Phylobioactive hotspots identified through multidimensional profiling of botanical drugs used to treat Chagas disease in Bolivia and Dioscorides' De Materia Medica

Globally, more than six million people are infected with Trypanosoma cruzi, the causative protozoan parasite of the vector-borne Chagas disease (CD). In Bolivia, CD is hyperendemic and a major health problem among indigenous communities. Although botanical drugs are used widely among different ethnic groups in Bolivia, studies challenging the hypothesis that effective antitrypanosomal medicinal agents were identified empirically are lacking. We conducted a cross-sectional ethnopharmacological field study in Bolivia among different ethnic groups in the Chaco, Chiquitania and Inter-Andean valleys. We compared botanical drugs used in Bolivia in the context of CD with botanical drugs from unrelated indications from the Mediterranean De Materia Medica (DMM) compiled by Dioscorides two thousand years ago. A total of 775 ethyl acetate plant extracts with and without ethnomedical indications for CD treatment were profiled against T. cruzi epimastigote and procyclic T. brucei proliferation, parasite release from T. cruzi trypomastigote infected cells, as well as for host cell cytotoxicity in vitro. Inhibition of parasite release was monitored using a flow cytometry-based celluar assay. At 25 µg/mL, less than 5% of all extracts exhibited selective toxicity for T. cruzi. We found no evidence that ethnomedicine-inspired bioprospecting significantly increased the probability of finding selective antichagasic botanical drugs. The ethnomedical data further indicate a discrepancy between local and scientific concepts about CD among the studied ethnic groups. Intriguingly, the phylobioactive anthraquinone hotspot identified in this study matched the antichagasic activity of Senna chloroclada, the taxon with the strongest consensus for treating CD among the Izoceno-Guarani.  Selected antitrypanosomal plant extracts from DMM were subjected to HPLC-based activity profiling and targeted isolation of active compounds yielding sesquiterpene lactones, naphtoquinones and anthraquinones. Because the anthraquinone emodin selectively and potently inhibited T. cruzi in host cell infection, we performed a preliminary structure-activity relationship analysis for the 9,10-anthracenedione scaffold, exploring the impact of differential hydroxylation. This study shows that the multidimensional phylobioactivity-guided identification of antichagasic natural products enables comparative bioprospecting and is suitable to challenge ethnopharmacological hypotheses.