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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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avocado proanthocyanidins as a source of tyrosinase inhibitors structure characterization inhibitory activity and mechanism
Journal of Agricultural and Food Chemistry, 2015Co-Authors: Wei-ming Chai, Mankun Wei, Rui Wang, Ronggen Deng, Zhengrong Zou, Yiyuan PengAbstract:Proanthocyanidins were purified from avocado (Persea americana) fruit, and their structures were analyzed by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry (MALDI–TOF MS) and high-performance liquid chromatography–electrospray ionization–QTRAP mass spectrometry (HPLC–ESI–QTRAP MS) techniques. The results obtained from mass spectrometry (MS) analysis demonstrated that the proanthocyanidins were homo- and heteropolymers of procyanidins, Prodelphinidins, propelargonidins, and procyanidin gallate. From the enzyme analysis, the results showed that they could inhibit the monophenolase and diphenolase activities of tyrosinase. The inhibition mechanism of the proanthocyanidins on the enzyme was further studied, and the results indicated that they were reversible and competitive inhibitors. Finally, the results acquired from molecular docking, fluorescence quenching, and copper ion interacting tests revealed that adjacent hydroxyl groups on the B ring of proanthocyanidins could chelat...
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structural analysis of proanthocyanidins isolated from fruit stone of chinese hawthorn with potent antityrosinase and antioxidant activity
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Wei-ming Chai, Yan Shi, Hui-ling Feng, Chihmin Chen, Yusen Gao, Yumei Ding, Hantao Zhou, Qing-xi ChenAbstract:Proanthocyanidins were isolated from fruit stone of Chinese hawthorn (Crataegus pinnatifida Bge. var. major N.E.Br.). Their structures were analyzed and elucidated by methods of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and high performance liquid chromatography electrospray ionization mass spectrometry (HPLC-ESI-MS). The results demonstrated that these compounds are complicated mixtures of homo- and heteropolymers consisting of procyanidin/procyanidin gallate and Prodelphinidin. They possessed structural heterogeneity in monomer units, polymer length, and interflavan linkage (A-type and B-type). Their antityrosinase and antioxidant activity were then investigated. The results revealed that they can inhibit tyrosinase activities, including the monophenolase activity and the diphenolase activity. In addition, proanthocyanidins possessed potent antioxidant activity. Our studies revealed that proanthocyanidins isolated from fruit stone of Chinese hawthorn may...
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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.
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maldi tof ms analysis of condensed tannins with potent antioxidant activity from the leaf stem bark and root bark of acacia confusa
Molecules, 2010Co-Authors: Shu-dong Wei, Yi-ming Lin, Hai-chao Zhou, Meng-meng Liao, Wei-ming ChaiAbstract:The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and Prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.
Hai-chao Zhou - One of the best experts on this subject based on the ideXlab platform.
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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.
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antioxidant activities of extract and fractions from the hypocotyls of the mangrove plant kandelia candel
International Journal of Molecular Sciences, 2010Co-Authors: Hai-chao ZhouAbstract:The antioxidant activities of 70% acetone extract (70% AE) from the hypocotyls of the mangrove plant Kandelia candel and its fractions of petroleum ether (PF), ethyl acetate (EF), water (WF), and the LF (WF fraction further purified through a Sephadex LH-20 column), were investigated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that all the extract and fractions possessed potent antioxidant activity. There was a significant linear correlation between the total phenolics concentration and the ferric reducing power or free radical scavenging activity of the extract and fractions. Among the extract and fractions, the LF fraction exhibits the best antioxidant performance. The MALDT-TOF MS and HPLC analyses revealed that the phenolic compounds associated with the antioxidant activity of the LF fraction contains a large number of procyanidins and a small amount of Prodelphinidins, and the epicatechin is the main extension unit.
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antioxidant tannins from stem bark and fine root of casuarina equisetifolia
Molecules, 2010Co-Authors: Shangju Zhang, Yi-ming Lin, Hai-chao Zhou, Shu-dong Wei, Guanghui LinAbstract:Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with Prodelphinidin and propelargonidin, and epicatechin is the main extension unit. The condensed tannins had different polymer chain lengths, varying from trimers to tridecamer for stem bark and to pentadecamer for fine root. The antioxidant activities were measured by two models: 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/ antioxidant power (FRAP). The condensed tannins extracted from C. equisetifolia showed very good DPPH radical scavenging activity and ferric reducing/ antioxidant power, suggesting that these extracts may be considered as new sources of natural antioxidants for food and nutraceutical products.
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maldi tof ms analysis of condensed tannins with potent antioxidant activity from the leaf stem bark and root bark of acacia confusa
Molecules, 2010Co-Authors: Shu-dong Wei, Yi-ming Lin, Hai-chao Zhou, Meng-meng Liao, Wei-ming ChaiAbstract:The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and Prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.
