Dennis M. Kubrak

Etodolac selectively inhibits human prostaglandin G/H synthase 2 (PGHS-2) versus human PGHS-1

The isozymes of prostaglandin G/H synthase (PGHS) are shown to be differentially inhibited in vitro by currently marketed nonsteroidal anti-inflammatory drugs (NSAIDs) using microsomal rhPGHS-1 and rhPGHS-2. Comparison of selectivity ratios (IC50 rhPGHS-1/IC50 rhPGHS-2) demonstrated a 10-fold selectivity of etodolac (Lodine) for rhPGHS-2, whereas the other NSAIDs evaluated demonstrated no preference or a slight preference for inhibition of rhPGHS-1. In vitro enzyme results were supported by a human whole blood assay where etodolac also demonstrated a 10-fold selectivity for inhibition of PGHS-2 mediated TxB2 production. Taken together, these data may be key to explaining the clinically observed gastrointestinal safety of etodolac versus other marketed NSAIDs.

Discovery of Begacestat, a Notch-1-Sparing γ-Secretase Inhibitor for the Treatment of Alzheimer's Disease

SAR on HTS hits 1 and 2 led to the potent, Notch-1-sparing GSI 9, which lowered brain Abeta in Tg2576 mice at 100 mg/kg po. Converting the metabolically labile methyl groups in 9 to trifluoromethyl groups afforded the more stable analogue 10, which had improved in vivo potency. Further side chain modification afforded the potent Notch-1-sparing GSI begacestat (5), which was selected for development for the treatment of Alzheimers disease.

Discovery of a novel series of Notch-sparing γ-secretase inhibitors

Using a cell-based assay, we have identified a new series of Notch-sparing gamma-secretase inhibitors from HTS screening leads 2a and 2e. Lead optimization studies led to the discovery of analog 8e with improved gamma-secretase inhibitory potency and Notch-sparing selectivity.

(S)-N-(5-Chlorothiophene-2-sulfonyl)-β,β-diethylalaninol a Notch-1-sparing γ-secretase inhibitor

Accumulation of beta-amyloid (Abeta), produced by the proteolytic cleavage of amyloid precursor protein (APP) by beta- and gamma-secretase, is widely believed to be associated with Alzheimers disease (AD). Research around the high-throughput screening hit (S)-4-chlorophenylsulfonyl isoleucinol led to the identification of the Notch-1-sparing (9.5-fold) gamma-secretase inhibitor (S)-N-(5-chlorothiophene-2-sulfonyl)-beta,beta-diethylalaninol 7.b.2 (Abeta(40/42) EC(50)=28 nM), which is efficacious in reduction of Abeta production in vivo.

Structure-activity relationships leading to WAY-121,520, a tris aryl-type, indomethacin-based, phospholipase A2 (PLA2)/leukotriene biosynthesis inhibitor

We were intrigued by reports of the inhibition of phospholipase A2 (PLA2) by indomethacin. In order to increase the potency of the indomethacin system as an inhibitor of PLA2, it was decided to make more lipophilic analogs. Indeed, covalent attachment of a quinoline ring to the methoxy substituent of indomethacin affords WAY-122,220 which is almost an order of magnitude more potent than indomethacin in inhibiting human synovial fluid PLA2 (IC50=15 and 145 μM, respectively). TheN−p-chloro-benzyl analog of this compound, WAY-121,520, was an even more potent inhibitor of PLA2 (IC50=4 μM). Structural analyses and molecular modeling suggest that these compounds may inhibit PLA2 by mimicking arachidonic acid. WAY-121,520 is also a potent leukotriene biosynthesis inhibitor both in the rat PMN and mouse macrophage assays (IC50=10 and 4 nM, respectively), possibly acting via a 5-LO (5-lipoxygenase) translocation inhibition mechanism. The multiple actions of WAY-121,520 may contribute to its favorable anti-inflammatory profile.

Analogs of the marine natural product scalaradial lacking the α,β-unsaturated aldehyde: effects on human synovial fluid phospholipase A2 and macrophage lipid mediator production

Abstract The role of the α,β-unsaturated aldehyde in the inhibition of PLA2 by scalaradial was investigated by reduction to the triol and oxidation to the diacid. The results demonstrate that the reactivity of the α,β-unsaturated aldehyde of scalaradial is not absolutely essential to its ability to inhibit PLA2 and lipid mediator production in the intact cell but adds significantly to its inhibitory potency.

Pharmacological characterization of WAY-121,520 : a potent anti-inflammatory indomethacin-based inhibitor of 5-lipoxygenase (5-LO)/phospholipase A2 (PLA2)

WAY-121,520 inhibited human synovial fluid PLA2 (HSF-PLA2) (IC50=4 μM) using arachidonic acid-labeledE. coli as substrate. Further biochemical characterization of WAY-121,520 demonstrated potent inhibition of 5-lipoxygenase (5-LO) activity in the murine macrophage (LTC4, IC50=4nM) and rat PMN (LTB4, IC50=10 nM) and an ability to antagonize LTD4 binding to isolated guinea-pig trachea (pKB=6.0).In vivo anti-inflammatory activity was noted in murine TPA-induced (ED50=91 μg/ear) and arachidonic acid-induced (66% inhibition at 400 μg/ear) ear edema and in leukotriene-dependent antigen-induced bronchoconstriction in the guinea pig (73% inhibition at 50 mg/kg, p.o.). WAY-121,520 represents a novel series of indomethacin-based inhibitors of PLA2 with anti-inflammatory activity resulting from a combination of biochemical activities (inhibition of 5-LO and PLA2 and LTD4 antagonism). This agent may provide added therapeutic efficacy over more selective inhibitors.

Pulmonary pharmacology of WAY-126299A: A dual-acting 5-lipoxygenase inhibitor and leukotriene D4 antagonist

Leukotrienes have been implicated in the pathogenesis of asthma [1]. For this reason we previously sought a compound which could simultaneously act as a 5lipoxygenase (5-LO) inhibitor and a leukotriene D 4 (LTD4) receptor antagonist. WY50295 tromethamine (WY-50295T) exhibited this unique dual mechanism of action in vitro and in vivo, including the inhibition of leukotriene production in human neutrophils, rat whole blood and guinea-pig lung fragments [2, 3]. However, WY-50295T was recently found to be inactive in human whole blood, presumably due to a high degree of plasma protein binding. Therefore, we subsequently sought to identify a compound which exhibited dual 5-LO inhibitory and LTD4 antagonist activity, with oral potency and efficacy equivalent to WY-50295T in an animal model of asthma, which was also active in human whole blood. To our knowledge there are no compounds reported in the literature which exhibit 5-LO inhibitory activity in human whole blood and leukotriene antagonist activity. The present study compares WAY-126299A ((S)-6-(2-Benzothiazolylmethoxy)-N-hydroxy-.alpha., Ndimethyl-2-naphthalene acetamide sodium salt) to WY50295T and zileuton (a reference 5-LO inhibitor in development for the treatment of asthma [4-6]).