Design and synthesis of cyanamides as potent and selective N-acylethanolamine acid amidase inhibitors

Bioorg Med Chem. 2020 Jan 1;28(1):115195. doi: 10.1016/j.bmc.2019.115195. Epub 2019 Nov 11.


N-acylethanolamine acid amidase (NAAA) inhibition represents an exciting novel approach to treat inflammation and pain. NAAA is a cysteine amidase which preferentially hydrolyzes the endogenous biolipids palmitoylethanolamide (PEA) and oleoylethanolamide (OEA). PEA is an endogenous agonist of the nuclear peroxisome proliferator-activated receptor-α (PPAR-α), which is a key regulator of inflammation and pain. Thus, blocking the degradation of PEA with NAAA inhibitors results in augmentation of the PEA/PPAR-α signaling pathway and regulation of inflammatory and pain processes. We have prepared a new series of NAAA inhibitors exploring the azetidine-nitrile (cyanamide) pharmacophore that led to the discovery of highly potent and selective compounds. Key analogs demonstrated single-digit nanomolar potency for hNAAA and showed >100-fold selectivity against serine hydrolases FAAH, MGL and ABHD6, and cysteine protease cathepsin K. Additionally, we have identified potent and selective dual NAAA-FAAH inhibitors to investigate a potential synergism between two distinct anti-inflammatory molecular pathways, the PEA/PPAR-α anti-inflammatory signaling pathway,1-4 and the cannabinoid receptors CB1 and CB2 pathways which are known for their antiinflammatory and antinociceptive properties.5-8 Our ligand design strategy followed a traditional structure-activity relationship (SAR) approach and was supported by molecular modeling studies of reported X-ray structures of hNAAA. Several inhibitors were evaluated in stability assays and demonstrated very good plasma stability (t1/2 > 2 h; human and rodents). The disclosed cyanamides represent promising new pharmacological tools to investigate the potential role of NAAA inhibitors and dual NAAA-FAAH inhibitors as therapeutic agents for the treatment of inflammation and pain.

Keywords: Anandamide (AEA); Antinociception; CB1, CB2 cannabinoid receptors; Fatty acid amide hydrolase (FAAH); Inflammation; Monoacylglycerol lipase (MGL); N-acylethanolamine acid amidase (NAAA); N-palmitoylethanolamide (PEA); Nuclear peroxisome proliferator-activated receptor-α (PPAR-α).

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amidohydrolases / antagonists & inhibitors*
  • Amidohydrolases / metabolism
  • Animals
  • Cyanamide / chemical synthesis
  • Cyanamide / chemistry
  • Cyanamide / pharmacology*
  • Dose-Response Relationship, Drug
  • Drug Design*
  • Enzyme Inhibitors / chemical synthesis
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Mice
  • Models, Molecular
  • Molecular Structure
  • Rats
  • Structure-Activity Relationship


  • Enzyme Inhibitors
  • Cyanamide
  • Amidohydrolases
  • NAAA protein, human