Interaction of the antioxidant flavonoid quercetin with planar lipid bilayers

Liviu Movileanu, Ioana Neagoe, Maria Luiza Flonta

Research output: Contribution to journalArticlepeer-review

116 Scopus citations

Abstract

Our capacitance and conductance measurements on reconstituted planar lipid bilayers (BLM) suggest an insertion of the flavonoid quercetin (QCT) in the membranes, which is concentration- and pH-dependent. Interaction of the flavonoid with the membrane has no impact on either structure or integrity of the lipid bilayer. The QCT molecules penetrate the lipid bilayer by intercalating between the flexible acyl chains of the phospholipids, the deepest insertion occuring in acidic medium, when QCT is neutral and completely liposoluble. Results indicated that aggregation of QCT within the hydrophobic core is accompanied by an increase of the transmembrane conductance following an alteration of the hydrophobic barrier for small electrolytes. By contrast, within alkaline media where QCT is deprotonated, the reaction site of the flavonoid is restricted to the hydrophilic domain of the membrane. This significantly changes the double layer capacitance as the negatively charged QCT molecules become sandwiched between polar headgroups at the bilayer surface. At highest alkaline pH, the transmembrane conductance was not affected, since QCT did not perturb the molecular packing of the hydrocarbonic acyl chains of the phospholipids. Results also demonstrated that changes in physical properties of the lipid bilayers following interstitial QCT embedding within either the hydrophobic domain or the polar headgroup domain may be related to both its lipophilic nature and interactions with the electric dipole moments of the polar headgroups of phospholipids. Data also demonstrated that translocation of QCT in the polar part of the lipid bilayer, at physiological pH and salt conditions, may be correlated with its optimized radical scavenging activity. This paper discusses the significance of the free radical scavenging capacity and antioxidant efficiency of QCT. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)135-146
Number of pages12
JournalInternational Journal of Pharmaceutics
Volume205
Issue number1-2
DOIs
StatePublished - Sep 15 2000
Externally publishedYes

Keywords

  • Bilayer lipid membranes
  • Bioflavonoid
  • Hydrophobic barrier
  • Molecular interaction
  • Quercetin

ASJC Scopus subject areas

  • Pharmaceutical Science

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