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Tannins are one of the four key components determining wine organoleptic quality. First, they play an important gustative role since they are responsible for wine astringency and/or bitterness. Second, they act as a structuring compound directly linked to red wine turbidity and stability. This second role is the consequence of their colloidal behavior. In the present work, we demonstrate that wine tannins exhibit different colloidal behaviour whether they are or not galloylated. Procyanidins, when galloylated, are more inclined to form micelles than their non-galloylated form, letting us suggest that they could act as structuring agent in wine. However, the size of the formed micelles is of the nanometer range suggesting that procyanidins, up to trimers, are not involved alone in wine turbidity.

Pregnenolone is considered the inactive precursor of all steroid hormones, and its potential functional effects have been largely uninvestigated. The administration of the main active principle of Cannabis sativa (marijuana), Δ(9)-tetrahydrocannabinol (THC), substantially increases the synthesis of pregnenolone in the brain via activation of the type-1 cannabinoid (CB1) receptor. Pregnenolone then, acting as a signaling-specific inhibitor of the CB1 receptor, reduces several effects of THC. This negative feedback mediated by pregnenolone reveals a previously unknown paracrine/autocrine loop protecting the brain from CB1 receptor overactivation that could open an unforeseen approach for the treatment of cannabis intoxication and addiction. Supported by the EU-FP7 (REPROBESITY, HEALTH-F2-2008-223713, G.M.), the European Research Council (ENDOFOOD, ERC-2010-StG-260515, G.M.), the Agence Nationale pour la Recherche (contracts HICOMET and TIMMS, P.V.P.), the U.S. National Institutes of Health (NIH) (grants DA-03672, DA-003934, and DA-09789, R.A.R. and G.L.B., and RO1 DA003934 and KO5 DA021358, P.H.R.

International audience; Chromatographic separation using fluorescence as a detection mode revealed, besides a series of flavan-3-ols, the recurrent presence of an undefined compound in Bordeaux red wine. Its isolation and structure characterization by complementary means (high-resolution mass spectrometry, nuclear magnetic resonance, and chemical synthesis) has permitted us to identify it as the nitrogen-containing glycoconjugate 3-indolyl-(2R)-O-β-D-glucosyl-lactic acid. Its quantification was performed for different wines of different vine varieties and terroirs with the aim to assess whether this compound may be used as a terroir, variety, or wine process tag.

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 sali- va proteins, mainly proline-rich proteins (PRP), which leads to the formation and precipitation of a complex. A dry and rough sensation is then per- ceived in the mouth. To get an insight into astrin- gency at the molecular level we investigated: (i) An efficient and iterative method for 4-8 procya- nidin synthesis, which gives rise to all possible 4- 8 procyanidins up to the tetramer with total con- trol of degree of oligomerization and stereochem- istry. (ii) The 3D‑structural preferences, which take into account their internal movements, using 2DNMR and molecular modeling. (iii) The self-as- sociation process in water or hydroalcoholic solu- tions using diffusion NMR spectroscopy that gives the active proportion of tannins able to fix pro- teins. (iv) A comprehensive description of the PRP-procyanidin complex formation to get infor- mation about stoichiometry, binding site localiza- tion, and affinity constants for different procyani- dins. The data collected suggest that the interac- tions are controlled by both procyanidin confor- mational and colloidal state preferences. All these results provide new insights into the molecular interpretation of tannin astringency. " procyanidin l " proline rich peptide l " astringency l " NMR l " molecular dynamics

In the present work, we used NMR (chemical shift variations and diffusion measurement) to determine the affinity and the number of sites of four different 4-8 procyanidin dimers for a model PRP peptide. A number of three binding sites has been identified for every tannin, but significant affinity differences are highlighted from one to another dimer (a factor 10 approximately) that could be related to their specific 3D-structure.