title: A fluorometric method for measurement of peroxyl radical scavenging activities of lipophilic antioxidants.
abstract: A fluorometric method for evaluation of activities of lipophilic antioxidants toward peroxyl radicals in a lipophilic medium (octane:butyronitrile; 9:1, v/v) and dioleoylphosphatidyl choline (DOPC) liposomal suspension in Tris-HCl buffer (pH 7.4 at 40 degrees C) has been developed. This fluorometric method is based on the use of the fatty acid 4,4-difluoro-5-(4-phenyl-1, 3-butadienyl)-4-bora-3a,4a-diaza-s-indacene-3-undec anoic acid (BODIPY 581/591 C11) as an indicator, 2,2'-azobis-2,4-dimethyl valeronitrile (AMVN) as a peroxyl radical generator, and 6-hydroxy-2, 5,7,8-tetramethyl chroman-2-carboxylic acid (Trolox) as a calibrator. In the absence of antioxidants, a linear correlation was found between the fluorescence decay of BODIPY 581/591 C11 and the concentration of AMVN. Trolox was used as a standard reference material for validating this newly developed method. A linear correlation was found between the net protection of the fluorescence of BODIPY 581/591 C11 and the amounts of added Trolox. Employing this method, the relative peroxyl radical scavenging activities of Trolox, alpha-tocopherol, alpha-carotene, beta-carotene, lutein, and probucol in octane:butyronitrile (9:1, v/v) were determined to be 1. 0:0.7:0.5:0.3:0.4:0.3. In the DOPC system, beta-carotene showed an antioxidant activity which is a factor of two greater than that of alpha-tocopherol. This assay is suitable for measurement of activities of antioxidants in an organic lipid environment and a liposomal medium.
authors.affiliation: Phytochem Technologies, 22 Alpha Road, Chelmsford, Massachusetts, 01824, USA.
authors.forename: Y M
authors.initials: YM
authors.lastname: Naguib
mesh_terms: D000975:Antioxidants / Q000378:metabolism / Q000494:pharmacology*; D001896:Boron Compounds / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D016166:Free Radical Scavengers / Q000378:metabolism / Q000494:pharmacology*; D008081:Liposomes; D010545:Peroxides; D010713:Phosphatidylcholines / Q000378:metabolism; D013050:Spectrometry, Fluorescence
chemical_list: C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D000975:Antioxidants; D001896:Boron Compounds; D005456:Fluorescent Dyes; D016166:Free Radical Scavengers; D008081:Liposomes; D010545:Peroxides; D010713:Phosphatidylcholines; C049375:perhydroxyl radical; C017251:1,2-oleoylphosphatidylcholine