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Victor De Freitas - One of the best experts on this subject based on the ideXlab platform.
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carbohydrates inhibit salivary proteins precipitation by Condensed Tannins
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Condensed Tannins are a group of polyphenols that are associated with the astringency sensation, as they readily interact and precipitate salivary proteins. As this interaction is affected by carbohydrates, the aim of this work was to study the effect of some carbohydrates used in the food industry [arabic gum (AG), pectin, and poligalacturonic acid (PGA)] on the salivary proteins/grape seed procyanidins interaction. This was assessed monitoring the salivary proteins that remain soluble in the presence of Condensed Tannins with the addition of carbohydrates (HPLC) and analysis of the respective precipitates (SDS-PAGE). The results show that pectin was the most efficient in inhibiting protein/tannin precipitation, followed by AG and PGA. The results suggest that pectin and PGA exert their effect by formation of a ternary complex protein/polyphenol/carbohydrate, while AG competes with proteins for tannin binding (competition mechanism). The results also point out that both hydrophilic and hydrophobic intera...
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Effect of Condensed Tannins Addition on the Astringency of Red Wines
Chemical Senses, 2011Co-Authors: Susana Soares, André M. M. Sousa, Nuno Mateus, Victor De FreitasAbstract:Astringency has been defined as a group of sensations involving dryness, tightening, and shrinking of the oral surface. It has been accepted that astringency is due to the tannin-induced interaction and/or precipitation of the salivary proline-rich proteins (PRPs) in the oral cavity, as a result of the ingestion of food products rich in Tannins, for example, red wine. The sensory evaluation of astringency is difficult, and the existence of fast and reliable methods to its study in vitro is scarce. So, in this work, the astringency of red wine supplemented with oligomeric procyanidins (Condensed Tannins), and the salivary proteins (SP) involved in its development were evaluated by high-performance liquid chromatography analysis of human saliva after its interaction with red wine and by sensorial evaluation. The results show that for low concentration of Tannins, the decrease of acidic PRPs and statherin is correlated with astringency intensity, with these families having a high relative complexation and precipitation toward Condensed Tannins comparatively to the other SP. However, for higher concentrations of Tannins, the relative astringency between wines seems to correlate’s to the glycosylated PRPs changes. This work shows for the first time that the several families of SP could be involved in different stages of the astringency development.
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Inhibition of trypsin by Condensed Tannins and wine.
Journal of agricultural and food chemistry, 2007Co-Authors: Rui Gonçalves, Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Phenolic compounds are abundant vegetable secondary metabolites in the human diet. The ability of procyanidin oligomers and wine polyphenols to inhibit trypsin activity was studied using a versatile and reliable in vitro method. The hydrolysis of the chromogenic substrate N-benzoyl-d,l-arginine-p-nitroanilide (BApNA) by trypsin was followed by spectrophotometry in the presence and absence of Condensed Tannins and wine. A clear relationship between the degree of polymerization of procyanidins and enzymatic inhibition was observed. Trypsin activity inhibition was also detected in several types of wine. In general, the inhibition increased with the concentration of phenolic compounds in wines. These results may be relevant when considering these compounds as antinutritional factors, thereby contributing to a reduced absorption of nutrients. Keywords: Trypsin; Condensed Tannins; procyanidin; BApNA; wine; grape seeds
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influence of wine pectic polysaccharides on the interactions between Condensed Tannins and salivary proteins
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Elisabete Carvalho, Nuno Mateus, Benoit Plet, Isabelle Pianet, Erick J Dufourc, Victor De FreitasAbstract:α-Amylase, a major human salivary protein, and IB8c, a representative of the proline-rich proteins, were obtained by isolation from saliva and by solid-phase synthesis, respectively. The interactions between these proteins and Condensed Tannins isolated from grape seeds were studied at different protein and tannin concentrations by measuring their aggregation. Pectic polysaccharides were isolated from wine, and their effect on protein tannin aggregation was assessed. The results presented in this study showed that the most acidic fractions of arabinogalactan proteins have the ability to inhibit the formation of aggregates between the grape seed Tannins and the two different salivary proteins. Rhamnogalacturonan II has the same ability toward α-amylase but not IB8c under the conditions of the present study. Polysaccharides show effects at concentrations at which they are present in wine, which could mean an influence in wine astringency. The interaction between Condensed Tannins and α-amylase is differentl...
