- Screening for the active anti-inflammatory and antioxidant polyphenols of gaultheria procumbens and their application for standardisation: From identification through cellular studies to quantitative determination
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Aerial parts, leaves, and stems of Gaultheria procumbens are polyphenol-rich herbal medicines with anti-inflammatory and antioxidant effects. The present study focused on identifying active markers of the G. procumbens extracts in an integrated approach combining phytochemical and biological capacity tests. The target compounds, representing all classes of Gaultheria polyphenols, were pre-selected by LC-ESI-PDA-MS/MS. For unambiguous identification, the key analytes, including a rare procyanidin trimer (cinnamtannin B-1), miquelianin potassium salt, and two new natural products: quercetin and kaempferol 3-O-β-D-xylopyranosyl-(1→2)-β-D-glucuronopyranosides, were isolated by preparative HPLC and investigated by spectroscopy (HR-ESI-MS, UV-vis, CD, 1D-and 2D-NMR), thiolysis, flame photometry, optical rotation experiments, and absolute configuration studies. The significant contribution of the pre-selected compounds to the biological effects of the extracts was confirmed in vitro: the analytes significantly and in a dose-dependent manner down-regulated the pro-oxidant and pro-inflammatory functions of human neutrophils ex vivo (inhibited the release of reactive oxygen species, IL-1β, TNF-α, and neutrophils elastase, ELA-2), inhibited two key pro-inflammatory enzymes (cyclooxygenase, COX-2, and hyaluronidase), and most of them, except gaultherin, exerted potent direct antioxidant activity (ferric reducing antioxidant power and superoxide anion scavenging capacity). Moreover, cellular safety was confirmed for all compounds by flow cytometry. Eventually, as these mechanisms have been connected to the health benefits of G. procumbens, 11 polyphenols were accepted as active markers, and a simple, accurate, reproducible, and fully validated RP-HPLC-PDA method for standardisation of the target extracts was proposed.
- Granica, Sebastian,Magiera, Anna,Michel, Piotr,Olszewska, Monika Anna,Owczarek, Aleksandra
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- 11-β-hydroxysterols as possible endogenous stimulators of mitochondrial biogenesis as inferred from epicatechin molecular mimicry
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Currently, there is great interest in identifying endogenous (i.e. physiological) stimulators of mitochondrial biogenesis (MB), in particular, those that may mediate the effects of exercise. The molecular size of the cacao flavanols (epicatechin and catechin) highly resembles that of sterols and epicatechin has been reported to activate cells surface receptors leading to the stimulation of MB in endothelial and skeletal muscle cells translating into enhanced exercise capacity. We therefore hypothesize, that epicatechin may be acting as a structural mimic of an as yet unknown sterol capable of stimulating MB. We developed a new synthetic process for obtaining enantiomerically pure preparations of (-)-epicatechin and (+)-epicatechin. Applying spatial analytics and molecular modeling, we found that the two isoforms of epicatechin, (-) and (+), have a structural resemblance to 11-β-hydroxypregnenolone, a sterol with no previously described biological activity. As reported in this proof-of-concept study performed in primary cultures of endothelial and muscle cells, 11-β-hydroxypregnenolone is one of the most potent inducers of MB as significant activity can be detected at femtomolar levels. The relative potency of (-)/(+)-epicatechin isoforms and on inducing MB correlates with their degree of spatial homology towards the 11-β-hydroxypregnenolone. On the basis of these results, the detailed in vivo characterization of the potential for these sterols to act as endogenous modulators of MB is warranted.
