Protease-activated receptor 4 (PAR4) is a G-protein coupled receptor that is expressed on human platelets and activated by the coagulation enzyme thrombin. PAR4 plays a key role in blood coagulation, and its importance in pathological thrombosis has been increasingly recognized in recent years. Herein, we describe the optimization of a series of imidazothiadiazole PAR4 antagonists to a first-in-class clinical candidate, BMS-986120 (43), and a backup clinical candidate, BMS-986141 (49). Both compounds demonstrated excellent antithrombotic efficacy and minimal bleeding time prolongation in monkey models relative to the clinically important antiplatelet agent clopidogrel and provide a potential opportunity to improve the standard of care in the treatment of arterial thrombosis.

A number of new amine scaffolds with good inhibitory activity in the ADP-induced platelet aggregation assay have been found to be potent antagonists of the P2Y1 receptor. SAR optimization led to the identification of isoindoline 3c and piperidine 4a which showed good in vitro binding and functional activities, as well as improved aqueous solubility. Among them, the piperidine 4a showed the best overall profile with favorable PK parameters.

The crystal structure of the ligand-binding domain of RARbeta, a suspect tumour suppressor, reveals important features that distinguish it from the two other RAR isotypes. The most striking difference is an extra cavity allowing RARbeta to bind more bulky agonists. Accordingly, we identified a ligand that shows RARbeta selectivity with a 100-fold higher affinity to RARbeta than to alpha or gamma isotypes. The structural differences between the three RAR ligand-binding pockets revealed a rationale explaining how a single retinoid can be at the same time an RARalpha, gamma antagonist and an RARbeta agonist. In addition, we demonstrate how to generate an RARbeta antagonist by gradually modifying the bulkiness of a single substitution. Together, our results provide structural guidelines for the synthesis of RARbeta-selective agonists and antagonists, allowing for the first time to address pharmacologically the tumour suppressor role of RARbeta in vitro and in animal models.

A series of potent inhibitors of P-selectin as potential anti-inflammatory agents is reported. These compounds are derivatives of galactocerebrosides bearing a malonate side chain in positions 2 and 3 of the galactose moiety. Based on the binding mode of sialyl Lewis X, the two acidic groups of the malonate are designed to form ionic interactions with two important lysines in the active site of P-selectin, Lys113 and Lys111. On the other hand, the 4- and 6-hydroxy groups on the galactose ring are arranged to chelate the calcium ion in the P-selectin active site. The synthesis and the biological activity of this series of compounds are described. Lead compounds having a greater potency than sialyl Lewis X are identified.

The focus of this study was to develop retinoic acid receptor (RAR) RAR alpha/beta selective agonists with anticancer efficacy and reduced toxicity associated with RAR gamma activity. In these studies, we report the identification and characterization of high-affinity RAR alpha/beta selective agonists with limited RAR gamma activity. These compounds inhibited human tumor cell line proliferation with similar efficacy to that observed for a pan-RAR agonist. However, for most tumor cell lines, the efficacy of these compounds was restricted to the micromolar range. To determine whether the RAR alpha/beta selective agonists could be additive or synergistic with existing agents, we investigated the effects of combining RAR alpha/beta selective agonists with various cytotoxic agents. Our results showed that the alpha/beta selective retinoids dramatically lowered the effective dose of Taxol needed to induce cytotoxicity of a wide range of tumor cell lines. This synergy was specific to tubulin-modifying agents and could not be observed with a variety of other cytotoxic agents of diverse function. Examination of pathways common to Taxol and retinoid signaling revealed that this synergy was related in part to effects on Bcl-2 expression/phosphorylation as well as the activity of the c-Jun NH(2)-terminal kinase and activator protein-1. In contrast, the tubulin polymerization induced by Taxol was not further affected by cotreatment with a variety of retinoid receptor ligands. These observations indicate that potent RAR alpha/beta selective agonists may be of therapeutic benefit in combination with Taxol therapy.

Native sulfatides, as well as many sulfated glycolipids, have been shown to avidly bind to the selectin receptors. In vivo, native sulfatides significantly block activity in selectin-dependent inflammatory responses. The fact that nonsulfated galactocerebrosides did not inhibit selectin-mediated adhesion identified a critical role for the anionic sulfate residue. We therefore initiated a program to evaluate the activity of position isomers. This study showed a binding selectivity for the positions 2 and 3 of the sulfate group on the carbohydrate ring as well as enhanced activity for the disulfated analogs, Furthermore, it was discovered that the attachment of lipophilic substituents on the carbohydrate ring was tolerated, consistent with the presence of a lipophilic pocket in the binding cavity. This resulted in compounds with a 6-fold increased potency.

BMS-200475, a novel carbocyclic analog of 2′-deoxyguanosine, is a potent inhibitor of hepatitis B virus in vitro (ED50 = 3 nM) with relatively low cytotoxicity (CC50 = 21–120 μM). A practical 10-step asymmetric synthesis was developed affording BMS-200475 in 18% overall chemical yield and >99% optical purity. The enantiomer of BMS-200475 as well as the adenine, thymine, and iodouracil analogs are much less active.

