Open AccessBioactivation mechanism of the cytotoxic and nephrotoxic S-conjugate S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine.
Author(s) -
W. Dekant,
Lawrence H. Lash,
M.W. Anders
Publication year - 1987
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.84.21.7443
Subject(s) - chemistry , bromide , fluoride , cysteine , conjugate , hydrolysis , medicinal chemistry , organic chemistry , stereochemistry , nuclear chemistry , enzyme , inorganic chemistry , mathematical analysis , mathematics
The bioactivation of S-(2-chloro-1,1,2-trifluoroethyl)-L-cysteine (CTFC) was studied with purified bovine kidney cysteine conjugate beta-lyase and with N-dodecylpyridoxal bromide in cetyltrimethylammonium bromide micelles as a pyridoxal model system. The beta-lyase and the pyridoxal model system converted CTFC to chlorofluoroacetic acid and inorganic fluoride, which were identified by 19F NMR spectrometry. 2-Chloro-1,1,2-trifluoroethanethiol and chlorofluorothionoacetyl fluoride were formed as metabolites of CTFC and were trapped with benzyl bromide and diethylamine, respectively, to yield benzyl 2-chloro-1,1,2-trifluoroethyl sulfide and N,N-diethyl chlorofluorothioacetamide, which were identified by gas chromatography/mass spectrometry. The bioactivation mechanism of CTFC therefore involves the initial formation of the unstable thiol 2-chloro-1,1,2-trifluoroethanethiol, which loses hydrogen fluoride to form the acylating agent chlorofluorothionoacetyl fluoride; hydrolysis of the thionoacyl fluoride affords the stable, terminal metabolites chlorofluoroacetic acid and inorganic fluoride. The intermediate acylating agent and chlorofluoroacetic acid may contribute to the cytotoxic effects of CTFC.