title: Unambiguous Determination of the Absolute Configuration of Dimeric Stilbene Glucosides from the Rhizomes of Gnetum africanum.
abstract: Dimeric stilbene glucosides 1-3 [two diastereomers of (-)-gnemonoside A (1a and 1b), (-)-gnemonoside C (2), and (-)-gnemonoside D (3)] as well as a mixture of the two enantiomers of gnetin C (4) were isolated from the rhizomes of Gnetum africanum. The two enantiomers of gnetin C, (+)-4 and (-)-4, were obtained from the aglycones of 1a and 1b, respectively. The configurations of these stilbenoids were investigated by NMR and vibrational circular dichroism (VCD) experiments. The absolute configurations of (-)-1a, (-)-2, (-)-3, and (-)-4 were established as 7aS,8aS by VCD spectroscopy in combination with density functional theory calculations. The antiamyloidogenic activity of the isolated stilbenes was also evaluated versus beta-amyloid fibrils. The four glucosides of gnetin C (1a, 1b, 2, and 3) were found to be the most active compounds, with inhibition percentages of 56, 56, 58, and 54 at 10 μM, respectively.
authors.affiliation: Institut des Sciences Moléculaires, UMR 5255-CNRS, Université Bordeaux , 351 Cours de la Libération, F-33405 Talence, France.
authors.forename: Thierry
authors.initials: T
authors.lastname: Buffeteau
authors.affiliation: Institut des Sciences Moléculaires, UMR 5255-CNRS, Université Bordeaux , 351 Cours de la Libération, F-33405 Talence, France.
authors.forename: Dominique
authors.initials: D
authors.lastname: Cavagnat
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Bisson
authors.affiliation: Unité de Recherche Œnologie, EA 4577, INRA USC 1366, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Axel
authors.initials: A
authors.lastname: Marchal
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Gilbert D
authors.initials: GD
authors.lastname: Kapche
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Battistini
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Gregory
authors.initials: G
authors.lastname: Da Costa
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Badoc
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Monti
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Mérillon
authors.affiliation: Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Waffo-Téguo
mesh_terms: D001572:Benzofurans / Q000737:chemistry / Q000302:isolation & purification; D002163:Cameroon; D002942:Circular Dichroism; D005960:Glucosides / Q000737:chemistry* / Q000302:isolation & purification; D035684:Gnetum / Q000737:chemistry*; D015394:Molecular Structure; D018696:Neuroprotective Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D019906:Nuclear Magnetic Resonance, Biomolecular; D027343:Rhizome / Q000737:chemistry; D013237:Stereoisomerism; D013267:Stilbenes / Q000737:chemistry* / Q000302:isolation & purification
chemical_list: C489707:2',3',4',5'-tetrahydroxystilbene-2-O-beta-D-glucoside; D001572:Benzofurans; D005960:Glucosides; D018696:Neuroprotective Agents; D013267:Stilbenes; C584041:gnemonoside A; C575740:gnetin C