Publications by authors named "Axel Marchal"

32 Publications

Methyl salicylate, a grape and wine chemical marker and sensory contributor in wines elaborated from grapes affected or not by cryptogamic diseases.

Food Chem 2021 Oct 15;360:130120. Epub 2021 May 15.

Univ. Bordeaux, Unité de recherche Œnologie, EA 4577, USC 1366 INRAE, F-33140 Villenave d'Ornon, France. Electronic address:

Methyl salicylate (MeSA) is a plant metabolite that induces plant defence resistance and an odorous volatile compound presenting green nuances. This volatile compound was shown to be present in wine samples, sometimes at concentrations above its olfactory detection threshold. MeSA is localized in grapes, particularly in the skins and stems, and is extracted during red wine vinification. It was detected at the highest concentrations in wines of several grape varieties, made from grapes affected by cryptogamic diseases, namely downy mildew caused by Plasmopara viticola, and black rot caused by Guignardia bidwellii. It has also been detected in wines from vines affected by Esca, a Grapevine Trunk Disease. MeSA can also be considered to be a chemical marker in grapes and wine indicative of the level of development of several vine cryptogamic diseases.
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http://dx.doi.org/10.1016/j.foodchem.2021.130120DOI Listing
October 2021

Untargeted LC-HRMS profiling followed by targeted fractionation to discover new taste-active compounds in spirits.

Food Chem 2021 Oct 20;359:129825. Epub 2021 Apr 20.

Univ. Bordeaux, Unité de Recherche Œnologie, EA 4577, USC 1366 INRA, ISVV, 33882 Villenave d'Ornon Cedex, France. Electronic address:

Taste is a key driver of food and beverage acceptability due to its role in consumers' pleasure. The great interest that natural food and beverages now arouse lies notably in the complexity of their taste, which in turn is related to a wide range of taste-active compounds. Going beyond the classic divide between targeted and untargeted strategies, an integrative methodology to spirits was applied. Untargeted profiling of several cognac spirits was implemented by LC-HRMS to identify compounds of interest among hundreds of ions. A targeted fractionation protocol was then developed. By using HRMS and NMR, dihydrodehydrodiconiferyl alcohol was identified and described for the first time in spirits and oak wood. It was characterized as sweet at 2 mg/L in two matrices and was quantified in spirits up to 4 mg/L. These findings demonstrated how this methodology is relevant and effective to discover new taste-active compounds.
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http://dx.doi.org/10.1016/j.foodchem.2021.129825DOI Listing
October 2021

Investigation of lipase-ligand interactions in porcine pancreatic extracts by microscale thermophoresis.

Anal Bioanal Chem 2021 Jun 2;413(14):3667-3681. Epub 2021 Apr 2.

Institut de Chimie Organique et Analytique (ICOA), CNRS FR 2708 - UMR 7311, Université d'Orléans, 45067, Orléans, France.

The evaluation of binding affinities between large biomolecules and small ligands is challenging and requires highly sensitive techniques. Microscale thermophoresis (MST) is an emerging biophysical technique used to overcome this limitation. This work describes the first MST binding method to evaluate binding affinities of small ligands to lipases from crude porcine pancreatic extracts. The conditions of the MST assay were thoroughly optimized to successfully evaluate the dissociation constant (K) between pancreatic lipases (PL) and triterpenoid compounds purified from oakwood. More precisely, the fluorescent labeling of PL (PL*) using RED-NHS dye was achieved via a buffer exchange procedure. The MST buffer was composed of 20 mM NaHPO + 77 mM NaCl (pH 6.6) with 0.05% Triton-X added to efficiently prevent protein aggregation and adsorption, even when using only standard, uncoated MST capillaries. Storage at -20 °C ensured stability of PL* and its fluorescent signal. MST results showed that crude pancreatic extracts were suitable as a source of PL for the evaluation of binding affinities of small ligands. Quercotriterpenoside-I (QTT-I) demonstrated high PL* binding affinity (31 nM) followed by 3-O-galloylbarrinic acid (3-GBA) (500 nM) and bartogenic acid (BA) (1327 nM). To enrich the 50 kDa lipase responsible for the majority of hydrolysis activity in the crude pancreatic extracts, ammonium sulfate precipitation was attempted and its efficiency confirmed using capillary electrophoresis (CE)-based activity assays and HRMS. Moreover, to accurately explain enzyme modulation mechanism, it is imperative to complement binding assays with catalytic activity ones.
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http://dx.doi.org/10.1007/s00216-021-03314-7DOI Listing
June 2021

Understanding sweetness of dry wines: First evidence of astilbin isomers in red wines and quantitation in a one-century range of vintages.

Food Chem 2021 Aug 15;352:129293. Epub 2021 Feb 15.

Univ. de Bordeaux, ISVV, EA 5477, Unité de recherche ŒNOLOGIE, USC 1366 INRA, F-33882 Villenave d'Ornon, France. Electronic address:

Astilbin (2R, 3R) was recently reported to contribute to wine sweetness. As its aglycon contains two stereogenic centers, three other stereoisomers may be present: neoisoastilbin (2S, 3R), isoastilbin (2R, 3S), and neoastilbin (2S, 3S). This work aimed at assaying their presence for the first time in wines as well as their taste properties. The isomers were synthesized from astilbin and purified by semi-preparative HPLC. With the four stereoisomers, a sweet taste was perceived whose intensity varied with the configuration. Their content was assayed by developing a UHPLC-Q-Exactive method. The method was applied to screen astilbin and isomers in various wines, especially in different vintages from the same estate. While young wines contained higher concentrations of astilbin than the old ones, the concentrations of the other isomers, mainly neoastilbin, were higher in the old wines, suggesting their formation over time.
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http://dx.doi.org/10.1016/j.foodchem.2021.129293DOI Listing
August 2021

Screening for pancreatic lipase natural modulators by capillary electrophoresis hyphenated to spectrophotometric and conductometric dual detection.

