- Study on in Vitro Preparation and Taste Properties of N-Ethyl-2-Pyrrolidinone-Substituted Flavan-3-Ols
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N-ethyl-2-pyrrolidinone-substituted flavan-3-ols (EPSFs) were prepared by an in vitro model reaction, and the taste thresholds of EPSFs and their dose-over-threshold factors in large-leaf yellow tea (LYT) were investigated. The effects of initial reactant
- Han, Zisheng,Ho, Chi-Tang,Jiang, Zongde,Lai, Guoping,Qin, Chunyin,Wan, Xiaochun,Wen, Mingchun,Zhai, Xiaoting,Zhang, Hui,Zhang, Liang
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- The oxidation of (-)-epigallocatechin-3-gallate inhibits T-cell acute lymphoblastic leukemia cell line HPB-ALL: Via the regulation of Notch1 expression
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T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy, and commonly associated with activating mutations in the Notch1 pathway. (-)-Epigallocatechin-3-gallate (EGCG) is the most abundant and active catechin and has been shown to regulate Notch signaling. Taking into account the highly oxidizable and unstable of EGCG, we proposed that EGCG oxides may have greater potential to regulate Notch signaling than EGCG. In this study, we isolated and identified EGCG oxides (compound 2-4), using a chemical oxidation strategy, and evaluated for cytotoxicity against T-cell acute lymphoblastic leukemia cell line (HPB-ALL) by using the MTS assay. We found compound 3 significantly induced cell proliferation inhibition (38.3858 ± 1.67106 μM), cell apoptosis and cell cycle arrest in a dose-dependent manner. Remarkably, compound 3 inhibited expression of Notch1 compared with EGCG in HPB-ALL cells. Meanwhile, we found that compound 3 significantly inhibited c-Myc and Hes1, which are downstream target genes of Notch1. The findings demonstrate for the first time that an oxidation product of EGCG (compound 3) inhibits T-cell acute lymphoblastic leukemia cell line (HPB-ALL) and is a promising agent for cancer therapy deserving further research.
- Wang, Yu-Na,Wang, Jing,Yang, Hao-Nan,Zhang, Bang-Lei,Zhang, Pan,Sun, Pei-Yuan,Zhang, Nin,Wang, Ya,Sheng, Jun,Wang, Xuan-Jun,Zi, Cheng-Ting
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p. 1679 - 1684
(2020/01/28)
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- Oligomerization mechanism of tea catechins during tea roasting
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Roasting of green tea causes oligomerization of tea catechins, which decreases the astringency. The aim of this study was to elucidate the oligomerization mechanism. The 13C NMR spectrum of the oligomer fraction showed signals arising from catechin and sugar residues. Heating of epigallocatechin-3-O-gallate with 13C-labeled glucose (150 °C for 2 h) suggested that condensation of sugars with catechin A-rings caused the oligomerization. The dimeric product obtained by heating for a shorter period (30 min) suggested cross-linking occurred between sugars and catechin A-rings. Furthermore, heating of phloroglucinol, a catechin A-ring mimic, with glucose, methylglyoxal, and dihydroxyacetone, confirmed that the basic mechanism included reaction of the catechin A-ring methine carbons with carbonyl carbons of glucose and their pyrolysis products.
- Morikawa, Hitomi,Okuda, Keita,Kunihira, Yuji,Inada, Aoi,Miyagi, Chika,Matsuo, Yosuke,Saito, Yoshinori,Tanaka, Takashi
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p. 252 - 259
(2019/02/14)
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- Molecular Mechanism by Which Tea Catechins Decrease the Micellar Solubility of Cholesterol
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Tea polyphenols lower the levels of cholesterol in the blood by decreasing the cholesterol micellar solubility. To clarify this mechanism, the interactions between taurocholic acid and (-)-epigallocatechin gallate (EGCg) and its derivatives were investigated. 13C NMR studies revealed remarkable chemical-shift changes for the carbonyl carbon atom and the 1″- and 4″-positions in the galloyl moiety. Furthermore, 1H NMR studies using (-)-EGCg derivatives showed that the number of hydroxyl groups on the B ring did not affect these interactions, whereas the carbonyl carbon atom and the aromatic ring of the galloyl moiety had remarkable effects. The configuration at the 2- and 3-positions of the catechin also influenced these interactions, with the trans-configuration resulting in stronger inhibition activity than the cis-configuration. Additionally, a 1:1 component ratio for the catechin-taurocholic acid complex was determined by electrospray ionization-mass spectrometry. These molecular mechanisms contribute to the development of cholesterol-absorption inhibitors.
