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Jeanfrancois Drilleau - One of the best experts on this subject based on the ideXlab platform.
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procyanidins are the most abundant polyphenols in dessert apples at maturity
Lwt - Food Science and Technology, 2002Co-Authors: Sylvain Guyot, Nathalie Marnet, Le C Bourvellec, Jeanfrancois DrilleauAbstract:Abstract Direct Thiolysis of crude plant materials and HPLC analysis of the reaction media were used to quantify and to characterise procyanidins (condensed tanins) and other main polyphenols of three dessert apple varieties. Results showed evidence of the large predominance of the procyanidin class in the polyphenolic composition of dessert apple skin and flesh. The structure of procyanidins was wholly homogeneous with (-)-epicatechin representing more than 95% of the constitutive flavan-3-ol units and with average degrees of polymerisation in the 5–7 range.
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (−)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions. Keywords: Apple; chromatographic fractionation; HPLC; Thiolysis; proc...
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (-)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions.
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polyphenol profiles of french cider apple varieties malus domestica sp
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Philippe Sanoner, Nathalie Marnet, Sylvain Guyot, Daniel Molle, Jeanfrancois DrilleauAbstract:The cortex of 14 French apple varieties (12 cider and 2 juice varieties), one English cider variety, and one dessert apple (i.e., Golden Delicious) were studied for their polyphenol composition. Total polyphenols were assayed by the Folin-Ciocalteu method, and the precise polyphenolic composition (monomeric catechins, proanthocyanidins, hydroxycinnamic acids, and dihydrochalcones) was obtained by HPLC following Thiolysis. ESI-MS and ESI-MS/MS analyses showed that chlorogenic acid and p-coumaroylquinic acid were methylated under the conditions of Thiolysis. Depending on the variety, the global polyphenol concentration varied from 1 to 7 g per kilogram of fresh cortex. Cider varieties globally showed a higher polyphenol concentration than the dessert apple Golden Delicious, bitter varieties being the more concentrated. The proportion of the polyphenol classes varied greatly from one cultivar to another. For all varieties, procyanidins were always the predominant class. They were mainly constituted of (-)-epicatechin units with a small proportion of (+)-catechin as a terminal unit. The average degree of polymerization ranged between 4.2 and 7.5 depending upon the variety with an exception for the sharp varieties Guillevic and Avrolles which showed significant concentrations of procyanidins with DPn of 40 and 50, respectively.
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reversed phase hplc following Thiolysis for quantitative estimation and characterization of the four main classes of phenolic compounds in different tissue zones of a french cider apple variety malus domestica var kermerrien
Journal of Agricultural and Food Chemistry, 1998Co-Authors: Sylvain Guyot, Nathalie Marnet, Philippe Sanoner, Djamel Laraba, Jeanfrancois DrilleauAbstract:Phenolic compounds, which are present in the epidermis zone, parenchyma zone, core zone, and seeds of fruit (Malus domestica var. Kermerrien), were extracted from freeze-dried material by three successive solvent extractions. The dry methanol extract and the dry aqueous acetone extracts were analyzed using reversed-phase HPLC coupled with diode array detection following Thiolysis to quantify phenolic compounds according to their classes (hydroxycinnamic acid derivatives, flavan-3-ols, flavonols, and dihydrochalcones). The method is suitable for the determination of the relative proportions of the different classes of polyphenols and provided information on the constitutive units and the average degree of polymerization of oligomeric and polymeric procyanidin structures. Results showed that procyanidins are the predominant phenolic constituents in cider apple fruits, much of them corresponding to highly polymerized structures. Keywords: Apple; phenolics; procyanidins; cider; HPLC; Thiolysis
Sylvain Guyot - One of the best experts on this subject based on the ideXlab platform.
