Approved drugs successfully repurposed against Leishmania – based on machine learning predictions

Provisionally accepted

Drug repurposing is a promising approach to discover new treatments against neglected tropical diseases such as leishmaniasis, as it offers the advantage of reducing both cost and time in drug discovery. In previous work, our group has developed a machine learning pipeline for the repurposing of FDA-approved drugs against Leishmania parasites. The present study focuses on an in vitro validation of this approach by evaluating the antleishmanial activity of 10 predicted drug candidates. First, we used an MTT assay to investigate the activity of the drugs against promastigotes of two strains of L. infantum and one of L. major that caused clear clinical manifestations. The standard anti-Leishmania drug amphotericin B was used as a positive control. Five molecules showed antleishmanial activity, of which acebutolol, prilocaine and phenylephrine are described here for the first time. When tested for promastigote growth, acebutolol showed IC50 values ​​between 69.28 and 145.53 µg/ml. Prilocaine showed IC50 values ​​between 33.10 and 45.81 µg/ml. Phenylephrine, on the other hand, showed IC50 values ​​of >200 µg/ml. The two remaining drugs, dibucaine and domperidone, showed significantly low IC50 values ​​between 0.58 and 1.05 µg/ml and 6.30 and 8.17 µg/ml, respectively. Both compounds have been previously described as anti-leishmanial agents in vivo. All five compounds showed no appreciable cytotoxic effects on THP-1-derived macrophages at the IC50 concentrations, allowing them to be tested on the intracellular form of the parasites L. major and L. infantum. Interestingly, all compounds demonstrated anti-leishmanial activity on amastigotes with increased IC50 values ​​compared to the corresponding promastigotes. Notably, dibucaine and domperidone showed IC50 values ​​of 1.99 µg/mL or less. Acebutolol, prilocaine, and phenylephrine showed IC50 values ​​ranging from 13.84 to 66.81 µg/mL. Our previously published computational repositioning pipelines of FDA-approved drugs as anti-leishmanial agents identified dibucaine and domperidone as candidates to support previous in vivo studies. This study consolidates such findings through in vitro validation against 2 Leishmania species widely distributed in Africa and the Middle East and reveals acebutolol, prilocaine, and phenylephrine as novel anti-Leishmania effectors, confirming the relevance of our approach and warranting further investigation.