Bioactive stilbenes from Vitis vinifera grapevine shoots extracts.

BACKGROUND: Viticultural residues from commercial viticultural activities represent a potentially important source of bioactive stilbenes such as resveratrol. The main aim of the present study was therefore to isolate, identify and perform biological assays against amyloid-ß peptide aggregation of original stilbenes from Vitis vinifera shoots. RESULTS: A new resveratrol oligomer, (Z)-cis-miyabenol C (3), was isolated from Vitis vinifera grapevine shoots together with two newly reported oligostilbenes from Vitis vinifera shoots, vitisinol C (1) and (E)-cis-miyabenol C (2), and six known compounds: piceatannol, resveratrol, (E)-ε-viniferin (trans-ε-viniferin), ω-viniferin, vitisinol C and (E)-miyabenol C. The structures of these resveratrol derivatives were established on the basis of detailed spectroscopic analysis including nuclear magnetic resonance experiments. All the newly reported compounds were tested for their anti-aggregative activity against amyloid-ß fibril formation. Vitisinol C was found to exert a significant activity against amyloid-ß aggregation. CONCLUSION: Vitis vinifera grapevine shoots are potentially interesting as a source of new bioactive stilbenes, such as vitisinol C.

Anthocyanin phytochemical profiles and anti-oxidant activities of Vitis candicans and Vitis doaniana.

INTRODUCTION: Grapes are one of the most important fruit crops in the world. The quality of red grape berries greatly depends on skin colour, mainly due to the anthocyanin profile. Today, the American Vitis species have the greatest potential for breeding work. They have multiple resistance properties in comparison with Vitis vinifera but little is known about their anthocyanin content. OBJECTIVE: To determine the anti-oxidant properties and anthocyanin profile of two American species, Vitis candicans and Vitis doaniana, by using LC-MS(n) and LC-NMR. METHODS: Grape extracts were prepared by extraction of berry skins with acidified methanol. The complete structure elucidation of the individual anthocyanins was performed with LC-MS(n) , LC-NMR and NMR experiments. Individual anthocyanins in the extracts were quantified by using malvidin glucoside as external standard. The anti-oxidant activities of grape skin extracts were evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging and oxygen radical absorbance capacity (ORAC) assays. RESULTS: By using LC-MS(n) and LC-NMR experiments, 30 anthocyanins were identified and quantified in the two Vitis species, including two new cis-p-coumaroyl derivatives. Vitis candicans and V. doaniana showed significant differences in their anthocyanin profile. These two Vitis species possess low-to-medium anti-oxidant activities in comparison with V. vinifera. CONCLUSION: The profiles of 30 anthocyanins were established unambiguously in two American Vitis species.

New stilbene dimers against amyloid fibril formation.

Twenty stilbene derivatives and moracin M extracted from natural products were tested against amyloid-beta peptide (Abeta) aggregation. Results of stilbene monomer derivatives indicated that interaction with resveratrol and piceid was specific. Concerning oligomers, scirpusin A and epsilon-viniferin glucoside demonstrated a strong inhibition of the aggregation process.

The polyphenol piceid destabilizes preformed amyloid fibrils and oligomers in vitro: hypothesis on possible molecular mechanisms.

Alzheimer's disease (AD) is characterized by deposits of amyloid in various tissues. The neuronal cytotoxicity of Abeta peptides is attributed not only to various mechanisms but also to amyloid fibrils and soluble oligomeric intermediates. Consequently, finding molecules to prevent or reverse the oligomerization and fibrillization of Abeta could be of therapeutic value in the treatment of AD. We show that piceid, a polyphenol of the stilbene family, destabilized fibrils and oligomers to give back monomers that are not neurotoxic molecules. The mechanism of this destabilization could be a dynamic interaction between the polyphenol and the Abeta that could open the hydrophobic zipper and shift the reversible equilibrium "random coil<-->beta-sheet" to the disordered structure.

Hopeaphenol: the first resveratrol tetramer in wines from North Africa.