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characterization and estimation of proanthocyanidins and other phenolics in coffee pulp coffea arabica by Thiolysis high performance liquid chromatography
Journal of Agricultural and Food Chemistry, 2004Co-Authors: Ma Ascencion Ramirezcoronel, Nathalie Marnet, V Kumar S Kolli, Sylvain Guyot, Sevastianos Roussos, Christopher AugurAbstract:Fresh and 3-day-old coffee pulp of the Arabica variety were analyzed for polyphenol composition followed by characterization by two different methods. The first method consisted in subjecting coffee pulp powder to direct Thiolysis. For the second method, coffee pulp was subjected to successive solvent extractions, followed by Thiolysis. Quantification of phenolic compounds was then achieved by high-performance liquid chromatography (HPLC) analysis of Thiolysis products. Four major classes of polyphenols were identified: flavan-3-ols (monomers and procyanidins), hydroxycinnamic acids, flavonols, and anthocyanidins. Differences in concentration of procyanidins were observed between fresh and 3-day-old coffee pulp. Constitutive units were mainly epicatechin, representing more than 90% of the proanthocyanidin units, with average degrees of polymerization in the range of 3.8-9.1. Monomer to hexamer units of flavan-3-ols from fresh coffee pulp were separated by normal-phase HPLC. Molecular size of oligomeric proanthocyanidins was obtained by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results obtained confirm the presence of oligomers of the flavan-3-ol (-)-epicatechin.
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procyanidins are the most abundant polyphenols in dessert apples at maturity
Lwt - Food Science and Technology, 2002Co-Authors: Sylvain Guyot, Nathalie Marnet, Le C Bourvellec, Jeanfrancois DrilleauAbstract:Abstract Direct Thiolysis of crude plant materials and HPLC analysis of the reaction media were used to quantify and to characterise procyanidins (condensed tanins) and other main polyphenols of three dessert apple varieties. Results showed evidence of the large predominance of the procyanidin class in the polyphenolic composition of dessert apple skin and flesh. The structure of procyanidins was wholly homogeneous with (-)-epicatechin representing more than 95% of the constitutive flavan-3-ol units and with average degrees of polymerisation in the 5–7 range.
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (−)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions. Keywords: Apple; chromatographic fractionation; HPLC; Thiolysis; proc...
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (-)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions.
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polyphenol profiles of french cider apple varieties malus domestica sp
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Philippe Sanoner, Nathalie Marnet, Sylvain Guyot, Daniel Molle, Jeanfrancois DrilleauAbstract:The cortex of 14 French apple varieties (12 cider and 2 juice varieties), one English cider variety, and one dessert apple (i.e., Golden Delicious) were studied for their polyphenol composition. Total polyphenols were assayed by the Folin-Ciocalteu method, and the precise polyphenolic composition (monomeric catechins, proanthocyanidins, hydroxycinnamic acids, and dihydrochalcones) was obtained by HPLC following Thiolysis. ESI-MS and ESI-MS/MS analyses showed that chlorogenic acid and p-coumaroylquinic acid were methylated under the conditions of Thiolysis. Depending on the variety, the global polyphenol concentration varied from 1 to 7 g per kilogram of fresh cortex. Cider varieties globally showed a higher polyphenol concentration than the dessert apple Golden Delicious, bitter varieties being the more concentrated. The proportion of the polyphenol classes varied greatly from one cultivar to another. For all varieties, procyanidins were always the predominant class. They were mainly constituted of (-)-epicatechin units with a small proportion of (+)-catechin as a terminal unit. The average degree of polymerization ranged between 4.2 and 7.5 depending upon the variety with an exception for the sharp varieties Guillevic and Avrolles which showed significant concentrations of procyanidins with DPn of 40 and 50, respectively.
Aina Ramsay - One of the best experts on this subject based on the ideXlab platform.
