trans,trans-2,4-Decadienal (tt-
DDE), a lipid peroxidation product of linolieic
acid, is the most abundant
aldehyde identified in cooking oil fumes and is readily detectable in food products as well as in restaurant emissions. Previously, we have reported the toxicological effects of tt-
DDE in vitro and in vivo. However, the metabolic pathways of tt-
DDE in vivo remain unclear. In our present study, we combined liquid chromatography-mass spectrometry with triple quadrupole and time-of-flight to identify tt-
DDE metabolites in the urine of mice orally administered tt-
DDE. We identified two tt-
DDE metabolites, 2,4-decadienoic
acid and
cysteine-conjugated 2,4-decadien-1-ol, in the urine of mice gavaged with tt-
DDE and in human
hepatoma cell cultures. The structure of 2,4-decadienoic
acid was confirmed upon comparison of its tandem mass spectrometry (MS/MS) spectrum and retention time with those of synthetic standards. The moieties of
cysteine and alcohol on
cysteine-conjugated 2,4-decadien-1-ol were validated by treating cell cultures with stable-
isotope-labeled
cysteine and
4-methylpyrazole, an
alcohol dehydrogenase inhibitor. The MS/MS spectra of a
cysteine standard and ionized
cysteine detached from
cysteine-conjugated 2,4-decadien-1-ol were identical. Two metabolic pathways for the biotransformation of tt-
DDE in vivo are proposed: (i) the oxidation of tt-
DDE to the corresponding
carboxylic acid, 2,4-decadienoic
acid, in liver cells and (ii)
glutathione (GHS) conjugation, GSH breakdown, and
aldehyde reduction, which generate
cysteine-conjugated 2,4-decadien-1-ol in both liver and lung cells. In conclusion, this platform can be used to identify tt-
DDE metabolites, and
cysteine-conjugated 2,4-decadien-1-ol can serve as a
biomarker for assessing exposure to tt-
DDE.