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Condensed tannins from mangrove species Kandelia candel and Rhizophora mangle and their antioxidant activity.
Molecules, 2010Co-Authors: Liang-liang Zhang, Yi-ming Lin, Hai-chao Zhou, Shu-dong Wei, Jia-hong ChenAbstract:The structures of condensed tannins isolated from two mangrove species, Kandelia candel and Rhizophora mangle, were characterized by 13C nuclear magnetic resonance (NMR) spectroscopy and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. Results demonstrate that large heterogeneity occurs in degree of polymerization, pattern of hydroxylation, and substitution with monosaccharides in the structures of the condensed tannins. Condensed tannin oligomers from K. candel and R. mangle were shown to be heterogeneous mixtures consisting of procyanidin and Prodelphinidin structural units with the former dominating. The MALDI-TOF mass spectra contained masses corresponding to a distinct oligomeric series of glycosylated heteropolyflavan units. In addition, condensed tannins from two mangrove plants were screened for their potential antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) model systems.
W C Mcnabb - One of the best experts on this subject based on the ideXlab platform.
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the phenols and Prodelphinidins of white clover flowers
Phytochemistry, 2000Co-Authors: L Y Foo, Abdullateef Molan, D R Woodfield, W C McnabbAbstract:Abstract White clover flowers ( Trifolium repens L.) contain an abundance of phenolics, namely cis - and trans-p -coumaric acid 4- O -β- D -glucopyranoside, the 3- O -β- D -galactopyranosides of myricetin, quercetin and kaempferol together with two new derivatives namely myricetin 3-O-(6″-acetyl)-β- D -galactopyranoside and kaempferol 3- O -(6″-acetyl)-β- D -galactopyranoside. Gallocatechin, epigallocatechin, gallocatechin-(4α-8)-epigallocatechin and their corresponding Prodelphinidin polymers were also present. The 13 C-NMR spectra showed that the polymers consisted of only gallocatechin and epigallocatechin monomeric units with the latter being about twice as abundant in the extenders but only slightly more than that in the terminating units. The average degree of polymerization was estimated by 13 C-NMR and ES–MS, which gave a remarkably consistent result of about 5.8 flavanol units.
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the phenols and Prodelphinidins of white clover flowers
Phytochemistry, 2000Co-Authors: L Y Foo, Abdullateef Molan, D R Woodfield, W C McnabbAbstract:White clover flowers (Trifolium repens L.) contain an abundance of phenolics, namely cis- and trans-p-coumaric acid 4-O-beta-D-glucopyranoside, the 3-O-beta-D-galactopyranosides of myricetin, quercetin and kaempferol together with two new derivatives namely myricetin 3-O-(6"-acetyl)-beta-D-galactopyranoside and kaempferol 3-O-(6"-acetyl)-beta-D-galactopyranoside. Gallocatechin, epigallocatechin, gallocatechin-(4alpha-8)-epigallocatechin and their corresponding Prodelphinidin polymers were also present. The 13C-NMR spectra showed that the polymers consisted of only gallocatechin and epigallocatechin monomeric units with the latter being about twice as abundant in the extenders but only slightly more than that in the terminating units. The average degree of polymerization was estimated by 13C-NMR and ES-MS, which gave a remarkably consistent result of about 5.8 flavanol units.
Yi-ming Lin - One of the best experts on this subject based on the ideXlab platform.
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antioxidant tannins from stem bark and fine root of casuarina equisetifolia
Molecules, 2010Co-Authors: Shangju Zhang, Yi-ming Lin, Hai-chao Zhou, Shu-dong Wei, Guanghui LinAbstract:Structures of condensed tannins from the stem bark and fine root of Casuarina equisetifolia were identified using MALDI-TOF MS and HPLC analyses. The condensed tannins from stem bark and fine root consist predominantly of procyanidin combined with Prodelphinidin and propelargonidin, and epicatechin is the main extension unit. The condensed tannins had different polymer chain lengths, varying from trimers to tridecamer for stem bark and to pentadecamer for fine root. The antioxidant activities were measured by two models: 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing/ antioxidant power (FRAP). The condensed tannins extracted from C. equisetifolia showed very good DPPH radical scavenging activity and ferric reducing/ antioxidant power, suggesting that these extracts may be considered as new sources of natural antioxidants for food and nutraceutical products.
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maldi tof ms analysis of condensed tannins with potent antioxidant activity from the leaf stem bark and root bark of acacia confusa
Molecules, 2010Co-Authors: Shu-dong Wei, Yi-ming Lin, Hai-chao Zhou, Meng-meng Liao, Wei-ming ChaiAbstract:The structures of the condensed tannins from leaf, stem bark and root bark of Acacia confusa were characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis, and their antioxidant activities were measured using 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging and ferric reducing/antioxidant power (FRAP) assays. The results showed that the condensed tannins from stem bark and root bark include propelargonidin and procyanidin, and the leaf condensed tannins include propelargonidin, procyanidin and Prodelphinidin, all with the procyanidin dominating. The condensed tannins had different polymer chain lengths, varying from trimers to undecamers for leaf and root bark and to dodecamers for stem bark. The condensed tannins extracted from the leaf, stem bark and root bark all showed a very good DPPH radical scavenging activity and ferric reducing power.
