Three metabotropic glutamate receptor subtype 5 (mGluR5) PET tracers have been labeled with either carbon-11 or fluorine-18 and their in vitro and in vivo behavior in rhesus monkey has been characterized. Each of these tracers share the common features of high affinity for mGluR5 (0.08-0.23 nM vs. rat mGluR5) and moderate lipophilicity (log P 2.8-3.4). Compound 1b was synthesized using a Suzuki or Stille coupling reaction with [11C]MeI. Compounds 2b and 3b were synthesized by a SNAr reaction using a 3-chlorobenzonitrile precursor. Autoradiographic studies in rhesus monkey brain slices using 2b and 3b showed specific binding in cortex, caudate, putamen, amygdala, hippocampus, most thalamic nuclei, and lower binding in the cerebellum. PET imaging studies in monkey showed that all three tracers readily enter the brain and provide an mGluR5-specific signal in all gray matter regions, including the cerebellum. The specific signal observed in the cerebellum was confirmed by the autoradiographic studies and saturation binding experiments that showed tracer binding in the cerebellum of rhesus monkeys. In vitro metabolism studies using the unlabeled compounds showed that 1a, 2a, and 3a are metabolized slower by human liver microsomes than by monkey liver microsomes. In vivo metabolism studies showed 3b to be long-lived in rhesus plasma with only one other more polar metabolite observed.

Convergent, stereocontrolled total syntheses of the microtubule-stabilizing macrolides epothilones A (2) and B (3) have been achieved. Four distinct ring-forming strategies were pursued (see Scheme ). Of these four, three were reduced to practice. In one approach, the action of a base on a substance possessing an acetate ester and a nonenolizable aldehyde brought about a remarkably effective macroaldolization see (89 → 90 + 91; 99 → 100 + 101), simultaneously creating the C2−C3 bond and the hydroxyl-bearing stereocenter at C-3. Alternatively, the 16-membered macrolide of the epothilones could be fashioned through a C12−C13 ring-closing olefin metathesis (e.g. see 111 → 90 + 117; 122 → 105 + 123) and through macrolactonization of the appropriate hydroxy acid (e.g. see 88 → 93). The application of a stereospecific B-alkyl Suzuki coupling strategy permitted the establishment of a cis C12−C13 olefin, thus setting the stage for an eventual site- and diastereoselective epoxidation reaction (see 96 → 2; 106 → 3). The development of a novel cyclopropane solvolysis strategy for incorporating the geminal methyl groups of the epothilones (see 39 → 40 → 41), and the use of Lewis acid catalyzed diene−aldehyde cyclocondensation (LACDAC) (see 35 + 36 → 37) and asymmetric allylation (see 10 → 76) methodology are also noteworthy.

Given the significant body of data supporting an essential role for c-jun-N-terminal kinase (JNK) in neurodegenerative disorders, we set out to develop highly selective JNK inhibitors, with good cell potency, and good brain penetration properties. The structure activity relationships (SAR) around a series of aminopyrimidines was evaluated utilizing biochemical and cell- based assays to measure JNK inhibition, and brain penetration in mice. Microsomal stability in three species, P450 inhibition, inhibition of generation of reactive oxygen species (ROS), and pharmacokinetics in rats were also measured. Compounds 9g, 9i, 9j, and 9l had greater than 135-fold selectivity over p38, and cell-based IC50 values < 100 nM. Moreover, compound 9l showed an IC50= 0.8 nM for inhibition of ROS and had good pharmacokinetic properties in rat, along with a brain-to-plasma ratio of 0.75. These results suggest that biaryl substituted aminopyrimidines represented by compound 9l may serve as the first small molecule inhibitors to test efficacy of JNK inhibitors in neurodegenerative disorders.

21] Solutions of 6 and 7 (each 100 p~ at start) were titrated with a solution of sonicated calf thymus DNA, and the resulting spectral profiles were measured. For each run, volume changes due to DNA additions were taken into account in the calculation of the [DNA]:[drug] ratio. DNA concentration is given in pairs of base pairs (pbp), as this unit represents the minimum structural motif required for intercalation (Table 1).

c-Jun N-terminal kinase 3␣1 (JNK3␣1) is a mitogen-activated protein kinase family member expressed primarily in the brain that phosphorylates protein transcription factors, including c-Jun and activating transcription factor-2 (ATF-2) upon activation by a variety of stress-based stimuli. In this study, we set out to design JNK3-selective inhibitors that had >1000-fold selectivity over p38, another closely related mitogen-activated protein kinase family member. To do this we employed traditional medicinal chemistry principles coupled with structurebased drug design. Inhibitors from the aminopyrazole class, such as SR-3576, were found to be very potent JNK3 inhibitors (IC 50 ‫؍‬ 7 nM) with >2800-fold selectivity over p38 (p38 IC 50 > 20 M) and had cell-based potency of ϳ1 M. In contrast, indazole-based inhibitors exemplified by SR-3737 were potent inhibitors of both JNK3 (IC 50 ‫؍‬ 12 nM) and p38 (IC 50 ‫؍‬ 3 nM). These selectivity differences between the indazole class and the aminopyrazole class came despite nearly identical binding (root mean square deviation ‫؍‬ 0.33 Å ) of these two compound classes to JNK3. The structural features within the compounds giving rise to the selectivity in the aminopyrazole class include the highly planar nature of the pyrazole, N-linked phenyl structures, which better occupied the smaller active site of JNK3 compared with the larger active site of p38.Because the initial reports on the discovery of p38 (1) and c-Jun N-terminal kinase (JNK) 2 (2-6) these mitogen-activated protein kinase family members have generated great interest as drug targets. p38 especially has garnered considerable interest, particularly for the treatment of rheumatoid arthritis and Crohn disease, and numerous compounds have entered clinical trials for these indications (7-11). Because most of the p38 inhibitors are competitive versus ATP (12-17), and there are 518 kinases in the genome, it was crucial to develop compounds that are selective against a broad panel of kinases so that compounds could be advanced to clinical development. The molecular basis that gives rise to selective p38 inhibitors from numerous structural classes has been reported (18 -20) and is centered on amino acid differences at the so-called "gatekeeper" Thr-106 residue in p38 (Met in all of the JNK isoforms and Gln in extracellular regulated kinase, the other mitogenactivated protein kinase family member). Many compounds have been synthesized that take advantage of this deeper hydrophobic pocket in p38, compared with JNK3, and the structures of the compounds have included trifluoromethyl and other large moieties, which all contribute to p38 selectivity (21). In contrast to p38, there have been fewer reports for selective JNK inhibitors, and the clinical development of JNK inhibitors also lags that of p38. Despite the paucity of highly selective JNK inhibitors that have advanced to clinical development, numerous recent reports have begun to emerge that show compounds from various structural classes (benzothiazole pyrimidines, aminopyr...

