title: Design and synthesis of tricyclic JAK3 inhibitors with picomolar affinities as novel molecular probes.
abstract: The Janus kinase (JAK) signaling pathway is of particular importance in the pathology of inflammatory diseases and oncological disorders, and the inhibition of Janus kinase 3 (JAK3) with small molecules has proven to provide therapeutic immunosuppression. A novel class of tricyclic JAK inhibitors derived from the 3-methyl-1,6-dihydrodipyrrolo[2,3-b:2',3'-d]pyridine scaffold was designed based on the tofacitinib-JAK3 crystal structure by applying a rigidization approach. A convenient synthetic strategy to access the scaffold via an intramolecular Heck reaction was developed, and a small library of inhibitors was prepared and characterized using in vitro biochemical as well as cellular assays. IC50 values as low as 220 pM could be achieved with selectivity for JAK3 over other JAK family members. Both activity and selectivity were confirmed in a cellular STAT phosphorylation assay, providing also first-time data for tofacitinib. Our novel inhibitors may serve as tool compounds and useful probes to explore the role of JAK3 inhibition in pharmacodynamics studies.
authors.affiliation: Department of Pharmaceutical & Medicinal Chemistry, Institute of Pharmacy, Eberhard-Karls-University Tuebingen, Auf der Morgenstelle 8, 72076 Tuebingen (Germany).
authors.forename: Matthias
authors.initials: M
authors.lastname: Gehringer
authors.forename: Ellen
authors.initials: E
authors.lastname: Pfaffenrot
authors.forename: Silke
authors.initials: S
authors.lastname: Bauer
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Laufer
mesh_terms: D015195:Drug Design; D006367:HeLa Cells; D006801:Humans; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008958:Models, Molecular; D015335:Molecular Probes / Q000737:chemistry / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D010880:Piperidines / Q000737:chemistry* / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D011743:Pyrimidines / Q000737:chemistry* / Q000494:pharmacology*; D011758:Pyrroles / Q000737:chemistry* / Q000494:pharmacology*; D050791:STAT Transcription Factors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D015335:Molecular Probes; D010880:Piperidines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D011758:Pyrroles; D050791:STAT Transcription Factors; C479163:tofacitinib; D053616:Janus Kinase 3
keywords: inflammation; isoform selectivity; janus kinase 3; medicinal chemistry; tricyclic kinase inhibitors