title: Kinetics of the lipoperoxyl radical-scavenging activity of indicaxanthin in solution and unilamellar liposomes.
abstract: The reaction of the phytochemical indicaxanthin with lipoperoxyl radicals generated in methyl linoleate methanol solution by 2,2'-azobis(2,4-dimethylvaleronitrile), and in aqueous soybean phosphatidylcholine unilamellar liposomes by 2,2'-azobis(2-amidinopropane)hydrochloride, was studied. The molecule acts as a chain-terminating lipoperoxyl radical scavenger in solution, with a calculated inhibition constant of 3.63 x 10(5) M(-1) s(-1), and a stoichiometric factor approaching 2. Indicaxanthin incorporated in liposomes prevented lipid oxidation, inducing clear-cut lag periods and decrease of the propagation rate. Both effects were concentration-dependent, but not linearly related to the phytochemical concentration. The consumption of indicaxanthin during liposome oxidation was remarkably delayed, the lower the concentration the longer the time-interval during which it remained in its native state. Indicaxanthin and alpha-tocopherol, simultaneously incorporated in liposomes, exhibited cooperative antioxidant effects and reciprocal protective interactions. The extent of synergism decreased at the increase of the ratio (indicaxanthin)/(alpha-tocopherol). A potential antioxidant mechanism of indicaxanthin is discussed in the context of the chemistry of the molecule, and of the possible reactivity of a short-lived intermediate.
authors: Dipartimento Farmacochimico Tossicologico e Biologico, Università di Palermo, Via Archirafi, 32, Palermo, Italy.
authors: L
authors: L
authors: Tesoriere
authors: M
authors: M
authors: Allegra
authors: D
authors: D
authors: Butera
authors: C
authors: C
authors: Gentile
authors: M A
authors: MA
authors: Livrea
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000378:metabolism; D000578:Amidines / Q000494:pharmacology; D000975:Antioxidants / Q000378:metabolism* / Q000494:pharmacology; D001391:Azo Compounds / Q000494:pharmacology; D050860:Betaxanthins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D016166:Free Radical Scavengers / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008041:Linoleic Acids / Q000378:metabolism; D008051:Lipid Bilayers; D015227:Lipid Peroxidation; D008054:Lipid Peroxides / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism*; D000432:Methanol; D015394:Molecular Structure; D009570:Nitriles / Q000494:pharmacology; D010084:Oxidation-Reduction; D010713:Phosphatidylcholines / Q000378:metabolism; D011725:Pyridines / Q000378:metabolism*; D012996:Solutions; D012997:Solvents; D013535:Suspensions; D024502:alpha-Tocopherol / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000578:Amidines; D000975:Antioxidants; D001391:Azo Compounds; D050860:Betaxanthins; D016166:Free Radical Scavengers; D008041:Linoleic Acids; D008051:Lipid Bilayers; D008054:Lipid Peroxides; D008081:Liposomes; D009570:Nitriles; D010713:Phosphatidylcholines; D011725:Pyridines; D012996:Solutions; D012997:Solvents; D013535:Suspensions; C469628:indicaxanthin; C055792:2,2'-azobis(2,4-dimethylvaleronitrile); C005575:methyl linoleate; D015060:1,2-Dipalmitoylphosphatidylcholine; C046728:2,2'-azobis(2-amidinopropane); D024502:alpha-Tocopherol; D000432:Methanol