The solubilization site of indicaxanthin (Ind) in lipid bilayers was investigated by the kinetics of Indoxidation by peroxyl radicals in water and in aqueous/L-R-dipalmitoyl-phosphatidylcholine (DPPC)vesicles, pH 7.4, and 37.0 and 48.0 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 ofthe reaction kinetic mechanism by Gepasi software, supported a multistep pathway. Computerassistedanalysis allowed calculation of the rate constants associated with the reactions involved,the values of which decreased with increasing DPPC concentration. The binding constant calculatedaccording to a pseudo two-phase distribution model did not vary with the physicochemical state ofthe 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 measurementscarried out in the presence of dimyristoyl-phosphatidylcholine vesicles, indicated that the phytochemicalwas confined to the aqueous phase.
|Numero di pagine||5|
|Rivista||Journal of Agricultural and Food Chemistry|
|Stato di pubblicazione||Published - 2009|
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