Amino acid and protein scavenging of radicals generated by iron/hydroperoxide system: an electron spin resonance spin trapping study.
Reduction of free radicals generated by Fe(II)/cumene-hydroperoxide (CumOOH) by amino acids (Gly, Cys, Met, His, and Trp) and proteins (bovine serum albumin (BSA), beta-lactoglobulin, and lactoferrin) was followed by electron spin resonance spectroscopy using alpha-phenyl-N-tert-butylnitrone (PBN), 2-methyl-2-nitrosopropane (MNP), and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin traps. The radical species detected were mostly carbon-centered radicals from CumOOH fragmentation (methyl/*H3 and ethyl/*H2CH3), although carbon-centered radicals originated from amino acids could be formed in the presence of Cys, Met, His, or Trp. All proteins and amino acids, except Cys, were effective at inhibiting generation of radicals from the Fe(II)/CumOOH system. Trp was the amino acid with the highest antiradical activity, followed by His > Gly approximately Met. Lactoferrin was the protein showing the most efficient inhibition of radical formation from the Fe(II)/CumOOH system, and BSA and beta-lactoglobulin were not significantly different in their antiradical activities. These results suggest that proteins with higher inhibitory activity on lipid oxidation promoted by transition metal catalytic decomposition of hydroperoxides should be those with elevated metal-chelating and radical-scavenging properties as well as low concentration and accessibility of reducing groups from amino acids capable of activating metals, such as sulfhydryl groups.
Pazos
Manuel
M
Department of Food Science, Food Chemistry, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark. mpaz@kvl.dk
Andersen
Mogens L
ML
Skibsted
Leif H
LH
D000596:Amino Acids / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D000431:Ethanol / Q000494:pharmacology; D005296:Ferrous Compounds / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D010710:Phosphates / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry*; D013113:Spin Labels
D000596:Amino Acids; D001555:Benzene Derivatives; D005296:Ferrous Compounds; D016166:Free Radical Scavengers; D005609:Free Radicals; D010710:Phosphates; D011506:Proteins; D013113:Spin Labels; D000431:Ethanol; C007164:cumene hydroperoxide