Peptides as antioxidants and carbonyl quenchers in biological model systems

Subjecting selected peptides to in vitro analyses covering their ability to interfere with the lipid oxidation chain reaction as well as to protect proteins from direct and indirect oxidation has provided the basis for a more detailed understanding of peptide-mediated protection in biological systems. The efficiency of peptides as radical scavengers and chain-breaking antioxidants in oxidizing lipid membranes was found to be low. Previous studies on antioxidative activity of peptides tend not to include comparisons with efficiencies of more well-documented antioxidants and/or use irrelevantly high dosages of peptides. The present study demonstrates that the effect of the investigated peptides towards oxidation in biological membrane systems is mainly a protection of vital proteins from being oxidatively modified. This protection is obtained through a prevention of lipid oxidation derived carbonylation (indirect protein oxidation) and through interference with aqueous radical species (direct protein oxidation), and it is only achieved if the peptides are present in high concentrations as sacrificial antioxidants.