title: Ebsulfur is a benzisothiazolone cytocidal inhibitor targeting the trypanothione reductase of Trypanosoma brucei.
abstract: Trypanosoma brucei is the causing agent of African trypanosomiasis. These parasites possess a unique thiol redox system required for DNA synthesis and defense against oxidative stress. It includes trypanothione and trypanothione reductase (TryR) instead of the thioredoxin and glutaredoxin systems of mammalian hosts. Here, we show that the benzisothiazolone compound ebsulfur (EbS), a sulfur analogue of ebselen, is a potent inhibitor of T. brucei growth with a favorable selectivity index over mammalian cells. EbS inhibited the TryR activity and decreased non-protein thiol levels in cultured parasites. The inhibition of TryR by EbS was irreversible and NADPH-dependent. EbS formed a complex with TryR and caused oxidation and inactivation of the enzyme. EbS was more toxic for T. brucei than for Trypanosoma cruzi, probably due to lower levels of TryR and trypanothione in T. brucei. Furthermore, inhibition of TryR produced high intracellular reactive oxygen species. Hydrogen peroxide, known to be constitutively high in T. brucei, enhanced the EbS inhibition of TryR. The elevation of reactive oxygen species production in parasites caused by EbS induced a programmed cell death. Soluble EbS analogues were synthesized and cured T. brucei brucei infection in mice when used together with nifurtimox. Altogether, EbS and EbS analogues disrupt the trypanothione system, hampering the defense against oxidative stress. Thus, EbS is a promising lead for development of drugs against African trypanosomiasis.
authors.affiliation: Division of Biochemistry, Department of Medical Biochemistry and Biophysics.
authors.forename: Jun
authors.initials: J
authors.lastname: Lu
authors.affiliation: Department of Microbiology, Tumor and Cell Biology.
authors.forename: Suman K
authors.initials: SK
authors.lastname: Vodnala
authors.affiliation: Chemical Biology Consortium Sweden, Science for Life Laboratory, Division of Translational Medicine, Karolinska Institutet, SE-17177 Stockholm, Sweden.
authors.forename: Anna-Lena
authors.initials: AL
authors.lastname: Gustavsson
authors.affiliation: Division of Biochemistry, Department of Medical Biochemistry and Biophysics.
authors.forename: Tomas N
authors.initials: TN
authors.lastname: Gustafsson
authors.affiliation: Chemical Biology Consortium Sweden, Science for Life Laboratory, Division of Translational Medicine, Karolinska Institutet, SE-17177 Stockholm, Sweden.
authors.forename: Birger
authors.initials: B
authors.lastname: Sjöberg
authors.affiliation: Division of Biochemistry, Department of Medical Biochemistry and Biophysics; Department of Chemistry-BMC, Uppsala University, SE-751 23 Uppsala, Sweden.
authors.forename: Henrik A
authors.initials: HA
authors.lastname: Johansson
authors.affiliation: Chemistry Department, IISER Bhopal, MP, India.
authors.forename: Sangit
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Swedish Orphan Biovitrum AB, SE-112 76 Stockholm, Sweden.
authors.forename: Agneta
authors.initials: A
authors.lastname: Tjernberg
authors.affiliation: Department of Chemistry-BMC, Uppsala University, SE-751 23 Uppsala, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Engman
authors.affiliation: Department of Microbiology, Tumor and Cell Biology. Electronic address: Martin.Rottenberg@ki.se.
authors.forename: Martin E
authors.initials: ME
authors.lastname: Rottenberg
authors.affiliation: Division of Biochemistry, Department of Medical Biochemistry and Biophysics. Electronic address: Arne.Holmgren@ki.se.
authors.forename: Arne
authors.initials: A
authors.lastname: Holmgren
mesh_terms: D000818:Animals; D008297:Male; D051379:Mice; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry / Q000494:pharmacology; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013844:Thiazoles / Q000737:chemistry / Q000494:pharmacology*; D014344:Trypanocidal Agents / Q000737:chemistry / Q000494:pharmacology*; D014346:Trypanosoma brucei brucei / Q000201:enzymology*; D014353:Trypanosomiasis, African / Q000188:drug therapy* / Q000201:enzymology
chemical_list: D010975:Platelet Aggregation Inhibitors; D015800:Protozoan Proteins; D013844:Thiazoles; D014344:Trypanocidal Agents; D009247:NADH, NADPH Oxidoreductases; C049608:trypanothione reductase; C015699:1,2-benzisothiazoline-3-one
keywords: Drug Development; Enzyme Inhibitors; Parasite; Reactive Oxygen Species (ROS); Thiol; Thioredoxin
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