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Background Thapsigargin and nortrilobolide are sesquiterpene lactones found in the Mediterranean plant Thapsia garganica L. Thapsigargin is a potent inhibitor of the sarco/endoplasmic reticulum calcium ATPase pump, inducing apoptosis in mammalian cells. This mechanism has been used to develop a thapsigargin-based cancer drug first by GenSpera and later Inspyr Therapeutics (Westlake Village, California). However, a stable production of thapsigargin is not established. Results In vitro regeneration from leaf explants, shoot multiplication and rooting of T. garganica was obtained along with the production of thapsigargins in temporary immersion bioreactors (TIBs). Thapsigargin production was enhanced using reduced nutrient supply in combination with methyl jasmonate elicitation treatments. Shoots grown in vitro were able to produce 0.34% and 2.1% dry weight of thapsigargin and nortrilobolide, respectively, while leaves and stems of wild T. garganica plants contain only between 0.1 and 0.5% of thapsigargin and below detectable levels of nortrilobolide. In addition, a real-time reverse transcription PCR (qRT-PCR) study was performed to study the regulatory role of the biosynthetic genes HMG-CoA reductase (HMGR), farnesyl diphosphate synthase (FPPS), epikunzeaol synthase (TgTPS2) and the cytochrome P450 (TgCYP76AE2) of stem, leaf and callus tissues. Nadi staining showed that the thapsigargins are located in secretory ducts within these tissues. Conclusions Shoot regeneration, rooting and biomass growth from leaf explants of T. garganica were achieved, together with a high yield in vitro production of thapsigargin in TIBs. Electronic supplementary material The online version of this article (10.1186/s13007-018-0346-z) contains supplementary material, which is available to authorized users.

International audience; Grenache, Syrah, Carignan Noir, Mourvedre, Counoise and Alicante Bouchet grape seeds and skins, harvested in 2009 and 2010 in the Rhone valley area of France, and their respective pomaces remaining after vinification, were analyzed for their phenolic composition and antioxidant activity. The polyphenol content was quantified by HPLC and the Folin-Ciocalteu assay. The antioxidant potential was measured with four different assays: ORAC, FRAP, ABTS and DPPH. Seeds contained higher amounts of total polyphenols, up to 44.5 mg of gallic acid equivalent [GAE]/g dry weight in Alicante pomace, than skin extracts. The maximum total phenolic in skins was 31.6 mg GAE/g dry weight detected in 2010 Alicante pomace. Seeds also had the highest antioxidant capacity. HPLC analysis revealed that, despite the vinification process, pomaces still contained an appreciable amount of proanthocyanidins as well as several anthocyanin glycosides. Alicante and Syrah proved to be the varieties of most interest in terms of their potential development for nutraceutical purposes.

Background and Aims: The impact of grey mould (Botrytis cinerea (B. cinerea)) was quantified on chemical, phenolic and sensory qualities of grapes, derived musts and wines. Methods and Results: Analyses were carried out by using naturally or artificially infected grape berries at ripeness or overripeness. In grape seeds, chemical analyses revealed no major differences between healthy and rotten grapes. In grape skins of Botrytis-affected berries, concentrations of all the phenolic compounds (anthocyanins and proanthocyanidin monomers, dimers and trimer) decreased drastically. Mean degree of polymerization of the proanthocyanidin polymeric fraction was also affected in skins. Chemical analyses of musts and wines made with different percentages of rotten berries showed a moderate impact of the pathogen on their phenolic composition. Nevertheless, sensory analyses underlined a loss of wine sensory quality perceptible from a threshold as low as 5% of Botrytis-affected grapes onwards. Conclusion: Phenolic variations and the associated negative impact in grapes, derived musts and wines may be related to oxidation phenomena from B. cinerea. The main effects of severity/age of grey mould and the level of berry maturity are also discussed. Significance of the Study: B. cinerea drastically affects the phenolic and organoleptic properties of grape skins and derived wines. Therefore, prophylactic actions early in the vineyard, evaluation of the sanitary status of the harvested grapes and berry sorting are primordial even under low disease pressure.

