Optimization and Evaluation of Antiparasitic Benzamidobenzoic Acids as Inhibitors of Kinetoplastid Hexokinase 1

Kinetoplastid‐based infections are neglected diseases that represent a significant human health issue. Chemotherapeutic options are limited due to toxicity, parasite susceptibility, and poor patient compliance. In response, we studied a molecular‐target‐directed approach involving intervention of hexokinase activity—a pivotal enzyme in parasite metabolism. A benzamidobenzoic acid hit with modest biochemical inhibition of Trypanosoma brucei hexokinase 1 (TbHK1, IC50=9.1 μm), low mammalian cytotoxicity (IMR90 cells, EC50>25 μm), and no appreciable activity on whole bloodstream‐form (BSF) parasites was optimized to afford a probe with improved TbHK1 potency and, significantly, efficacy against whole BSF parasites (TbHK1, IC50=0.28 μm; BSF, ED50=1.9 μm). Compounds in this series also inhibited the hexokinase enzyme from Leishmania major (LmHK1), albeit with less potency than toward TbHK1, suggesting that inhibition of the glycolytic pathway may be a promising opportunity to target multiple disease‐causing trypanosomatid protozoa. Power play: The discovery of novel target‐based, antiparasitic agents is necessary to address the dearth of therapeutic options for neglected diseases such as sleeping sickness and leishmaniasis. Inhibitors of hexokinase 1, a key metabolic enzyme in these parasites, have been identified and explored as a means to interrupting glucose metabolism on which these parasites rely. Low micromolar efficacy has been observed in whole bloodstream‐form trypanosomes, suggesting that this strategy may be useful in targeting glucose‐dependent parasites.