Wei-ming Chai - One of the best experts on this subject based on the ideXlab platform.
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Condensed Tannins from longan bark as inhibitor of tyrosinase structure activity and mechanism
Journal of Agricultural and Food Chemistry, 2018Co-Authors: Wei-ming Chai, Qian Huang, Meizhen Lin, Chong Ouyang, Wenyang Huang, Yingxia Wang, Hui-ling FengAbstract:In this study, the content, structure, antityrosinase activity, and mechanism of longan bark Condensed Tannins were evaluated. The findings obtained from mass spectrometry demonstrated that longan bark Condensed Tannins were mixtures of procyanidins, propelargonidins, prodelphinidins, and their acyl derivatives (galloyl and p-hydroxybenzoate). The enzyme analysis indicated that these mixtures were efficient, reversible, and mixed (competitive is dominant) inhibitor of tyrosinase. What’s more, the mixtures showed good inhibitions on proliferation, intracellular enzyme activity and melanogenesis of mouse melanoma cells (B16). From molecular docking, the results showed the interactions between inhibitors and tyrosinase were driven by hydrogen bond, electrostatic, and hydrophobic interactions. In addition, high levels of total phenolic and extractable Condensed Tannins suggested that longan bark might be a good source of tyrosinase inhibitor. This study would offer theoretical basis for the development of lon...
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Isolation and Purification of Condensed Tannins from Flamboyant Tree and Their Antioxidant and Antityrosinase Activities
Applied biochemistry and biotechnology, 2014Co-Authors: Hui-ling Feng, Wei-ming Chai, Xiao-xin Chen, Yan Shi, Ling Tian, Yu-sen Gao, Chongling Yan, Qing-xi ChenAbstract:Flamboyant tree, a kind of medicinal plant, was studied as a source of Condensed Tannins. The antioxidant activities of the Condensed Tannins from the leaf, fruit, and stem bark of flamboyant tree were screened by ABTS radical and hydroxyl radical scavenging activity methods. The results indicated that these compounds possessed potent antioxidant activity. Their structures were then characterized by high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) after thiolytic degradation. The results showed that the leaf Condensed Tannins were composed of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin, while the fruit and stem bark Condensed Tannins had afzelechin/epiafzelechin and catechin/epicatechin. In addition, the Condensed Tannins were evaluated for their antityrosinase ability. They were found to have significant antityrosinase activity. The IC50 values were 35 ± 2.0 and 40 ± 0.5 μg/ml for the Condensed Tannins of fruit and stem bark, respectively. Further, fluorescence quenching and copper interacting techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group of the Condensed Tannins could chelate the dicopper center of the enzyme and interact with tryptophan residues. Our studies revealed that Condensed Tannins might be suitable for use in food, agriculture, cosmetic, nutraceutical, and pharmaceutical applications.
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Condensed Tannins from Ficus virens as Tyrosinase Inhibitors: Structure, Inhibitory Activity and Molecular Mechanism
PloS one, 2014Co-Authors: Xiao-xin Chen, Wei-ming Chai, Yan Shi, Hui-ling Feng, Jiang-xing Zhuang, Qing-xi ChenAbstract:Condensed Tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark Condensed Tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the Condensed Tannins were studied. The results indicated that the Condensed Tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark Condensed Tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the Condensed Tannins on the diphenolase activity were further investigated. The results indicated that the Condensed Tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the Condensed Tannins could chelate the dicopper irons of the enzyme. Moreover, the Condensed Tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.
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HPLC chromatograms and MALDI-TOF MS of the Condensed Tannins.
2014Co-Authors: Xiao-xin Chen, Wei-ming Chai, Yan Shi, Hui-ling Feng, Jiang-xing Zhuang, Qing-xi ChenAbstract:(1) Reversed-phase HPLC chromatograms of the Condensed Tannins. Terminal units: epicatechin (EC). Extender units: afzelechin (AF-thio), epiafzelechin (EAF-thio), catechin (C-thio), epicatechin (EC-thio), BM, benzyl mercaptan. (2) MALDI-TOF positive reflectron mode mass spectra of the Condensed Tannins. DP, degree of polymerization. (3) Enlarged picture of the DP 4 of the Condensed Tannins. a, b, and c represented the Condensed Tannins from leaves fruit, and stem bark of F. virens, respectively.