Analyst 2021 Feb;146(4):1386-1401

Institut de Chimie Organique et Analytique (ICOA), CNRS FR 2708 - UMR 7311, Université d'Orléans, 45067 Orléans, France.

The search for novel pancreatic lipase (PL) inhibitors has gained increasing attention in recent years. For the first time, a dual detection capillary electrophoresis (CE)-based homogeneous lipase assay was developed employing both the offline and online reaction modes. The hydrolysis of 4-nitrophenyl butyrate (4-NPB) catalyzed by PL into 4-nitrophenol and butyrate was monitored by spectrophotometric and conductimetric detection, respectively. The assays presented several advantages such as economy in consumption (few tens of nanoliters for online assays to few tens of microliters for offline assays), no modification of lipase, rapidity (<10 min) and versatility. Tris/MOPS (10 mM, pH 6.6) was used as the background electrolyte and the incubation buffer for enzymatic reactions. We confirmed that in the conditions of the study (small substrate 4-NPB, 37 °C, pH 6.6), the PL was active even in the absence of dipalmitoylphosphatidylcholine (DPPC) vesicles, generally used to mimic the lipid-water interface. This was confirmed by the maximum velocity (Vmax) and the Michaelis-Menten constant (Km) values that were the same order of magnitude in the absence and presence of DPPC. The developed method was used to screen crude aqueous plant extracts and purified compounds. We were able to identify the promising PL inhibition of hawthorn leaf herbal infusions at 1 mg mL-1 (37%) and PL activation by fresh and dry hawthorn flowers (∼24%). Additionally, two triterpenoids purified from extracts of oakwood were identified for the first time as potent PL inhibitors demonstrating 51 and 58% inhibition at 1 mg mL-1, respectively.
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http://dx.doi.org/10.1039/d0an02234aDOI Listing
February 2021

Role of Oak Coumarins in the Taste of Wines and Spirits: Identification, Quantitation, and Sensory Contribution through Perceptive Interactions.

J Agric Food Chem 2020 Jul 6;68(28):7434-7443. Epub 2020 Jul 6.

Université Bordeaux, Unité de Recherche Œnologie, EA 4577, USC 1366 INRA, ISVV, 33882 Villenave d'Ornon Cedex, France.

During barrel aging, wines and spirits undergo sensory changes as a result of the release of aroma and taste molecules. Among the nonvolatile compounds, various coumarins have already been identified in oak wood but their sensory role remained unclear. In this study, the presence of coumarins in oak wood extract, wine, and spirits was first assessed by targeted screening. Fraxetin was identified for the first time in these matrices. After development and validation of a liquid chromatography-high-resolution mass spectrometry quantitation method, esculetin, scopoletin, fraxetin, umbelliferone, 4-methylumbelliferone, and coumarin were assayed in various wines and spirits. The concentrations measured were generally below the gustatory detection thresholds determined in wines and spirits. Nevertheless, by adding a mixture of coumarins in wines and spirits, a significant increase in bitterness was observed, thus demonstrating their potential contribution to the taste of wines and spirits through perceptive interactions.
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http://dx.doi.org/10.1021/acs.jafc.0c02619DOI Listing
July 2020

Polyethylene glycol crowding effect on hyaluronidase activity monitored by capillary electrophoresis.

Anal Bioanal Chem 2020 Jul 6;412(17):4195-4207. Epub 2020 May 6.

Institut de Chimie Organique et Analytique (ICOA), CNRS FR 2708 - UMR 7311, Université d'Orléans, 45067, Orléans, France.

To mimic the activity of hyaluronidase in natural environment, the hydrolysis of hyaluronic acid (HA) by hyaluronidase was investigated for the first time in the presence of crowding agents using capillary electrophoresis (CE) as a simple and reliable technique for conducting enzymatic assay. Polyethylene glycol (PEG) 6000 was selected as a model crowder and the hyaluronic acid degradation catalyzed by bovine testes hyaluronidase (BTH) was carried out at different PEG concentrations (0%, 10%, and 17%). After optimization of the CE analytical method and enzymatic assay, the degradation products were monitored at different HA concentrations. At 10% of PEG and 0.3 mg mL of HA, the activity of the enzyme was significantly reduced showing inconvenient interactions of PEG with the hyaluronidase blocking the release of hydrolysis products. A similar reduction of hyaluronidase activity was observed at 1 mg mL of HA due to the presumable formation of the BTH-substrate complex. The experimental curves obtained by CE also evidence that the overall kinetics are governed by the hydrolysis of hexasaccharide intermediates. Finally, the effect of PEG on hyaluronidase activity was evaluated in the presence of natural or synthetic inhibitors. Our results show a significant difference of the inhibitors' affinity toward hyaluronidase in the presence of PEG. Surprisingly, the presence of the crowding agent results in a loss of the inhibition effect of small polycyclic inhibitors, while larger charged inhibitors were less affected. In this work, CE analyses confirm the importance of mimicking the cellular environment for the discovery and development of reliable inhibitors. Graphical abstract.
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http://dx.doi.org/10.1007/s00216-020-02659-9DOI Listing
July 2020

Isolation of Taste-Active Triterpenoids from : Sensory Assessment and Identification in Wines and Spirit.

