title: Development of alpha-keto-based inhibitors of cruzain, a cysteine protease implicated in Chagas disease.
abstract: Trypanosoma cruzi, a protozoan parasite, is the causative agent of Chagas disease, a major cause of cardiovascular disease in many Latin American countries. There is an urgent need to develop an improved therapy due to the toxicity of existing drugs and emerging drug resistance. Cruzain, the primary cysteine protease of T. cruzi, is essential for the survival of the parasite in host cells and therefore is an important target for the development of inhibitors as potential therapeutics. A novel series of alpha-ketoamide-, alpha-ketoacid-, alpha-ketoester-, and aldehyde-based inhibitors of cruzain has been developed. The inhibitors were identified by screening protease targeted small molecule libraries and systematically optimizing the P1, P2, P3, and P1' residues using specific structure-guided methods. A total of 20 compounds displayed picomolar potency in in vitro assays and three inhibitors representing different alpha-keto-based inhibitor scaffolds demonstrated anti-trypanosomal activity in cell culture. A 2.3A crystallographic structure of cruzain bound with one of the alpha-ketoester analogs is also reported. The structure and kinetic assay data illustrate the covalent binding, reversible inhibition mechanism of the inhibitor. Information on the compounds reported here will be useful in the development of new lead compounds as potential therapeutic agents for the treatment of Chagas disease and as biological probes to study the role that cruzain plays in the pathology. This study also demonstrates the validity of structure-guided approaches to focused library design and lead compound optimization.
authors.affiliation: Department of Pharmaceutical Chemistry, 600 16th Street, University of California at San Francisco, San Francisco, CA 94143-2280, USA.
authors.forename: Youngchool
authors.initials: Y
authors.lastname: Choe
authors.forename: Linda S
authors.initials: LS
authors.lastname: Brinen
authors.forename: Mark S
authors.initials: MS
authors.lastname: Price
authors.forename: Juan C
authors.initials: JC
authors.lastname: Engel
authors.forename: Meinolf
authors.initials: M
authors.lastname: Lange
authors.forename: Corinna
authors.initials: C
authors.lastname: Grisostomi
authors.forename: Scott G
authors.initials: SG
authors.lastname: Weston
authors.forename: Peter V
authors.initials: PV
authors.lastname: Pallai
authors.forename: Hong
authors.initials: H
authors.lastname: Cheng
authors.forename: Larry W
authors.initials: LW
authors.lastname: Hardy
authors.forename: David S
authors.initials: DS
authors.lastname: Hartsough
authors.forename: Marsha
authors.initials: M
authors.lastname: McMakin
authors.forename: Robert F
authors.initials: RF
authors.lastname: Tilton
authors.forename: Carmen M
authors.initials: CM
authors.lastname: Baldino
authors.forename: Charles S
authors.initials: CS
authors.lastname: Craik
mesh_terms: D000577:Amides / Q000737:chemistry; D000818:Animals; D002460:Cell Line; D014355:Chagas Disease / Q000188:drug therapy* / Q000469:parasitology*; D018360:Crystallography, X-Ray; D003546:Cysteine Endopeptidases / Q000737:chemistry / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology* / Q000627:therapeutic use; D015195:Drug Design; D004952:Esters / Q000737:chemistry; D020128:Inhibitory Concentration 50; D007700:Kinetics; D051379:Mice; D008958:Models, Molecular; D015394:Molecular Structure; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000201:enzymology*
chemical_list: D000577:Amides; D015853:Cysteine Proteinase Inhibitors; D004952:Esters; D015800:Protozoan Proteins; D003546:Cysteine Endopeptidases; C074032:cruzain, Trypanosoma cruzi