Preventing in vitro lipoperoxidation in the malondialdehyde-thiobarbituric assay.

The malondialdehyde-thiobarbituric acid assay is widely used to study lipid peroxidation. Among the various methods used to perform the assay, the most widely accepted is the quantification of malondialdehyde using the thiobarbituric acid reaction, followed by reversed-phase chromatography. However, unacceptable results may be obtained as malondialdehyde can be produced in vitro. To study the conditions that inhibit in vitro lipid peroxidation, malondialdehyde levels were measured in cultured cells using different concentrations of butylated hydroxytoluene, EDTA or a combination of both. Butylated hydroxytoluene alone inhibits in vitro lipid peroxidation effectively. EDTA reduces artificially produced malondialdehyde, but not totally. Finally, the combination of EDTA and butylated hydroxytoluene does not improve the results obtained using butylated hydroxytoluene alone. The conclusion is that in the malondialdehyde-thiobarbituric acid assay it is necessary to add an inhibitor of the in vitro lipid peroxidation and assay the necessary concentration depending on the specimen used.