Oxygen radical absorbance capacity (ORAC) of cyclodextrin-solubilized flavonoids, resveratrol and astaxanthin as measured with the ORAC-EPR method

Yoshimi Sueishi, Misa Ishikawa, Daisuke Yoshioka, Nobuyuki Endoh, Shigeru Oowada, Masashi Shimmei, Hirotada Fujii, Yashige Kotake

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Recently, we proposed an oxygen radical absorbance capacity method that directly quantifies the antioxidant's scavenging capacity against free radicals and evaluated the radical scavenging abilities for water soluble antioxidant compounds. In this study, we determined the radical scavenging abilities of lipophilic antioxidants which were solubilized by cyclodextrin in water. Commonly employed fluorescence-based method measures the antioxidant's protection capability for the fluorescent probe, while we directly quantify free-radical level using electron para- magnetic resonance spin trapping technique. In addition, the spin trapping-based method adopted controlled UV-photolysis of azo- initiator for free radical generation, but in fluorescence-based method, thermal decomposition of azo-initiator was utilized. We determined the radical scavenging abilities of seven wellknown lipophilic antioxidants (five flavonoids, resveratrol and astaxanthin), using methylated β-cyclodextrin as a solubilizer. The results indicated that the agreement between spin trapping-based and fluorescence-based values was only fair partly because of a large variation in the previous fluorescence-based data. Typical radical scavenging abilities in trolox equivalent unit are: catechin 0.96; epicatechin 0.94; epigallocatechin gallate 1.3; kaempferol 0.37; myricetin 3.2; resveratrol 0.64; and astaxanthin 0.28, indicating that myricetin possesses the highest antioxidant capacity among the compounds tested. We sorted out the possible causes of the deviation between the two methods.

Original languageEnglish
Pages (from-to)127-132
Number of pages6
Journaljournal of clinical biochemistry and nutrition
Volume50
Issue number2
DOIs
Publication statusPublished - Mar 2012

Keywords

  • Cyclodextrin
  • Inclusion complex
  • Lipophilic antioxidant
  • Oxygen radical absorbance capacity
  • Spin trapping

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Nutrition and Dietetics
  • Clinical Biochemistry

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