EPOXIDATION OF PLASMALOGENS - SOURCE FOR LONG-CHAIN ALPHA-HYDROXYALDEHYDES IN SUBCELLULAR-FRACTIONS OF BOVINE LIVER

1. Masked long-chain alpha-hydroxyaldehydes were trapped in all subcel lular fractions of bovine liver by application of pentafluorbenzyloxim e derivatization [van Kuijk, Thomas, Stephens and Dratz (1986) Biochem . Biophys. Res. Commun. 139, 144-149] and quantified via GLC/MS using characteristic ion traces. 2, The chain-length profile of long-chain 2 -hydroxyalkanales clearly indicates their relationship to plasmalogens as precursor molecules. 3. The previously postulated existence of alp ha-acyloxyplasmalogens as precursor molecules of masked long-chain alp ha-hydroxyaldehydes in bovine tissue lipids [Lutz and Spiteller (1991) Liebigs Ann. Chem. 1998, 563-567] was excluded. 4. The constant oxida tion rate of plasmalogens in all subcellular fractions provides conclu sive evidence for a non-enzymic plasmalogen epoxidation process (proba bly via hydroperoxy radicals). 5. The high reactivity of alpha-hydroxy aldehydes sheds some doubt on the postulation that plasmalogens protec t mammalian cells against oxidative stress as postulated previously [M orand, Zoeller and Raetz (1988) J. Biol. Chem. 263, 11590-11596; Moran d, Zoeller and Raetz (1988) J. Biol. Chem. 263, 11597-11606].