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Condensed tannins from mangrove species Kandelia candel and Rhizophora mangle and their antioxidant activity.
Molecules, 2010Co-Authors: Liang-liang Zhang, Yi-ming Lin, Hai-chao Zhou, Shu-dong Wei, Jia-hong ChenAbstract:The structures of condensed tannins isolated from two mangrove species, Kandelia candel and Rhizophora mangle, were characterized by 13C nuclear magnetic resonance (NMR) spectroscopy and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analyses. Results demonstrate that large heterogeneity occurs in degree of polymerization, pattern of hydroxylation, and substitution with monosaccharides in the structures of the condensed tannins. Condensed tannin oligomers from K. candel and R. mangle were shown to be heterogeneous mixtures consisting of procyanidin and Prodelphinidin structural units with the former dominating. The MALDI-TOF mass spectra contained masses corresponding to a distinct oligomeric series of glycosylated heteropolyflavan units. In addition, condensed tannins from two mangrove plants were screened for their potential antioxidant activities using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) model systems.
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hplc nmr and maldi tof ms analysis of condensed tannins from lithocarpus glaber leaves with potent free radical scavenging activity
Molecules, 2008Co-Authors: Liang-liang Zhang, Yi-ming LinAbstract:Using acid-catalyzed degradation in the presence of cysteamine, the condensed tannins from Lithocarpus glaber leaves were characterized, following thiolysis, by means of reversed-phase HPLC, 13C-NMR and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analyses. The thiolysis reaction products showed the presence of the procyanidin (PC) and Prodelphinidin (PD) structures. The 13C-NMR spectrum revealed that the condensed tannins were comprised of PD (72.4%) and PC (27.6%), and with a greater content of cis configuration rather than the trans configuration of C2–C3. The MALDI-TOF MS analysis proved the presence of PD units, and the maximum degree of polymerization (DP) was an undecamer. The antioxidant activity of condensed tannins from L. glaber leaves was evaluated by using a free radical scavenging activity assay.
Peter Winterhalter - One of the best experts on this subject based on the ideXlab platform.
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semisynthetic preparation and isolation of dimeric procyanidins b1 b8 from roasted hazelnut skins corylus avellana l on a large scale using countercurrent chromatography
Journal of Agricultural and Food Chemistry, 2014Co-Authors: Tuba Esatbeyoglu, Victor Wray, Andreas Juadjur, Peter WinterhalterAbstract:Dimeric procyanidins B1-B8 were produced via semisynthesis from a polymeric proanthocyanidin fraction of hazelnut skins (Corylus avellana L.). This polymeric fraction was found to consist mostly of (+)-catechin and (-)-epicatechin as upper units. Therefore, according to the choice of nucleophile agent, it is possible to semisynthesize dimeric procyanidins B1, B3, B6, and B7 with (+)-catechin and B2, B4, B5, and B8 with (-)-epicatechin. The semisynthetic mixtures were separated on a preparative scale using high-speed countercurrent chromatography (HSCCC) and low-speed rotary countercurrent chromatography (LSRCCC). C4 → C8 linked dimeric procyanidins B1-B4 were isolated in amounts of 350-740 mg. To the best of the authors' knowledge this is the first study isolating dimeric procyanidins B1-B8 in large amounts with countercurrent chromatography. Moreover, the dimeric Prodelphinidins B1, B2, and B3 and their structural elucidation by (1)H NMR spectroscopy without derivatization are described for hazelnuts as natural compounds for the first time.
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Identification of two novel Prodelphinidin A-type dimers from roasted hazelnut skins ( Corylus avellana L.).
Journal of agricultural and food chemistry, 2013Co-Authors: Tuba Esatbeyoglu, Victor Wray, Peter WinterhalterAbstract:Two new A-type dimeric Prodelphinidins, EGC-(2β→O7, 4β→8)-C and EGC-(2β→O5, 4β→6)-C, were isolated from the skins of roasted hazelnut (Corylus avellana L.) by low-speed rotary countercurrent chromatography (LSRCCC) and final purification by preparative HPLC. Their structures were determined by a combination of mass spectrometry (HPLC-ESI-MSn and HR-ESI-MS) and NMR spectroscopy that included the application of 2D methods (1H–1H COSY, HSQC, HMBC, and NOESY). Furthermore, circular dichroism (CD) and acid-catalyzed degradation (phloroglucinolysis) confirmed the proposed structures.