O-Hydroxyacetamide Carbamates as a Highly Potent and Selective Class of Endocannabinoid Hydrolase Inhibitors

Abstract

The two major endocannabinoid transmitters, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are degraded by distinct enzymes in the nervous system, fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively. FAAH and MAGL inhibitors cause elevations in brain AEA and 2-AG levels, respectively, and reduce pain, anxiety, and depression in rodents without causing the full spectrum of psychotropic behavioral effects observed with direct cannabinoid receptor-1 (CB1) agonists. These findings have inspired the development of several classes of endocannabinoid hydrolase inhibitors, most of which have been optimized to show specificity for either FAAH or MAGL or, in certain cases, equipotent activity for both enzymes. Here, we investigate an unusual class of Ohydroxyacetamide carbamate inhibitors and find that individual compounds from this class can serve as selective FAAH or dual FAAH/MAGL inhibitors in vivo across a dose range (0.125−12.5 mg kg ) suitable for behavioral studies. Competitive and click chemistry activity-based protein profiling confirmed that the O-hydroxyacetamide carbamate SA-57 is remarkably selective for FAAH and MAGL in vivo, targeting only one other enzyme in brain, the additional 2-AG hydrolase ABHD6. These data designate O-hydroxyacetamide carbamates as a versatile chemotype for creating endocannabinoid hydrolase inhibitors that display excellent in vivo activity and tunable selectivity for FAAH-anandamide versus MAGL (and ABHD6)-2-AG pathways.

Simultaneous Inhibition of Fatty Acid Amide Hydrolase and Monoacylglycerol Lipase Shares Discriminative Stimulus Effects with Δ9-Tetrahydrocannabinol in Mice

“…FAAH and MAGL inhibition was evidenced by quantification of increases in AEA/OEA and 2-AG, respectively, in the medial prefrontal cortex, hippocampus, and caudate putamen of mouse brain. In general, the degree of selectivity of each drug for FAAH and MAGL, as reported previously (Fegley et al, 2005;Ahn et al, 2009;Long et al, 2009c;Niphakis et al, 2012), was confirmed under the current experimental conditions. Because changes in endocannabinoid content were not region dependent, these particular brain areas did not appear to differ in their potential contribution to the discriminative stimulus effects of Δ 9 -THC.…”

“…SA-57 was synthesized in the laboratory of B.F.C. as previously described (Niphakis et al, 2012). Rimonabant base and URB597 were obtained from the National Institute on Drug Abuse Research Technology Branch.…”

The Endocannabinoid System as a Potential Therapeutic Target for Pain Modulation

“…Dual FAAH/MAGL inhibition and using peripherally restricted inhibitors of FAAH and MAGL are also among the promising strategies (38,39,48). Moving to the inhibition of endocannabinoid cellular uptake, there are some potential therapeutic effects observed with the use of membrane transporter inhibitors in animal models (30,38,40).…”

Δ9-Tetrahydrocannabinol and Endocannabinoid Degradative Enzyme Inhibitors Attenuate Intracranial Self-Stimulation in Mice

“…Testing commenced following pretreatment times of 10 minutes for cocaine; 30 minutes for THC; and 120 minutes for PF-3845, JZL184, and SA-57. The selection of these pretreatment times was based on previous reports with enzyme inhibitors and preliminary studies with cocaine and THC (Ahn et al, 2009;Long et al, 2009b;Niphakis et al, 2012). To investigate the role of CB 1 and CB 2 receptors in the effects of each drug on ICSS, rimonabant or SR144528 was administered 15 minutes prior to each test compound in a separate set of experiments.…”

“…Toward this end, we examined the dose-response relationships of the FAAH inhibitor Ahn et al, 2009), the MAGL inhibitor JZL184 (4-[bis(1,3-benzodioxol-5-yl) hydroxymethyl]-1-piperidinecarboxylic acid 4-nitrophenyl ester; Long et al, 2009a), and the dual FAAH/MAGL inhibitor SA-57 (4-[2-(4-chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester; Niphakis et al, 2012). SA-57 inhibits FAAH more potently than MAGL, resulting in elevated levels of AEA and other FAAH substrates at low doses, and increased 2-AG levels with higher doses (Niphakis et al, 2012). Cocaine was included as a comparison drug, because it is well established to increase ICSS (Fish et al, 2010;Straub et al, 2010).…”