Mechanistic Exploration of N,N'-Disubstituted Diamines as Promising Chagas Disease Treatments.

Introduction

Chagas disease, caused by the protozoan Trypanosoma cruzi, remains a major public health concern due to the limited effectiveness of current treatments, especially in the chronic stage.

Objective

Here, we wanted to advance a library of 30 N,N'-disubstituted diamines as promising antichagasic agents and gain insight into the mechanism of action.

Methods

The library was evaluated for activity against the T. cruzi amastigote stage and trypanocidal efficacy. In addition, selected compounds were tested as potential polyamine transport inhibitors, and a fluorescent analog was employed to investigate compound internalization.

Results

Five compounds exhibited potent activity (pIC50 > 6.0), particularly those with short aliphatic linkers (3-6 carbon atoms), suggesting a structure-activity relationship favouring shorter chains. Mechanistic studies showed that compound 3c strongly inhibited polyamine transport, a vital pathway in T. cruzi, though this was not a universal mechanism among active hits, indicating the potential for multiple targets. A fluorescent analog confirmed intracellular uptake in amastigotes but lacked antiparasitic activity, likely due to disrupted pharmacophoric features. Importantly, none of the compounds demonstrated trypanocidal activity in long-term assays, and some showed cytotoxicity, particularly in the benzyloxy-substituted series.

Conclusions

These findings position N,N'-disubstituted diamines as a viable scaffold for Chagas disease drug discovery. However, further optimization is required to enhance selectivity, achieve trypanocidal effects, and better understand the underlying mechanisms of action.