Syntheses and characterization of the acyl glucuronide and hydroxy metabolites of diclofenac

J Med Chem. 2004 May 20;47(11):2816-25. doi: 10.1021/jm030891w.


In humans, metabolism of the commonly used nonsteroidal antiinflammatory drug diclofenac 1 yields principally the 4'-hydroxy 2, 5-hydroxy 3, and acyl glucuronide 4 metabolites. All three metabolites have been implicated in rare idiosyncratic adverse reactions associated with this widely used drug. Therefore, for mechanistic toxicological studies of 1, substantial quantities of 2-4 are required and their syntheses and characterization are described here. Key steps were a convenient two-step preparation of aniline 5 from phenol, efficient and selective 6-iodination of amide 18, and high-yielding Ullmann couplings to generate diarylamines 11 and 21. The acyl glucuronide 4 was obtained by Mitsunobu reaction of 1 (free acid) with allyl glucuronate 23 followed by Pd(0) deprotection, using a modification of a published procedure. We report full characterization of 4 and note that this important metabolite has been made available pure and in quantity for the first time. We report also the metabolic fates of the synthetic metabolites: 2 and 3 were glucuronidated in rats, but only 3 formed glutathione adducts in vivo and by enzymatic synthesis via a quinoneimine intermediate. A previously undescribed glutathione adduct of 3 was obtained by enzymatic synthesis. Compound 4 formed an imine-linked protein conjugate as evinced by sodium cyanoborohydride trapping.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Diclofenac / analogs & derivatives
  • Diclofenac / chemical synthesis*
  • Diclofenac / chemistry
  • Diclofenac / metabolism*
  • Glucuronides / chemical synthesis*
  • Glucuronides / chemistry
  • Glucuronides / metabolism
  • Glutathione / chemistry
  • Humans
  • Protein Binding
  • Rats
  • Rats, Wistar
  • Serum Albumin / chemistry


  • 1-O-(2-((2',6'-dichlorophenyl)amino)phenylacetyl)glucopyranuronic acid
  • Glucuronides
  • Serum Albumin
  • Diclofenac
  • Glutathione