Isotorachrysone inhibited iron-induced lipid peroxidation with an IC50 value of 1.64 ± 0.08 μM in rat brain homogenates, and was comparable in potency to butylated hydroxytoluene and was more potent than α-tocopherol or desferrioxamine. The mechanism of antioxidant properties were then examined. Isotorachrysone could scavenge the stable free radical diphenyl-p-picrylhydrazyl. And it was an efficient direct scavenger of water-soluble peroxyl radicals with stoichiometry factor of 0.53 ± 0.05 in the aqueous phase and also toward lipid-soluble peroxyl radicals in tissue homogenates. The oxygen consumption during peroxidation induced by radicals on human erythrocyte ghosts was suppressed by isotorachrysone. Furthermore, it was reactive towards superoxide anion with a second-order rate constant of 5.06 ± 0.65 x 105 M-1 S-1. But it did not react with hydrogen peroxide detected within the sensitivity limit of our assay. Using ascorbate/iron ion/H2O2 as a hydroxyl radical generating system and deoxyribose as a probe, isotorachrysone was effective with hydroxyl radicals with a second-order rate constant of 3.88 ± 0.54 x 1011 M-1 S-1 under stimulation by iron-EDTA. On the other hand, isotorachrysone retarded the peroxidation of human low density lipoprotein (LDL) initiated by both aqueous and lipophilic peroxyl radicals. And it also suppressed copper-catalyzed human LDL oxidation, as measured by fluorescence intensity, electrophoretic mobility, and thiobarbituric acid-reactive substances formation in a concentration-dependent manner. Our results show that isotorachrysone is potentially an effective and versatile antioxidant, and can help protecting LDL against oxidation.

Original languageEnglish
Pages (from-to)119-130
Number of pages12
JournalBiochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
Issue number1
Publication statusPublished - Nov 14 1996


  • Antioxidant
  • Free radical
  • Hydroxyl radical
  • Isotorachrysone
  • Lipid peroxidation
  • Low density lipoprotein
  • Peroxyl radical
  • Superoxide anion

ASJC Scopus subject areas

  • Molecular Biology
  • Biophysics
  • Structural Biology
  • Biochemistry


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