Wood and roots of major grapevine cultivars and rootstocks: A comparative analysis of stilbenes by UHPLC-DAD-MS/MS and NMR.

INTRODUCTION: Grapevine wood and roots are by-products obtained during vineyard management. This plentiful biomass is known to be rich in stilbenes and can be used as a source of high-value compounds as well as active natural extracts. However, the stilbenes in grapevine wood and roots from different cultivars and rootstocks remain to be characterized. OBJECTIVE: The present study investigated the stilbene content of eight major Vitis vinifera cultivars and six different rootstocks. In addition, the distribution of stilbenes was established for each of seven parts into which the plants were sub-divided. METHODOLOGY: For stilbene characterization and quantification purposes, an ultra-high performance liquid chromatography-diode array detector-mass spectrometry (UHPLC-DAD-MS/MS) analysis of different samples was carried out. Moreover, structural data of stilbenes was unambiguously studied by nuclear magnetic resonance (NMR) spectra. RESULTS: Whatever the cultivar/rootstock combination, stilbenes were found to be oligomerized from the aerial part to the root system. Furthermore, stilbene content varied widely depending on the cultivars and rootstocks. For instance, the cultivars Merlot, Tannat and Gamay noir were the richest in stilbenes while the rootstocks Gravesac, Fercal and 3390C contained the highest amounts. CONCLUSION: These findings provide insight into the knowledge that major grapevine cultivars and rootstocks can be used as a potential source of complex stilbenes.

Antifungal Activities of a Grapevine Byproduct Extract Enriched in Complex Stilbenes and Stilbenes Metabolization by Botrytis cinerea.

Grapevine co-products, as canes, represent a source of compounds of interest to control vineyard diseases with a sustainable approach. We chose to study an extract that we produced from grapevine trunk and roots. This extract, enriched in complex stilbenes, strongly reduced mycelial growth and spore germination of Botrytis cinerea, the fungal agent causing gray mold. The most active stilbenes were resveratrol, r-viniferin, and ε-viniferin. This grapevine extract also inhibited the production of Botrytis laccases. Conversely, Botrytis secretome metabolized resveratrol into δ-viniferin and pallidol (2 dimers); and ε-viniferin, a dimer, into hopeaphenol, r-viniferin, and r2-viniferin (3 tetramers). r-Viniferin and hopeaphenol (2 tetramers) were not metabolized. The biotransformed extract maintained an effective antimycelial activity. This study provides evidence that a grapevine extract enriched in oligomerized stilbenes exerts different anti-Botrytis activities, notwithstanding the ability of the fungus to metabolize some stilbenes.

Chiroptical and potential in vitro anti-inflammatory properties of viniferin stereoisomers from grapevine (Vitis vinifera L.).

Determination of stereochemistry and enantiomeric excess in chiral natural molecules is a research of great interest because enantiomers can exhibit different biological activities. Viniferin stilbene dimers are natural molecules present in grape berries and wine but also, in larger amount, in stalks of grapevine. Four stereoisomers of viniferin stilbene dimers (7aS,8aS)-E-ε-viniferin (1a), (7aR,8aR)-E-ε-viniferin (1b), (7aS,8aR)-E-ω-viniferin (2a), and (7aR,8aS)-E-ω-viniferin (2b) were isolated from grapevine stalks of Cabernet Sauvignon, Merlot and Sauvignon Blanc, using a combination of centrifugal partition chromatography (CPC), preparative and chiral HPLC. The structure elucidation of these molecules was achieved by NMR whereas the absolute configurations of the four stereoisomers were investigated by vibrational circular dichroism spectroscopy in combination with density functional theory (DFT) calculations. This study unambiguously established the (+)-(7aS,8aS) and (+)-(7aR,8aS) configurations for E-ε-viniferin and E-ω-viniferin, respectively. Finally, we show that Cabernet Sauvignon provided the quasi enantiopure (+)-(7aS,8aS)-E-ε-viniferin compound which presents the best anti-inflammatory and anti-oxidant activities.

