Complex sentence: Chloroquine has long been used in the treatment or prevention of malaria from "Plasmodium vivax", "P. ovale", and "P. malariae", excluding the malaria parasite "Plasmodium falciparum", for it started to develop widespread resistance to it.
Split into simpler sentences: Chloroquine has long been used in the treatment or prevention of malaria from "Plasmodium vivax", "P. ovale", and "P. malariae". After the malaria parasite "Plasmodium falciparum" started to develop widespread resistance to it.