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nmr hplc esi ms and maldi tof ms analysis of Condensed Tannins from delonix regia bojer ex hook raf and their bioactivities
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Wei-ming Chai, Hai-chao Zhou, Yan Shi, Hui-ling Feng, Chongling Yan, Ling Qiu, Ziwei Deng, Qing-xi ChenAbstract:The structures of the Condensed Tannins isolated from leaf, fruit, and stem bark of Delonix regia (Bojer ex Hook.) Raf. have been investigated with (13)C nuclear magnetic resonance ((13)C NMR) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. The results showed that these Condensed Tannins from D. regia possessed structural heterogeneity in monomer units and degree of polymerization. Propelargonidin (PP) and procyanidin (PC) were found in the leaf, fruit, and stem bark of D. regia, while prodelphinidin (PD) was found only in the leaves. The polymer chain lengths of Condensed Tannins from leaf and fruit organs were detected to be trimers to hexadecamers but from trimers to tridecamers for stem bark. B-type linkages were present in all these compounds. Condensed Tannins from different parts of D. regia can be explored as tyrosinase inhibitors and food antioxidants because of their potent antityrosinase and antioxidant activities. The inhibitor concentration leading to 50% enzyme activity (IC(50)) was estimated to be 38 ± 1, 73 ± 2, and 54 ± 1.5 μg/mL for the Condensed Tannins of leaf, fruit, and stem bark. Condensed Tannins extracted from stem bark exhibited the highest antioxidant activity; the DPPH scavenging activity (IC(50)) and the FRAP values were 90 ± 2 μg/mL and 5.42 ± 0.09 mmol AAE/g, respectively.
Nuno Mateus - One of the best experts on this subject based on the ideXlab platform.
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carbohydrates inhibit salivary proteins precipitation by Condensed Tannins
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Condensed Tannins are a group of polyphenols that are associated with the astringency sensation, as they readily interact and precipitate salivary proteins. As this interaction is affected by carbohydrates, the aim of this work was to study the effect of some carbohydrates used in the food industry [arabic gum (AG), pectin, and poligalacturonic acid (PGA)] on the salivary proteins/grape seed procyanidins interaction. This was assessed monitoring the salivary proteins that remain soluble in the presence of Condensed Tannins with the addition of carbohydrates (HPLC) and analysis of the respective precipitates (SDS-PAGE). The results show that pectin was the most efficient in inhibiting protein/tannin precipitation, followed by AG and PGA. The results suggest that pectin and PGA exert their effect by formation of a ternary complex protein/polyphenol/carbohydrate, while AG competes with proteins for tannin binding (competition mechanism). The results also point out that both hydrophilic and hydrophobic intera...
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Effect of Condensed Tannins Addition on the Astringency of Red Wines
Chemical Senses, 2011Co-Authors: Susana Soares, André M. M. Sousa, Nuno Mateus, Victor De FreitasAbstract:Astringency has been defined as a group of sensations involving dryness, tightening, and shrinking of the oral surface. It has been accepted that astringency is due to the tannin-induced interaction and/or precipitation of the salivary proline-rich proteins (PRPs) in the oral cavity, as a result of the ingestion of food products rich in Tannins, for example, red wine. The sensory evaluation of astringency is difficult, and the existence of fast and reliable methods to its study in vitro is scarce. So, in this work, the astringency of red wine supplemented with oligomeric procyanidins (Condensed Tannins), and the salivary proteins (SP) involved in its development were evaluated by high-performance liquid chromatography analysis of human saliva after its interaction with red wine and by sensorial evaluation. The results show that for low concentration of Tannins, the decrease of acidic PRPs and statherin is correlated with astringency intensity, with these families having a high relative complexation and precipitation toward Condensed Tannins comparatively to the other SP. However, for higher concentrations of Tannins, the relative astringency between wines seems to correlate’s to the glycosylated PRPs changes. This work shows for the first time that the several families of SP could be involved in different stages of the astringency development.
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Inhibition of trypsin by Condensed Tannins and wine.
