Synthesis and anti-Chagas activity profile of a novel redox-active lead 3-benzylmenadione revealed by high-content imaging

Chagas’ disease or American trypanosomiasis is a neglected tropical disease, which is a top priority target of the World Health Organization. The disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and has spread around the globe due to human migration. There are multiple transmission routes, from vectorial, congenital, oral to iatrogenic. Less than 1% of patients have access to treatment, limited to two old redox-active drugs, but these have poor pharmacokinetics and severe adverse effects. Hence, the priorities for the next steps of R&D include i) the discovery of new drugs/chemical classes for clinical trials; ii) filling the pipeline with drug candidates that have new mechanisms of action, iii) the need for more research and access to new chemical entities. In the present work, we first identified a hit (4a), from a library of 3-benzylmenadiones, that had potent anti-T.cruzi activity. We then designed a synthetic strategy to build a library of 49 3-(4-mono-amino)benzylmenadione derivatives, via reductive amination to obtain diazacyclic benz(o)ylmenadiones. Among them, we identified an anti-amastigote “early lead” 11b (henceforth called cruzidione) by high content imaging with optimized pharmacokinetic properties and better specificity. Studies in a yeast model revealed that a cruzidione metabolite, the 3-benzoylmenadione (cruzidione oxide), enters redox-cycling with the NADH-dehydrogenase, generating reactive oxygen species, as hypothesized for the early hit (4a).