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Facile Purification of Milligram to Gram Quantities of Condensed Tannins According to Mean Degree of Polymerization and Flavan-3-ol Subunit Composition
2017Co-Authors: Ron H. Brown, Wayne E. Zeller, Christos Fryganas, Honorata M. Ropiak, Irene Mueller-harvey, Elisabetta Stringano, An Gea, Christopher Drake, Laurie Reinhardt, Aina RamsayAbstract:Unambiguous investigation of condensed tannin (CT) structure–activity relationships in biological systems requires well-characterized, high-purity CTs. Sephadex LH-20 and Toyopearl HW-50F resins were compared for separating CTs from acetone/water extracts, and column fractions analyzed for flavan-3-ol subunits, mean degree of polymerization (mDP), and purity. Toyopearl HW-50F generated fractions with higher mDP values and better separation of procyanidins (PC) and prodelphinidins (PD) but required a prepurification step, needed more time for large scale purifications, and gave poorer recoveries. Therefore, two gradient elution schemes were developed for CT purification on Sephadex LH-20 providing 146–2000 mg/fraction. Fractions were analyzed by Thiolysis and NMR spectroscopy. In general, PC/PD ratios decreased and mDP increased during elution. 1H NMR spectroscopy served as a rapid screening tool to qualitatively determine CT enrichment and carbohydrate impurities present, guiding fractionation toward repurification or 1H–13C HSQC NMR spectroscopy and Thiolysis. These protocols provide options for preparing highly pure CT samples
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Senna alata leaves are a good source of propelargonidins
Natural Product Research, 2015Co-Authors: Aina Ramsay, Irene Mueller-harveyAbstract:Proanthocyanidins (PA) in Senna alata leaves were investigated by Thiolysis with benzyl mercaptan, LC–MS and NMR and consisted of almost pure propelargonidins with 94%) and epicatechin a minor constituent (6.4%) in residual PA and mainly detected as an extension unit.
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1H-13C HSQC NMR spectroscopy for estimating procyanidin/prodelphinidin and cis/trans-flavan-3-ol ratios of condensed tannin samples: correlation with Thiolysis
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Wayne E. Zeller, Chris Drake, Christos Fryganas, Honorata M. Ropiak, Aina Ramsay, Irene Mueller-harvey, R.h. Brown, John H GrabberAbstract:Studies with a diverse array of 22 purified condensed tannin (CT) samples from nine plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans-flavan-3-ol ratios can be appraised by 1H–13C HSQC NMR spectroscopy. The method was developed from samples containing 44–∼100% CT, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios ranging from 58/42 to 95/5 as determined by Thiolysis with benzyl mercaptan. Integration of cross-peak contours of H/C-6′ signals from PC and of H/C-2′,6′ signals from PD yielded nuclei-adjusted estimates that were highly correlated with PC/PD ratios obtained by Thiolysis (R2 = 0.99). cis/trans-Flavan-3-ol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by Thiolysis (R2 = 0.89). Overall, 1H–13C HSQC NMR spectroscopy appears to be a viable alternative to Thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.
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1h 13c hsqc nmr spectroscopy for estimating procyanidin prodelphinidin and cis trans flavan 3 ol ratios of condensed tannin samples correlation with Thiolysis
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Wayne E. Zeller, Chris Drake, Christos Fryganas, Honorata M. Ropiak, Aina Ramsay, R.h. Brown, Irene Muellerharvey, John H GrabberAbstract:Studies with a diverse array of 22 purified condensed tannin (CT) samples from nine plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans-flavan-3-ol ratios can be appraised by 1H–13C HSQC NMR spectroscopy. The method was developed from samples containing 44–∼100% CT, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios ranging from 58/42 to 95/5 as determined by Thiolysis with benzyl mercaptan. Integration of cross-peak contours of H/C-6′ signals from PC and of H/C-2′,6′ signals from PD yielded nuclei-adjusted estimates that were highly correlated with PC/PD ratios obtained by Thiolysis (R2 = 0.99). cis/trans-Flavan-3-ol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by Thiolysis (R2 = 0.89). Overall, 1H–13C HSQC NMR spectroscopy appears to be a viable alternative to Thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.
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Sodium Hydroxide Enhances Extractability and Analysis of Proanthocyanidins in Ensiled Sainfoin (Onobrychis viciifolia)
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Aina Ramsay, Chris Drake, Anja Grosse Brinkhaus, Marion Girard, Giuseppe Copani, Frigga Dohme-meier, Giuseppe Bee, Vincent Niderkorn, Irene Mueller-harveyAbstract:Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone butanol-HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (Thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to Thiolysis. We now report that a pretreatment step with sodium hydroxide prior to Thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.