- Dugar, Sundeep,Villarreal, Francisco,Hollinger, Frank H.,Mahajan, Dinesh,Ramirez-Sanchez, Israel,Moreno-Ulloa, Aldo,Ceballos, Guillermo,Schreiner, George
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- Preparation and evaluation of a triazole-bridged bis(β-cyclodextrin)–bonded chiral stationary phase for HPLC
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A triazole-bridged bis(β-cyclodextrin) was synthesized via a high-yield Click Chemistry reaction between 6-azido-β-cyclodextrin and 6-propynylamino-β-cyclodextrin, and then it was bonded onto ordered silica gel SBA-15 to obtain a novel triazole-bridged bis (β-cyclodextrin)–bonded chiral stationary phase (TBCDP). The structures of the bridged cyclodextrin and TBCDP were characterized by the infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis. The chiral performance of TBCDP was evaluated by using chiral pesticides and drugs as probes including triazoles, flavanones, dansyl amino acids and β-blockers. Some effects of the composition in mobile phase and pH value on the enantioseparations were investigated in different modes. The nine triazoles, eight flavanones, and eight dansyl amino acids were successfully resolved on TBCDP under the reversed phase with the resolutions of hexaconazole, 2′-hydroxyflavanone, and dansyl-DL-tyrosine, which were 2.49, 5.40, and 3.25 within 30 minutes, respectively. The ten β-blockers were also separated under the polar organic mode with the resolution of arotinolol reached 1.71. Some related separation mechanisms were discussed preliminary. Compared with the native cyclodextrin stationary phase (CDSP), TBCDP has higher enantioselectivity to separate more analytes, which benefited from the synergistic inclusion ability of the two adjacent cavities and bridging linker of TBCDP, thereby enabling it a promising prospect in chiral drugs and food analysis.
- Shuang, Yazhou,Liao, Yuqin,Wang, Hui,Wang, Yuanxing,Li, Laisheng
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p. 168 - 184
(2019/11/25)
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- Metabolic characterization of the anthocyanidin reductase pathway involved in the biosynthesis of flavan-3-ols in elite Shuchazao tea (Camellia sinensis) cultivar in the field
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Anthocyanidin reductase (ANR) is a key enzyme in the ANR biosynthetic pathway of flavan-3-ols and proanthocyanidins (PAs) in plants. Herein, we report characterization of the ANR pathway of flavan-3-ols in Shuchazao tea (Camellia sinesis), which is an elite and widely grown cultivar in China and is rich in flavan-3-ols providing with high nutritional value to human health. In our study, metabolic profiling was preformed to identify two conjugates and four aglycones of flavan-3-ols: (-)-epigallocatechin-gallate [(-)-EGCG], (-)-epicatechin-gallate [(-)-ECG], (-)-epigallocatechin [(-)-EGC], (-)-epicatechin [(-)-EC], (+)-catechin [(+)-Ca], and (+)-gallocatechin [(+)-GC], of which (-)-EGCG, (-)-ECG, (-)-EGC, and (-)-EC accounted for 70-85% of total flavan-3-ols in different tissues. Crude ANR enzyme was extracted from young leaves. Enzymatic assays showed that crude ANR extracts catalyzed cyanidin and delphinidin to (-)-EC and (-)-Ca and (-)-EGC and (-)-GC, respectively, in which (-)-EC and (-)-EGC were major products. Moreover, two ANR cDNAs were cloned from leaves, namely CssANRa and CssANRb. His-Tag fused recombinant CssANRa and CssANRb converted cyanidin and delphinidin to (-)-EC and (-)-Ca and (-)-EGC and (-)-GC, respectively. In addition, (+)-EC was observed from the catalysis of recombinant CssANRa and CssANRb. Further overexpression of the two genes in tobacco led to the formation of PAs in flowers and the reduction of anthocyanins. Taken together, these data indicate that the majority of leaf flavan-3-ols in Shuchazao's leaves were produced from the ANR pathway.
- Zhao, Lei,Jiang, Xiao-Lan,Qian, Yu-Mei,Wang, Pei-Qiang,Xie, De-Yu,Gao, Li-Ping,Xia, Tao
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- A catechin preparation method of compound (by machine translation)
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The invention relates to a method for preparing a catechin compound. The method comprises the following steps: by taking 2,4,6-trihydroxy acetophenone and p-hydroxy benzaldehyde as raw materials, carrying out condensation reaction, restored deoxidation, cyclization reaction of acid catalysis, so as to obtain the catechin compound. The invention also provides a technology for producing the catechin compound. In the synthesis process of an immediate 9, reduction is carried out by using sodium borohydride which is catalyzed by a lewis acid, so that side reaction caused by double bond transfer is greatly reduced while a highly toxic reagent osmium tetroxide is replaced with hydrogen peroxide oxidation.
