Peroxidation of linolenic acid--catalysis by transition metal ions.

Numerous studies have demonstrated that several indices of oxidative damage are enhanced in target tissues of rodents exposed to various transition metal ions. Whether or not these indices represent primary or secondary effects are not known, since tissues injured by other mechanisms are susceptible to an increased rate of lipid peroxidation (LP). In the current study, the reaction mixtures (metal ions with linolenic acid) were preincubated at 37 degrees C for 24 hours prior to the measurement of malondialdehyde (MDA) by liquid chromatography, and conjugated dienes at 233 nm. These metal-catalyzed reactions were also compared in the presence of butylated hydroxytoluene (BHT), a free radical scavenger. Our results showed that Cd(II), Co(II), Cu(II), Fe(II & III), Mn(II), and Ni(II) all significantly increased the concentration of MDA and conjugated dienes over LA controls (P less than 0.001 by Mann-Whitney test). The production of MDA and conjugated dienes was also increased by Al(III) but to a lesser degree (P less than 0.05 and 0.01, respectively); As(V) did not increase either index. The addition of butylated hydroxytoluene (BHT) to the reaction mixtures significantly reduced the production of MDA (P less than 0.001). These in vitro studies support prior in vivo reports that the primary mechanism of the acute toxic effects of these metal ions is due, at least in part, to metal-catalyzed peroxidation of polyunsaturated fatty acids.