Structural Insights into the Enzymes of the Trypanothione Pathway: Targets for Antileishmaniasis Drugs

Leishmaniasis is a neglected disease that kills 60,000 people worldwide, and which is caused by the protozoa Leishmania. The enzymes of the trypanothione pathway: trypanothione synthetase-amidase, trypanothione reductase (TR) and tryparedoxin-dependent peroxidase are absent in human hosts, and are essential for parasite survival and druggable. The most promising target is trypanothione synthetase-amidase, which has been also chemically validated. However, the structural data presented in this review show that TR also should be considered as a good target. Indeed, it is strongly inhibited by silver- and gold-containing compounds, which are active against Leishmania parasites and can be used for the development of novel antileishmanial agents. Moreover, TR trypanothione-binding site is not featureless but contains a sub-pocket where inhibitors bind, potentially useful for the design of new lead compounds.