Lymphocyte trafficking is critically regulated by the Sphingosine 1-phosphate receptor-1 (S1P(1)), a G protein-coupled receptor that has been highlighted as a promising therapeutic target in autoimmunity. Fingolimod (FTY720, Gilenya) is a S1P(1) receptor agonist that has recently been approved for the treatment of multiple sclerosis (MS). Here, we report the discovery of NIBR-0213, a potent and selective S1P(1) antagonist that induces long-lasting reduction of peripheral blood lymphocyte counts after oral dosing. NIBR-0213 showed comparable therapeutic efficacy to fingolimod in experimental autoimmune encephalomyelitis (EAE), a model of human MS. These data provide convincing evidence that S1P(1) antagonists are effective in EAE. In addition, the profile of NIBR-0213 makes it an attractive candidate to further study the consequences of S1P(1) receptor antagonism and to differentiate the effects from those of S1P(1) agonists.
The synthetic oligopeptide I undergoes a spontaneous, reversible transition from an α‐helix to a β‐sheet structure in mixtures of 45% 2,2,2‐trifluoroethanol and 55% H2O. The amphiphilic oligopeptide 1 and two isomers were expressly designed for this investigation. Such peptides, which can exist in several conformations, might find application as “switches” in the de novo design of artificial proteins.
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A new general strategy for the construction of artificial proteins with predetermined tertiary structure is presented. Amphiphilic a -helix and 8-sheet-forming oligopeptides are assembled on a multifunctional template molecule which directs the peptide blocks to adopt characteristic folding topologies. The design, synthesis, and conformational properties of these template-assembled synthetic proteins (TASP) are exemplified for pep-, ahelix-bundle-and /I-barrel-like tertiary structures using specially designed oligopeptides as template molecules. In contrast to linear polypeptide chains of comparable molecular weights, these conceptually novel macromolecules are readily accessible to chemical synthesis and exhibit excellent solubility in a number of solvents. Experimental evidence is provided for a template-induced intramolecular folding to secondary and tertiary structures in aqueous solutions. This approach opens new prospects for the chemical construction of biomacromolecules with tailormade structural and functional properties.
Recently, four subtypes of the human phosphodiesterase type 4 (PDE4A-D) enzyme have been described. So far, only very few PDE4 subtype-selective inhibitors are known. Herein, we describe the synthesis of 6,8-disubstituted 1,7-naphthyridines and their characterization as potent and selective inhibitors of PDE4D which suppress the oxidative burst in human eosinophils with IC(50) values as low as 0.7 nM. SAR development and the extended use of palladium-catalyzed cross-coupling reactions led to compound 11 which inhibited human PDE4D with an IC(50) value of 1 nM. Thus, compound 11 was 55, 175, and 1000 times more potent in inhibiting PDE4D over PDE4B, PDE4A, and PDE4C. In a Brown Norway rat model of allergic asthma, compound 11 when given by the oral route (1 mg/kg) reduced by more than 50% the influx of eosinophils, T-cells, and neutrophils into bronchoalveolar lavage fluid (BALF) samples obtained from antigen-challenged animals. Thus, PDE4D-selective inhibitors of the 1,7-naphthyridine class have the potential as an oral therapy for treating asthma.
We investigated the pharmacology of a new class of phosphodiesterase 4 (PDE4) inhibitor, 6,8-disubstituted 1,7-naphthyridines, by using 4-(8-benzo[1,2,5]oxadiazol-5-yl- [1,7]naphthyridin-6-yl)-benzoic acid (NVP-ABE171) as a representative compound and compared its potency with the most advanced PDE4 inhibitor, undergoing clinical trials, Ariflo [cis-4-cyano-4-(3-cyclopentyloxy-4-methoxyphenyl-r-1-cyclohexanecarboxylic acid)]. NVP-ABE171 inhibited the activity of phosphodiesterase 4A, 4B, 4C, and 4D with respective IC 50 values of 602, 34, 1230, and 1.5 nM. Ariflo was about 40 times less potent. In human cells, NVP-ABE171 inhibited the eosinophil and neutrophil oxidative burst, the release of cytokines by T cells, and the tumor necrosis factor-␣ release from monocytes, in the nanomolar range. Ariflo presented a similar inhibition profile but was 7 to 50 times less potent. In BALB/c mice challenged with lipopolysaccharide, NVP-ABE171 inhibited the airway neutrophil influx and activation with an ED 50 in the range of 3 mg/kg. Ariflo was inactive up to a dose of 10 mg/kg. In ovalbumin sensitized Brown Norway rats, NVP-ABE171 inhibited the lipopolysaccharide-induced airway neutrophil influx and activation (ED 50 of 0.2 mg/kg) and the ovalbumin-induced airway eosinophil influx and activation (ED 50 of 0
The construction of a template-assembled synthetic protein (TASP) designed to contain both a 4-helix bundle and a beta-barrel as two folding "domains" is described. For the de novo design of proteins, amphiphilic helices (alpha) and beta-sheets (beta) are covalently attached to a template peptide (T) carrying functional side chains suitably oriented to promote intramolecular folding of the secondary structure blocks into a characteristic packing arrangement, i.e., T8-(4 alpha)(4 beta). The design of this new macromolecule was assisted by computer modeling, which suggested a low-energy conformation with tight hydrophobic packing of the secondary structure subunits. Solid-phase synthesis of the "two-domain" TASP molecule was achieved using orthogonal protection techniques. The solution properties as well as circular dichroism (CD) and infrared spectroscopy (IR) data under various experimental conditions are consistent with the folded conformation suggested by modeling.
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