Grapes and wines are now known to constitute a rich source of phenolics such as stilbenes and flavonoids. These compounds have been shown to have cancer chemopreventive activity and potential beneficial effects on cardiovascular diseases thanks to their antioxidant and antiplatelet properties. However, because little is known about African wines and their phenolic compositions, we investigated wine samples from North Africa. A three-step method was used for the fractionation of the Merlot variety wine: column chromatography followed by centrifugal partition chromatography and reversed-phase semipreparative high-performance liquid chromatography (HPLC). Six polyphenolic compounds of the Merlot variety (from Algeria) were isolated and identified by NMR spectroscopy, five of which are known (trans-resveratrol, trans-piceid, trans-epsilon-viniferin, pallidol, and astilbin) and one that is reported for the first time in wine, (+)-hopeaphenol, a stilbene tetramer. Furthermore, these molecules were quantified in 10 commercial wines from North Africa by means of an analytical HPLC system coupled with diode array detection. Differences in concentrations were found ranging in mg/L from 4.6 to 45 (trans-piceid), 0.66 to 3.45 (trans-resveratrol), 0.2 to 1.2 (trans-epsilon-viniferin), 0.2 to 9.2 (pallidol), 0.3 to 3.8 (hopeaphenol), and 10.8 to 24.22 (astilbin). Such a high level of pallidol and astilbin has never been recorded in wine. North African wines may contribute to a significant proportion of dietary intake of stilbene and astilbin, which may have health benefits.

Two new benzylbenzoate glucosides from Curculigo orchioides.

An extract from in vitro cultures of Curculigo orchioides grown as bulbils in shake flasks, afforded two new glucosides of substituted benzylbenzoate - curculigoside C (3) and curculigoside D (4) - together with two known compounds - curculigoside A (1) and curculigoside B (2). Their structures were elucidated on the basis of spectral evidence, in particular by using 2D NMR methods. Their vasoactive properties were assessed in isolated rat aortic rings.

Unusual compounds from Galium mollugo and their inhibitory activities against ROS generation in human fibroblasts.

Three unusual dioxatricyclodecenone compounds, mollugoside A, E-mollugoside B and Z-mollugoside B and, together with known flavonoids, were isolated from the aerial parts of Galium mollugo collected in north-eastern Algeria. Their structures were elucidated by analysis of spectroscopic data, including 1D and 2D NMR. Flavonoids and mollugoside A significantly reduced reactive oxygen species (ROS) generation in human fibroblasts.

Determination of stilbenes (delta-viniferin, trans-astringin, trans-piceid, cis- and trans-resveratrol, epsilon-viniferin) in Brazilian wines.

Phenolics from grapes and wines can play a role against oxidation and development of atherosclerosis. Stilbenes have been shown to protect lipoproteins from oxidative damage and to have cancer chemopreventive activity. We describe a method for the direct determination of stilbenes in several red wines using high-performance liquid chromatography with UV detection. In a survey of 12 commercial wines from the south of Brazil (Rio Grande del Sul), levels of delta-viniferin are reported for the first time in different varieties of red wines. Brazilian red wine contains trans-astringin, trans-piceid, trans-resveratrol, cis-resveratrol (in high quantity: 5 times more than the trans form), epsilon-viniferin, and a compound isolated for the first time in wine, trans-delta-viniferin. Isolation and identification of delta-viniferin was achieved by NMR after extraction and fractionation of red wine phenolics. delta-Viniferin contributes, as well as cis-resveratrol and trans-piceid, to a significant proportion of stilbenes in wine dietary intake, particularly with Merlot varieties containing an average level of 10 mg/L for delta-viniferin, 15 mg/L for cis-resveratrol, and 13 mg/L for trans-piceid. The total stilbene intake from wine origin was estimated for the Brazilian population as 5.3 mg/day per person (on the basis of a regular wine consumption of 160 mL/day). delta-Viniferin can contribute to around 20% of total stilbenes in wine (average of 6.4 mg/L in red Brazilian wines). It would be important in the future to investigate the origins of the differences in wine stilbene levels in relation to the vine varieties, and the bioavailability of the newly extracted stilbene delta-viniferin in plasma after consumption of different types of wines.

Flavonol profiles in berries of wild Vitis accessions using liquid chromatography coupled to mass spectrometry and nuclear magnetic resonance spectrometry.