Journal of agricultural and food chemistry, 2007Co-Authors: Rui Gonçalves, Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Phenolic compounds are abundant vegetable secondary metabolites in the human diet. The ability of procyanidin oligomers and wine polyphenols to inhibit trypsin activity was studied using a versatile and reliable in vitro method. The hydrolysis of the chromogenic substrate N-benzoyl-d,l-arginine-p-nitroanilide (BApNA) by trypsin was followed by spectrophotometry in the presence and absence of Condensed Tannins and wine. A clear relationship between the degree of polymerization of procyanidins and enzymatic inhibition was observed. Trypsin activity inhibition was also detected in several types of wine. In general, the inhibition increased with the concentration of phenolic compounds in wines. These results may be relevant when considering these compounds as antinutritional factors, thereby contributing to a reduced absorption of nutrients. Keywords: Trypsin; Condensed Tannins; procyanidin; BApNA; wine; grape seeds
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influence of wine pectic polysaccharides on the interactions between Condensed Tannins and salivary proteins
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Elisabete Carvalho, Nuno Mateus, Benoit Plet, Isabelle Pianet, Erick J Dufourc, Victor De FreitasAbstract:α-Amylase, a major human salivary protein, and IB8c, a representative of the proline-rich proteins, were obtained by isolation from saliva and by solid-phase synthesis, respectively. The interactions between these proteins and Condensed Tannins isolated from grape seeds were studied at different protein and tannin concentrations by measuring their aggregation. Pectic polysaccharides were isolated from wine, and their effect on protein tannin aggregation was assessed. The results presented in this study showed that the most acidic fractions of arabinogalactan proteins have the ability to inhibit the formation of aggregates between the grape seed Tannins and the two different salivary proteins. Rhamnogalacturonan II has the same ability toward α-amylase but not IB8c under the conditions of the present study. Polysaccharides show effects at concentrations at which they are present in wine, which could mean an influence in wine astringency. The interaction between Condensed Tannins and α-amylase is differentl...
Qing-xi Chen - One of the best experts on this subject based on the ideXlab platform.
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Condensed Tannins from Ficus altissima leaves: Structural, antioxidant, and antityrosinase properties
Process Biochemistry, 2016Co-Authors: Yi-tao Deng, Yan Shi, Qing-xi Chen, Ge Liang, Jing Zhang, Xiao-mei Mao, Wei-xi Peng, Dong-yan ShenAbstract:Abstract The total phenolic content and the concentration of extractable and bound Condensed Tannins of Ficus altissima leaves were determined. The antioxidant activity of crude extracts and Condensed Tannins of F. altissima leaves was evaluated using 2,2-diphenyl-1-pichydrazyl (DPpH), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and ferric-reducing antioxidant power (FRAP) methods. The results showed that Condensed Tannins possessed higher free radical scavenging power. The structure of Condensed Tannins was characterized using high-performance liquid chromatography electrospray ionization mass spectrometry coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The findings showed that Condensed Tannins from F. altissima leaves were mixtures of procyanidins, prodelphinidins, and propelargonidins with a degree of polymerization up to 30-mer. In addition, Condensed Tannins effectively protected plasmid DNA against free radical damage and alleviated t-butylhydroperoxide-induced cytotoxicity on human hepatocyte LO2 cells. Condensed Tannins exhibited remarkable inhibitory effects on both monophenolase and diphenolase activities of tyrosinase. The IC50 values were estimated to be 256.7 ± 0.3 and 41.3 ± 0.2 μg/mL, respectively. For the diphenolase activity, inhibition by Condensed Tannins was reversible and of mixed-type. Condensed Tannins from leaves of F. altissima were indicated to possess significant antioxidant and antityrosinase activities, suggesting that F. altissima might be a good source of proanthocyanidins with biological activity.
