Background
Access to high-throughput phenotypic screening of large compound libraries has enabled the discovery of many compounds which can kill pathogens that are responsible for common infectious diseases. Translating these ‘hits’ into new anti-infective drugs faces a number of challenges. Finding the mode of action of these compounds can help in focussing efforts to develop the most promising compounds. Such knowledge can also help in designing new combination therapies by targeting discrete pathways that can overcome the problem of emerging drug-resistance.
Methods
We performed untargeted metabolomics analyses of Trypanosoma brucei brucei, a kinetoplastid parasite which causes a neglected tropical disease commonly known as sleeping sickness. This allowed us to investigate the mode of action of over 20 potent trypanocidal compounds from the Pathogen Box (available from Medicines for Malaria Venture) which contains diverse, drug-like molecules active against a number of infectious disease-causing bacterial, viral, helminth, apicomplexan and kinetoplastid pathogens.
Results
Over 500 metabolite features were identified in this study which were mapped to the predicted metabolic network of T. b. brucei. This approach revealed significant metabolic perturbation associated with the most potent compounds, and identified the most likely pathways targeted by each compound. These pathways spanned nucleotide metabolism, lipid metabolism, co-factor synthesis and redox metabolism. Multivariate analyses allowed grouping of novel compounds based on their mode of action. Interestingly, compounds with similar chemical structures did not always have similar biochemical activities in the parasite.
Conclusions
This study showed that a simple and efficient metabolomics assay can rapidly reveal the biochemical basis of the mode of action of newly discovered anti-infective compounds. This information can be used for prioritising compounds before progressing them through the optimization pipeline and further development.