J Nat Prod 2020 05 28;83(5):1611-1622. Epub 2020 Apr 28.

Univ. Bordeaux, ISVV, Unité de Recherche Œnologie, EA 4577, USC 1366 INRA, ISVV, 33882 Villenave d'Ornon Cedex, France.

Six new triterpenoids (-), two known genins ( and ), and five known functionalized triterpenoids (-) were isolated from a heartwood extract. The purification protocol was guided by LC-HRMS by searching for structural analogues of bartogenic acid on the basis of their putative empirical formula. The structures of the new compounds were unequivocally elucidated using HRESIMS and 1D/2D NMR experiments. Sensory analyses were performed in water and in a non-oaked white wine on the pure compounds - at 5 mg/L. All molecules were perceived as bitter in water and wine, but they were mostly reported as modifying the wine taste balance. Using LC-HRMS, compounds - were observed in oaked red wine and cognac and were semiquantified in oak wood extracts. The influence of two cooperage parameters, oak species and toasting process, on compounds - content was studied. All compounds were found in quantities significantly higher in pedunculate than in sessile oak wood. Toasting is a key step in barrel manufacture and modulates the concentration of the discussed compounds. Significantly higher quantities were observed in untoasted wood compared to medium or highly toasted wood. These findings provide new insights into the molecular origin of taste changes due to oak aging.
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http://dx.doi.org/10.1021/acs.jnatprod.0c00106DOI Listing
May 2020

Development and validation of an LC-FTMS method for quantifying natural sweeteners in wine.

Food Chem 2020 May 9;311:125881. Epub 2019 Nov 9.

Univ. de Bordeaux, ISVV, EA 5477, Unité de recherche ŒNOLOGIE, USC 1366 INRA, F-33882 Villenave d'Ornon, France. Electronic address:

The quality of a wine largely depends on the balance between its sourness, bitterness and sweetness. Recently, epi-dihydrophaseic acid-3'-O-β-glucopyranoside (epi-DPA-G) and astilbin, two molecules obtained from grapes, have been shown to contribute notably to the sweet taste of dry wines. To study the parameters likely to affect their concentration, a new method was developed and optimized by LC-FTMS. Three gradients and five C18 columns were tested. Good results in terms of linearity (r > 0.9980), repeatability (RSD ≤ 3%), recovery (≥89%) and LOQ (≤20 µg.L) were obtained. The method was used to screen epi-DPA-G and astilbin in red wines of several vintages over one century. Both compounds were detected in all wines at concentrations varying from 1.2 to 14.7 mg/L for epi-DPA-G and from 0.5 to 42.6 mg/L for astilbin. Therefore, this new method can be used to quantify epi-DPA-G and astilbin reliably in wine.
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http://dx.doi.org/10.1016/j.foodchem.2019.125881DOI Listing
May 2020

Triterpenoids from Quercus petraea: Identification in Wines and Spirits and Sensory Assessment.

J Nat Prod 2019 02 28;82(2):265-275. Epub 2019 Jan 28.

Univ. Bordeaux , Unité de Recherche Oenologie, EA 4577, USC 1366 INRA, ISVV, 33882 Villenave d'Ornon Cedex , France.

Eight new triterpenoids (1-8), the known genin (9), and two known functionalized triterpenoids (10 and 11) were isolated from a Quercus petraea heartwood extract. The structures of the new compounds were unequivocally elucidated using HRESIMS and 1D/2D NMR experiments. Sensory analyses were performed in a non-oaked wine on the pure compounds 1-11. Except compounds 1 and 11, all molecules exhibited a sweet taste at 5 mg/L that was particularly intense for compounds 3 and 9. Using LC-HRMS, compounds 1-11 were observed in an oak wood extract and in oaked red wine and cognac. They were also semiquantified in several samples of sessile ( Q. petraea) and pedunculate ( Q. robur) oak wood extract. All compounds were found in quantities significantly higher in sessile than in pedunculate oak wood. These results support the hypothesis of their contribution to the increase in sweetness during oak aging and show that they can be used as chemical markers to identify the species of oak used for cooperage.
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http://dx.doi.org/10.1021/acs.jnatprod.8b00682DOI Listing
February 2019

Lignans in Spirits: Chemical Diversity, Quantification, and Sensory Impact of (±)-Lyoniresinol.

Molecules 2018 Dec 30;24(1). Epub 2018 Dec 30.

Unité de recherche Œnologie, EA 4577, USC 1366 INRA, Université de Bordeaux, ISVV, 33882 Villenave d'Ornon, France.

During barrel aging, spirits undergo organoleptic changes caused by the release of aroma and taste compounds. Recently, studies have revealed the bitter properties of oak wood lignans, such as (±)-lyoniresinol, and their contribution to wine taste. To evaluate the impact of lignans in spirits, a targeted screening of 11 compounds was set up and served to validate their presence in this matrix, implying their release by oak wood during aging. After development and validation of a quantification method, the most abundant and the bitterest lignan, (±)-lyoniresinol, was assayed by liquid chromatography⁻high resolution mass spectrometry (LC-HRMS) in spirits. Its gustatory detection threshold was established at 2.6 mg/L in spirits. A large number of samples quantified were above this detection threshold, which suggests its effect of increased bitterness in spirit taste. Significant variations were observed in commercial spirits, with concentrations ranging from 0.2 to 11.8 mg/L, which could be related to differences in barrel aging processes. In "eaux-de-vie" of cognac, concentrations of (±)-lyoniresinol were observed in the range from 1.6 mg/L to 12 mg/L. Lower concentrations were measured for older vintages.
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http://dx.doi.org/10.3390/molecules24010117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6337434PMC
December 2018

Tissular Distribution and Metabolism of -ε-Viniferin after Intraperitoneal Injection in Rat.

