FORMATION OF REACTIVE ALDEHYDES FROM FATTY-ACIDS IN A FE2+/H2O2 OXIDATION SYSTEM

The lipid peroxidation products formed from arachidonic acid, linoleic acid, linoleic acid, oleic acid, and their esters upon Fe2+/H-2O2 oxidation were analyzed by two derivatization methods. alpha,beta-Unsaturated aldehydes, such as acolein and 4-hydroxy-2-nonenal, and beta-dicarbonyl compounds, such as malonaldehyde, were derivatized with N-methylhydrazine. Saturated normal aldehydes, such as formaldehyde and hexanal, were derivatized with cysteamine. Subsequently, a specific quantity of each derivative 1-methylpyrazoline, 1-methylpyrazole, and thiazoline was analyzed by gas chromatography. Formaldehyde, which has never been quantified satisfactorily in a lipid peroxidation system, was the major product, and its quantities ranged from 142 nmol/mg in ethyl linolenate to 50 nmol/mg in ethyl arachidonate. Malonaldehyde was found in all samples, in levels between trace in oleic acid and 97 nmol/mg in ethyl arachidonate. 4-Hydroxy-2-nonenal was found in arachidonic and linoleic acids and their ethyl esters, whereas 4-hydroxy-2-hexenal was found only in linolenic acid and its ethyl ester. Hexanal was one of the main aldehydes formed from arachidonic acid (43 nmol/mg) and linoleic acid (141 nmol/mg) and from their ethyl esters, but propanal was produced in significant amounts only from linolenic acid and its ethyl ester (35 and 23 nmol/mg, respectively).