Excretion of malondialdehyde, formaldehyde, acetaldehyde, acetone and methyl ethyl ketone in the urine of rats given an acute dose of malondialdehyde.

A high pressure liquid chromatographic system (HPLC) has recently been developed for the simultaneous detection of malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON). We have examined the urinary excretion of these four lipid metabolites in the urine of rats following the acute oral administration of MDA (158 mg/kg body weight). During the first 12 h, increases in the urinary excretion of MDA and ACT of approximately 192- and 70-fold, respectively, were observed. The urinary excretion of both MDA and ACT decreased thereafter. An increase in FA excretion was observed only 12-24 h after MDA administration. A significant decrease in ACON relative to control values was observed 12-48 h after MDA treatment. Two new peaks were present in the HPLC chromatograms of urine samples 0-24 h after MDA administration. Both peaks were shown to be due to methyl ethyl ketone (MEK) which appears to be formed as a result of MDA metabolism. The results demonstrate that orally administered MDA is rapidly excreted in the urine, and alters the metabolism and excretion of other lipid metabolites.