title: Antioxidant and membrane effects of procyanidin dimers and trimers isolated from peanut and cocoa.
abstract: The antioxidant and membrane effects of dimer (Dim) and trimer (Trim) procyanidins isolated from cocoa (Theobroma cacao) (B- and C-bonded) and peanut (Arachis hypogea L.) skin (A-bonded) were evaluated in phosphatidyl choline liposomes. When liposomes were oxidized with a steady source of oxidants, the above dimers and trimers inhibited to a similar extent lipid oxidation in a concentration (0.33-5 microM)-dependent manner. With respect to membrane effects, Dim A1, Dim B, Trim A, and Trim C increased (Dim A1 = Dim B and Trim A = Trim C), while Dim A2 decreased, membrane surface potential. All of the procyanidins tested decreased membrane fluidity as determined by fluorescent probes at the water-lipid interface, an effect that extended into the hydrophobic region of the bilayer. Both dimers and trimers protected the lipid bilayer from disruption by Triton X-100. The magnitude of the protection was Dim A1 > Dim A2 > Dim B and Trim C > Trim A. Thus, dimers and trimers can interact with membrane phospholipids, presumably with their polar headgroup. As a consequence of this interaction, they can provide protection against the attack of oxidants and other molecules that challenge the integrity of the bilayer.
authors.affiliation: IQUIFIB-Department of Biological Chemistry (UBA-CONICET), School of Pharmacy and Biochemistry, University of Buenos Aires, Junin 956, 1113-Buenos Aires, Argentina.
authors.forename: Sandra V
authors.initials: SV
authors.lastname: Verstraeten
authors.forename: John F
authors.initials: JF
authors.lastname: Hammerstone
authors.forename: Carl L
authors.initials: CL
authors.lastname: Keen
authors.forename: César G
authors.initials: CG
authors.lastname: Fraga
authors.forename: Patricia I
authors.initials: PI
authors.lastname: Oteiza
mesh_terms: D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D010367:Arachis / Q000737:chemistry*; D002099:Cacao / Q000737:chemistry*; D002462:Cell Membrane / Q000187:drug effects*; D019281:Dimerization; D008051:Lipid Bilayers; D015227:Lipid Peroxidation / Q000187:drug effects; D008081:Liposomes / Q000737:chemistry; D008560:Membrane Fluidity / Q000187:drug effects; D010084:Oxidation-Reduction; D044945:Proanthocyanidins / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D012639:Seeds / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D008051:Lipid Bilayers; D008081:Liposomes; D044945:Proanthocyanidins