Elucidation of antioxidant activity of dihydrolipoic acid toward hydroxyl radical using a novel hydroxyl radical generator NP-III

S. Matsugo, Liang-Jun Yan, D. Han, H. J. Tritschler, L. Packer

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

The photosensitive organic hydroperoxide, NP-III, which produces hydroxyl radicals on illumination by UVA light, was used to examine the antioxidant activity of dihydrolipoic acid toward hydroxyl radical. Apolipoprotein (apo-B) of human low density lipoprotein (LDL), and bovine serum albumin (BSA), were irradiated with UVA in the presence of NP-III and dihydrolipoic acid. The oxidation of BSA and apo-B of LDL by NP-III was completely inhibited by dihydrolipoic acid. ESR studies using dimethylpyrroline oxide (DMPO) as a spin trapping reagent also revealed that in the presence of dihydrolipoic acid, the DMPO-OH adduct produced from the irradiation of NP-III and DMPO completely disappeared. Hence, the scavenging activity of dihydrolipoic acid is not due to its chelating activity toward transition metals (ferrous ions). The results lead us to conclude that dihydrolipoic acid is an efficient hydroxyl radical scavenger through the direct reaction of dihydrolipoic acid with hydroxyl radical.

Original languageEnglish
Pages (from-to)375-383
Number of pages9
JournalBiochemistry and Molecular Biology International
Volume37
Issue number2
StatePublished - 1 Dec 1995

Keywords

  • Antioxidant activity
  • Dihydrolipoic acid
  • Hydroxyl radical
  • Photo-fenton reagent
  • Protein oxidation

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