Abstract

Mesocarb (Sydnocarb®) has been used for doping purposes due to its central nervous system stimulating effects. Presently, the metabolites of mesocarb are not commercially available, and additionally, the exact chemical structures of several mesocarb metabolites have not been solved yet. The aim of this WADA-funded project was to synthesize six potential mono-, di-, and trihydroxylated regioisomeric metabolites of mesocarb. To solve the exact chemical structure of the main urinary metabolites of mesocarb, the chemically synthesized metabolites were compared both to metabolites synthesized enzymatically in vitro, using humane liver microsomal protein and fraction S9 of humane liver protein, and to an authentic human urine sample, which was collected during 0-48 hours after p.o. administration of 5 mg of mesocarb (a gift from Moscow Anti-Doping Laboratory). Enzymatic synthesis yielded only p-OH-mesocarb. p-OH-Mesocarb was also the main metabolite found in human urine collected after oral administration of mesocarb. Most of the p-OH-mesocarb in urine was sulphated (76%) but also some glucuronidated (22%) and free (2%) metabolite was observed. Traces of a dihydroxylated metabolite were also found in urine. Methods to synthesize, analyze and characterize urinary hydroxylated metabolites of mesocarb were developed. p-Hydroxymesocarb was found to be the main metabolite in human urine. The synthesized and fully characterized p-hydroxymesocarb enables the reliable and legally defensible confirmation analysis of mesocarb in doping control, and could also be used in quality assurance and in development of new analytical methods. The metabolite synthesized in this project is available to all WADA-accredited anti-doping laboratories. Aus dem Text