Christos Fryganas - One of the best experts on this subject based on the ideXlab platform.
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carbon 13 cross polarization magic angle spinning nuclear magnetic resonance for measuring proanthocyanidin content and procyanidin to prodelphinidin ratio in sainfoin onobrychis viciifolia tissues
Journal of Agricultural and Food Chemistry, 2018Co-Authors: Christos Fryganas, Chris Drake, Honorata M. Ropiak, Irene Muellerharvey, Marina Moraortiz, Lydia M J Smith, Radoslaw M KowalczykAbstract:A procedure based on 13C CPMAS NMR was developed to study procyanidins (PCs) and prodelphinidins (PDs) directly in milled sainfoin plant tissues. Blackcurrant and Tilia samples enabled reference spectra of purified proanthocyanidin (PA) fractions, crude extracts, and milled plant tissues, with characteristic resonances at 155, 144, and 132 ppm. PC/PD ratios were estimated from the I132/I155 intensity ratio and differed by 2.5 to 5.9% compared to Thiolysis data. Normalization to the 155 ppm signal intensity from reference spectra enabled analysis of PA contents with an error of ca. 8 g PAs/100 g plant tissue. The procedure estimates the lignin contribution and allows for a correction of the PA content. In six sainfoin accessions, estimated PA contents were 1.6- to 20.8-fold higher than the Thiolysis and 1.4- to 2.6-fold higher than the HCl–butanol–acetone results. Method differences may reflect the presence of unextractable, possibly high molecular weight PAs in sainfoin.
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Carbon-13 Cross-Polarization Magic-Angle Spinning Nuclear Magnetic Resonance for Measuring Proanthocyanidin Content and Procyanidin to Prodelphinidin Ratio in Sainfoin (Onobrychis viciifolia) Tissues
2018Co-Authors: Christos Fryganas, Honorata M. Ropiak, Irene Mueller-harvey, Lydia M J Smith, Christopher Drake, Marina Mora-ortiz, Radoslaw M KowalczykAbstract:A procedure based on 13C CPMAS NMR was developed to study procyanidins (PCs) and prodelphinidins (PDs) directly in milled sainfoin plant tissues. Blackcurrant and Tilia samples enabled reference spectra of purified proanthocyanidin (PA) fractions, crude extracts, and milled plant tissues, with characteristic resonances at 155, 144, and 132 ppm. PC/PD ratios were estimated from the I132/I155 intensity ratio and differed by 2.5 to 5.9% compared to Thiolysis data. Normalization to the 155 ppm signal intensity from reference spectra enabled analysis of PA contents with an error of ca. 8 g PAs/100 g plant tissue. The procedure estimates the lignin contribution and allows for a correction of the PA content. In six sainfoin accessions, estimated PA contents were 1.6- to 20.8-fold higher than the Thiolysis and 1.4- to 2.6-fold higher than the HCl–butanol–acetone results. Method differences may reflect the presence of unextractable, possibly high molecular weight PAs in sainfoin
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Facile Purification of Milligram to Gram Quantities of Condensed Tannins According to Mean Degree of Polymerization and Flavan-3-ol Subunit Composition
2017Co-Authors: Ron H. Brown, Wayne E. Zeller, Christos Fryganas, Honorata M. Ropiak, Irene Mueller-harvey, Elisabetta Stringano, An Gea, Christopher Drake, Laurie Reinhardt, Aina RamsayAbstract:Unambiguous investigation of condensed tannin (CT) structure–activity relationships in biological systems requires well-characterized, high-purity CTs. Sephadex LH-20 and Toyopearl HW-50F resins were compared for separating CTs from acetone/water extracts, and column fractions analyzed for flavan-3-ol subunits, mean degree of polymerization (mDP), and purity. Toyopearl HW-50F generated fractions with higher mDP values and better separation of procyanidins (PC) and prodelphinidins (PD) but required a prepurification step, needed more time for large scale purifications, and gave poorer recoveries. Therefore, two gradient elution schemes were developed for CT purification on Sephadex LH-20 providing 146–2000 mg/fraction. Fractions were analyzed by Thiolysis and NMR spectroscopy. In general, PC/PD ratios decreased and mDP increased during elution. 1H NMR spectroscopy served as a rapid screening tool to qualitatively determine CT enrichment and carbohydrate impurities present, guiding fractionation toward repurification or 1H–13C HSQC NMR spectroscopy and Thiolysis. These protocols provide options for preparing highly pure CT samples
