Michael N. Greco

Dual Inhibition of Cathepsin G and Chymase Is Effective in Animal Models of Pulmonary Inflammation

RATIONALE Mast cells and neutrophils are key contributors to the pathophysiological inflammatory processes that underpin asthma and chronic obstructive pulmonary disease, partly through the release of noxious serine proteases, including cathepsin G (Cat G) and chymase. From this standpoint, a dual inhibitor of neutrophil Cat G and mast cell chymase could protect against these disease-related inflammatory responses. OBJECTIVES We examined the antiinflammatory pharmacology of RWJ-355871, a dual inhibitor of Cat G and chymase, in animal models of inflammation that evince pathophysiological pathways relevant to asthma and chronic obstructive pulmonary disease to determine the therapeutic potential of this compound. METHODS In an ovalbumin (OVA)-sensitized rat model, RWJ-355871 was administered to block the mast-cell-mediated increase in paw volume caused by OVA injection. In a sheep asthma model, antigen-induced airway responses were assessed with and without aerosol treatment with RWJ-355871. In a murine tobacco-smoke model of airway inflammation, the effect of RWJ-355871 on smoke-induced neutrophilia was determined. MEASUREMENTS AND MAIN RESULTS Intravenous treatment of OVA-sensitized rats with RWJ-355871 provided dose-dependent reduction in the increase in rat paw volume. In allergic sheep, aerosol pretreatment with RWJ-355871 showed dose-dependent inhibition of the antigen-induced early response, late response, and post-antigen-induced airway hyperreponsiveness. In tobacco-smoke-exposed mice, nebulized RWJ-355871 significantly reduced the smoke-induced neutrophilia from the levels observed in untreated mice. CONCLUSIONS The preclinical antiinflammatory effects of RWJ-355871 in these animal models of inflammation indicate that this dual inhibitor may have therapeutic utility for treating airway inflammatory diseases involving mechanisms that depend on Cat G and/or chymase.

Solid-phase synthesis via N-terminal attachment to the 2-chlorotrityl resin

Abstract Connection of a secondary amine to the 2-chlorotrityl resin followed by iterative saponification/coupling sequences provided a basis for generating focused peptidomimetic mini-libraries.

Cyclotheonamide derivatives: Synthesis and thrombin inhibition. Exploration of specific structure-function issues

Macrocyclic pentapeptide analogues (5-9) of the sponge natural product cyclotheonamide A (CtA, 3) were prepared by means of our convergent [3 + 2] synthetic protocol, in which a late-stage primary amine group is available for substitution (Maryanoff et al. Proc. Natl Acad. Sci. U.S.A. 1993, 90, 8048). These analogues, as well as CtA and cyclotheonamide B (CtB, 4), were examined for their ability to inhibit the serine protease alpha-thrombin, in comparison with suitable reference standards. We characterized Michaelis-Menten and slow-binding kinetics for the cyclotheonamide derivatives. An attempt was made to utilize the unoccupied hydrophobic S3 subsite of thrombin via analogues 5 and 6. Also, removal of the hydroxyphenyl group, which is thought to be involved in an aromatic stacking interaction with Trp60D of thrombin, was explored via analogue 9. The importance of the alpha-keto and olefin groups was examined via 7 and 8, respectively. The relationship of structure and function with the analogues proved to be less predictable than anticipated.

Highly stereoselective synthesis of substituted hydrindanes related to the antiepileptic drug topiramate

Abstract Multistep syntheses of two “carbocyclic” analogues 2 and 3 of topiramate ( 1 ) were effected with excellent stereocontrol. Two key reactions employed were: deoxygenation-rearrangement of an enone with p -tosylhydrazine and catecholborane ( 14 --> 15 and 5 --> 7 ) and face-selective vicinal dihydroxylation with OsO 4 (viz. 15 --> 16 and 8 --> 9 ).

Intramolecular azide cycloaddition (IAC) reactions in the indole series - an approach to clavicipitic acid

Abstract The intramolecular [3+2] cycloaddition of azide to olefin has been explored as a possible route to the structurally unique alkaloid clavicipitic acid.

Transformation of the marine natural product cyclotheonamide A by aqueous base. X-ray analysis of a novel ligand complexed with human α-thrombin

Abstract Treatment of the macrocyclic pentapeptide cyclotheonamide A ( 1 ) with aqueous sodium carbonate or triethylamine at 23°C generated two isomeric products. X-ray analysis of a complex with α-thrombin indicates a ring-opened pentapeptide, 2 , from cleavage at the α-keto amide bond. However, given the MS data for 3 and a model study in which 4 provides 5 , structure 3 is suggested for the product from base treatment of 1 .

6-Benzhydryl-4-amino-quinolin-2-ones as Potent Cannabinoid Type 1 (CB1) Receptor Inverse Agonists and Chemical Modifications for Peripheral Selectivity

A novel series of 6-benzhydryl-4-amino-quinolin-2-ones was discovered as cannabinoid type 1 receptor (CB1R) inverse agonists based on the high-throughput screening hit, compound 1a. Structure-activity relationships were studied to improve in vitro/in vivo pharmacology and restrict distribution to the peripheral circulation. We adopted several strategies such as increasing topological polar surface area, incorporating discrete polyethylene glycol side chains, and targeting P-glycoprotein (P-gp) to minimize access to the brain. Compound 6a is a P-gp substrate and a potent and highly selective CB1R inverse agonist, demonstrating excellent in vivo metabolic stability and a low brain to plasma ratio. However, brain receptor occupancy studies showed that compound 6a may accumulate in brain with repeat dosing. This was evidenced by compound 6a inhibiting food intake and inducing weight loss in diet-induced obese mice. Thus, a strategy based on P-gp efflux may not be adequate for peripheral restriction of the disclosed quinolinone series.