title: Towards a molecular interpretation of astringency: synthesis, 3D structure, colloidal state, and human saliva protein recognition of procyanidins.
abstract: Astringency is a sensation in the mouth used in judging the quality of red wine. The rough, dry, and puckering sensation called astringency is the result of an interaction between tannins and saliva proteins, mainly proline-rich proteins (PRP), which leads to the formation and precipitation of a complex. A dry and rough sensation is then perceived in the mouth. To get an insight into astringency at the molecular level we investigated: (i) An efficient and iterative method for 4-8 procyanidin synthesis, which gives rise to all possible 4-8 procyanidins up to the tetramer with total control of degree of oligomerization and stereochemistry. (ii) The 3D-structural preferences, which take into account their internal movements, using 2D NMR and molecular modeling. (iii) The self-association process in water or hydroalcoholic solutions using diffusion NMR spectroscopy that gives the active proportion of tannins able to fix proteins. (iv) A comprehensive description of the PRP-procyanidin complex formation to get information about stoichiometry, binding site localization, and affinity constants for different procyanidins. The data collected suggest that the interactions are controlled by both procyanidin conformational and colloidal state preferences. All these results provide new insights into the molecular interpretation of tannin astringency.
authors.affiliation: UMR 5255 ISM CESAMO, Université Bordeaux, CNRS, Talence, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Cala
authors.forename: Sandy
authors.initials: S
authors.lastname: Fabre
authors.forename: Noël
authors.initials: N
authors.lastname: Pinaud
authors.forename: Erick J
authors.initials: EJ
authors.lastname: Dufourc
authors.forename: Eric
authors.initials: E
authors.lastname: Fouquet
authors.forename: Michel
authors.initials: M
authors.lastname: Laguerre
authors.forename: Isabelle
authors.initials: I
authors.lastname: Pianet
mesh_terms: D001252:Astringents / Q000737:chemistry*; D001665:Binding Sites; D003102:Colloids; D004058:Diffusion; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D058105:Polymerization; D044945:Proanthocyanidins / Q000138:chemical synthesis*; D055273:Salivary Proline-Rich Proteins / Q000138:chemical synthesis*; D013237:Stereoisomerism; D014920:Wine / Q000032:analysis
chemical_list: D001252:Astringents; D003102:Colloids; D044945:Proanthocyanidins; D055273:Salivary Proline-Rich Proteins