Background and purpose:  The aim of this study was to assess the potential of an antagonist selective for the lysophosphatidic acid receptor, LPA1, in treating lung fibrosis We evaluated the in vitro and in vivo pharmacological properties of the high affinity, selective, oral LPA1‐antagonist (4′‐{4‐[(R)‐1‐(2‐chloro‐phenyl)‐ethoxycarbonylamino]‐3‐methyl‐isoxazol‐5‐yl}‐biphenyl‐4‐yl)‐acetic acid (AM966). Experimental approach:  The potency and selectivity of AM966 for LPA1 receptors was determined in vitro by calcium flux and cell chemotaxis assays using recombinant and native cell cultures. The in vivo efficacy of AM966 to reduce tissue injury, vascular leakage, inflammation and fibrosis was assessed at several time points in the mouse bleomycin model. Key results:  AM966 was a potent antagonist of LPA1 receptors, with selectivity for this receptor over the other LPA receptors. In vitro, AM966 inhibited LPA‐stimulated intracellular calcium release (IC50= 17 nM) from Chinese hamster ovary cells stably expressing human LPA1 receptors and inhibited LPA‐induced chemotaxis (IC50= 181 nM) of human IMR‐90 lung fibroblasts expressing LPA1 receptors. AM966 demonstrated a good pharmacokinetic profile following oral dosing in mice. In the mouse, AM966 reduced lung injury, vascular leakage, inflammation and fibrosis at multiple time points following intratracheal bleomycin instillation. AM966 also decreased lactate dehydrogenase activity and tissue inhibitor of metalloproteinase‐1, transforming growth factor β1, hyaluronan and matrix metalloproteinase‐7, in bronchoalveolar lavage fluid. Conclusions and implications:  These findings demonstrate that AM966 is a potent, selective, orally bioavailable LPA1 receptor antagonist that may be beneficial in treating lung injury and fibrosis, as well as other diseases that are characterized by pathological inflammation, oedema and fibrosis.

Lysophosphatidic acid (LPA) is a bioactive phospholipid that signals through a family of at least six G protein-coupled receptors designated LPA [1][2][3][4][5][6] . LPA type 1 receptor (LPA 1 ) exhibits widespread tissue distribution and regulates a variety of physiological and pathological cellular functions. Here, we evaluated the in vitro pharmacology, pharmacokinetic, and pharmacodynamic properties of the LPA 1 -selective antagonist AM095 (sodium, {4Ј-[3-methyl-4-((R)-1-phenyl-ethoxycarbonylamino)-isoxazol-5-yl]-biphenyl-4-yl}-acetate) and assessed the effects of AM095 in rodent models of lung and kidney fibrosis and dermal wound healing. In vitro, AM095 was a potent LPA 1 receptor antagonist because it inhibited GTP␥S binding to Chinese hamster ovary (CHO) cell membranes overexpressing recombinant human or mouse LPA 1 with IC 50 values of 0.98 and 0.73 M, respectively, and exhibited no LPA 1 agonism. In functional assays, AM095 inhibited LPAdriven chemotaxis of CHO cells overexpressing mouse LPA 1 (IC 50 ϭ 778 nM) and human A2058 melanoma cells (IC 50 ϭ 233 nM). In vivo, we demonstrated that AM095: 1) had high oral bioavailability and a moderate half-life and was well tolerated at the doses tested in rats and dogs after oral and intravenous dosing, 2) dose-dependently reduced LPA-stimulated histamine release, 3) attenuated bleomycin-induced increases in collagen, protein, and inflammatory cell infiltration in bronchalveolar lavage fluid, and 4) decreased kidney fibrosis in a mouse unilateral ureteral obstruction model. Despite its antifibrotic activity, AM095 had no effect on normal wound healing after incisional and excisional wounding in rats. These data demonstrate that AM095 is an LPA 1 receptor antagonist with good oral exposure and antifibrotic activity in rodent models.

Herein, we describe the first total syntheses of five members of the dimeric nuphar alkaloids: (+)-6,6′-dihydroxythiobinupharidine (+)-1a, (+)-6-hydroxythiobinupharidine (+)-1b, (−)-6,6′-dihydroxythionuphlutine (−)-2a, (−)-6,6′-dihydroxyneothiobinupharidine (−)-3a, and (+)-6,6′-dihydroxyneothionuphlutine (+)-4a. The latter two have not been found in Nature. We have also made each of their enantiomers (−)-1a–b, (+)-2a, (+)-3a, and (−)-4a. The key step in these syntheses was the dimerization of an α-aminonitrile (a hydrolytically-stable surrogate for its corresponding hemiaminal) with chiral Lewis acid complexes. We have also reassigned the literature structures of (+)-1a–1b—for those instances in which the NMR spectra were obtained in CD3OD—to their corresponding CD3O– adducts. Our efforts provide for the first time apoptosis data for (−)-3a, (+)-4a, and all five non-natural antipodes prepared. The data indicate high apoptotic activity regardless of the enantiomer or relative stereochemical configuration at C7 and C7′.

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The potent and selective 5-lipoxygenase-activating protein leukotriene synthesis inhibitor 3-[3-tert-butylsulfanyl-1-[4-(6-methoxy-pyridin-3-yl)-benzyl]-5-(pyridin-2-ylmethoxy)-1H-indol-2-yl]-2,2-dimethyl-propionic acid (11j) is described. Lead optimization was designed to afford compounds with superior in vitro and in vivo inhibition of leukotriene synthesis in addition to having excellent pharmacokinetics and safety in rats and dogs. The key structural features of these new compounds are incorporation of heterocycles on the indole N-benzyl substituent and replacement of the quinoline group resulting in compounds with excellent in vitro and in vivo activities, superior pharmacokinetics, and improved physical properties. The methoxypyridine derivative 11j has an IC(50) of 4.2 nM in a 5-lipoxygenase-activating protein (FLAP) binding assay, an IC(50) of 349 nM in the human blood LTB(4) inhibition assay, and is efficacious in a murine ovalbumin model of allergen-induced asthma. Compound 11j was selected for clinical development and has successfully completed phase 1 trials in healthy volunteers.