- Sakakibara, Takumi,Sawada, Yoshiharu,Wang, Jilite,Nagaoka, Satoshi,Yanase, Emiko
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- Oxidation derivative of (-)-epigallocatechin-3-gallate (EGCG) inhibits RANKL-induced osteoclastogenesis by suppressing RANK signaling pathways in RAW 264.7 cells
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Tea consumption has positive effects on the skeletal system and prevents postmenopausal osteoporosis, mainly by inhibiting osteoclastogenesis. In green tea, (-)-epigallocatechin-3-gallate (EGCG) is the most abundant and active compound and has been shown to inhibit RANKL-induced osteoclast formation. Taking into account the highly oxidizable and unstable nature of EGCG, we hypothesized that EGCG oxidation product exhibits greater anti-osteoclastogenesis potential than EGCG. In this study, we successfully isolated and identified an EGCG oxidation derivative, (-)-gallocatechin gallate (compound 2), using a chemical oxidation strategy. We then compared the ability of compound 2 and EGCG to inhibit RANKL-induced osteoclastogenesis in RAW 264.7 cells. The results of TRAP staining and F-actin ring immunofluorescent staining showed that compound 2 exhibits stronger inhibition of RANKL-induced osteoclast differentiation and F-actin ring formation, respectively, than EGCG. Additionally, quantitative real-time PCR (qRT-PCR) and western blotting analyses showed that compound 2 significantly and more strongly inhibited the expression of osteoclastogenesis-related marker genes and proteins, including c-Src, TRAP, cathepsin K, β3-Integrin, and MMP-9, compared with EGCG. Furthermore, compound 2 significantly suppressed RANKL-induced expression of NFATc1 and c-Fos, the master transcriptional regulators of osteoclastogenesis, more strongly than EGCG. Mechanistically, molecular interaction assays showed that compound 2 binds to RANK with high affinity (KD = 189 nM) and blocks RANKL–RANK interactions, thereby suppressing RANKL-induced early RANK signaling pathways including p65, JNK, ERK, and p38 in osteoclast precursors. Taken together, this study demonstrates for the first time that an oxidation derivative of EGCG (compound 2) inhibits RANKL-induced osteoclastogenesis by suppressing RANK signaling pathways in RAW 264.7 cells.
- Xu, Huanhuan,Liu, Titi,Li, Jin,Xu, Jing,Chen, Fei,Hu, Lihong,Zhang, Banglei,Zi, Chengting,Wang, Xuanjun,Sheng, Jun
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- METHODS OF TREATING COGNITIVE AND BEHAVIORAL IMPAIRMENT IN DOWN SYNDROME AND ALZHEIMERS DISEASE PATIENTS
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The present invention relates to methods of treating cognitive and behavioral impairment in Down syndrome and/or Alzheimer's disease patients, Alzheimer's disease, neurodegenerative disease, cancer, DYRK1A-mediated disorders and methods of modulating and inhibiting DYRK1-A comprising use of catechins.
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- Reagent-controlled stereoselective synthesis of (±)-gallo- and (±)-epigallo-catechin gallates
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Synthesis of (±)-gallocatechin and (±)-epigallocatechin gallates by electrophilic cycloarylation is reported. The precursors for cyclization were prepared by reagent-controlled stereo-selective opening of epoxide with phenol. Activation of the S-oxidized S,O-acetal enabled electrophilic cycloarylation to stereoselectively provide the acylated catechins.