The flavonol profiles of grape berry skins were analysed in order to assess phenotypic variation between six grapevines belonging to six different species: Vitis vinifera, Vitiscandicans, Vitischampinii, Vitisamurensis, Vitiscinerea and Vitisdoaniana. High-performance liquid chromatography coupled to mass spectrometry (LC-MS) and NMR spectrometry (LC-NMR) were used to separate and identify the flavonols present in these species. The combination of LC-MS and LC-NMR data resulted in the identification of eighteen flavonols. In particular, the new flavonol diglycoside and pentoside derivatives were determined. In addition, the antioxidant capacities of flavonol grape skin extracts were evaluated by using an oxygen radical absorbance capacity method (ORAC).

Preparative isolation of polyphenolic compounds from Vitis vinifera by centrifugal partition chromatography.

This study deals with a centrifugal partition chromatography developed for the separation of phenolic compounds from Vitis vinifera. EtOAc grape seed extracts were separated using the solvent system hexane-ethyl acetate-ethanol-water (1:8:2:7; v/v) in two fractions: one containing about 75% of flavanol monomers (catechin and epicatechin) corresponding to 18% of crude extract and another fraction B-type dimers (22% of crude extract). From the stalk extracts, we could separate stilbenoid compounds (resveratrol and its oligomers; 12% of crude extract) which were eluted in less than 30 min from flavanols (which required a few hours of additional elution). Using the same solvent system but in different ratios (4:5:3:3; v/v), we isolated the trans-resveratrol (7@1000; 90% purity).

Levels of stilbene oligomers and astilbin in French varietal wines and in grapes during noble rot development.

Phenolics from grapes and wines can play a role against oxidation and development of atherosclerosis. Stilbenes have been shown to have cancer chemopreventive activity and to protect lipoproteins from oxidative damage. A method for the direct determination of stilbene oligomers (viniferin and pallidol) as well as astilbin in different types of wine using high-performance liquid chromatography with UV detection is described. In a survey of 21 commercial wines from the south of France, levels of pallidol and viniferin are reported for the first time in different types of wines. Viniferin was found to be present only in red and botrytized sweet white wines with levels between 0.1 and 1.63 mg/L; pallidol was not found in dry and sweet white wines but only in wines made by maceration with stems, with levels between 0.38 and 2.22 mg/L. Highest levels of astilbin were found in Egiodola (15.13 mg/L), Merlot (11.61 mg/L), and Cabernet Sauvignon (8.24 mg/L) for red wines and in Sauvignon (5.04 mg/L) for white varietal wines. Astilbin levels are highest for recent vintages, but pallidol is not found in older vintages. During noble rot development in Sauvignon or Sémillon grapes from the Sauternes area, levels of trans-astringin, trans-resveratrol, trans-piceid, and pallidol are quite low (<0.5 mg/kg of grapes). Viniferin and astilbin levels become optimum at 2 and 30 mg/kg, respectively, during spot grape and speckle grape stages.

Polyphenols from the stems of Morus alba and their inhibitory activity against nitric oxide production by lipopolysaccharide-activated microglia.

Neuroinflammatory processes are involved in the pathogenesis of many neurodegenerative disorders. Microglial cells, the main immune cells of the central nervous system, represent a target of interest to search for naturally occurring anti-inflammatory products. In this study, we evaluated the anti-inflammatory properties of polyphenols obtained from the stems of Morus alba. This edible species, known as white mulberry, is frequently studied because of its traditional use in Asian medicine and its richness in different types of polyphenols, some of which are known to be phytoalexins. One new coumarin glycoside, isoscopoletin 6-(6-O-ß-apiofuranosyl-ß-glucopyranoside) (1) was mainly isolated by CPC (centrifugal partition chromatography) from this plant, together with seven known polyphenols (2-8). Their structures were established on the basis of spectroscopic analyses including extensive 2D NMR studies. The eight isolated compounds were evaluated for their inhibitory activities on nitric oxide (NO) production in lipopolysaccharide (LPS)-induced BV-2 microglial cells. The absence of cell toxicity is checked by a MTT assay.

