title: Partition of indicaxanthin in membrane biomimetic systems. A kinetic and modeling approach.
abstract: The solubilization site of indicaxanthin (Ind) in lipid bilayers was investigated by the kinetics of Ind oxidation by peroxyl radicals in water and in aqueous/L-alpha-dipalmitoyl-phosphatidylcholine (DPPC) vesicles, pH 7.4, and 37.0 and 48.0 degrees C, that is, in a gel-like and a crystal liquidlike bilayer state, respectively. The time-dependent Ind absorbance decay, matched with a successful simulation of the reaction kinetic mechanism by Gepasi software, supported a multistep pathway. Computer-assisted analysis allowed calculation of the rate constants associated with the reactions involved, the values of which decreased with increasing DPPC concentration. The binding constant calculated according to a pseudo two-phase distribution model did not vary with the physicochemical state of the vesicle, indicating location of Ind in a region whose state is not affected by temperature changes, at the interface between hydrophobic core and hydrophilic head groups. Other measurements carried out in the presence of dimyristoyl-phosphatidylcholine vesicles, indicated that the phytochemical was confined to the aqueous phase.
authors.affiliation: Dipartimento di Chimica Fisica F. Accascina, Viale delle Scienze, Pad. 17, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: Maria Liria
authors.initials: ML
authors.lastname: Turco Liveri
authors.forename: Luciana
authors.initials: L
authors.lastname: Sciascia
authors.forename: Mario
authors.initials: M
authors.lastname: Allegra
authors.forename: Luisa
authors.initials: L
authors.lastname: Tesoriere
authors.forename: Maria A
authors.initials: MA
authors.lastname: Livrea
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D050860:Betaxanthins / Q000737:chemistry*; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D012984:Software; D014867:Water / Q000737:chemistry
chemical_list: D050860:Betaxanthins; D008051:Lipid Bilayers; D008081:Liposomes; D010545:Peroxides; D011725:Pyridines; C469628:indicaxanthin; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; C049375:perhydroxyl radical