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Isolation and Purification of Condensed Tannins from Flamboyant Tree and Their Antioxidant and Antityrosinase Activities
Applied biochemistry and biotechnology, 2014Co-Authors: Hui-ling Feng, Wei-ming Chai, Xiao-xin Chen, Yan Shi, Ling Tian, Yu-sen Gao, Chongling Yan, Qing-xi ChenAbstract:Flamboyant tree, a kind of medicinal plant, was studied as a source of Condensed Tannins. The antioxidant activities of the Condensed Tannins from the leaf, fruit, and stem bark of flamboyant tree were screened by ABTS radical and hydroxyl radical scavenging activity methods. The results indicated that these compounds possessed potent antioxidant activity. Their structures were then characterized by high-performance liquid chromatography-electrospray ionization mass spectrometry (HPLC-ESI-MS) after thiolytic degradation. The results showed that the leaf Condensed Tannins were composed of afzelechin/epiafzelechin, catechin/epicatechin, and gallocatechin/epigallocatechin, while the fruit and stem bark Condensed Tannins had afzelechin/epiafzelechin and catechin/epicatechin. In addition, the Condensed Tannins were evaluated for their antityrosinase ability. They were found to have significant antityrosinase activity. The IC50 values were 35 ± 2.0 and 40 ± 0.5 μg/ml for the Condensed Tannins of fruit and stem bark, respectively. Further, fluorescence quenching and copper interacting techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group of the Condensed Tannins could chelate the dicopper center of the enzyme and interact with tryptophan residues. Our studies revealed that Condensed Tannins might be suitable for use in food, agriculture, cosmetic, nutraceutical, and pharmaceutical applications.
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Condensed Tannins from Ficus virens as Tyrosinase Inhibitors: Structure, Inhibitory Activity and Molecular Mechanism
PloS one, 2014Co-Authors: Xiao-xin Chen, Wei-ming Chai, Yan Shi, Hui-ling Feng, Jiang-xing Zhuang, Qing-xi ChenAbstract:Condensed Tannins from Ficus virens leaves, fruit, and stem bark were isolated and their structures characterized by 13C nuclear magnetic resonance spectrometry, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The results showed that the leaves, fruit, and stem bark Condensed Tannins were complex mixtures of homo- and heteropolymers of B-type procyanidins and prodelphinidins with degrees of polymerization up to hexamer, dodecamer, and pentadecamer, respectively. Antityrosinase activities of the Condensed Tannins were studied. The results indicated that the Condensed Tannins were potent tyrosinase inhibitors. The concentrations for the leaves, fruit, and stem bark Condensed Tannins leading to 50% enzyme activity were determined to be 131.67, 99.89, and 106.22 μg/ml on monophenolase activity, and 128.42, 43.07, and 74.27 μg/ml on diphenolase activity. The inhibition mechanism, type, and constants of the Condensed Tannins on the diphenolase activity were further investigated. The results indicated that the Condensed Tannins were reversible and mixed type inhibitors. Fluorescence quenching, copper interacting, and molecular docking techniques were utilized to unravel the molecular mechanisms of the inhibition. The results showed that the hydroxyl group on the B ring of the Condensed Tannins could chelate the dicopper irons of the enzyme. Moreover, the Condensed Tannins could reduce the enzyme product o-quinones into colourless compounds. These results would contribute to the development and design of antityrosinase agents.
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HPLC chromatograms and MALDI-TOF MS of the Condensed Tannins.
2014Co-Authors: Xiao-xin Chen, Wei-ming Chai, Yan Shi, Hui-ling Feng, Jiang-xing Zhuang, Qing-xi ChenAbstract:(1) Reversed-phase HPLC chromatograms of the Condensed Tannins. Terminal units: epicatechin (EC). Extender units: afzelechin (AF-thio), epiafzelechin (EAF-thio), catechin (C-thio), epicatechin (EC-thio), BM, benzyl mercaptan. (2) MALDI-TOF positive reflectron mode mass spectra of the Condensed Tannins. DP, degree of polymerization. (3) Enlarged picture of the DP 4 of the Condensed Tannins. a, b, and c represented the Condensed Tannins from leaves fruit, and stem bark of F. virens, respectively.
