Current Prospects of Saponins as Promising Anti-Trypanosoma brucei Compounds: Insight into the Mechanisms of Action

Abstract

Background: Human African trypanosomiasis (HAT) is a parasitic infection that may lead to death if left untreated. This disease is caused by a protozoan parasite of the genus Trypanosoma and is transmitted to humans through tsetse fly bites. The disease is widespread across Sub-Saharan Africa, with 70% of cases in recent reports in the Democratic Republic of the Congo and an average of less than 1000 cases are declared annually. Since there is no appropriate treatment for HAT, steroidal and triterpenoid saponins have been reported to be effective in in vitro studies and might serve as scaffolds for the discovery of new treatments against this disease. Aim of the Study: The present study aimed to summarize up-to-date information on the anti-Trypanosoma brucei activity of steroidal and triterpenoid saponins. The mechanisms of action of in vitro bioactive compounds were also discussed. Methods: Information on the anti-Trypanosoma brucei activity of plant saponins was obtained from published articles, dissertations, theses, and textbooks through a variety of libraries and electronic databases. Results: There has been incredible progress in the identification of steroidal and triterpenoid saponins with pronounced in vitro activity against Trypanosoma brucei. Indeed, more than forty saponins were identified as having anti-T. brucei effect with activity ranging from moderate to highly active. The mechanisms of action of most of these saponins included DNA damage, cell cycle arrest, induction of apoptosis through downregulation of bcl-2 and MDM2, and upregulation of Bax and Bak, among others. Conclusion: Referring to in vitro studies, plant saponins have shown anti-Trypanosoma brucei activity; however, more cytotoxic and in vivo studies and detailed mechanisms of action of the bioactive saponins should be further considered.