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1H-13C HSQC NMR spectroscopy for estimating procyanidin/prodelphinidin and cis/trans-flavan-3-ol ratios of condensed tannin samples: correlation with Thiolysis
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Wayne E. Zeller, Chris Drake, Christos Fryganas, Honorata M. Ropiak, Aina Ramsay, Irene Mueller-harvey, R.h. Brown, John H GrabberAbstract:Studies with a diverse array of 22 purified condensed tannin (CT) samples from nine plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans-flavan-3-ol ratios can be appraised by 1H–13C HSQC NMR spectroscopy. The method was developed from samples containing 44–∼100% CT, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios ranging from 58/42 to 95/5 as determined by Thiolysis with benzyl mercaptan. Integration of cross-peak contours of H/C-6′ signals from PC and of H/C-2′,6′ signals from PD yielded nuclei-adjusted estimates that were highly correlated with PC/PD ratios obtained by Thiolysis (R2 = 0.99). cis/trans-Flavan-3-ol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by Thiolysis (R2 = 0.89). Overall, 1H–13C HSQC NMR spectroscopy appears to be a viable alternative to Thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.
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1h 13c hsqc nmr spectroscopy for estimating procyanidin prodelphinidin and cis trans flavan 3 ol ratios of condensed tannin samples correlation with Thiolysis
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Wayne E. Zeller, Chris Drake, Christos Fryganas, Honorata M. Ropiak, Aina Ramsay, R.h. Brown, Irene Muellerharvey, John H GrabberAbstract:Studies with a diverse array of 22 purified condensed tannin (CT) samples from nine plant species demonstrated that procyanidin/prodelphinidin (PC/PD) and cis/trans-flavan-3-ol ratios can be appraised by 1H–13C HSQC NMR spectroscopy. The method was developed from samples containing 44–∼100% CT, PC/PD ratios ranging from 0/100 to 99/1, and cis/trans ratios ranging from 58/42 to 95/5 as determined by Thiolysis with benzyl mercaptan. Integration of cross-peak contours of H/C-6′ signals from PC and of H/C-2′,6′ signals from PD yielded nuclei-adjusted estimates that were highly correlated with PC/PD ratios obtained by Thiolysis (R2 = 0.99). cis/trans-Flavan-3-ol ratios, obtained by integration of the respective H/C-4 cross-peak contours, were also related to determinations made by Thiolysis (R2 = 0.89). Overall, 1H–13C HSQC NMR spectroscopy appears to be a viable alternative to Thiolysis for estimating PC/PD and cis/trans ratios of CT if precautions are taken to avoid integration of cross-peak contours of contaminants.
Nathalie Marnet - One of the best experts on this subject based on the ideXlab platform.
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characterization and estimation of proanthocyanidins and other phenolics in coffee pulp coffea arabica by Thiolysis high performance liquid chromatography
Journal of Agricultural and Food Chemistry, 2004Co-Authors: Ma Ascencion Ramirezcoronel, Nathalie Marnet, V Kumar S Kolli, Sylvain Guyot, Sevastianos Roussos, Christopher AugurAbstract:Fresh and 3-day-old coffee pulp of the Arabica variety were analyzed for polyphenol composition followed by characterization by two different methods. The first method consisted in subjecting coffee pulp powder to direct Thiolysis. For the second method, coffee pulp was subjected to successive solvent extractions, followed by Thiolysis. Quantification of phenolic compounds was then achieved by high-performance liquid chromatography (HPLC) analysis of Thiolysis products. Four major classes of polyphenols were identified: flavan-3-ols (monomers and procyanidins), hydroxycinnamic acids, flavonols, and anthocyanidins. Differences in concentration of procyanidins were observed between fresh and 3-day-old coffee pulp. Constitutive units were mainly epicatechin, representing more than 90% of the proanthocyanidin units, with average degrees of polymerization in the range of 3.8-9.1. Monomer to hexamer units of flavan-3-ols from fresh coffee pulp were separated by normal-phase HPLC. Molecular size of oligomeric proanthocyanidins was obtained by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). Results obtained confirm the presence of oligomers of the flavan-3-ol (-)-epicatechin.
