title: Exploration and optimization of substituted triazolothiadiazines and triazolopyridazines as PDE4 inhibitors.
abstract: An expansion of structure-activity studies on a series of substituted 7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine PDE4 inhibitors and the introduction of a related [1,2,4]triazolo[4,3-b]pyridazine based inhibitor of PDE4 is presented. The development of SAR included strategic incorporation of known substituents on the critical catachol diether moiety of the 6-phenyl appendage on each heterocyclic core. From these studies, (R)-3-(2,5-dimethoxyphenyl)-6-(4-methoxy-3-(tetrahydrofuran-3-yloxy)phenyl)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (10) and (R)-3-(2,5-dimethoxyphenyl)-6-(4-methoxy-3-(tetrahydrofuran-3-yloxy)phenyl)-[1,2,4]triazolo[4,3-b]pyridazine (18) were identified as highly potent PDE4A inhibitors. Each of these analogues was submitted across a panel of 21 PDE family members and was shown to be highly selective for PDE4 isoforms (PDE4A, PDE4B, PDE4C, PDE4D). Both 10 and 18 were then evaluated in divergent cell-based assays to assess their relevant use as probes of PDE4 activity. Finally, docking studies with selective ligands (including 10 and 18) were undertaken to better understand this chemotypes ability to bind and inhibit PDE4 selectively.
authors.affiliation: NIH Chemical Genomics Center, National Human Genome Research Institute, NIH 9800 Medical Center Drive, MSC 3370 Bethesda, MD 20892-3370, USA.
authors.forename: Amanda P
authors.initials: AP
authors.lastname: Skoumbourdis
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Leclair
authors.forename: Eduard
authors.initials: E
authors.lastname: Stefan
authors.forename: Adrian G
authors.initials: AG
authors.lastname: Turjanski
authors.forename: William
authors.initials: W
authors.lastname: Maguire
authors.forename: Steven A
authors.initials: SA
authors.lastname: Titus
authors.forename: Ruili
authors.initials: R
authors.lastname: Huang
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Auld
authors.forename: James
authors.initials: J
authors.lastname: Inglese
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Austin
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Michnick
authors.forename: Menghang
authors.initials: M
authors.lastname: Xia
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Thomas
mesh_terms: D001665:Binding Sites; D002460:Cell Line; D003198:Computer Simulation; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000378:metabolism; D005663:Furans / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D006801:Humans; D058988:Phosphodiesterase 4 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000378:metabolism; D011724:Pyridazines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013829:Thiadiazines / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D014230:Triazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology
chemical_list: C542904:(R)-3-(2,5-dimethoxyphenyl)-6-(4-methoxy-3-(tetrahydrofuran-3-yloxy)phenyl)-7H-(1,2,4)triazolo(3,4-b)(1,3,4)thiadiazine; D005663:Furans; D058988:Phosphodiesterase 4 Inhibitors; D010726:Phosphodiesterase Inhibitors; D020033:Protein Isoforms; D011724:Pyridazines; D013829:Thiadiazines; D014230:Triazoles; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4