In vitro efficacy of herbicides on Sarcocystis cruzi bradyzoites

Abstract

Sarcocystis causes various veterinary and human infections. A few agents are available for treating Sarcocystis infections, but their mechanisms of action are not known. Phytohormonal herbicides are antiparasitic agents that reduce the viability of organisms belonging to the phylum, Apicomplexa. Some of these herbicides prevent Apicomplexan parasites from infecting cells and organisms, yet the effects of such drugs on Sarcocystis are unclear. We evaluated the activity of phytohormonal herbicides against Sarcocystis bradyzoites using mortality and morphological changes with methylene blue staining as an indicator. Antiparasitic activity of 17 agrochemicals that act on plant plastids—classified into the following six herbicide groups: acetyl-CoA carboxylase (ACC) inhibitors, acetolactate synthase (ALS) inhibitors, photosynthesis inhibitors, protoporphyrinogen oxidase (protox) inhibitors, carotenoid biosynthesis pathway inhibitors, very-long-chain fatty acid (VLCFA) biosynthesis inhibitors, and auxinlike herbicides—were examined. The in vitro system enables the screening of drugs against Sarcocystis species, for which a well-established culturing method is not yet available. Nine herbicides, including ALS inhibitors, ACC inhibitors, and auxin-like herbicides, caused mortality of Sarcocystis cruzi bradyzoites by more than 90%. Further, all ACC inhibitors caused the formation of vacuolar structures in bradyzoites, and two ALS inhibitors caused bradyzoites rounding