Pinus pinaster Knot: A Source of Polyphenols against Plasmopara viticola.

Pine knot extract from Pinus pinaster byproducts was characterized by UHPLC-DAD-MS and NMR. Fourteen polyphenols divided into four classes were identified as follows: lignans (nortrachelogenin, pinoresinol, matairesinol, isolariciresinol, secoisolariciresinol), flavonoids (pinocembrin, pinobanksin, dihydrokaempferol, taxifolin), stilbenes (pinosylvin, pinosylvin monomethyl ether, pterostilbene), and phenolic acids (caffeic acid, ferulic acid). The antifungal potential of pine knot extract, as well as the main compounds, was tested in vitro against Plasmopara viticola. The ethanolic extract showed a strong antimildew activity. In addition, pinosylvins and pinocembrin demonstrated significant inhibition of zoospore mobility and mildew development. These findings strongly suggest that pine knot is a potential biomass that could be used as a natural antifungal product.

n-3 FA increase liver uptake of HDL-cholesterol in mice.

In humans, diets rich in fish oil (containing n-3 FA) decrease the incidence of coronary artery diseases. This is thought to be caused by the induction in liver and skeletal muscle of genes involved in lipid oxidation, and to the repression in liver and adipose tissue of genes responsible for lipogenesis. n-3 FA are known to reduce the synthesis of FA and TG in the liver, resulting in a decrease of plasma concentrations of TG-rich lipoproteins. On the other hand, little is known of a possible effect of n-3 FA on HDL metabolism. To investigate this question, female C57Bl/6J mice were fed an n-3 FA-enriched diet for 16 wk. As expected from previous studies, we found that total cholesterol, TG, and phospholipids were reduced in the plasma of treated mice. We also found that HDL-cholesterol decreased after this treatment and that the in vivo fractional catabolic rate of HDL-cholesteryl ester was significantly higher in treated mice than in control mice fed a standard diet. Consistent with these results, treated mice exhibited increased uptake of HDL-cholesteryl ester in the liver. Moreover, quantitative reverse transcriptase-PCR analysis showed a two- to threefold increase in scavenger receptor B-1 gene expression. Taken together, these results suggest that an n-3 FA-enriched diet stimulates one step in the reverse cholesterol transport in mice, probably by increasing the amount of the scavenger receptor class B-1. These effects of n-3 FA on HDL metabolism may contribute to their beneficial effects on the vasculature.

Low amounts of trans 18:1 fatty acids elevate plasma triacylglycerols but not cholesterol and alter the cellular defence to oxidative stress in mice.

Trans fatty acids are found mainly in processed foods. It has been shown that when their intake is high, total cholesterol, LDL-cholesterol and triacylglycerols are elevated, while HDL-cholesterol decreases. To evaluate a possible effect of these compounds, even in low amounts, C57Bl/6J mice were fed for 7 weeks a diet containing 13.6 % energy as partially hydrogenated rapeseed oil-enriched diet (Trans diet). The Trans diet contained 3 % energy as trans 18:1 fatty acid (elaidic acid). Control mice were on an isologous diet containing native rapeseed oil (Rapeseed diet) in which trans fatty acids were undetectable. Total, free and HDL-cholesterol as well as reverse cholesterol transport did not change. However, plasma triacylglycerol and VLDL levels increased. Hepatic gene expression in the Trans v. Rapeseed diet were compared using quantitative RT-PCR. The Trans diet produced a 2-3-fold elevation in mRNA of fatty acid synthase and microsomal transfer protein mRNA, explaining (at least in part) the observed increase in triacylglycerols and VLDL. In addition, mice on the Trans diet developed a deficiency in plasma vitamin E accompanied by a higher concentration of F2-isoprostanes, indicative of increased oxidative stress. The 78 kDa glucose-related protein (GRP78) mRNA expression increased 3-4-fold in liver, suggesting that a response against apoptosis was provoked by lipid peroxidation.