title: Metabolism of synthetic cannabinoids PB-22 and its 5-fluoro analog, 5F-PB-22, by human hepatocyte incubation and high-resolution mass spectrometry.
abstract: BACKGROUND
  PB-22 (1-pentyl-8-quinolinyl ester-1H-indole-3-carboxylic acid) and 5F-PB-22 (1-(5-fluoropentyl)-8-quinolinyl ester-1H-indole-3-carboxylic acid) are new synthetic cannabinoids with a quinoline substructure and the first marketed substances with an ester bond linkage. No human metabolism data are currently available, making it difficult to document PB-22 and 5F-PB-22 intake from urine analysis, and complicating assessment of the drugs' pharmacodynamic and toxicological properties.
  
  
  METHODS
  We incubated 10 μmol/l PB-22 and 5F-PB-22 with pooled cryopreserved human hepatocytes up to 3 h and analyzed samples on a TripleTOF 5600+ high-resolution mass spectrometer. Data were acquired via TOF scan, followed by information-dependent acquisition triggered product ion scans with mass defect filtering (MDF). The accurate mass full scan MS and MS/MS metabolite datasets were analyzed with multiple data processing techniques, including MDF, neutral loss and product ion filtering.
  
  
  RESULTS
  The predominant metabolic pathway for PB-22 and 5F-PB-22 was ester hydrolysis yielding a wide variety of (5-fluoro)pentylindole-3-carboxylic acid metabolites. Twenty metabolites for PB-22 and 22 metabolites for 5F-PB-22 were identified, with the majority generated by oxidation with or without glucuronidation. For 5F-PB-22, oxidative defluorination occurred forming PB-22 metabolites. Both compounds underwent epoxide formation followed by internal hydrolysis and also produced a cysteine conjugate.
  
  
  CONCLUSIONS
  Human hepatic metabolic profiles were generated for PB-22 and 5F-PB-22. Pentylindole-3-carboxylic acid, hydroxypentyl-PB-22 and PB-22 pentanoic acid for PB-22, and 5'-fluoropentylindole-3-carboxylic acid, PB-22 pentanoic acid and the hydroxy-5F-PB-22 metabolite with oxidation at the quinoline system for 5F-PB-22 are likely the best targets to incorporate into analytical methods for urine to document PB-22 and 5F-PB-22 intake.
authors: Chemistry and Drug Metabolism, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, 251 Bayview Boulevard, Baltimore, MD, 21224, USA.
authors: Ariane
authors: A
authors: Wohlfarth
authors: Adarsh S
authors: AS
authors: Gandhi
authors: Shaokun
authors: S
authors: Pang
authors: Mingshe
authors: M
authors: Zhu
authors: Karl B
authors: KB
authors: Scheidweiler
authors: Marilyn A
authors: MA
authors: Huestis
mesh_terms: D002186:Cannabinoids / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D007211:Indoles / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry
chemical_list: D002186:Cannabinoids; D007211:Indoles; C012382:indole-3-carboxylic acid