title: Triazole double-headed ribonucleosides as inhibitors of eosinophil derived neurotoxin.
abstract: Eosinophil derived neurotoxin (EDN) is an eosinophil secretion protein and a member of the Ribonuclease A (RNase A) superfamily involved in the immune response system and inflammatory disorders. The pathological actions of EDN are strongly dependent on the enzymatic activity and therefore, it is of significant interest to discover potent and specific inhibitors of EDN. In this framework we have assessed the inhibitory potency of triazole double-headed ribonucleosides. We present here an efficient method for the heterologous production and purification of EDN together with the synthesis of nucleosides and their biochemical evaluation in RNase A and EDN. Two groups of double-headed nucleosides were synthesized by the attachment of a purine or a pyrimidine base, through a triazole group at the 3'-C position of a pyrimidine or a purine ribonucleoside, respectively. Based on previous data with mononucleosides these compounds were expected to improve the inhibitory potency for RNase A and specificity for EDN. Kinetics data revealed that despite the rational, all but one, double-headed ribonucleosides were less potent than the respective mononucleosides while they were also more specific for ribonuclease A than for EDN. Compound 11c (9-[3'-[4-[(cytosine-1-yl)methyl]-1,2,3-triazol-1-yl]-β-d-ribofuranosyl]adenine) displayed a stronger preference for EDN than for ribonuclease A and a Ki value of 58μM. This is the first time that an inhibitor is reported to have a better potency for EDN than for RNase A. The crystal structure of EDN-11c complex reveals the structural basis of its potency and selectivity providing important guidelines for future structure-based inhibitor design efforts.
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Demetra S M
authors.initials: DS
authors.lastname: Chatzileontiadou
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Parmenopoulou
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Stella
authors.initials: S
authors.lastname: Manta
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Anastassia L
authors.initials: AL
authors.lastname: Kantsadi
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Paroula
authors.initials: P
authors.lastname: Kylindri
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Marianna
authors.initials: M
authors.lastname: Griniezaki
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Filitsa
authors.initials: F
authors.lastname: Kontopoulou
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Aikaterini
authors.initials: A
authors.lastname: Telopoulou
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Helena
authors.initials: H
authors.lastname: Prokova
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Panagopoulos
authors.affiliation: Department of Biochemistry and Molecular Biology, Faculty of Biosciences, Universitat Autònoma de Barcelona, Spain.
authors.forename: Ester
authors.initials: E
authors.lastname: Boix
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece.
authors.forename: Nikolaos A A
authors.initials: NA
authors.lastname: Balatsos
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece. Electronic address: dkom@bio.uth.gr.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Komiotis
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, 26 Ploutonos Str., 41221 Larissa, Greece. Electronic address: ddleonidas@bio.uth.gr.
authors.forename: Demetres D
authors.initials: DD
authors.lastname: Leonidas
mesh_terms: D000818:Animals; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004804:Eosinophils / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D015394:Molecular Structure; D009498:Neurotoxins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012259:Ribonuclease, Pancreatic / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012263:Ribonucleosides / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D009498:Neurotoxins; D012263:Ribonucleosides; D014230:Triazoles; D012259:Ribonuclease, Pancreatic; C504335:pancreatic ribonuclease B, bovine
keywords: Double-headed nucleosides; Eosinophil derived neurotoxin; Inhibition; Ribonuclease A; Structure-assisted inhibitor design; Triazole derivatives; X-ray crystallography