title: Cholesterol induces surface localization of polyphenols in model membranes thus enhancing vesicle stability against lysozyme, but reduces protection of distant double bonds from reactive-oxygen species.
abstract: The main scope of the present study was to analyze the membrane interaction of members of different classes of polyphenols, i.e. resveratrol, naringenin, epigallocatechin gallate and enterodiol, in model systems of different compositions and phase states. In addition, the possible association between membrane affinity and membrane protection against both lipid oxidation and bilayer-disruptive compounds was studied. Gibbs monolayer experiments indicated that even though polyphenols showed poor surface activity, it readily interacted with lipid films. Actually, a preferential interaction with expanded monolayers was observed, while condensed and cholesterol-containing monolayers decreased the affinity of these phenolic compounds. On the other hand, fluorescence anisotropy studies showed that polyphenols were able to modulate membrane order degree, but again this effect was dependent on the cholesterol concentration and membrane phase state. In fact, cholesterol induced a surface rather than deep into the hydrophobic core localization of phenolic compounds in the membranes. In general, the polyphenolic molecules tested had a better antioxidant activity when they were allowed to get inserted into the bilayers, i.e. in cholesterol-free membranes. On the other hand, a membrane-protective effect against bilayer permeabilizing activity of lysozyme, particularly in the presence of cholesterol, could be assessed. It can be hypothesized that phenolic compounds may protect membrane integrity by loosely covering the surface of lipid vesicles, once cholesterol push them off from the membrane hydrophobic core. However, this cholesterol-driven distribution may lead to a reduced antioxidant activity of linoleic acid double bonds.
authors.affiliation: Instituto Superior de Investigaciones Biológicas (INSIBIO) CONICET-UNT, Instituto de Química Biológica "Dr. Bernabe Bloj", Facultad de Bioquímica, Química y Farmacia, UNT, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina.
authors.forename: Alejandro
authors.initials: A
authors.lastname: de Athayde Moncorvo Collado
authors.affiliation: Instituto Superior de Investigaciones Biológicas (INSIBIO) CONICET-UNT, Instituto de Química Biológica "Dr. Bernabe Bloj", Facultad de Bioquímica, Química y Farmacia, UNT, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina.
authors.forename: Fernando G
authors.initials: FG
authors.lastname: Dupuy
authors.affiliation: Instituto Superior de Investigaciones Biológicas (INSIBIO) CONICET-UNT, Instituto de Química Biológica "Dr. Bernabe Bloj", Facultad de Bioquímica, Química y Farmacia, UNT, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina.
authors.forename: Roberto D
authors.initials: RD
authors.lastname: Morero
authors.affiliation: Instituto Superior de Investigaciones Biológicas (INSIBIO) CONICET-UNT, Instituto de Química Biológica "Dr. Bernabe Bloj", Facultad de Bioquímica, Química y Farmacia, UNT, Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina. Electronic address: cminahk@fbqf.unt.edu.ar.
authors.forename: Carlos
authors.initials: C
authors.lastname: Minahk
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000975:Antioxidants / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry*; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D044950:Flavanones / Q000737:chemistry; D005454:Fluorescence Polarization; D057927:Hydrophobic and Hydrophilic Interactions; D017705:Lignans / Q000737:chemistry; D019787:Linoleic Acid / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D015227:Lipid Peroxidation; D008081:Liposomes / Q000737:chemistry; D009113:Muramidase / Q000737:chemistry*; D017382:Reactive Oxygen Species / Q000737:chemistry*; D000077185:Resveratrol; D013267:Stilbenes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000975:Antioxidants; D044950:Flavanones; D017705:Lignans; D008051:Lipid Bilayers; D008081:Liposomes; D017382:Reactive Oxygen Species; D013267:Stilbenes; D015060:1,2-Dipalmitoylphosphatidylcholine; C029498:2,3-bis(3'-hydroxybenzyl)butane-1,4-diol; D002392:Catechin; D002784:Cholesterol; D019787:Linoleic Acid; C045651:epigallocatechin gallate; D009113:Muramidase; C005273:naringenin; D000077185:Resveratrol; D004134:Dimyristoylphosphatidylcholine
keywords: Fluorescence anisotropy; Langmuir monolayers; Lipid oxidation; Liposome leakage; Liposomes; Polyphenols