Antischistosomal, antionchocercal and antitrypanosomal potentials of some Ghanaian traditional medicines and their constituents (vol 14, e0008919, 2020)

BackgroundGhana is endemic for some neglected tropical diseases (NTDs) including schistosomiasis, onchocerciasis and lymphatic filariasis. The major intervention for these diseases is mass drug administration of a few repeatedly recycled drugs which is a cause for major concern due to reduced efficacy of the drugs and the emergence of drug resistance. Evidently, new treatments are needed urgently. Medicinal plants, on the other hand, have a reputable history as important sources of potent therapeutic agents in the treatment of various diseases among African populations, Ghana inclusively, and provide very useful starting points for the discovery of much-needed new or alternative drugs.Methodology/Principal findingsIn this study, extracts of fifteen traditional medicines used for treating various NTDs in local communities were screened in vitro for efficacy against schistosomiasis, onchocerciasis and African trypanosomiasis. Two extracts, NTD-B4-DCM and NTD-B7-DCM, prepared from traditional medicines used to treat schistosomiasis, displayed the highest activity (IC50 = 30.5 mu g/mL and 30.8 mu g/mL, respectively) against Schistosoma mansoni adult worms. NTD-B2-DCM, also obtained from an antischistosomal remedy, was the most active against female and male adult Onchocera ochengi worms (IC50 = 76.2 mu g/mL and 76.7 mu g/mL, respectively). Antitrypanosomal assay of the extracts against Trypanosoma brucei brucei gave the most promising results (IC50 = 5.63 mu g/mL to 18.71 mu g/mL). Incidentally, NTD-B4-DCM and NTD-B2-DCM, also exhibited the greatest antitrypanosomal activities (IC50 = 5.63 mu g/mL and 7.12 mu g/mL, respectively). Following the favourable outcome of the antitrypanosomal screening, this assay was selected for bioactivity-guided fractionation. NTD-B4-DCM, the most active extract, was fractionated and subsequent isolation of bioactive constituents led to an eupatoriochromene-rich oil (42.6%) which was 1.3-fold (IC50 <0.0977 mu g/mL) more active than the standard antitrypanosomal drug, diminazene aceturate (IC50 = 0.13 mu g/mL).Conclusion/SignificanceThese findings justify the use of traditional medicines and demonstrate their prospects towards NTDs drug discovery.Author summaryThe discovery of new drugs is vital to achieving the World Health Organization eradication targets for neglected tropical diseases (NTDs). Traditional medicines serve as sources of primary healthcare needs for most affected populations and therefore represent a valuable resource in this regard, albeit largely underdeveloped. We investigated extracts of a selection of traditional medicines for efficacy and safety to justify their use for treating NTDs in Ghana. We screened the extracts for activity against schistosomiasis (Schistosoma mansoni), onchocerciasis (Onchocera ochengi) and trypanosomiasis (Trypanosoma brucei brucei). Generally, more extracts effectively inhibited O. ochengi than S. mansoni lifecycle stages. Further, S. mansoni juvenile and O. ochengi adult-stage male worms were more susceptible to the extracts than adult-stage S. mansoni and O. ochengi female worms. Overall, the extracts were most active against the trypanosomes. Hence, we selected the antitrypanosomal assay to identify active principles and this resulted in a non-toxic oil which was more active than the extract, and also more effective than the standard antitrypanosomal drug, diminazene aceturate. The major oil constituent, eupatriochromene, has demonstrated antitrypanosomal activity in other studies. We recommend that the quality of traditional medicines is improved.