title: Design, synthesis, and structure-activity relationships of alkylcarbamic acid aryl esters, a new class of fatty acid amide hydrolase inhibitors.
abstract: Fatty acid amide hydrolase (FAAH), an intracellular serine hydrolase enzyme, participates in the deactivation of fatty acid ethanolamides such as the endogenous cannabinoid anandamide, the intestinal satiety factor oleoylethanolamide, and the peripheral analgesic and anti-inflammatory factor palmitoylethanolamide. In the present study, we report on the design, synthesis, and structure-activity relationships (SAR) of a novel class of potent, selective, and systemically active inhibitors of FAAH activity, which we have recently shown to exert potent anxiolytic-like effects in rats. These compounds are characterized by a carbamic template substituted with alkyl or aryl groups at their O- and N-termini. Most compounds inhibit FAAH, but not several other serine hydrolases, with potencies that depend on the size and shape of the substituents. Initial SAR investigations suggested that the requirements for optimal potency are a lipophilic N-alkyl substituent (such as n-butyl or cyclohexyl) and a bent O-aryl substituent. Furthermore, the carbamic group is essential for activity. A 3D-QSAR analysis on the alkylcarbamic acid aryl esters showed that the size and shape of the O-aryl moiety are correlated with FAAH inhibitory potency. A CoMSIA model was constructed, indicating that whereas the steric occupation of an area corresponding to the meta position of an O-phenyl ring improves potency, a region of low steric tolerance on the enzyme active site exists corresponding to the para position of the same ring. The bent shape of the O-aryl moieties that best fit the enzyme surface closely resembles the folded conformations observed in the complexes of unsaturated fatty acids with different proteins. URB524 (N-cyclohexylcarbamic acid biphenyl-3-yl ester, 9g) is the most potent compound of the series (IC(50) = 63 nM) and was therefore selected for further optimization.
authors.affiliation: Istituto di Chimica Farmaceutica e Tossicologica, Università degli Studi di Urbino Carlo Bo, Piazza del Rinascimento 6, Italy.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Tarzia
authors.forename: Andrea
authors.initials: A
authors.lastname: Duranti
authors.forename: Andrea
authors.initials: A
authors.lastname: Tontini
authors.forename: Giovanni
authors.initials: G
authors.lastname: Piersanti
authors.forename: Marco
authors.initials: M
authors.lastname: Mor
authors.forename: Silvia
authors.initials: S
authors.lastname: Rivara
authors.forename: Pier Vincenzo
authors.initials: PV
authors.lastname: Plazzi
authors.forename: Chris
authors.initials: C
authors.lastname: Park
authors.forename: Satish
authors.initials: S
authors.lastname: Kathuria
authors.forename: Daniele
authors.initials: D
authors.lastname: Piomelli
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D001095:Arachidonic Acids / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects; D001713:Biphenyl Compounds / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D001921:Brain / Q000201:enzymology; D002219:Carbamates / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D015195:Drug Design; D063388:Endocannabinoids; D004791:Enzyme Inhibitors / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D004952:Esters; D006801:Humans; D066298:In Vitro Techniques; D008958:Models, Molecular; D008968:Molecular Conformation; D053284:Polyunsaturated Alkamides; D021281:Quantitative Structure-Activity Relationship; D014407:Tumor Cells, Cultured; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D001095:Arachidonic Acids; D001713:Biphenyl Compounds; D002219:Carbamates; D063388:Endocannabinoids; D004791:Enzyme Inhibitors; D004952:Esters; D053284:Polyunsaturated Alkamides; D000099252:Fatty Acid Amide Hydrolases; C475427:cyclohexylcarbamic acid biphenyl-3-yl ester; C078814:anandamide