Background and Aims: The impact of Esca, a cryptogamic disease affecting woody tissues of grapevines (trunk, branches and shoots), was investigated on phenolic and sensory qualities of Cabernet Sauvignon grapes, derived musts and wines. Methods and Results: Global phenolic analyses revealed no major difference between healthy and affected grapes whereas high-performance liquid chromatography analyses showed decreases in the skin concentrations of catechin and epicatechin and of anthocyanins for the two vintages assessed. Proanthocyanidin characteristics, and particularly mean degree of polymerisation, were strongly decreased in skin proanthocyanidin polymeric fractions. Chemical analyses of wines made with different percentages of fruit from Esca infected grapevines confirmed the moderate impact of Esca on phenolic composition. Nevertheless, sensory analyses revealed a loss of wine sensory quality perceptible with as little as 5% of affected fruit in wines. Conclusions: Phenolic variations in grapes and in derived wines may be related to changes to grapevine physiology caused by Esca fungi that impact on flavonoid metabolism. The chemical and sensory variations between wines can also be related to the delayed ripening delay of fruit from Esca infected grapevines. Significance of the Study: Esca moderately affected the phenolic composition of grapes and decreased the sensory quality of wines, suggesting a dramatic increase in the economic importance of Esca if no control methods are found.

International audience; The proanthocyandin composition of skins and seeds of Bordeaux Merlot (M) and Cabernet Sauvignon (CS) grapes was evaluated by HPLC-UV-fluorescence for four consecutive vintages (2006 to 2009). The results indicated a strong vintage effect on the tannin profile of each variety. However, and in spite of the vintage effect, some tannin characteristics such as mDP, %G and %P allow discrimination of both Bordeaux varieties. The same analyses were carried out for the 2009 vintage of five Mediterranean grape varieties (Syrah, Grenache, Mourvedre, Carignan and Counoise). The results demonstrated differences among these five varieties. Syrah appeared to exhibit the highest concentrations of flavanol monomers and dimmers, especially in skins. The comparison study between Bordeaux and Mediterranean grape varieties for the same vintage (2009) revealed that mDP and %G for seed extracts were parameters specific to each vineyard area.

The antioxidant activity of eight synthetic 4-methylcoumarins was systematically studied. The antioxidant capacity was measured using: (i) a competition kinetic test, to measure the relative capacity to quench peroxyl radical; (ii) the in vitro oxidative modification of human low-density lipoprotein, initiated by AAPH or catalyzed by copper. In both models, the ortho-OH substitutes were found to be better antioxidant than the meta one. The most efficient antioxidant was the 7,8-dihydroxy-4-methylcoumarin and the corresponding diacetoxy-substituted was unexpectedly a good antioxidant. Finally, the presence of an ethoxycarbonylethyl substituent at the C-3 position increased the antioxidant capacity of both 7,8-dihydroxy-4-methylcoumarin and 7,8-diacetoxy-4-methylcoumarin.

International audience; The gastric tract may be the first site exposed to diet-related oxidative stress. After food intake, dietary iron such as (met)myoglobin, the pigment of meat, oxygen, and polyunsaturated lipids come into close contact. The main goal of this work is the in vitro investigation of lipid oxidation taking place in the gastric compartment and its inhibition by dietary polyphenols. Oil-in-water emulsions stabilized either by bovine serum albumin (BSA) or egg yolk phospholipids (PL) were designed to model the gastric content. The metmyoglobin-initiated lipid oxidation led to the accumulation of lipid-derived conjugated dienes and volatile aldehydes. These reactions were faster in the BSA model than in the PL model, highlighting the influence of the interfacial composition. Quercetin, rutin, (+)-catechin, caffeic acid, and chlorogenic acid proved to be better inhibitors than α-tocopherol and ascorbic acid. Emulsions as models of the gastric environment are valuable tools to study the stability of macro- and micronutrients

International audience; The aim of the present study was to validate the joint sensory impact of target compounds on the typicality degree of wine. Target compounds were selected from previous gas chromatography-olfactometry analysis. The preliminary experiment consisted in selecting odorants thought to have a positive effect on typical Chardonnay wines. Two sets of target compounds were chosen with regard to expected relationships between their concentrations and typicality scores. Target compounds were quantified in 20 wines. The second experiment was dedicated to the sensory evaluation of aroma models obtained by supplementation in wines. Three Chardonnay wines with intermediate typicality scores were supplemented with 6- or 10-compound combinations. The typicality degree of 24 samples was assessed by expert orthonasal perception. Wines supplemented with the 6-compound combinations were judged to be intermediate, whereas wines including the 10-compound combinations were considered to be quite representative of the Chardonnay concept. Such results confirm the active contribution of the 10 combined target compounds to typical Chardonnay wines.

