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MARIO ALLEGRA

Partition of Indicaxanthin in Membrane Biomimetic Systems. A Kinetic and Modeling Approach

  • Autori: TURCO LIVERI, M.; Sciascia, L.; Allegra, M.; Tesoriere, L.; Livrea, M.
  • Anno di pubblicazione: 2009
  • Tipologia: Articolo in rivista (Articolo in rivista)
  • Parole Chiave: Betalain pigments; biomimetic membranes; DPPC; vesicles; phospholipids; Gepasi simulation.
  • OA Link: http://hdl.handle.net/10447/54030

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-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 of the reaction kinetic mechanism by Gepasi software, supported a multistep pathway. Computerassisted 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.