There are currently no drugs to treat neurodegeneration in Parkinson’s disease (PD) and all existing medications only treat symptoms, lose efficacy over time, and produce untoward side effects. In the current work, we report the first highly selective, orally bioavailable, c-jun-N-terminal kinase (JNK) inhibitor for protection of dopaminergic neurons in vitro and in vivo. At 300 nM this compound showed statistically significant protection of primary dopaminergic neurons exposed to 1-methyl-4-phenylpyridinium (MPP+), had pharmacokinetic properties in rodents consistent with twice daily (b.i.d.) dosing, and was orally efficacious at 30 mg/kg in a mouse 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson’s disease. Moreover, a dose-dependent target modulation of c-jun phosphorylation served as a biomarker for demonstrating on-target inhibition of JNK as the mechanism of action for this compound. Collectively these results suggest that this JNK inhibitor could be a promising therapeutic neuroprotective agent in the treatment of Parkinson’s disease.

nem der Segmente auf das andere schatzten wir von Anfang an gering ein. Demnach schien es kluger, die Konfiguration jedes Segments einzeln zu behandeln. Im Acylsegment mul3te sowohl der relativen als auch der absoluten Konfiguration des ,,Polypropionat-ahnlichen" Teilstucks Rechnung getragen werden. Im Alkylsegment boten sich zwei Moglichkeiten an: In einem Fall wiirde das C12-Cl3-Epoxid in den Baustein eingefuhrt, der mit der Acyl-Substruktur zu verknupfen war. Hierbei ware es notwendig, die relativen stereochemischen Beziehungen der Kohlenstoffatome C-15, C-13 und C-12 festzulegen. Im anderen Fall bestand die Moglichkeit, das Epoxid der Alkylseite vor der Kupplung wegzulassen. Diese Strategie ware nur durchfiihrbar, wenn das Epoxid nach dem RingschluD zum Makrocyclus unter akzeptabler Stereokontrolle eingefuhrt werden konnte. In einer fruheren ArbeitL6I beschrieben wir die Synthese der Verbindung 4, die den groBten Teil der fur das Acylfragment erforderlichen stereochemischen Information enthielt. Diese Zwischenverbindung wurde durch eine neuartige, oxidativ induzierte, solvolytische Spaltung des Cyclopropanopyrans 3 erhalten. Wir beschrieben zudem einen Baustein, der den Alkylseiten-Kupplungspartner mit der absoluten und relativen Konfiguration der Kohlenstoffatome C-15, C-13 und C-12 enthielt, allerdings nicht in den hier prasentierten Studien verwendet wurde ['].Fur die Verknupfung der Alkyl-und der Acyldomane bieten sich mehrere potentielle ,,Nahtstellen" an. Offensichtlich war an irgendeinem Punkt der Synthese eine Acylierung durchzufuhren, um eine Ester-(oder Lacton-) Bindung zu erhalten (siehe Pfeil2, Schema 1). Die C2-C3-Bindungskniipfung konnte durch

c-jun-N-Terminal kinase 3alpha1 (JNK3alpha1) is a mitogen-activated protein (MAP) kinase family member expressed primarily in the brain that phosphorylates protein transcription factors including c-jun and activating transcription factor 2 (ATF2) upon activation by a variety of stress-based stimuli. In this study, the kinetic mechanism for JNK3alpha1 was determined via initial velocity patterns in the presence and absence of both ATP and ATF2 competitive inhibitors. Peptide inhibitors from both ATF2 (peptide 1) and JNK-interacting protein 1 (JIP-1) (peptide 3), derived from the homologous delta-domain JNK docking sequence, inhibited JNK3alpha1 activity in a competitive fashion versus ATF2 while being pure noncompetitive toward ATP. In contrast, peptides derived from the phosphoacceptor activation domain on ATF2 (peptides 4 and 5) were recognized neither as substrates nor as inhibitors of JNK3alpha1. AMP-PCP and compound 6, a small molecule analinopyrimidine, exhibited pure noncompetitive inhibition versus ATF2 and competitive inhibition versus ATP. Peptide inhibitors based on the delta-domain sites of JIP ( 3) and ATF2 ( 1) were not recognized by p38, also of the MAPK family, which may give insight into finding more selective inhibitors for the JNK family of kinases. Collectively these data showed that JNK3alpha1 proceeded by a random sequential kinetic mechanism and that the ATP and ATF2 substrate sites were non-interacting. Moreover, these results established the 11-mer JIP peptide ( 3) as a potent ( K i = 25 +/- 6 nM) competitive inhibitor versus ATF2 in JNK3alpha1.