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- NOVEL APPROACH FOR SYNTHESIS OF CATECHINS
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A process for synthesis of enatiomerically pure or enatiomerically enriched or racemic mixture of (+and/or?) epicatechin echm and its intermediates, comprising the steps of: (i) obtaining penta-protected quercetin; (ii) reducing the penta-protected quercetin obtained from step (i); (iii) optionally deprotecting the compound of step (ii); (iv) reducing the compound obtained from step (ii) or step (iii) in the presence of a chiral/achiral reducing agent to obtain a chiral intermediate; (v) deprotecting and/or hydrogenation of the chiral intermediate obtained from step (iv) to obtain (?)-epicatechin; (vi) optionally simultaneously deprotecting and by drogenation of the compound obtained from step (ii) to obtain racemic epicatechin.
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- NOVEL PROCESS FOR SYNTHESIS OF POLYPHENOLS
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The present invention provides synthetic processes for preparing racemic and/or optically pure epicatechin, epigallocatechin and related polyphenols as such or as their variously functionalized derivatives. A principle objective of the disclosure is to provide a new and useful method of synthesis to obtain polyphenols in isomerically pure and/or racemic forms.
- -
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Paragraph 0207; 0208; 0209; 0210; 0211
(2014/02/16)
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- Potential α-glucosidase inhibitors from thermal transformation of (+)-catechin
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Thermal transformation of the (+)-catechin (1) with heating processing afforded a new oxidation product, gambiriin D (2), along with catechin [6′-8]-catechin (3), and (+)-epicatechin (4). The structure of a new catechin dimer with C-C linkage was determined on the basis of spectroscopic data interpretation. The catechin dimers 2 and 3 exhibited significantly improved inhibitory activities against α-glucosidase, with IC50 values of 0.16 ± 0.2 and 0.14 ± 0.2 μM, respectively, when compared to parent (+)-catechin. Kinetic analysis showed that the two effective compounds 2 and 3 have noncompetitive modes of action.
- Kim, Taewan,Choi, Hyo Jin,Eom, Sung-Hwan,Lee, Jaemin,Kim, Tae Hoon
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p. 1621 - 1624
(2014/03/21)
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- A NOVEL PROCESS FOR SYNTHESIS OF POLYPHENOLS
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The present invention provides synthetic processes for preparing racemic and/or optically pure epicatechin, epigallocatechin and related polyphenols as such or as their variously functionalized derivatives.
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Page/Page column 42
(2012/08/08)
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- High molecular weight persimmon (Diospyros kaki L.) proanthocyanidin: A highly galloylated, a-linked tannin with an unusual flavonol terminal unit, myricetin
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MALDI-TOF MS suggested that the high molecular weight proanthocyanidin (condensed tannin) from persimmon (Diospyros kaki L.) pulp comprised a heteropolyflavanol series with flavan-3-O-galloylated extenders, flavan-3-ol and flavonol terminal units, and A-type interflavan linkages. Thiolysis-HPLC-ESI-MS with DAD, electrochemical, and ESI-MS detection confirmed a previously unreported terminal unit, the flavonol myricetin, in addition to the typical flavan-3-ols catechin and epigallocatechin gallate. The extender units were epicatechin, epigallocatechin, (epi)gallocatechin-3-O-gallate, and (epi)catechin-3-O-gallate. The crude tannin had a high prodelphinidin content (65%) and a high degree of 3-O-galloylation (72%). The material was fractionated on Toyopearl TSK-HW-50-F to yield fractions distinguished by degree of polymerization (DP). Thiolysis suggested that the persimmon tannin was composed of polymers ranging from 7 to 20 kDa (DP 19-47), but sizes estimated by GPC were 50-70% smaller. The crude material was chemically degraded with acid to yield products that were amenable to NMR and ESI-MS analysis, which were used to establish for the first time that persimmon tannin has a mixture of B-type and A-type linkages. 2010 American Chemical Society.
- Li, Chunmei,Leverence, Rachael,Trombley, John D.,Xu, Shufen,Yang, Jie,Tian, Yan,Reed, Jess D.,Hagerman, Ann E.