Nutrients 2018 Nov 4;10(11). Epub 2018 Nov 4.

Unité de Recherche Œnologie, Molécules d'Intérêt Biologique, EA 4577, USC 1366 INRA, Université de Bordeaux, Bordeaux INP, Institut des Sciences de la Vigne et du Vin, 210 Chemin de Leysottes, 33882 Villenave d'Ornon, France.

Background: Recent studies showed that -ε-viniferin (ε-viniferin), a -resveratrol dehydrodimer, has anti-inflammatory and anti-obesity effects in rodents. The main purpose of this work was to assess the tissue distribution study of ε-viniferin and its metabolites after intraperitoneal (IP) administration in rat.

Methods: After IP injection of 50 mg/kg, ε-viniferin and its metabolites were identified and quantified in plasma, liver, kidneys, adipose tissues, urine, and faeces by Liquid Chromatography-High Resolution Mass Spectrometry (LC-HRMS).

Results: ε-Viniferin underwent a rapid hepatic metabolism mostly to glucuronides but also to a lesser extent to sulphate derivatives. The highest glucuronide concentrations were found in liver followed by plasma and kidneys whereas only traces amounts were found in adipose tissues. In contrast the highest ε-viniferin areas under concentration (AUC) and mean residence times (MRT) values were found in white adipose tissues. Finally, much lower levels of ε-viniferin or its metabolites were found in urine than in faeces, suggesting that biliary excretion is the main elimination pathway.

Conclusion: A rapid and large metabolism of ε-viniferin and a high bioaccumulation in white adipose tissues were observed. Thus, these tissues could be a reservoir of the native form of ε-viniferin that could allow its slow release and a sustained presence within the organism.
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http://dx.doi.org/10.3390/nu10111660DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6266173PMC
November 2018

Taste-guided isolation of sweet-tasting compounds from grape seeds, structural elucidation and identification in wines.

Food Chem 2019 Jan 18;272:388-395. Epub 2018 Aug 18.

Univ de Bordeaux, ISVV, EA 4577, Unité de recherche OENOLOGIE, F-33882 Villenave d'Ornon, France; INRA, ISVV, USC 1366 OENOLOGIE, F-33882 Villenave d'Ornon, France. Electronic address:

This work aimed at improving knowledge about sweetness in dry wines. Following on from the empirical observations of winegrowers, we assessed the contribution of grape seeds to wine sensory properties. An inductive fractionation method guided by gustatometry was used to isolate and characterize sweet-tasting compounds from grapes. Fractionation of grape seed macerates was achieved by liquid-liquid extraction, centrifugal partition chromatography (CPC) and preparative HPLC. Then, the structures of the purified compounds were elucidated by use of FTMS and NMR. Five compounds were identified: two new compounds, 2-hydroxy-3-methylpentanoic-2-O-β-glucopyranoside (H3MP-G) and 2-hydroxy-4-methylpentanoic-2-O-β-glucopyranoside acids (H4MP-G), along with gallic-4-O-β-glucopyranoside acid (AG-G), 3-indolyl-(2R)-O-β-d-glycoside lactic acid (ILA-G) and epi-DPA-3'-O-β-glucopyranoside acid (epi-DPA-G). These compounds exhibited various levels of sweetness in a hydro-ethanolic solution and in white and red wines. Additionally, H3MP-G, H4MP-G and epi-DPA-G were identified for the first time in grapes and wines, whereas AG-G has already been reported in white grapes but never in wine.
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http://dx.doi.org/10.1016/j.foodchem.2018.08.070DOI Listing
January 2019

The complexity of wine: clarifying the role of microorganisms.

Appl Microbiol Biotechnol 2018 May 18;102(9):3995-4007. Epub 2018 Mar 18.

Unité de recherche Œnologie EA 4577, USC 1366 INRA, Bordeaux INP, Univ. Bordeaux, ISVV, 33140, Villenave d'Ornon, France.

The concept of wine complexity has gained considerable interest in recent years, both for wine consumers and wine scientists. As a consequence, some research programs concentrate on the factors that could improve the perceived complexity of a wine. Notably, the possible influence of microbiological factors is particularly investigated. However, wine complexity is a multicomponent concept not easily defined. In this review, we first describe the actual knowledge regarding wine complexity, its perception, and wine chemical composition. In particular, we emphasize that, contrary to expectations, the perception of wine complexity is not related to wine chemical complexity. Then, we review the impact of wine microorganisms on wine complexity, with a specific focus on publications including sensory analyses. While microorganisms definitively can impact wine complexity, the underlying mechanisms and molecules are far from being deciphered. Finally, we discuss some prospective research fields that will help improving our understanding of wine complexity, including perceptive interactions, microbial interactions, and other challenging phenomena.
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http://dx.doi.org/10.1007/s00253-018-8914-8DOI Listing
May 2018

Phytochemical study of the trunk bark of Citharexylum spinosum L. growing in Tunisia: Isolation and structure elucidation of iridoid glycosides.

