The new pyrazolyltetrazole derivative MSN20 is effective via oral delivery against cutaneous leishmaniasis.

An orally delivered, safe and effective treatment for leishmaniasis is an unmet medical need. Azoles and the pyrazolylpyrimidine allopurinol present leishmanicidal activity, but their clinical efficacies are variable. Here, we describe the activity of the new pyrazolyltetrazole hybrid, 5-[5-amino-1-(4'-methoxyphenyl)1H-pyrazole-4-yl]1H-tetrazole (MSN20). MSN20 showed a 50% inhibitory concentration (IC50) of 22.3 μM against amastigotes of Leishmania amazonensis and reduced significantly the parasite load in infected mice, suggesting its utility as a lead compound for the development of an oral treatment for leishmaniasis.