A novel series of [2-[methyl(2-phenethyl)amino]-2-oxoethyl] benzene-containing leukotriene B4 antagonists: initial structure-activity relationships.

This report describes the synthesis of a new class of LTB4 receptor antagonists containing [2-[methyl(2-phenethyl)amino]-2-oxoethyl]benzene as a key binding domain for interaction with high-affinity LTB4 receptors. In addition to this binding domain, two other structural features, an acid function and a lipophilic group, are also required by these compounds for high binding affinity. Our studies indicate that maximal binding affinity in this series is controlled by the spatial relationship of these groups relative to one another. The structure-activity relationships are discussed. The most potent compound in this chemical series, (E)-5-[2-[methyl(2-phenethyl)-amino]-2-oxoethyl]-2-(benzyloxy)cinn amic acid (32), has an IC50 of 2 nM in a guinea pig spleen cell membrane assay. In the whole-cell human neutrophils binding assay, (Z)-5-[2-[methyl-(2-phenethyl)amino]-2-oxoethyl]-2-(benzyloxy)cinn amic acid (30) was the most potent compound with an IC50 of 50 nM.

Structure-activity relationships study of two series of leukotriene B4 antagonists: novel indolyl and naphthyl compounds substituted with a 2-[methyl(2-phenethyl)amino]-2-oxoethyl side chain.

N-Methyl-N-phenethylphenylacetamide has been reported to be a key binding domain to LTB4 receptors. Here we describe the synthesis and structure-activity relationship (SAR) studies of two new series of LTB4 receptor antagonists in which the phenyl ring of this receptor binding domain is replaced with indole and naphthalene, respectively. Results of these studies indicate that, in addition to the 2-[methyl(2-phenethyl)amino]-2-oxoethyl moiety, the presence of an acid group and a lipophilic side chain, as well as the spatial relationship of these three functions, is crucial for high binding affinity with LTB4 receptors. Our SAR studies also reveal that an arenecarboxylic acid, or an enoic acid in which the carboxyl group is conjugated with the central ring, is the preferred polar group. The lipophilic side chain of the naphthyl series was found to tolerate minor variations, ranging from a phenylmethoxy group to phenyl and alkyloxy groups. The most active compounds are 2-ethyl-3-[1-[2-[methyl(2-phenethyl) amino]-2-oxoethyl]-5-(phenylmethoxy)indol-3-yl]propenoic+ ++ acid (4g) of the indolyl series and 4-[2-[methyl(2-phenethyl)amino]-2-oxoethyl]-8-(phenylmethoxy )-2-naphthalenecarboxylic acid (2a) or the naphthyl series, with IC50 of 8 and 4.7 nM respectively, in the receptor binding assay using intact human neutrophils.

Development of a novel series of (2-quinolinylmethoxy)phenyl-containing compounds as high-affinity leukotriene D4 receptor antagonists. 2. Effects of an additional phenyl ring on receptor affinity.

This series of reports describe the development of orally active, highly potent, specific antagonists of the peptidoleukotrienes containing a (2-quinolinylmethoxy)phenyl moiety. The compounds reported in this paper contain an additional phenyl ring, which has significantly improved the receptor affinity. The effect of changes in the linkage between the two phenyl rings as well as the orientation of the acidic functional group on biological activity are discussed. Many of these compounds have high affinity to the sulfidopeptide leukotriene D4 receptors with Ki values ranging between 2 and 20 nM and are orally active. Compound 27 [RG 12525, 5-[[2-[[4-(2-quinolinylmethoxy)phenoxy]- methyl]phenyl]methyl]-1H-tetrazole] represents the best combination of in vitro and in vivo biological activity in this series and has been selected for further evaluation in clinical studies of asthma.