Phytochemistry 2018 Feb 22;146:47-55. Epub 2017 Dec 22.

Laboratoire de Chimie Hétérocyclique, Produits Naturels et Réactivité (LR11ES39), Equipe: Chimie Médicinale et Produits Naturels, Faculté des Sciences de Monastir, Université de Monastir, Avenue de l'environnement, 5019 Monastir, Tunisia. Electronic address:

A phytochemical investigation of the trunk bark ethyl acetate extract of Citharexylum spinosum L. has led to the isolation of four previously undescribed iridoid glycosides, tunispinosides A-D, and five known phenylethanoid glycosides, verbascoside, leucosceptoside A, martynoside, isoverbascoside and plantainoside C, together with 4-hydroxy-2,6-dimethoxyphenyl 6'-O-vanilloyl-β-D-glucopyranoside, two 8,3'-neolignan glycosides, plucheosides D-D, coniferyl aldehyde, vanillic acid, syringic acid, ferulic acid and tyrosol. All compounds were isolated for the first time from C. spinosum. Their isolation was carried out using silica gel column and high performance liquid chromatography (HPLC). Structures were established by spectroscopic means including 1D and 2D NMR experiments, and spectrometric ESI-HRMS analysis.
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http://dx.doi.org/10.1016/j.phytochem.2017.11.012DOI Listing
February 2018

Influence of lactic acid bacteria strains on ester concentrations in red wines: Specific impact on branched hydroxylated compounds.

Food Chem 2018 Jan 21;239:252-259. Epub 2017 Jun 21.

Univ. Bordeaux, ISVV, EA 4577 œnologie, 210 chemin de Leysotte CS 50008, 33882 Villenave d'Ornon Cedex, France; INRA, ISVV, USC 1366 œnologie, 210 chemin de Leysotte CS 50008, 33882 Villenave d'Ornon, France. Electronic address:

This research investigated the influence of lactic acid bacteria (LAB) strains on ester levels in Bordeaux red wines. These wines were made in five Bordeaux areas in two vintages, using three yeast strains. Malolactic fermentation (MLF) was carried out using industrial starters or indigenous strains, each in triplicate. Ester concentrations were determined by liquid-liquid-extraction- or HS-SPME-GC/MS at various stages in the winemaking process. The levels of most compounds were slightly impacted by LAB, depending on grape variety. Nevertheless, branched hydroxylated esters, such as ethyl 2-hydroxy-3-methylbutanoate and ethyl 2-hydroxy-4-methylpentanoate were the only compounds to be strongly influenced by the bacteria strain, regardless of matrix composition or the yeasts used for alcoholic fermentation. Moreover, the effect observed after MLF persisted over time, for at least 12months. These esters are apparently important markers of LAB esterase activity. To our knowledge, this was the first time they had been identified in this role.
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http://dx.doi.org/10.1016/j.foodchem.2017.06.123DOI Listing
January 2018

Production and Purification of the Native Saccharomyces cerevisiae Hsp12 in Escherichia coli.

J Agric Food Chem 2017 Sep 11;65(37):8154-8161. Epub 2017 Sep 11.

Bordeaux INP, CBMN, UMR 5248, F-33600 Pessac, France.

Hsp12 is a small heat shock protein produced in many organisms, including the yeast Saccharomyces cerevisiae. It has been described as an indicator of yeast stress rate and has also been linked to the sweetness sensation of wine. To obtain a sufficient amount of protein, we produced and purified Hsp12 without tag in Escherichia coli. A simple fast two-step process was developed using a microplate approach and a design of experiments. A capture step on an anion-exchange salt-tolerant resin was followed by size exclusion chromatography for polishing, leading to a purity of 97%. Thereafter, specific anti-Hsp12 antibodies were obtained by rabbit immunization. An ELISA was developed to quantify Hsp12 in various strains of Saccharomyces cerevisiae. The antibodies showed high specificity and allowed the quantitation of Hsp12 in the yeast. The quantities of Hsp12 measured in the strains differed in direct proportion to the level of expression found in previous studies.
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http://dx.doi.org/10.1021/acs.jafc.7b02477DOI Listing
September 2017

Toward a Molecular Understanding of the Typicality of Chardonnay Wines: Identification of Powerful Aromatic Compounds Reminiscent of Hazelnut.

J Agric Food Chem 2017 Feb 26;65(5):1058-1069. Epub 2017 Jan 26.

Université de Bordeaux, ISVV , EA 4577, Unité de recherche ŒNOLOGIE, F-33882 Villenave d'Ornon, France.

Chardonnay wines impart a unique complex aroma characterized by its buttery, yellow stone fruit, melon, bready, and woody notes. Among the terms used in the sensory analysis of these wines, this study investigated hazelnut-like attributes. Multidimensional gas chromatography coupled to olfactometry identified five pyrroles reminiscent of hazelnut: 1-ethylpyrrole-2-carboxaldehyde, 1H-pyrrole, 2-acetyl-1H-pyrrole (first identification in wine), 1-methylpyrrole-2-carboxaldehyde, and 1H-pyrrole-2-carboxaldehyde. Quantitative analyses demonstrated their significantly higher abundance in Chardonnay wines. However, they proved irrelevant in sensory terms, given the low amounts measured in wine compared to their olfactory detection threshold. Nevertheless, the presence of methanethiol derivatives from these pyrroles was investigated in wine. 1-Methylpyrrole-2-methanethiol and 1-ethylpyrrole-2-methanethiol were identified and exhibited hazelnut-like aroma. These compounds, which have not been observed in natural products to date, are potent volatile compounds with detection thresholds of 0.7 and 1.4 ng/L, respectively, in model wine. These findings open up promising perspectives concerning the interpretation of the typical aromatic nuances of some Chardonnay wines.
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http://dx.doi.org/10.1021/acs.jafc.6b04516DOI Listing
February 2017

Taste-Guided Isolation of Bitter Lignans from Quercus petraea and Their Identification in Wine.

