Lipophilic aldehydes and related carbonyl compounds in rat and human urine

Rat and human urine samples were analyzed for lipophilic aldehydes and othe r carbonyl products of lipid peroxidation. The following compounds were ide ntified 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, d eca-2,4-dienal, 4-hydroxybex-2-enal, and 4-hydroxynon-2-enal. In general, f asted rats excreted less of these compounds than fed rats, indicating they were partially of dietary origin or that the endogenous compounds were excr eted in a form not susceptible to hydrazone formation. The compounds excret ed in human urine were similar to those excreted in rat urine but were pres ent in lower concentrations. Identification of the conjugated forms of the lipophilic aldehydes and related carbonyl compounds excreted in urine may b e a source of information about their reactions in vivo.