Lipophilic aldehydes and related carbonyl compounds in rat and human urine.

Rat and human urine samples were analyzed for lipophilic aldehydes and other carbonyl products of lipid peroxidation. The following compounds were identified as their 2,4-dinitrophenyl hydrazones by cochromatography with pure standards using three solvent systems: butanal, butan-2-one, pentan-2-one, hex-2-enal, hexanal, hepta-2,4-dienal, hept-2-enal, octanal, non-2-enal, deca-2,4-dienal, 4-hydroxyhex-2-enal, and 4-hydroxynon-2-enal. In general, fasted rats excreted less of these compounds than fed rats, indicating they were partially of dietary origin or that the endogenous compounds were excreted in a form not susceptible to hydrazone formation. The compounds excreted in human urine were similar to those excreted in rat urine but were present in lower concentrations. Identification of the conjugated forms of the lipophilic aldehydes and related carbonyl compounds excreted in urine may be a source of information about their reactions in vivo.