J Nat Prod 2016 10 29;79(10):2432-2438. Epub 2016 Sep 29.

Université de Bordeaux, ISVV , EA 4577, Unité de Recherche OENOLOGIE, 210 Chemin de Leysotte, CS 50008, 33882 Villenave d'Ornon, France.

Quercoresinosides A and B (1 and 2), two new lignans, were isolated from a toasted Quercus petraea heartwood extract along with a known compound, 3-methoxy-4-hydroxyphenol 1-O-β-d-(6'-O-galloyl)glucopyranoside (3). The purification protocol was based on a taste-guided approach that sought to reveal new bitter compounds released from oak wood into wines and spirits. HRMS and NMR data were used to establish that compounds 1 and 2 are lignan derivatives bearing a glucosyl unit and a galloyl unit at the same positions. Hydrolysis of these compounds showed that they could be distinguished by the absolute configuration of their respective lyoniresinol genin as determined by chiral LC-HRMS in comparison with (+)- and (-)-lyoniresinol standards. Sensory analyses were performed in a non-oaked wine on the pure compounds 1-3. The three molecules exhibited a bitter taste at 2 mg/L that was particularly intense for compounds 2 and 3. Finally, LC-HRMS demonstrated the occurrence of compounds 1-3 in oaked wine and brandy, which supports the hypothesis of their contributions to the increase in bitterness during oak aging.
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http://dx.doi.org/10.1021/acs.jnatprod.6b00142DOI Listing
October 2016

Development of a quantitation method to assay both lyoniresinol enantiomers in wines, spirits, and oak wood by liquid chromatography-high resolution mass spectrometry.

Anal Bioanal Chem 2016 05 21;408(14):3789-99. Epub 2016 Mar 21.

Univ. de Bordeaux, ISVV, EA 4577, Unité de recherche Oenologie, 33882, Villenave d'Ornon, France.

Wine taste balance evolves during oak aging by the release of volatile and non-volatile compounds from wood. Among them, an enantiomer of lyoniresinol, (+)-lyoniresinol, has been shown to exhibit bitterness. To evaluate the impact of (+)-lyoniresinol on wine taste, a two-step quantitation method was developed and validated. First, (±)-lyoniresinol was assayed in wines, spirits, and oak wood macerates by C-18 liquid chromatography-high resolution mass spectrometry (LC-HRMS). Then, the lyoniresinol enantiomeric ratio was determined by chiral LC-HRMS in order to calculate the (+)-lyoniresinol content. In red and white wines, the average concentrations of (+)-lyoniresinol were 1.9 and 0.8 mg/L, respectively. The enantiomer proportions were not affected by bottle aging, and lyoniresinol appeared to remain stable over time. The sensory study of (+)-lyoniresinol established its perception threshold at 0.46 mg/L in wine. All the commercial wines quantitated were above this perception threshold, demonstrating its impact on wine taste by an increase in bitterness. In spirits, (+)-lyoniresinol ranged from 2.0 to 10.0 mg/L and was found to be released continuously during oak aging. Finally, neither botanical origin nor toasting was found to significantly affect the (+)-lyoniresinol content of oak wood. Graphical abstract From oak wood to wine: evaluation of the influence of (+)-lyoniresinol on the bitterness of wines and spirits.
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http://dx.doi.org/10.1007/s00216-016-9466-3DOI Listing
May 2016

New Approach for Differentiating Sessile and Pedunculate Oak: Development of a LC-HRMS Method To Quantitate Triterpenoids in Wood.

J Agric Food Chem 2016 Jan 12;64(3):618-26. Epub 2016 Jan 12.

Université de Bordeaux , ISVV, EA 4577, Unité de recherche Oenologie, F-33882 Villenave d'Ornon, France.

Oak aging is a crucial step in winemaking during which the organoleptic properties of wine are modified. Various parameters affect the chemical composition of oak wood including botanical origin, which has been previously shown to be a determinant factor. This study focused on the development of a LC-HRMS method to assay four recently discovered taste-active triterpenes (three sweet and one bitter). The method was applied to evaluate the effect of oak species (Quercus petraea and Quercus robur) on the concentration of these molecules in wood. The results showed that sessile oak was richer in sweet triterpenes and poorer in the bitter one than pedunculate oak, with high interindividual variations within species. Furthermore, a triterpenoid index was calculated to reveal the triterpenoid composition of oak wood. This index appears to be a promising tool for the unambiguous discrimination of oak species and could offer new insights into oak wood selection by coopers and the monitoring of oak aging by winemakers.
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http://dx.doi.org/10.1021/acs.jafc.5b05056DOI Listing
January 2016

How stereochemistry influences the taste of wine: Isolation, characterization and sensory evaluation of lyoniresinol stereoisomers.

Anal Chim Acta 2015 Aug 10;888:191-8. Epub 2015 Aug 10.