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experimental part
p. 9033 - 9042
(2011/05/05)
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- The epimerase activity of anthocyanidin reductase from Vitis vinifera and its regiospecific hydride transfers
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Anthocyanidin reductase (ANR) from Vitis vinifera catalyzes an NADPH-dependent double reduction of anthocyanidins producing a mixture of (2S,3R)- and (2S,3S)-flavan-3-ols. At pH 7.5 and 30°C, the first hydride transfer to anthocyanidin is irreversible, and no intermediate is released during catalysis. ANR reverse activity was assessed in the presence of excess NADPq. Analysis of products by reverse phase and chiral phase HPLC demonstrates that ANR acts as a flavan-3-ol C3-epimerase under such conditions, but this is only observed with 2R-flavan-3-ols, not with 2S-flavan-3-ols produced by the enzyme in the forward reaction. In the presence of deuterated coenzyme 4S-NADPD, ANR transforms anthocyanidins into dideuterated flavan-3-ols. The regiospecificity of deuterium incorporation into catechin and afzelechin - derived from cyanidin and pelargonidin, respectively - was analyzed by liquid chromatography coupled with electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS), and it was found that deuterium was always incorporated at C2 and C4. We conclude that 3-epimerization should be achieved by tautomerization between the two hydride transfers and that this produces a quinone methide intermediate which serves as C4 target of the second hydride transfer, thereby avoiding any stereospecific modification of carbon 3. The inversion of C2 stereochemistry required for reverse epimerization suggests that the 2S configuration induces an irreversible product dissociation.
- Gargouri, Mahmoud,Chaudiere, Jean,Manigand, Claude,Mauge, Chloe,Bathany, Katell,Schmitter, Jean-Marie,Gallois, Bernard
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experimental part
p. 219 - 227
(2011/11/05)
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- PREPARATION OF (+)-CATECHIN, (-)-EPICATECHIN, (-)-CATECHIN, (+)-EPICATECHIN, AND THEIR 5,7,3',4'-TETRA-O-BENZYL ANALOGUES
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Processes for preparing racemic mixtures of 5,7,3',4'-tetra-O-benzyl-(±)-catechin and (±)-epicatechin involves (i) condensing 2-hydroxy-4,6-bis(benzyloxy)-acetophenone and 3,4-bis(benzyloxy)benzaldehyde, cyclizing the resulting compound, oxidizing the resulting compound; (ii) dihydroxylating (E)-3-(3',4'-bis(benzyloxy)phenyl)prop-2-ene-1 -ol and reducing the 1 ,2-diol; or (iii) coupling 3,5-bis(benzyloxy)phenol with (£)-3,5-bis(benzyloxy)-2-(3',4'-bis(benzyloxy)phenyl)allyl)phenol and cyclizing the resulting chalcone. A process for preparing the benzylated epimers of catechin and epicatechin involves seven steps. 3,4-Bis(benzyloxy)benzaldehyde is coupled with 2-hydroxy-4,6-benzyloxy-acetophenone to form a chalcone. The chalcone is selectively reduced to an alkene. The phenolic group of the alkene is protected. The protected alkene is asymetrically dihydroxylated. The resulting compound is deprotected, cyclized, and finally hydrolyzed. Epimers resulting from these processes are chemically resolved or separated by chiral high pressure liquid chromatography. Also disclosed is a method for preparing enantiomerically pure 5,7,3',4'-tetra-O-benzyl-(+)-catechin from a racemic mixture using dibenzoyl-L-tartaric acid monomethyl ester. Further, disclosed is an improved process for preparing dibenzoyl-L-tartaric acid monomethyl ester.
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Page/Page column 13; 37-38
(2010/11/25)
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- DIMERIC AND TRIMERIC PROANTHOCYANIDINS POSSESSING A DOUBLY LINKED STRUCTURE FROM PAVETTA OWARIENSIS
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Pavetannin A-2, a new A-type proanthocyanidin, along with the trimers cinnamtannin B-1, pavetannin B-1, B-2, B-3, B-5 and B-6 have been isolated in their free phenolic form from the stem bark of Pavetta owariensis.Spectral data and partial acid-catalysed degradation established their structures as ent-epicatechin-(4α->8,2α->O->7)-catechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4α->8)-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4β->8)-ent-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4β->8)-epicatechin, epicatechin-(4β->6,2β->O->7)-epicatechin-(4β->8)-epicatechin, epicatechin-(4β->6,2β->O->7)-catechin-(4β->8)-epicatechin, epicatechin-(4β->8,2β->O->7)-epicatechin-(4α->8)-catechin, respectively. Key Word Index - Pavetta owariensis; Rubiaceae; stem bark; proanthocyanidins; doubly linked structures; dimer; trimer; thiolytic degradation.
