title: Novel mechanistic class of fatty acid amide hydrolase inhibitors with remarkable selectivity.
abstract: Fatty acid amide hydrolase (FAAH) is an integral membrane enzyme that degrades the fatty acid amide family of signaling lipids, including the endocannabinoid anandamide. Genetic or pharmacological inactivation of FAAH leads to analgesic, anti-inflammatory, anxiolytic, and antidepressant phenotypes in rodents without showing the undesirable side effects observed with direct cannabinoid receptor agonists, indicating that FAAH may represent an attractive therapeutic target for treatment of pain, inflammation, and other central nervous system disorders. However, the FAAH inhibitors reported to date lack drug-like pharmacokinetic properties and/or selectivity. Herein we describe piperidine/piperazine ureas represented by N-phenyl-4-(quinolin-3-ylmethyl)piperidine-1-carboxamide (PF-750) and N-phenyl-4-(quinolin-2-ylmethyl)piperazine-1-carboxamide (PF-622) as a novel mechanistic class of FAAH inhibitors. PF-750 and PF-622 show higher in vitro potencies than previously established classes of FAAH inhibitors. Rather unexpectedly based on the high chemical stability of the urea functional group, PF-750 and PF-622 were found to inhibit FAAH in a time-dependent manner by covalently modifying the enzyme's active site serine nucleophile. Activity-based proteomic profiling revealed that PF-750 and PF-622 were completely selective for FAAH relative to other mammalian serine hydrolases. We hypothesize that this remarkable specificity derives, at least in part, from FAAH's special ability to function as a C(O)-N bond hydrolase, which distinguishes it from the vast majority of metabolic serine hydrolases in mammals that are restricted to hydrolyzing esters and/or thioesters. The piperidine/piperazine urea may thus represent a privileged chemical scaffold for the synthesis of FAAH inhibitors that display an unprecedented combination of potency and selectivity for use as potential analgesic and anxiolytic/antidepressant agents.
authors.affiliation: Pfizer Global Research and Development, Ann Arbor, Michigan 48105, USA. kay.ahn@pfizer.com
authors.forename: Kyunghye
authors.initials: K
authors.lastname: Ahn
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Johnson
authors.forename: Laura R
authors.initials: LR
authors.lastname: Fitzgerald
authors.forename: Marya
authors.initials: M
authors.lastname: Liimatta
authors.forename: Andrea
authors.initials: A
authors.lastname: Arendse
authors.forename: Tracy
authors.initials: T
authors.lastname: Stevenson
authors.forename: Eric T
authors.initials: ET
authors.lastname: Lund
authors.forename: Richard A
authors.initials: RA
authors.lastname: Nugent
authors.forename: Tyzoon K
authors.initials: TK
authors.lastname: Nomanbhoy
authors.forename: Jessica P
authors.initials: JP
authors.lastname: Alexander
authors.forename: Benjamin F
authors.initials: BF
authors.lastname: Cravatt
mesh_terms: D000581:Amidohydrolases / Q000037:antagonists & inhibitors*; D000813:Anilides / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001665:Binding Sites / Q000187:drug effects; D002219:Carbamates / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D010879:Piperazines / Q000737:chemistry / Q000494:pharmacology*; D010880:Piperidines / Q000737:chemistry / Q000494:pharmacology*; D012694:Serine / Q000737:chemistry; D013997:Time Factors; D000099252:Fatty Acid Amide Hydrolases
chemical_list: D000581:Amidohydrolases; D000813:Anilides; D001549:Benzamides; D002219:Carbamates; D004791:Enzyme Inhibitors; D010879:Piperazines; D010880:Piperidines; D012694:Serine; D000099252:Fatty Acid Amide Hydrolases; C525147:N-phenyl-4-(quinolin-2-ylmethyl)piperazine-1-carboxamide; C525146:N-phenyl-4-(quinolin-3-ylmethyl)piperidine-1-carboxamide; C500528:cyclohexyl carbamic acid 3'-carbamoylbiphenyl-3-yl ester