title: Chemical-biological characterization of a cruzain inhibitor reveals a second target and a mammalian off-target.
abstract: Inhibition of the Trypanosoma cruzi cysteine protease cruzain has been proposed as a therapeutic approach for the treatment of Chagas' disease. Among the best-studied cruzain inhibitors to date is the vinylsulfone K777 (1), which has proven effective in animal models of Chagas' disease. Recent structure-activity studies aimed at addressing potential liabilities of 1 have now produced analogues such as N-[(2S)-1-[[(E,3S)-1-(benzenesulfonyl)-5-phenylpent-1-en-3-yl]amino]-3-(4-methylphenyl)-1-oxopropan-2-yl]pyridine-4-carboxamide (4), which is trypanocidal at ten-fold lower concentrations than for 1. We now find that the trypanocidal activity of 4 derives primarily from the inhibition of T. cruzi 14-α-demethylase (TcCYP51), a cytochrome P450 enzyme involved in the biosynthesis of ergosterol in the parasite. Compound 4 also inhibits mammalian CYP isoforms but is trypanocidal at concentrations below those required to significantly inhibit mammalian CYPs in vitro. A chemical-proteomics approach employing an activity-based probe derived from 1 was used to identify mammalian cathepsin B as a potentially important off-target of 1 and 4. Computational docking studies and the evaluation of truncated analogues of 4 reveal structural determinants for TcCYP51 binding, information that will be useful in further optimization of this new class of inhibitors.
authors: Small Molecule Discovery Center, University of California San Francisco, 1700 4th Street, San Francisco, CA, 94158, USA ; Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, CA, 94158, USA ; Department of Cellular and Molecular Pharmacology, University of California San Francisco, 1700 4th Street, San Francisco, CA, 94158, USA.
authors: Jonathan W
authors: JW
authors: Choy
authors: Clifford
authors: C
authors: Bryant
authors: Claudia M
authors: CM
authors: Calvet
authors: Patricia S
authors: PS
authors: Doyle
authors: Shamila S
authors: SS
authors: Gunatilleke
authors: Siegfried S F
authors: SS
authors: Leung
authors: Kenny K H
authors: KK
authors: Ang
authors: Steven
authors: S
authors: Chen
authors: Jiri
authors: J
authors: Gut
authors: Juan A
authors: JA
authors: Oses-Prieto
authors: Jonathan B
authors: JB
authors: Johnston
authors: Michelle R
authors: MR
authors: Arkin
authors: Alma L
authors: AL
authors: Burlingame
authors: Jack
authors: J
authors: Taunton
authors: Matthew P
authors: MP
authors: Jacobson
authors: James M
authors: JM
authors: McKerrow
authors: Larissa M
authors: LM
authors: Podust
authors: Adam R
authors: AR
authors: Renslo
keywords: 14-α-demethylase; CYP51; Chagas’ disease; Trypanosoma cruzi; activity-based probes; cruzain; hybrid drugs
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