National audience

National audience; Étude de l'impact de Botrytis cenerea sur la composition chimique de raisins de Merlot, de moûts et vins vinifiés à partir de différents pourcentages de raisins affectés par le Botrytis.

International audience; Impact of (+)-catechin and gallic acid on sensory perception and volatility of isoamyl acetate, ethyl isobutyrate, ethyl butyrate and ethyl octanoate was investigated in model solutions, by means of triangle tests, detection threshold determination and HS-GC-MS analyses. Catechin significantly altered the sensory perception of most esters (ethyl isobutyrate, ethyl butyrate and ethyl octanoate) while gallic acid displayed no impact. Ethyl butyrate and ethyl octanoate odour thresholds doubled or tripled in the presence of catechin, underlining a retention impact of phenolic compounds in liquid matrix. The headspace analyses displayed a decrease only in ethyl octanoate volatility in presence of catechin, whereas no significant difference in other esters concentrations was observed. This study indicated that phenolic compounds have a variable impact on aroma compounds' volatility and their sensory perception. The polarity of phenolic and volatile compounds as well as their spatial conformation also appeared to influence the interaction strength.

International audience; Grape and wine phenolics are structurally diverse, from simple molecules to oligomers and polymers usually designated as tannins. They have an important impact on the organoleptic properties of wines, that's why their analysis and quantification are of primordial importance. The extraction of phenolics from grapes and from wines is the first step involved in the analysis. Then, several analytical methods have been developed for the determination of total content of phenolic, while chromatographic and spectrophotometric analyses are continuously improved in order to achieve adequate separation of phenolic molecules, their subsequent identification and quantification. This review provides a summary of evolution of analysis of polyphenols from grapes, wines and extracts.

Aims: Fourier Transform-Near Infrared (FT-NIR) spectrum and instrumental texture parameters were assessed as total phenol content and extractability predictors in intact grape seeds. Methods and results: The study was carried out on Cabernet-Sauvignon seeds from grapes harvested at six different advanced physiological stages throughout ripening and calibrated by flotation to reduce the in-field heterogeneity inside each sample. Among the instrumental mechanical properties tested (i.e., break force, break energy, Young's modulus of elasticity and deformation index), the seed Young's modulus of elasticity showed an increase during the first four weeks of ripening. This parameter also showed significant correlations with phenol content and extractability, although with low R coefficients. These correlations highlighted that the springier seed tissues greatly increase phenol extractability. Nevertheless, the best prediction of seed phenol content, performed directly on intact seeds, was found using FT-NIR spectroscopy in transmittance mode. The standard error of prediction for total phenol content was less than 8 %, while that for phenol extractability was worse. Conclusion: On the basis of these results, the two analytical methods could be applied in oenology for the rapid monitoring of seed phenolic maturity. Significance and impact of the study: The phenolic composition of grapes at the harvest time is a key factor determining their quality, and thus the quality of the finished wine. The chemical methods used for the determination of seed phenol content and extractability are generally slow because they require a preliminary extraction. Therefore, a rapid evaluation of these parameters could be highly interesting for the oenological sector., Objectifs: Le spectre FT-NIR (Fourier Transform-Near Infrared) et les paramètres instrumentaux de la texture sont assumés comme indices de la teneur en phénols et de leur extractibilité de pépins entiers. Méthodes et résultats: L’étude concerne les pépins de raisins de Cabernet- Sauvignon cueillis pendant la maturation des baies. Parmi les propriétés mécaniques instrumentales testées (résistance des pépins à la rupture, force de rupture, formule d’élasticité de Young, indice de déformation), la formule d’élasticité de Young a montré une augmentation pendant les quatre premières semaines de maturation. Ce paramètre a également montré une corrélation significative avec la teneur en phénols et avec l’extractibilité, bien qu’avec un faible coefficient R. Ces corrélations soulignent une extractibilité des phénols plus accentuée dans les tissus des pépins plus élastiques. Néanmoins, la meilleure prédiction de la teneur en phénols, évaluée directement sur les pépins intacts, a été celle obtenue par l’emploi de la spectrophotométrie FT-NIR en transmittance. L’erreur standard pour la prédiction de la teneur en phénols totaux était inférieure à 8% tandis que celle pour l’extractibilité était moins fiable. Conclusion: Sur la base de ces résultats, les deux techniques peuvent être proposées pour la détermination rapide de la maturité phénolique des pépins. Signification et impact de l’étude: La composition phénolique des raisins à la récolte est un élément clé pour leur qualité et donc pour la qualité du vin produit. Les méthodes chimiques pour la détermination de la teneur en phénols des pépins et de leur extractibilité sont généralement longues, parce qu’une extraction préliminaire est requise. Une évaluation rapide de ces paramètres peut donc être très utile pour le secteur oenologique