Selectin binding is the first step in extravasation of leukocytes through the endothelium. Infiltration of leukocytes is a hallmark of an inflammatory response. Blockade of selectin-dependent adhesion, therefore, represents a specific mechanism-based anti-inflammatory strategy. We have used the natural product sulfatide, one of the selectin ligands, as a template to design a novel selectin antagonist. BMS-190394, a structural analog of sulfatide, is an inhibitor of cell binding to P-, E- and L-selectin-Ig fusion proteins. BMS-190394 also inhibits binding mediated by native P-selectin expressed on the surface of activated platelets. Pharmacokinetic analysis of BMS-190394 showed that the compound remained in circulation with a T1/2 of 7 hr, long enough to inhibit the development of an acute inflammatory response. The in vitro activity and pharmacokinetic profile of this selectin-blocking compound led to the determination of its in vivo anti-inflammatory activity. BMS-190394 was a potent inhibitor of the dermal immune complex-induced reverse passive Arthus reaction in rats when delivered by the i.v. or i.p. route. The ED50 of the compound in the reverse passive Arthus reaction compares favorably to that for dexamethasone. BMS-190394 was also an effective inhibitor of the delayed-type hypersensitivity reaction in the rat. Compared with previous reports of the use of antibodies and complex oligosaccharides to inhibit the activity of the selectins, this low-molecular-weight inhibitor of the selectins presents a novel class of anti-inflammatory agents.

Poly(aspartic acids) of different chain lengths (11, 14, 18, 24, 30, 52, 58, almost-equal-to 115) were prepared, for the use in aminoglycoside-induced nephrotoxicity inhibition studies, some in their pure L- or D-configuration and in pure alpha-linkage form by the polymerization of alpha-amino acid N-carboxyanhydride (NCA) derivatives with a variety of dialkyl aspartate molecules as primary amine initiators. The primary amine chosen served as an internal reference in the H-1 NMR spectrum for the estimation of the degree of polymerization (chain length) in these molecules. Poly(aspartic acids) with varying amounts Of D and L asymmetric centres and in pure alpha-linkage form were also prepared. Poly[(alpha-CO-beta)(L-CO-D) aspartic acid] was prepared by a simplified thermal polymerization procedure for biological studies and also to study the tacticity effects in its C-13 NMR spectrum. A qualitative correlation was demonstrated between the retention times from gel-permeation chromatographic analysis and the H-1 NMR method used to estimate the polymer chain length.

AbstractThe penem derivative (XIb) is prepared starting from the aminopenicillanic acid derivative (I) via the intermediates shown in the scheme; the methoxy analogue (XIc) is similarly synthesized.

The preparation of 6α-methyl-2-methyl-6β-phenoxyacetamidopenem-3-carboxylate, 6α-methoxy-2-methyl-6β-phenoxyacetamidopenem-3-carboxylate, and 6α-methoxy-2-methyl-6β-phenylmalonylamidopenem-3-carboxylate from penicillin V and 6-aminopenicillanic acid is described. These penems have been isolated and characterized as their sodium or potassium salt. The chemical stability of the above compounds was determined as their half-life in aqueous buffer. In this way, it was found that the 6α-methyl analog was more stable than the parent 6-monosubstituted acylaminopenem while the remaining analogs were of comparable stability.

The reaction of acetaldehyde with enolates of N-protected 4-tritylthio-2-azetidinones 4b and 4c was studied. While the lithium enolate of N-methoxymethylazetidinone 4b gave only transS* 3-(1′-hydroxyethyl)azetidinone 8 the corresponding tetrabutylammonium enolate gave a mixture of transR* and transS* azetidinones 8 and 9. The metal enolate of N-(tert-butyldimethylsilyl)-4-tritylthio-2-azetidinone 4c gave all four possible isomers.

The preparation of (4-tritylthio-2-azetidinon-l-yl)triphenylphosphoranylideneacetates from 4-acetoxyazetidin-2-one is described. They are easily converted to mercuric or silver mercaptides. These mercaptides are acylated with a wide variety of acylating agents and cyclized to 2-substituted penem-3-carboxylates.

AbstractDie Umsetzung der aus dem Glucal (I) erhältlichen dimeren Nitrosoverbindung (II) mit den Thiolen (III) liefert in stereospezifischer Reaktion di Oxime (IV).

The reaction of the dimeric 4-O-acetyl-6-azido-2,3,6-trideoxy-2-nitroso-α-D-ribo-hexopyranosyl chloride 2 with cyclohexanethiol and 2-propanethiol is stereospecific and produces the corresponding 2-hydroxyimino-1-thio-α-D-erythro-hexopyranosides 3a and 3c in high yields. Acetylation of the oxime 3a followed by reduction with borane, then by reduction with sodium borohydride and acetylation gave cyclohexyl 2,6-diacetamido-4-O-acetyl-2,3,6-trideoxy-l-thio-α-D-ribo-hexopyranoside (4b). By a similar sequence of reactions, the oxime 3c was converted to isopropyl 2,6-dibenzamido-4-O-benzoyl-2,3,6-trideoxy-l-thio-α-D-ribo-hexopyranoside (4c).Condensation of the nitrosochloro adduct 2 with (1S,2S,4R,5R)-2,4-diethoxycarbonylamino-5-hydroxycyclohexanethiol (5c) gave the α-D-thioglycoside 6c which, after acetylation followed by reduction and removal of the protective groups, yielded (1S,2S,4R,5R)-2,4-diamino-5-hydroxycyclohexyl 2,6-diamino-2,3,6-trideoxy-l-thio-α-D-ribo-hexopyranoside (7c), a thioanalogue of neamine.