title: Hematin polymerization assay as a high-throughput screen for identification of new antimalarial pharmacophores.
abstract: Hematin polymerization is a parasite-specific process that enables the detoxification of heme following its release in the lysosomal digestive vacuole during hemoglobin degradation, and represents both an essential and a unique pharmacological drug target. We have developed a high-throughput in vitro microassay of hematin polymerization based on the detection of (14)C-labeled hematin incorporated into polymeric hemozoin (malaria pigment). The assay uses 96-well filtration microplates and requires 12 h and a Wallac 1450 MicroBeta liquid scintillation counter. The robustness of the assay allowed the rapid screening and evaluation of more than 100, 000 compounds. Random screening was complemented by the development of a pharmacophore hypothesis using the "Catalyst" program and a large amount of data available on the inhibitory activity of a large library of 4-aminoquinolines. Using these methods, we identified "hit" compounds belonging to several chemical structural classes that had potential antimalarial activity. Follow-up evaluation of the antimalarial activity of these compounds in culture and in the Plasmodium berghei murine model further identified compounds with actual antimalarial activity. Of particular interest was a triarylcarbinol (Ro 06-9075) and a related benzophenone (Ro 22-8014) that showed oral activity in the murine model. These compounds are chemically accessible and could form the basis of a new antimalarial medicinal chemistry program.
authors.affiliation: Department of Pharmaceutical Screening, Nippon Roche Research Center, 200 Kajiwara, Kamakura, Kanagawa Prefecture 247, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: A
authors.initials: A
authors.lastname: Dorn
authors.forename: M
authors.initials: M
authors.lastname: Kitsuji-Shirane
authors.forename: H
authors.initials: H
authors.lastname: Shimada
authors.forename: T
authors.initials: T
authors.lastname: Satoh
authors.forename: H
authors.initials: H
authors.lastname: Matile
authors.forename: W
authors.initials: W
authors.lastname: Hofheinz
authors.forename: R
authors.initials: R
authors.lastname: Masciadri
authors.forename: M
authors.initials: M
authors.lastname: Kansy
authors.forename: R G
authors.initials: RG
authors.lastname: Ridley
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology*; D002384:Catalysis; D002470:Cell Survival / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D005189:False Positive Reactions; D006367:HeLa Cells; D006427:Hemin / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D010962:Plasmodium berghei / Q000187:drug effects / Q000235:genetics; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics; D011108:Polymers / Q000378:metabolism
chemical_list: D000962:Antimalarials; D011108:Polymers; D006427:Hemin