Malondialdehyde and 4-hydroxy-2-nonenal in plant tissue cultures: LC-MS determination of 2,4-dinitrophenylhydrazone derivatives

The cytologically active secondary lipid peroxidation products, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (HNE) have been detected as their 2,4-dinitrophenylhydrazone (DNP) derivatives in plant tissue cultures using LC-MS. This paper reports, for the first time, the use of LC-MS methodology to definitively identify 4-hydroxy-2-nonenal in plants. Limits of detection for the two derivatives are approximately 5 pmol (1.2 x 10(-9) g; 1 microM) and 0.1 pmol (3 x 10(-11) g; 20 nM) respectively. Mass spectrometer response was linear in the range from 2-200 microM DNP-MDA and 0.02-10 microM DNP-HNE. This methodology has been used to assess the formation of aldehydic secondary lipid peroxidation products in dedifferentiated callus cultures of Daucus carota. The finding that profiles of MDA and HNE can be correlated with embryogenic competence is of considerable interest as oxidative status has already been implicated as a regulatory factor in animal development.