Biphenyl-3-yl alkylcarbamates as fatty acid amide hydrolase (FAAH) inhibitors: Steric effects of N-alkyl chain on rat plasma and liver stability

Abstract

Secondary alkylcarbamic acid biphenyl-3-yl esters are a class of Fatty Acid Amide Hydrolase (FAAH) inhibitors, which include the reference compounds URB597 and URB694. Given the intrinsic reactivity of the carbamate group, the in vivo potency of these molecules in rats is strongly affected by their hydrolysis in plasma or hepatic metabolism. In the present study, in vitro chemical and metabolic stability assays (rat plasma and rat liver S9 fraction) were used to investigate the structure-property relationships (SPRs) for a focused series of title compounds, where lipophilicity and steric hindrance of the carbamate N-substituent had been modulated. The resulting degradation rates indicate that a secondary or tertiary alkyl group at the carbamate nitrogen atom increases hydrolytic stability towards rat plasma esterases. The calculated solvent accessible surface area (SASA) of the carbamate fragment was employed to describe the differences observed in rate constants of hydrolysis in rat plasma (log kplasma), suggesting that stability in plasma increases if the substituent exerts a shielding effect on the carbamate carbonyl. Stability in rat liver S9 fraction is increased when a tertiary carbon is bound to the carbamate nitrogen atom, while other steric effects showed complex relationships with degradation rates. The SPRs here described may be applied at the pharmacokinetic optimization of other classes of carbamate FAAH inhibitors.

Δ5-Cholenoyl-amino acids as selective and orally available antagonists of the Eph–ephrin system

“…They were carried out as previously described [53]. Briefly, stock solutions of 10 and 3 were prepared in DMSO immediately before use.…”

Irreversible Inhibition of Epidermal Growth Factor Receptor Activity by 3-Aminopropanamides

“…Chemical (pH 7.4, pH 9.0) and rat plasma stability was investigated at 37°C according to procedures reported previously. 70 (See the Supporting Information for details.) The reactivity of 3 and 5 toward cysteamine, NAC, dithiothreitol (DTT), and reduced GSH was evaluated by adding a freshly prepared thiol solution (2 mM) to PBS (pH 7.4) containing the test compound (1 μM).…”

N-(2-Oxo-3-oxetanyl)carbamic Acid Esters as N-Acylethanolamine Acid Amidase Inhibitors: Synthesis and Structure–Activity and Structure–Property Relationships

“…(2R,3R)-allo-2-tert-Butoxycarbonylamino-3-hydroxybutyric Acid (22c): 49 74 Stock solutions of compounds were prepared in DMSO, and each sample was incubated at a final concentration of 1−100 μM in a prewarmed (37°C) buffer solution; the final DMSO concentration in the samples was kept at 1%. The samples were maintained at 37°C in a temperature-controlled shaking water bath (60 rpm).…”

“…Rat plasma stability was investigated as previously reported. 74 Briefly, plasma was quickly thawed and diluted to 80% (v/v) with PBS (pH 7.4) to buffer the solution pH, which was checked during the course of the experiments. Pooled rat plasma (400 μL) was incubated with PBS buffer (95 μL, pH 7.4) and a compound stock solution (5 μL) in DMSO (final DMSO concentration in samples of 1%; final compound concentrations of 5−100 μM).…”