Steven M. Seiler

Azetidin-2-one derivatives as inhibitors of thrombin

A series of 3-(3-guanidinopropyl)-azetidin-2-one derivatives was prepared and evaluated as inhibitors of cleavage of synthetic substrates in vitro by the serine proteases thrombin, trypsin and plasmin. The N-unsubstituted, 4-phenethyl derivative 9a demonstrated weak inhibition of these enzymes but acetylation of the beta-lactam N atom afforded 9b, an effective, time-dependent inhibitor of thrombin and a potent inhibitor of plasmin. Variation of the 4-position of the beta-lactam ring was examined in conjunction with different N-substituents to provide a series of potent, time-dependent inhibitors of thrombin. A C-4 substituent was essential for good inhibitory properties and, in general, polar C-4 substituents enhanced the selectivity of inhibition for thrombin compared to plasmin. A trans relationship between the C-4 and C-3 substituents was found to be superior to a cis disposition whilst homologation of the guanidinopropyl side chain to that of a guanidinobutyl moiety reduced activity. Several compounds were effective inhibitors of thrombin-induced clot formation in human plasma in vitro but activity in this assay did not correlate well with inhibition of thrombin-induced cleavage of a synthetic substrate, presumably a consequence of inherent chemical instability and degradation in plasma.

Synthesis and SAR of 4-carboxy-2-azetidinone mechanism-based tryptase inhibitors

A series of N1-activated C4-carboxy azetidinones was prepared and tested as inhibitors of human tryptase. The key stereochemical and functional features required for potency, serine protease specificity and aqueous stability were determined. From these studies compound 2, BMS-262084, was identified as a potent and selective tryptase inhibitor which, when dosed intratracheally in ovalbumin-sensitized guinea pigs, reduced allergen-induced bronchoconstriction and inflammatory cell infiltration into the lung.

Synthesis of potent and highly selective inhibitors of human tryptase

The serine protease tryptase has been implicated in allergic and inflammatory diseases and associated with asthma. The synthesis and SAR of a series of N1-activated-4-carboxy azetidinones are described, resulting in identification of BMS-363131 (2) as a potent inhibitor of human tryptase (IC(50)<1.7 nM) with high selectivity (>3000-fold) for tryptase versus related serine proteases including trypsin.

Derivatives of 5-amidine indole as inhibitors of thrombin catalytic activity

Abstract Substituted 5-amidine indoles were constructed based upon a computational analysis of putative modes of binding to thrombin utilizing coordinates from the crystal structure of BMS-183,507-α-thrombin complex. These analogs display competitive kinetics for the inhibition of human α-thrombin. The most potent member of this series 17, shows marked potency for thrombin with an inhibition constant, Ki of 260 nM.

ARGATROBAN ANALOGS : SYNTHESIS, THROMBIN INHIBITORY ACTIVITY AND CELL PERMEABILITY OF AMINOHETEROCYCLIC GUANIDINE SURROGATES

Abstract A series of Argatroban analogs, 3–6 , in which the guanidino group was replaced by amino-substituted heterocycles of decreasing basicity were prepared and evaluated for their ability to inhibit human α-thrombin. Basicity was found to be important in determining inhibitory potency. Aminopyridine analog 3b (pK a ∼7) afforded the most potent inhibition (I 50 =0.47 μM) and exhibited enhanced Caco-2 cell permeability.

BMS-187257, a potent, selective, and novel heterocyclic β3 adrenergic receptor agonist

Abstract Novel heterocyclic β 3 adrenergic receptor agonists 2 were prepared and evaluated for their ability to bind to human β 1 , β 2 , and β 3 adrenergic receptors. Stimulatory effects on the β 3 adrenergic receptor were also measured. BMS-187257 ( 4b ) was found to be a potent and selective β 3 agonist.

α-hydroxy- and α-ketoester functionalized thrombin inhibitors

Abstract α-Hydroxy- and α-ketoester functionalized D-Phe-Pro-Lys tripeptides were found to be potent thrombin active site inhibitors. The ketoester derivatives were characterized by slow binding kinetics. The most potent of the series was 9 (BMS 181, 412) with an overall inhibition constant Ki* of 0.0017 μM.

Carboxyl-promoted enhancement of selectivity for the β3 adrenergic receptor. Negative charge of the sulfonic acid BMS-187413 introduces-β3 binding selectivity

Abstract Carboxyl and other negatively charged groups were found to be most effective at producing human β3 adrenergic receptor binding selectivity in 1 (BRL 37344) and related compounds. The sulfonic acid analog 7 (BMS-187413) is a novel and potent β3 adrenergic agonist that binds selectively, and thus has an in vitro profile that compares favorably with that of BRL 37344.

[3-[4-(4,5-Diphenyl-2-oxazolyl)-5-oxazolyl]phenoxy]acetic acid (BMY 45778) is a potent non-prostanoid prostacyclin partial agonist: effects on platelet aggregation, adenylyl cyclase, cAMP levels, protein kinase, and iloprost binding.

[3-[4-(4,5-diphenyl-2-oxazolyl)-5-oxazolyl]phenoxy]acetic acid (BMY 45778) inhibits human (IC50 = 35 nM), rabbit (136 nM) and rat (1.3 microM) platelet aggregation. This compound activates adenylyl cyclase (ED50 = 6-10 nM) and stimulates GTPase in human platelet membrane preparations. The potency (EC50) of BMY 45778 stimulating adenylyl cyclase is comparable to iloprost. However, maximal stimulation of GTPase by BMY 45778 is approximately half the iloprost-stimulated activity, and BMY 45778 limits the GTPase stimulation by iloprost suggesting that BMY 45778 is a partial agonist at the IP receptor. BMY 45778 completely prevents [3H]]Iloprost binding to platelet membranes (IC50 = 7 nM). In whole platelets, BMY 45778 causes elevation of platelet cAMP levels (cAMP content doubles at 13 nM) and activation of the cAMP-dependent protein kinase (cAMP-protein kinase ratio is twice basal at 2 nM). BMY 45778 treatment of whole platelets also desensitizes the adenylyl cyclase activation by iloprost. These results indicate that BMY 45778, which is structurally different from prostacyclin and most prostacyclin agonists, acts by stimulating prostacyclin (IP) receptors.

Molecular design and structure-activity relationships leading to the potent, selective, and orally active thrombin active site inhibitor BMS-189664.

A series of structurally novel small molecule inhibitors of human alpha-thrombin was prepared to elucidate their structure-activity relationships (SARs), selectivity and activity in vivo. BMS-189664 (3) is identified as a potent, selective, and orally active reversible inhibitor of human alpha-thrombin which is efficacious in vivo in a mouse lethality model, and at inhibiting both arterial and venous thrombosis in cynomolgus monkey models.