Antioxidant properties of isotorachrysone isolated from Rhamnus nakaharai

George Hsiao, Feng Nien Ko, Chun Nan Lin, Che Ming Teng

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

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
Volume1298
Issue number1
DOIs
Publication statusPublished - Nov 14 1996
Externally publishedYes

Fingerprint

Rhamnus
Antioxidants
LDL Lipoproteins
Iron
Hydroxyl Radical
Rate constants
Deoxyribose
Lipids
Butylated Hydroxytoluene
Oxidation
Electrophoretic mobility
Deferoxamine
Tocopherols
Thiobarbituric Acid Reactive Substances
Erythrocyte Membrane
Oxygen Consumption
Edetic Acid
Superoxides
Stoichiometry
Hydrogen Peroxide

Keywords

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

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Structural Biology
  • Biophysics

Cite this

Antioxidant properties of isotorachrysone isolated from Rhamnus nakaharai. / Hsiao, George; Ko, Feng Nien; Lin, Chun Nan; Teng, Che Ming.

In: Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology, Vol. 1298, No. 1, 14.11.1996, p. 119-130.

Research output: Contribution to journalArticle

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