been undertaken and the phytochemical profile established. Nonetheless, there is still a shortage of studies that have attempted to compile such data in a single review. Given the medicinal values that these plants possess and potential relevance towards bioproducts development and future bioprospecting studies, an endeavor has been made herein to provide an updated report on the therapeutic potential of S. tragacantha, Z. gilletii, and A. polycarpa. A comprehensive literature search via key databases (Google scholar, Pubmed, Scopus, Science Direct and Web of Science) was conducted to probe and compile relevant published information (1959–2018) such as ethnobotanical uses, phytochemistry and in vitro and in vivo studies of these three plants. This study also highlights important research gaps that need to be addressed in future studies. Despite the panoply of biological and pharmacological research already carried out and showing numerous biological activities of the studied species, an extensive investigation is needed to exploit other therapeutic utilities and validate other ethnobotanical uses of these species. It is anticipated that such compilation will also stimulate ongoing scientific documentation of African medicinal plants for future generations and possible application of this knowledge as instruments for sustainable therapeutic bioproducts development. However, further research needs to be designed to evaluate other potential activities of the crude extracts as well as the compounds already characterized.