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procyanidins are the most abundant polyphenols in dessert apples at maturity
Lwt - Food Science and Technology, 2002Co-Authors: Sylvain Guyot, Nathalie Marnet, Le C Bourvellec, Jeanfrancois DrilleauAbstract:Abstract Direct Thiolysis of crude plant materials and HPLC analysis of the reaction media were used to quantify and to characterise procyanidins (condensed tanins) and other main polyphenols of three dessert apple varieties. Results showed evidence of the large predominance of the procyanidin class in the polyphenolic composition of dessert apple skin and flesh. The structure of procyanidins was wholly homogeneous with (-)-epicatechin representing more than 95% of the constitutive flavan-3-ol units and with average degrees of polymerisation in the 5–7 range.
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (−)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions. Keywords: Apple; chromatographic fractionation; HPLC; Thiolysis; proc...
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Thiolysis hplc characterization of apple procyanidins covering a large range of polymerization states
Journal of Agricultural and Food Chemistry, 2001Co-Authors: Sylvain Guyot, Nathalie Marnet, Jeanfrancois DrilleauAbstract:Procyanidins from the cortex of two cider apple varieties (Malus domestica; Kermerrien and Avrolles) were extracted by solvents. After a solid-phase extraction step, they were fractionated by normal- or reversed-phase HPLC at the semipreparative scale to obtain a series of purified fractions covering a wide range of polymerization states. Freeze-dried fractions were characterized by reversed-phase HPLC following Thiolysis. Elution on normal-phase HPLC gave oligomeric procyanidins fractions with (average degree of polymerization) values varying from 2 to 8, whereas polymeric fractions ( values varying from 7 to 190) were obtained by reversed-phase HPLC. Constitutive units were mainly (-)-epicatechin with a proportion above 95% for all fractions. Thiolysis yields were wholly homogeneous with an average value of 75%, which indicates that the efficiency of the reaction did not depend on the polymerization state of the procyanidin fractions.
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polyphenol profiles of french cider apple varieties malus domestica sp
Journal of Agricultural and Food Chemistry, 1999Co-Authors: Philippe Sanoner, Nathalie Marnet, Sylvain Guyot, Daniel Molle, Jeanfrancois DrilleauAbstract:The cortex of 14 French apple varieties (12 cider and 2 juice varieties), one English cider variety, and one dessert apple (i.e., Golden Delicious) were studied for their polyphenol composition. Total polyphenols were assayed by the Folin-Ciocalteu method, and the precise polyphenolic composition (monomeric catechins, proanthocyanidins, hydroxycinnamic acids, and dihydrochalcones) was obtained by HPLC following Thiolysis. ESI-MS and ESI-MS/MS analyses showed that chlorogenic acid and p-coumaroylquinic acid were methylated under the conditions of Thiolysis. Depending on the variety, the global polyphenol concentration varied from 1 to 7 g per kilogram of fresh cortex. Cider varieties globally showed a higher polyphenol concentration than the dessert apple Golden Delicious, bitter varieties being the more concentrated. The proportion of the polyphenol classes varied greatly from one cultivar to another. For all varieties, procyanidins were always the predominant class. They were mainly constituted of (-)-epicatechin units with a small proportion of (+)-catechin as a terminal unit. The average degree of polymerization ranged between 4.2 and 7.5 depending upon the variety with an exception for the sharp varieties Guillevic and Avrolles which showed significant concentrations of procyanidins with DPn of 40 and 50, respectively.
