Inhibitors of methionyl-tRNA synthetase have potent activity against Giardia intestinalis trophozoites.

The methionyl-tRNA synthetase (MetRS) is a novel drug target for the protozoan pathogen Giardia intestinalis. This protist contains a single MetRS that is distinct from the human cytoplasmic MetRS. A panel of MetRS inhibitors was tested against recombinant Giardia MetRS, Giardia trophozoites, and mammalian cell lines. The best compounds inhibited trophozoite growth at 500 nM (metronidazole did so at ∼5,000 nM) and had low cytotoxicity against mammalian cells, indicating excellent potential for further development as anti-Giardia drugs.