Antioxidant activities of astaxanthin and related carotenoids.
The antioxidant activities of astaxanthin and related carotenoids have been measured by employing a newly developed fluorometric assay. This assay is based on 4,4-difluoro-3,5-bis(4-phenyl-1, 3-butadienyl)-4-bora-3a,4a-diaza-s-indacene (BODIPY 665/676) as an indicator; 2,2'-azobis-2,4-dimethylvaleronitrile (AMVN) as a peroxyl radical generator; and 6-hydroxy-2,5,7, 8-tetramethylchroman-2-carboxylic acid (Trolox) as a calibrator in an organic and liposomal media. By employing this assay, three categories of carotenoids were examined: namely, the hydrocarbon carotenoids lycopene, alpha-carotene, and beta-carotene; the hydroxy carotenoid lutein; and the alpha-hydroxy-ketocarotenoid astaxanthin. The relative peroxyl radical scavenging activities of Trolox, astaxanthin, alpha-tocopherol, lycopene, beta-carotene, lutein, and alpha-carotene in octane/butyronitrile (9:1, v/v) were determined to be 1.0, 1.0, 1.3, 0.5, 0.4, 0.3, and 0.2, respectively. In dioleoylphosphatidyl choline (DOPC) liposomal suspension in Tri-HCl buffer (pH 7.4 at 40 degrees C), the relative reactivities of astaxanthin, beta-carotene, alpha-tocopherol, and lutein were found to be 1.00, 0.9, 0.6, and 0.6, respectively. When BODIPY 665/676 was replaced by 4,4-difluoro-5-(4-phenyl-1,3-butadienyl)-4-bora-3a, 4a-diaza-s-indacene-3-undecanoic acid (BODIPY 581/591 C(11)) as an indicator, astaxanthin showed the highest antioxidant activity toward peroxyl radicals. The relative reactivities of Trolox, astaxanthin, alpha-tocopherol, alpha-carotene, lutein, beta-carotene, and lycopene were determined to be 1.0, 1.3, 0.9, 0.5, 0.4, 0.2, and 0.4, respectively.
Naguib
Y M
YM
Phytochem Technologies, Chelmsford, MA 01824, USA.
D000975:Antioxidants / Q000737:chemistry*; D001896:Boron Compounds; D002138:Calibration; D002338:Carotenoids / Q000737:chemistry*; D005456:Fluorescent Dyes; D016166:Free Radical Scavengers; D005609:Free Radicals; D007202:Indicators and Reagents; D010545:Peroxides; D013050:Spectrometry, Fluorescence; D014810:Vitamin E / Q000737:chemistry; D024341:Xanthophylls; D019207:beta Carotene / Q000031:analogs & derivatives* / Q000737:chemistry
D000975:Antioxidants; D001896:Boron Compounds; D005456:Fluorescent Dyes; D016166:Free Radical Scavengers; D005609:Free Radicals; D007202:Indicators and Reagents; D010545:Peroxides; D024341:Xanthophylls; C409489:bodipy 665-676; D019207:beta Carotene; D014810:Vitamin E; C049375:perhydroxyl radical; D002338:Carotenoids; C005948:astaxanthine