Plasmalogen degradation by oxidative stress: Production and disappearance of specific fatty aldehydes and fatty alpha-hydroxyaldehydes

Plasmalogens are often considered as antioxidant molecules that protect cel ls from oxidative stress. Their vinyl ether bond could indeed be among the first targets for newly formed radicals. However, the long chain aldehydes released from plasmalogens were seldom studied and possible injurious or ha rmless. effects were poorly examined. Thus, the sensitivity of the vinyl et her bond of plasmalogens was investigated in a cerebral cortex homogenate u nder UV irradiation- or Fe2+/ascorbate-induced peroxidation. Kinetics of al dehyde production was followed by gas chromatography/mass spectrometry. Thi s confirmed that plasmalogens were highly sensitive to oxidative stress (70 % cleavage after 90 min UV irradiation and 30% after 30 min of Fe2+/ascorba te). The aldehydes corresponding to sn-1 position 16:0, 18:0, or 18:1 were poorly detected. Conversely, oxidation of plasmalogens yielded preferential ly 15:0, 17:0, and 17:1 aldehydes under UV and the alpha -hydroxyaldehydes 16:0-OH and 18:0-OH following a Fe2+/ascorbate oxidation. Kinetics showed t hat free aldehydes and above all free alpha -hydroxyaldehydes disappeared f rom the medium as soon as produced. Consequently, the behavior of these rel eased aldehydes in the tissues has to be investigated in order to ascertain the protective effect of plasmalogens. against oxidation. (C) 2001 Elsevie r Science Inc.