Syntheses and characterization of the acyl glucuronide and hydroxy metabolites of diclofenac.
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.
Kenny
Jane R
JR
Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool L69 3GE, United Kingdom.
Maggs
James L
JL
Meng
Xiaoli
X
Sinnott
Deborah
D
Clarke
Stephen E
SE
Park
B Kevin
BK
Stachulski
Andrew V
AV
D000818:Animals; D004008:Diclofenac / Q000031:analogs & derivatives / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D020719:Glucuronides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D005978:Glutathione / Q000737:chemistry; D006801:Humans; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000737:chemistry
C487366:1-O-(2-((2',6'-dichlorophenyl)amino)phenylacetyl)glucopyranuronic acid; D020719:Glucuronides; D012709:Serum Albumin; D004008:Diclofenac; D005978:Glutathione