Revisiting Pyrazolo[3,4-]pyrimidine Nucleosides as Anti- and Antileishmanial Agents.

Chagas disease and visceral leishmaniasis are two neglected tropical diseases responsible for numerous deaths around the world. For both, current treatments are largely inadequate, resulting in a continued need for new drug discovery. As both kinetoplastid parasites are incapable of purine synthesis, they depend on purine salvage pathways that allow them to acquire and process purines from the host to meet their demands. Purine nucleoside analogues therefore constitute a logical source of potential antiparasitic agents. Earlier optimization efforts of the natural product tubercidin (7-deazaadenosine) involving modifications to the nucleobase 7-position and the ribofuranose 3'-position led to analogues with potent anti- brucei and anti- activities. In this work, we report the design and synthesis of pyrazolo[3,4-]pyrimidine nucleosides with 3'- and 7-modifications and assess their potential as anti- and antileishmanial agents. One compound was selected for evaluation in an acute Chagas disease mouse model.