International audience; The gastric tract may be the first site where food is exposed to postprandial oxidative stress and antioxidant activity by plant micronutrients. After food intake, dietary iron, dioxygen, and emulsified lipids come into close contact and lipid oxidation may take place. This study investigated lipid oxidation and its inhibition by dietary polyphenols in gastric-like conditions. Lipid oxidation induced by heme and nonheme iron was studied in acidic sunflower oil-in-water emulsions. The emulsifier type (bovine serum albumin, phospholipids), pH, and iron form were found to be factors governing the oxidation rates. Quercetin, rutin, and chlorogenic acid highly inhibited the metmyoglobin-initiated lipid oxidation in both emulsified systems at pH 5.8. Additionally, quercetin inhibited nonheme iron-initiated processes, while it was inefficient with hematin as an initiator. The presence of human gastric juice did not influence lipid oxidation, although it diminished the antioxidant activity of phenolics. Model emulsions may thus be valuable tools to study the gastric stability of polyunsaturated lipids.

International audience; Cabernet-Sauvignon and Merlot skin and seed extracts from Bordeaux grapes were investigated to determine both grape variety and vintage effect on phenolic composition. The total content of polyphenols and tannins in Merlot seeds was higher than that of Cabernet-Sauvignon allowing to discriminate the varieties. HPLC analyses underlined significant differences in the absolute concentration of proanthocyanidins amongst the two varieties and in their composition: mean degree of polymerisation (mDP) and percentage of galloylation of seed extracts were good indicators of grape variety. The vintage effect on the phenolic composition was confirmed for 2009 in comparison to previous vintages. Low values of mDP and concentrations of proanthocyanidins and anthocyanins were found in 2009 seeds and skins. The climatic conditions of 2009 (high rainfall before flowering followed by a strong hydric stress during berries development until ripening) let us hypothesise a lower activation of flavonoid pathway.

Metmyoglobin (MbFe III ), a major form of dietary iron, is an efficient inducer of lipid and protein oxidation. Indeed, MbFe III is able to cleave hydrogen peroxide and lipid hydroperoxides with subsequent formation of ferrylmyoglobin (MbFe IV = O) and lipid oxyl and peroxyl radicals. In the first part of this work, the mechanism of the reaction between MbFe III and H 2 O 2 is revisited with an emphasis on the influence of bovine serum albumin (BSA). BSA does not affect the rate of MbFe IV = O formation but inhibits the formation of a redox-inactive green pigment (heme-protein cross-link species). Although tightly bound to BSA, the flavonol quercetin is still able to reduce MbFe IV = O as a likely result of long-range electron transfers within a protein–protein complex. In the second part, BSA is shown to strongly slow down the metmyoglobin-catalyzed consumption of linoleic acid hydroperoxides with formation of ketones as the main products. In the process, only low concentrations of ferrylmyoglobin are slowly accumulated. A catalytic mechanism is proposed that involves a one-electron-oxidized metmyoglobin species distinct from ferrylmyoglobin.