EFFECTS OF ADDITIONAL IRON-CHELATORS ON FE2+-INITIATED LIPID PEROXIDATION - EVIDENCE TO SUPPORT THE FE2+ FE3+ COMPLEX AS THE INITIATOR

摘要

The addition of chelated Fe2+ ions in a liposomal system often results in a short lag period before peroxidation starts. The addition of a second chelator at the end of the lag period results in an inhibition of the lipid peroxidation. The degree of inhibition depends ow the stability constants of the chelator in ligating Fe2+ and/or Fe3+. A more striking inhibitory effect was observed for the chelators With higher stability constant for either or both Fe2+- and Fe3+-complex, bat much less inhibition was found for those with lower stability constants for both complexes. Assuming that the ''initiator'' for iron-dependent lipid peroxidation is formed through the redox process of iron ion and finally emerged at the end of the latent period, the inhibitory effect of the second chelator may be explained as the abstraction of either Fe2+ or Fe3+ from the initiator by an additional free chelator, which results in the decomposition of the initiator. This study supports the hypothesis that a Fe2+... Fe3+ complex is responsible for iron-initiated lipid peroxidation. [References: 27]