Identification and quantification of furanocoumarins in stem bark and wood of eight Algerian varieties of Ficus carica by RP-HPLC-DAD and RP-HPLC-DAD-MS.

Furanocoumarins are the major phytoalexins of Ficus carica and are effective natural drug candidates for treatment of several types of cancer and skin disease. The objectives of this study were to analyze and quantify linear furanocoumarins, mainly psoralen and bergapten, in wood and bark of stems from eight Algerian varieties of fig and to establish the differences in the content of these metabolites in the eight local samples. Psoralen and bergapten contents in the stem bark and wood (in microg/g DW) varied respectively from 146.6 to 1110.3 and from 395.7 to 1671.8 for psoralen, and from 114.3 to 524.0 and from 144.2 to 718.6 for bergapten. This study fills a gap in our knowledge of furanocoumarin distribution in different parts of the fig tree. Psoralen and bergapten concentrations were higher in the wood than in the stem bark. Most of the dark fruited fig trees produce these two coumarins more than the green ones.

Stilbenoid profiles of canes from Vitis and Muscadinia species.

We present stilbenoid profiles of canes from 16 grapevines. Fifteen stilbenoids were obtained through isolation and structure identification using MS, NMR, and [α](D) or as commercial standards. An HPLC-UV method for the simultaneous quantification of nine of these stilbenoids was developed and applied to canes of Vitis amurensis, Vitis arizonica, Vitis berlandieri, Vitis betulifolia, Vitis cinerea, Vitis × champini, Vitis × doaniana, Vitis labrusca, Vitis candicans (syn. Vitis mustangensis), Vitis riparia, Vitis rupestris, Vitis vinifera, Muscadinia rotundifolia, and a V. vinifera × M. rotundifolia hybrid. In these species, E-ampelopsin E, E-amurensin B, E-piceid, E-piceatannol, E-resveratrol, E-resveratroloside, E-ε-viniferin, E-ω-viniferin, and E-vitisin B were quantified, when found in sufficient amounts. Total concentrations ranged from ~2.2 to 19.5 g/kg of dry weight. Additional stilbenoids, E-3,5,4'-trihydroxystilbene 2-C-glucoside, Z-ampelopsin E, Z-trans-miyabenol C, E-trans-miyabenol C, scirpusin A, and Z-vitisin B, were identified but not quantified. Our results indicate that canes, particularly those of non-vinifera species, have substantial quantities of valuable, health-promoting stilbenoids.

Anthocyanin identification and composition of wild Vitis spp. accessions by using LC-MS and LC-NMR.

The composition and concentration of anthocyanins of grape berry skins were analyzed in order to assess phenotypic variation between four grape wine varieties belonging to 4 different species: Vitis vinifera, Vitis amurensis, Vitis cinerea and Vitis X champinii. High-performance liquid chromatography coupled to mass spectrometry (LC-MS) and NMR spectroscopy (LC-NMR) were used to separate and identify the structure of anthocyanins present in these species. Combination of LC-MS and LC-NMR data resulted in the identification of 33 anthocyanins. In particular, newly reported cis isomers of p-coumaric-derivatives were identified (petunidin-, peonidin- and malvidin-3-(6-p-coumaroyl)-5-diglucoside). In V. cinerea and V. vinifera, anthocyanins were monoglucoside derivatives whereas in V. amurensis and V. X champinii, both mono- and diglucoside derivatives were identified. Malvidin-, delphinidin- and petunidin-derivatives were, respectively, the most abundant components in V. cinerea and V. vinifera, V. amurensis and V. X champinii.

New stilbenoid glucosides isolated from Vitis vinifera cell suspension cultures (cv. Cabernet Sauvignon).

Three new monomeric stilbenoid glucosides, (Z)- and (E)-resveratrol 3,5- O-beta-diglucosides (1 and 2, respectively) and (Z)-resveratrol 3,5,4'- O-beta-triglucoside (3), were isolated from an extract of Vitis vinifera cell cultures (Cabernet Sauvignon) together with the known (E)- and (Z)-piceids and (E)- and (Z)-resveratrol 3,4'- O-beta-diglucosides that have already been identified in a Gamay cell culture extract. The structure determinations were based on spectroscopic data analysis.