– GSK3494245 (DDD01305143) is a potent, orally active, and selective inhibitor of the chymotrypsin-like activity of the parasite proteasome binding in a site sandwiched between the ?4 and ?5 subunits (IC50=0.16 ?M for WT L. donovani proteasomes). GSK3494245 moderately inhibits chymotrypsin-like activity of human proteasome (IC50: purified 26S=13 ?M; enriched THP-1 extracts IC50=40?M). GSK3494245 exhibits attractive biological and biosafety properties.