Lead optimization of ethyl 6-aminonicotinate acyl sulfonamides as antagonists of the P2Y12 receptor. separation of the antithrombotic effect and bleeding for candidate drug AZD1283.

Synthesis and structure-activity relationships of ethyl 6-aminonicotinate acyl sulfonamides, which are potent antagonists of the P2Y12 receptor, are presented. Shifting from 5-chlorothienyl to benzyl sulfonamides significantly increased the potency in the residual platelet count assay. Evaluation of PK parameters in vivo in dog for six compounds showed a 10-fold higher clearance for the azetidines than for the matched-pair piperidines. In a modified Folts model in dog, both piperidine 3 and azetidine 13 dose-dependently induced increases in blood flow and inhibition of ADP-induced platelet aggregation with antithrombotic ED50 values of 3.0 and 10 µg/kg/min, respectively. The doses that induced a larger than 3-fold increase in bleeding time were 33 and 100 µg/kg/min for 3 and 13, respectively. Thus, the therapeutic index (TI) was ≥ 10 for both compounds. On the basis of these data, compound 3 was progressed into human clinical trials as candidate drug AZD1283.

Discovery of phosphoinositide 3-kinases (PI3K) p110ß isoform inhibitor 4-[2-hydroxyethyl(1-naphthylmethyl)amino]-6-[(2S)-2-methylmorpholin-4-yl]-1H-pyrimidin-2-one, an effective antithrombotic agent without associated bleeding and insulin resistance.

Structure-based evolution of the original fragment leads resulted in the identification of 4-[2-hydroxyethyl(1-naphthylmethyl)amino]-6-[(2S)-2-methylmorpholin-4-yl]-1H-pyrimidin-2-one, (S)-21, a potent, selective phosphoinositide 3-kinases (PI3K) p110ß isoform inhibitor with favourable in vivo antiplatelet effect. Despite its antiplatelet action, (S)-21 did not significantly increase bleeding time in dogs. Additionally, due to its enhanced selectivity over p110α, (S)-21 did not induce any insulin resistance in rats.

Synthesis of ganglioside epitopes for oligosaccharide specific immunoadsorption therapy of Guillian-Barré syndrome.

Guillain-Barré syndrome is a postinfectious, autoimmune neuropathy resulting in neuromuscular paralysis. Auto-antibodies, often induced by bacterial infection, bind to human gangliosides possessing monosialoside and diasialoside epitopes and impair the function of nerve junctions, where these ganglioside structures are highly enriched. Truncated gangliosides representive of GD3, GQ1b and GM2 epitopes have been synthesized as methyl glycosides and as a glycosides of an eleven carbon tether. The synthetic oligosaccharide ligands are structural mimics of these highly complex ganglioside epitopes and via their ability to neutralize or remove auto-antibodies have the potential for therapy, either as soluble blocking ligands administered systemically, or as immuno-affinity ligands for use as extracorporeal immunoadsorbents.

Synthetic disialylgalactose immunoadsorbents deplete anti-GQ1b antibodies from autoimmune neuropathy sera.

Acute and chronic autoimmune neuropathies, including Guillain-Barré syndromes (GBS) are often characterized by the presence of autoantibodies that react with neural gangliosides. Evidence from human and animal studies indicates that anti-ganglioside antibodies play a primary neuropathogenic role, and their rapid elimination from the circulation through specific immunoadsorption therapy thus has the potential to ameliorate the course of the disease. Here we have tested this therapeutic principle in the Miller Fisher variant of GBS that is associated serologically with acute phase anti-GQ1b ganglioside immunoglobulin G (IgG) antibodies, and in chronic ataxic neuropathies associated with persistently elevated immunoglobulin M (IgM) antibodies that react with GQ1b, GD3 and other disialylated gangliosides. Human and mouse anti-GQ1b IgG and IgM antibodies may also react with GD3, suggesting the shared terminal disialoside epitope could be involved in antibody binding. We thus synthesized the terminal trisaccharide, NeuAc(alpha2-8)NeuAc(alpha2-3)Gal common to GQ1b and GD3, and conjugated it to bovine serum albumin (BSA). This disialylgalactose glycoconjugate (DSG-BSA) binds anti-GQ1b antibodies in 32/58 (55%) human sera containing IgG or IgM anti-GQ1b antibodies at titres up to 1/130 000; it also binds a wide range of mouse monoclonal anti-GQ1b and -GD3 antibodies. When conjugated to Sepharose as mock therapeutic immmunoaffinity columns, the immobilized trisaccharide (DSG-Sepharose) eliminates anti-GQ1b antibodies from positive sera in proportion to their level of binding to DSG-BSA. Oligosaccharide-specific immunoadsorption therapy thus provides a new therapeutic approach to anti-GQ1b antibody-associated syndromes that could be applied to clinical practice. Furthermore, modification of the immobilized oligosaccharide epitopes to incorporate other glycan structures may allow this approach to be adapted to other forms of autoimmune neuropathy associated with uniform anti-glycolipid antibody profiles.

1,5-Anhydro-D-fructose; a versatile chiral building block: biochemistry and chemistry.

There is a steadily increasing need to expand sustainable resources, and carbohydrates are anticipated to play an important role in this respect, both for bulk and fine chemical preparation. The enzyme alpha-(1-->4)-glucan lyase degrades starch to 1,5-anhydro-D-fructose. This compound, which has three different functional properties, a prochiral center together with a permanent pyran ring, renders it a potential chiral building block for the synthesis of valuable and potentially biologically active compounds. 1,5-Anhydro-D-fructose is found in natural materials as a degradation product of alpha-(1-->4)-glucans. The occurrence of lyases and the metabolism of 1,5-anhydro-D-fructose are reviewed in the biological part of this article. In the chemical part, the elucidated structure of 1,5-anhydro-D-fructose will be presented together with simple stereoselective conversions into hydroxy/amino 1,5-anhydro hexitols and a nojirimycin analogue. Synthesis of 6-O-acylated derivatives of 1,5-anhydro-D-fructose substituted with long fatty acid residues is carried out using commercially available enzymes. Those reactions lead to compounds with potential emulsifying properties. The use of protected derivatives of 1,5-anhydro-D-fructose for the synthesis of natural products is likewise reviewed. The potential utilization of this chemical building block is far from being exhausted. Since 1,5-anhydro-D-fructose now is accessible in larger amounts through a simple-enzyme catalyzed degradation of starch by alpha-(1-->4)-glucan lyase, the application of 1,5-anhydro-D-fructose may be considered a valuable contribution to the utilization of carbohydrates as the most abundant resource of sustainable raw materials.