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nmr hplc esi ms and maldi tof ms analysis of Condensed Tannins from delonix regia bojer ex hook raf and their bioactivities
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Wei-ming Chai, Hai-chao Zhou, Yan Shi, Hui-ling Feng, Chongling Yan, Ling Qiu, Ziwei Deng, Qing-xi ChenAbstract:The structures of the Condensed Tannins isolated from leaf, fruit, and stem bark of Delonix regia (Bojer ex Hook.) Raf. have been investigated with (13)C nuclear magnetic resonance ((13)C NMR) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS) coupled with thiolysis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. The results showed that these Condensed Tannins from D. regia possessed structural heterogeneity in monomer units and degree of polymerization. Propelargonidin (PP) and procyanidin (PC) were found in the leaf, fruit, and stem bark of D. regia, while prodelphinidin (PD) was found only in the leaves. The polymer chain lengths of Condensed Tannins from leaf and fruit organs were detected to be trimers to hexadecamers but from trimers to tridecamers for stem bark. B-type linkages were present in all these compounds. Condensed Tannins from different parts of D. regia can be explored as tyrosinase inhibitors and food antioxidants because of their potent antityrosinase and antioxidant activities. The inhibitor concentration leading to 50% enzyme activity (IC(50)) was estimated to be 38 ± 1, 73 ± 2, and 54 ± 1.5 μg/mL for the Condensed Tannins of leaf, fruit, and stem bark. Condensed Tannins extracted from stem bark exhibited the highest antioxidant activity; the DPPH scavenging activity (IC(50)) and the FRAP values were 90 ± 2 μg/mL and 5.42 ± 0.09 mmol AAE/g, respectively.
Susana Soares - One of the best experts on this subject based on the ideXlab platform.
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carbohydrates inhibit salivary proteins precipitation by Condensed Tannins
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Condensed Tannins are a group of polyphenols that are associated with the astringency sensation, as they readily interact and precipitate salivary proteins. As this interaction is affected by carbohydrates, the aim of this work was to study the effect of some carbohydrates used in the food industry [arabic gum (AG), pectin, and poligalacturonic acid (PGA)] on the salivary proteins/grape seed procyanidins interaction. This was assessed monitoring the salivary proteins that remain soluble in the presence of Condensed Tannins with the addition of carbohydrates (HPLC) and analysis of the respective precipitates (SDS-PAGE). The results show that pectin was the most efficient in inhibiting protein/tannin precipitation, followed by AG and PGA. The results suggest that pectin and PGA exert their effect by formation of a ternary complex protein/polyphenol/carbohydrate, while AG competes with proteins for tannin binding (competition mechanism). The results also point out that both hydrophilic and hydrophobic intera...
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Effect of Condensed Tannins Addition on the Astringency of Red Wines
Chemical Senses, 2011Co-Authors: Susana Soares, André M. M. Sousa, Nuno Mateus, Victor De FreitasAbstract:Astringency has been defined as a group of sensations involving dryness, tightening, and shrinking of the oral surface. It has been accepted that astringency is due to the tannin-induced interaction and/or precipitation of the salivary proline-rich proteins (PRPs) in the oral cavity, as a result of the ingestion of food products rich in Tannins, for example, red wine. The sensory evaluation of astringency is difficult, and the existence of fast and reliable methods to its study in vitro is scarce. So, in this work, the astringency of red wine supplemented with oligomeric procyanidins (Condensed Tannins), and the salivary proteins (SP) involved in its development were evaluated by high-performance liquid chromatography analysis of human saliva after its interaction with red wine and by sensorial evaluation. The results show that for low concentration of Tannins, the decrease of acidic PRPs and statherin is correlated with astringency intensity, with these families having a high relative complexation and precipitation toward Condensed Tannins comparatively to the other SP. However, for higher concentrations of Tannins, the relative astringency between wines seems to correlate’s to the glycosylated PRPs changes. This work shows for the first time that the several families of SP could be involved in different stages of the astringency development.
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Inhibition of trypsin by Condensed Tannins and wine.
Journal of agricultural and food chemistry, 2007Co-Authors: Rui Gonçalves, Susana Soares, Nuno Mateus, Victor De FreitasAbstract:Phenolic compounds are abundant vegetable secondary metabolites in the human diet. The ability of procyanidin oligomers and wine polyphenols to inhibit trypsin activity was studied using a versatile and reliable in vitro method. The hydrolysis of the chromogenic substrate N-benzoyl-d,l-arginine-p-nitroanilide (BApNA) by trypsin was followed by spectrophotometry in the presence and absence of Condensed Tannins and wine. A clear relationship between the degree of polymerization of procyanidins and enzymatic inhibition was observed. Trypsin activity inhibition was also detected in several types of wine. In general, the inhibition increased with the concentration of phenolic compounds in wines. These results may be relevant when considering these compounds as antinutritional factors, thereby contributing to a reduced absorption of nutrients. Keywords: Trypsin; Condensed Tannins; procyanidin; BApNA; wine; grape seeds