- Balde, A. M.,Pieters, L. A.,Wray, V.,Kolodziej, H.,Berghe, D. A. Vanden,et al.
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p. 4129 - 4136
(2007/10/02)
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- IODINATION AND DEUTERATION OF CATECHIN DERIVATIVES
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The preparation and 1H and 13C nuclear magnetic reonance spectra of ten monoiodocatechin derivatives are described.The iodination of catechin with N-iodosuccinimide (NIS) takes place regiospecifically at C-6 in acetone but preferentially at C-8 in dimethylformamide; both products can be derivatized at oxygen in alkali medium but lose iodine in the presence of acid. 3',4',5,7,-Tetra-O-methylcatechin reacts with NIS regiospecifically at C-8 while catechin pentaacetate resists iodination.The debromination of 6-bromo- and 6,8-dibromocatechin with sodium sulfite in CD3CN/D2O is accompained by H/D-exchange at C-6 and C-8.The synthesis of catechin pentaacetate from partially deuterated catechin and its conversion to terta-O-methylcatechin proceed without H/D-exchange and permit distinction between the H-6 and H-8 chemical shifts.
- Kiehlmann, E.,Lehto, N.,Cherniwchan, D.
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p. 2431 - 2439
(2007/10/02)
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- DEOXYGENATION OF ALDEHYDES AND KETONES WITH SODIUM CYANOBOROHYDRIDE
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Treatment of hydroxy-substituted aromatic aldehydes and ketones with sodium cyanoborohydride yields the corresponding methylene compounds under conditions which favor intermediate carbonium ion formation.
- Elliger, Carl A.
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p. 1315 - 1324
(2007/10/02)
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- PHYLLOFLAVAN, A CHARACTERISTIC CONSTITUENT OF PHYLLOCLADUS SPECIES
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Key Word Index - Phyllocladus alpinus; Podocarpaceae; catechin; epicatechin; phylloflavan; epimerization; configuration.Abstract - Selective visulaization of 2D TLC of extracts of Phyllocladus species with vanillin-hydrochloric acid showed a characteristic pattern of constituents attributable to catechin, epicatechin and phylloflavan, a new flavanoid compound.Optical rotation measurements showed that while catechin and epicatechin are of the normal type with the 2R configurations, the flavan moiety in phylloflavan is of the opposite 2S configuration.Spectroscopic data of the new compound and its hydrolysis products showed phylloflavan to be ent-epicatechin-3-δ-(3,4-dihydroxyphenyl)-β-hydroxypentanoate.
- Foo, Lai Yeap,Hrstich, Liana,Vilain, Christian
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p. 1495 - 1498
(2007/10/02)
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- Physico-Chemical Studies of Catechins and Epicatechins
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The physico-chemical properties of (-)-epicatechin, (+)-catechin have been found to be at variance from those reported in literature, and have been corrected after confirmation, by elemental analysis, TGA etc.A quasiracenate (C15H14O6*3H2O) of (-)-epicatechin and (+)-catechin (1 : 1) has also been isolated and characterised.
- Singh, Joginder,Ralhan, N. K.,Pant, T. K.
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p. 1044 - 1047
(2007/10/02)
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- Condensed Tannins: Preferential Substitution at the Interflavanoid Bond by Sulphite Ion
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The reaction of loblolly pine (Pinus taeda L.) bark tannins with sodium hydrogen sulphite gave sodium epicatechin-(4β)-sulphonate (1) and sodium epicatechin-(4β -> 8)-epicatechin-(4β)-sulphonate (2) in high yield with only a minor amount of sodium 1-(3,4-dihydroxyphenyl)-2-hydroxy-3-(2,4,6-trihydroxyphenyl)-propane-1-sulphonate (3).