Université de Bordeaux, ISVV, EA 4577, Unité de recherche OENOLOGIE, F-33882 Villenave d'Ornon, France; INRA, ISVV, USC 1366 OENOLOGIE, 33882 Villenave d'Ornon, France. Electronic address:

Wine expresses its beauty by sending a sensory message to the taster through molecules coming from grapes, yeast metabolism or oak wood. Among the compounds released during barrel aging, lyoniresinol has been recently reported as a relevant contributor to wine bitterness. As this lignan contains three stereogenic carbons, this work aimed at investigating the influence of stereochemistry on wine taste by combining analytical and sensorial techniques. First, an oak wood extract was screened by Liquid Chromatography-High Resolution Mass Spectrometry to target isomers separable in a symmetric environment and a diastereoisomer called epi-lyoniresinol was isolated for the first time. Then, an original racemic resolution based on natural xylose-derivatives was carried out to obtain lyoniresinol enantiomers. Chiroptical spectroscopic measurements associated with theoretical calculations allowed the unambiguous determination of their absolute configuration. The taste properties of all these stereoisomers revealed that only one lyoniresinol enantiomer is strongly bitter whereas the other one is tasteless and the diastereoisomer is slightly sweet. The presence of these three compounds was established in an oaked Bordeaux wine by chiral and non-chiral chromatography, suggesting the significant influence of stereochemistry on wine taste.
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http://dx.doi.org/10.1016/j.aca.2015.06.061DOI Listing
August 2015

Isolation and structure elucidation of bioactive compounds from the roots of the Tunisian Ononis angustissima L.

Bioorg Med Chem Lett 2015 Sep 26;25(18):3825-30. Epub 2015 Jul 26.

Laboratory of Heterocyclic Chemistry, Natural Products and Reactivity, Team: Medicinal Chemistry and Natural Products, Faculty of Science of Monastir, University of Monastir, Avenue of Environment, 5019 Monastir, Tunisia. Electronic address:

A phytochemical investigation of the roots of Ononis angustissima L. (Fabaceae) offered to the bio-guided isolation of new isoflavone 3-(4-(glucopyranosyloxy)-5-hydroxy-2-methoxyphenyl)-7-hydroxy-4H-chromen-4-one 1, together with nine known compounds, ononin 2, formononetin 3, (+)-puerol A-2'-O-β-D-glucose 4, (-)-puerol B-2'-O-β-D-glucopyranose ((-)-sophoraside A) 5, (+)-puerol A 6, (-)-trifolirhizin 7, (-)-trifolirhizin-6'-O-malonate 8, (-)-maackiain 9 and (-)-medicarpin 10. Compounds 2-10 were isolated and identified for the first time in Ononis angustissima. We investigated antioxidant capacities of isolated molecules and results showed that compound 6 exhibited the highest antioxidant activity with IC50 values of 19.53 μg/mL, 28.29 μg/mL and 38.53 μg/mL by DPPH radical, ABTS radical cation and reducing power assay, respectively, and an interesting IC50 (20.45 μg/mL) of 1 against DPPH. In addition, the neuroprotective activity of six isolated molecules (4-7, 9, 10) were evaluated. Following the exposure of PC12 cells to Aβ25-35, compounds 9 and 10 triggered a significant increase of cell viability and in a dose dependent manner.
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http://dx.doi.org/10.1016/j.bmcl.2015.07.076DOI Listing
September 2015

Fermentative conditions modulating sweetness in dry wines: genetics and environmental factors influencing the expression level of the Saccharomyces cerevisiae HSP12 gene.

J Agric Food Chem 2015 Jan;63(1):304-11

Yeast lees influence the organoleptic properties of wines by increasing their sweet taste. This effect is in part due to the protein Hsp12p, which is regulated by different stress response pathways in Saccharomyces cerevisiae. This work investigated the genetics and environmental factors influencing the expression level of the HSP12 gene in an enological context. RT-qPCR confirmed that the HSP12 expression level is regulated by temperature change and ethanol content during the alcoholic fermentation but not by the sugar content. Moreover, this gene shows an important variation according to the yeast strain used. For the first time yeast strain is demonstrated to play an important role in the perception of sweetness in red wine due to post-fermentation lees autolysis. Interestingly, a correlation between the expression level of HSP12 and the sweetness perception was found using yeast strains of different origins. All of the findings provide new insights on the contribution of yeast to wine taste.
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http://dx.doi.org/10.1021/jf504408tDOI Listing
January 2015

Development of an analytical methodology using Fourier transform mass spectrometry to discover new structural analogs of wine natural sweeteners.

Anal Chim Acta 2015 Jan 1;853:425-434. Epub 2014 Nov 1.

Univ. de Bordeaux, ISVV, EA 4577, Unité de recherche OENOLOGIE, F-33882 Villenave d'Ornon, France; INRA, ISVV, USC 1366 OENOLOGIE, 33882 Villenave d'Ornon, France.

