The present invention relates to a compound of Formula (I) or tautomers thereof having pharmacological activity, processes for its preparation, pharmaceutical compositions and their use in the treatment of certain parasitic certain parasitic protozoal infections such as malaria, in particular infection by Plasmodium falciparum. (R)-2-((3-(3,5-dichloropyridin-4-yl)-1H-1,2,4-triazol-5-yl)thio)-1-(1H-indol-3-yl)propan-1-one本發明係有關一種具有藥理活性之式(I)化合物或其互變異構物、其製法、醫藥組成物及其於治療某些寄生性原蟲感染(如:瘧疾,特定言之惡性瘧原蟲(Plasmodium falciparum)感染)上之用途。(R)-2-((3-(3,5-二氯吡啶-4-基)-1H-1,2,4-三唑-5-基)硫)-1-(1H-吲哚-3-基)丙-1-酮