- Foo, L. Yeap,McGraw, Gerald W.,Hemingway, Richard W.
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p. 672 - 673
(2007/10/02)
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- Synthesis and Conformation of Procyanidin Diastereoisomers
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The four theoretically possible diastereoisomeric 4->8 linked procyanidin dimers with two 2,3-cis-flavanoid units, epicatechin-(4β->8)-epicatechin (6), epicatechin-(4β->8)-ent-epicatechin (8), ent-epicatechin-(4α->8)-epicatechin (7), and ent-epicatechin-(4α->8)-ent-epicatechin (2), have been synthesized together with the 2,3-trans diastereoisomers catechin-(4α->8)-catechin (14) and catechin-(4α->8)-ent-catechin (15).The preferred rotamer conformations of the deca-acetate derivatives of (6), (8), (14), and (15) in chloroform were deduced from their 13C n.m.r. and high-field 1H n.m.r. spectra.The 1H n.m.r. spectra of the preferred conformers of the pairs of acetate derivatives of (6) and (15), and (8) and (14), were qualitatively similar as the relative configuration about the interflavanoid bond of one pair has a meso-relationship to the other.
- Foo, Lai Yeap,Porter, Lawrence J.
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p. 1535 - 1543
(2007/10/02)
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- One-Electron Redox Potentials of Phenols. Hydroxy- and Aminophenols and Related Compounds of Biological Interest
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The rate constants for reversible electron transfer between a series of substituted phenolate ions and anilines and various substituted phenoxyl or anilino radicals in aqueous solution were measured by observing the formation or depletion of the radicals involved.Nonequilibrium concentrations of the radicals were produced in the presence of the corresponding phenols or anilines by using the pulse radiolysis technique.The relaxation of the system to equilibrium was monitored by optical detection methods.From the equilibrium constants for one-electron transfer, the one-electron redox potentials (E2) for 38 phenolic or anilino type compounds were determined, many of which are natural products.The redox potentials are strongly influenced by electron-donating or -withdrawing substituents at the aromatic system.
- Steenken, S.,Neta, P.
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p. 3661 - 3667
(2007/10/02)
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- Kinetics of Epimerization of (+)-Catechin and Its Rearrangement to Catechinic Acid
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The rates of epimerization of (+)-catechin (1) to (+)-epicatechin (2) and of (-)-epicatechin to (-)-catechin in aqueous solution were measuredthe pH range 5.4-11.0 and the temperature range 34-100 deg C.The rate of conversion of (+)-catechin to catechinic acid (3) also was measured under these conditions.First-order kinetics were observed for all three processes.At low pH, k(epimerization) >> k(rearrangement), and epimerization approached an equilibrium in which (+)-catechin predominated(+)-epicatechin.Near pH 11 and at elevated temperatures,k(epimerization) was only slightly greater than k(rearrangement), and the rapid, irreversible formation of catechinic acid under these conditions determined product composition.Both the epimerization of catechin and its rearrangement to catechinic acid can be rationalized in terms of a quinone methide intermediate (4).
- Kiatgrajai, Preecha,Wellons, J. D.,Gollob, Lawrence,White, James D.
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p. 2910 - 2912
(2007/10/02)
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- Flavanoids of Acacia catechu Heartwood
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From the heartwood of Acacia catechu, kaempferol, dihydrokaempferol, taxifolin, isorhamnetin, (+)-afzelchin and a dimeric procyanidin (AC) have been isolated for the first time in addition to quercetin and (-)-epicatechin.
- Deshpandl, V. H.,Patil, A. D.
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- Novel Bioflavonoids, Chalcan-flavan Dimers from Gambir
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The homologous series of novel chalcan-flavan dimers, gambiriin A1, A2, A3, B1, B2 and B3, along with a proanthocyanidin dimer, gambiriin C (epiafzelechin-catechin), have been isolated from Gambir.Keywords---tannin, Gambir; Uncaria Gambir; Rubiaceae; chalcan-flavan dimer; proanthocyanidin; astringency
- Nonaka, Gen-Ichiro,Nishioka, Itsuo
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p. 3145 - 3149
(2007/10/02)
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