Volatile and non-volatile molecules are directly responsible for the thrill and excitement provided by wine-tasting. Their elucidation requires powerful analytical techniques and innovative methodologies. In a recent work, two novel sweet compounds called quercotriterpenosides (QTT) were identified in oak wood used for wine-ageing. The aim of the present study is to discover structural analogs of such natural sweeteners in oak wood. For this purpose, an analytical approach was developed as an alternative to chemical synthesis. Orbitrap mass spectrometry proved to be a crucial technique both to demonstrate the presence of QTT analogs in oak wood by targeted screening and to guide the purification pathway of these molecules using complementary chromatographic tools. Four compounds were isolated and identified for the first time: two isomers, one glucosyl derivative and one galloyl derivative of QTT. Their tasting showed that only the two new isomers were sweet, thus demonstrating both the pertinence of the strategy and the influence of functional groups on gustatory properties. Finally, this paper presents some developments involving multistage Fourier transform mass spectrometry (FTMS) to provide solid structural information on these functional groups prior to any purification of compounds. Such analytical developments could be particularly useful for research on taste-active or bio-active products.
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http://dx.doi.org/10.1016/j.aca.2014.10.039DOI Listing
January 2015

Unambiguous Determination of the Absolute Configuration of Dimeric Stilbene Glucosides from the Rhizomes of Gnetum africanum.

J Nat Prod 2014 Aug;77(8):1981-5

Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, Université Bordeaux, ISVV , 210 Chemin de Leysotte, F-33882 Villenave d'Ornon, France.

Dimeric stilbene glucosides 1-3 [two diastereomers of (-)-gnemonoside A (1a and 1b), (-)-gnemonoside C (2), and (-)-gnemonoside D (3)] as well as a mixture of the two enantiomers of gnetin C (4) were isolated from the rhizomes of Gnetum africanum. The two enantiomers of gnetin C, (+)-4 and (-)-4, were obtained from the aglycones of 1a and 1b, respectively. The configurations of these stilbenoids were investigated by NMR and vibrational circular dichroism (VCD) experiments. The absolute configurations of (-)-1a, (-)-2, (-)-3, and (-)-4 were established as 7aS,8aS by VCD spectroscopy in combination with density functional theory calculations. The antiamyloidogenic activity of the isolated stilbenes was also evaluated versus beta-amyloid fibrils. The four glucosides of gnetin C (1a, 1b, 2, and 3) were found to be the most active compounds, with inhibition percentages of 56, 56, 58, and 54 at 10 μM, respectively.
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http://dx.doi.org/10.1021/np500427vDOI Listing
August 2014

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

Fitoterapia 2014 Sep 7;97:253-60. Epub 2014 Jun 7.

GESVAB EA 3675, ISVV, Université de Bordeaux, F-33882 Villenave d'Ornon Cedex, France.

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-β-apiofuranosyl-β-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.
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http://dx.doi.org/10.1016/j.fitote.2014.06.001DOI Listing
September 2014

The antioxidant properties of new dimer and two monomers of phenolic acid amides isolated from Limoniastrum guyonianum.

Food Chem 2014 Mar 25;146:466-71. Epub 2013 Sep 25.

Laboratoire Des Plantes Extrêmophile, Centre de Biotechnologie de Borj Cédria, BP 901, 2050 Hammam-Lif, Tunisia; Univ. Bordeaux2, ISVV, Groupe d'Etude des Substances Végétales à Activité Biologique, EA 3675, F-33882 Villenave d'Ornon, France. Electronic address:

Limoniastramide, a new dimer of phenolic acid amide, isolated from Limoniastrum guyonianum, along with two natural monomers N-E-caffeoyl tyramine (1) and N-E-feruloyl tyramine (2), using centrifugal partition chromatography (CPC). Their structures were determined on the basis of spectroscopic data analysis. We investigate the antioxidant activities of Limoniastrum amides using various in vitro assays. Results showed that N-E-feruloyl tyramine and N-E-caffeoyl tyramine exhibited the highest DPPH scavenging activity compared to the dimer (IC50=0.5, 0.6 and 6.5μg/ml, respectively). In addition, they have significant capacities to inhibit the bleaching of β-carotene. Limoniastramide presented the best activity with an IC50 value equal to 8μg/ml. Finally, the N-E-caffeoyl tyramine showed the highest reducing power (EC50=26μg/ml) compared to the other molecules. The present study found that L. guyonianum amides have effective in vitro antioxidant and radical scavenging activity which can be used in pharmacological and food industry due to their antioxidant properties.
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http://dx.doi.org/10.1016/j.foodchem.2013.09.077DOI Listing
March 2014

Identification of new natural sweet compounds in wine using centrifugal partition chromatography-gustatometry and Fourier transform mass spectrometry.

Anal Chem 2011 Dec 14;83(24):9629-37. Epub 2011 Nov 14.

Université de Bordeaux, ISVV, EA 4577, Unité de Recherche OENOLOGIE, Villenave d'Ornon, France.

Sweetness contributes notably to the taste-balance of dry wines and increases during oak-barrel aging owing to the release of natural sweeteners from wood. The search for such taste-active molecules, which are sometimes present at very low concentrations in wine or other complex matrixes, requires both reliable purification tools and powerful identification techniques. Here, we report the development of an original inductive method using centrifugal partition chromatography (CPC) and sensorial analysis. This method, called CPC-gustatometry, was implemented to isolate a sweet fraction with only four compounds from a complex oak wood extract. The recently developed Fourier transform mass spectrometry (FT-MS, Orbitrap analyzer) was used jointly with two-dimensional nuclear magnetic resonance (2D (1)H and (13)C NMR) to obtain the structural elucidation of the purified compounds. The tandem mass spectrometry (MS/MS) spectra obtained with resonant and nonresonant fragmentation modes were compared, thus providing complementary information about the molecular structure. Two oleanane-type triterpenoids substituted with galloyl and glucosyl moieties were identified, one of which exhibits sweet properties. We term these compounds which have never been reported, Quercotriterpenoside I and II.
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http://dx.doi.org/10.1021/ac202499aDOI Listing
December 2011