1,4-Dihydroxynonene mercapturic acid, the major end metabolite of exogenous 4-hydroxy-2-nonenal, is a physiological component of rat and human urine.

In the present study 1,4-dihydroxynonene mercapturic acid (DHN-MA), previously shown to be the major urinary metabolite of 4-hydroxy-2-nonenal (HNE) administered to the rat, was characterized and determined to be a normal constituent of rat and human urine. DHN-MA was excreted as a mixture of at least two stereoisomers as determined by ion trap LC-MS/MS/MS after solid-phase extraction and HPLC purification. The 24-h urinary excretion of this compound was about 10 ng and 5 microg for rat and human, respectively. This end metabolite of the lipid peroxidation product HNE could represent a specific and noninvasive biomarker.