- Tanaka, Hiroshi,Chino, Ayaka,Takahashi, Takashi
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supporting information; experimental part
p. 2493 - 2495
(2012/06/16)
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- Semisynthesis of fluoro-substituted benzoates of Epi-gallocatechin
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In the present study, four fluoro-substituted benzoates of epi-gallocatechin (EGC) were prepared through a semisynthetic strategy, and the yield of benzylation of epi-gallocatechin gallate (-)-EGCG was improved by using freshly purified (-)-EGCG as starting material and a mild base of K 2CO3. All structures of new compounds were characterized by 1H NMR, 13C NMR, high-resolution mass spectrometry, and optical rotation.
- Qin, Xu Long,Li, Xue Min,Yuan, Jian,Chen, Di,Jiang, Tao,Dou, Q. Ping,Chan, Tak Hang,Wan, Sheng Biao
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experimental part
p. 3524 - 3531
(2012/09/25)
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- Isolation of two new bioactive proanthocyanidins from Cistus salvifolius herb extract
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Two new proanthocyanidins, epigallocatechin-3-O-p-hydroxybenzoate- (4β→8)-epigallocatechin (1) and epigallocatechin-3-O-p- hydroxybenzoate-(4β→8)-epigallocatechin-3-O-gallate (2) in addition to the known compound epigallocatechin-(4β→6)-epigallocatechin-3-O- gallate (3), were isolated from the air-dried herb of Cistus salvifolius. The chemical structures were determined on the basis of 1D-and 2D-NMR-spectra (HSQC, HMBC) of their peracetylated derivatives, MALDI-TOF-mass spectra, and by acid-catalysed degradation with phloroglucinol. The isolated compounds 1-3 and the water extract of C. salvifolius herb were tested for their inhibitory activities against COX-1 and COX-2. Compound 2 showed the strongest inhibitory effect on COX-2 followed by compound 3, compound 1 and the water extract, while compounds 1-3 exhibited moderate in vitro inhibition against COX-1.
- Qa'dan, Fadi,Nahrstedt,Schmidt
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experimental part
p. 454 - 457
(2012/01/12)
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- New oligomeric proanthocyanidins from Alhagi pseudalhagi
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Two new oligomeric proanthocyanidin glucosides were isolated from the aerial part and roots of Alhagi pseudalhagi. Their structures and relative configurations were elucidated as 7-O-β-D-Glc p→6 galloyl-(+)catechin-(4α-8)-(+)-catechin-(4α-8)-(-
- Alimova,Nishanbaev,Vdovin,Abdullaev,Aripova
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experimental part
p. 352 - 356
(2010/10/03)
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- General synthesis of epi-series catechins and their 3-gallates: Reverse polarity strategy
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A general synthetic route to the epi-series catechins was developed based on the reverse polarity strategy. Aromatic nucleophilic substitution reaction followed by the sulfinyl-metal exchange and cyclization enabled stereo-controlled access to various members of epi-series catechins and their 3-gallates.
- Ohmori, Ken,Yano, Takahisa,Suzuki, Keisuke
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supporting information; experimental part
p. 2693 - 2696
(2010/08/21)
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- Study of the release of gallic acid from (-)-epigallocatechin gallate in old oolong tea by mass spectrometry
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Liquid chromatography combined with multiple-stage mass spectrometry (LC/MSn) was used to study the pathway of the release of gallic acid (GA) from epigallocatechin gallate (EGCG) in infusion of old oolong tea. The possibility of releasing GA from EGCG in old tea preparations was supported by an in vitro observation of GA degraded from EGCG under heating conditions mimicking the drying process. Negative electrospray ionization with the data-dependent mode of MSn was used to study the formation pathway of GA in old oolong tea. The MSn data show that GA was released from the dimer of EGCG, not directly degraded from EGCG.
- Lee, Ren-Jye,Lee, Viola S. Y.,Tzen, Jason T. C.,Lee, Maw-Rong
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experimental part
p. 851 - 858
(2011/10/19)
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- Epimerization of tea catechins under weakly acidic and alkaline conditions
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Tea catechins in a buffer at pH 7 with N2 replacing O 2 epimerized rapidly at 80 °C with less than 10% of oxidative side reactions and gave catechin epimers in a 50-63% yield. The epimerization of catechins with three hydroxyl groups was faster than with two groups, and of galloyl-free catechins was faster than catechins with a galloyl ester.
- Ishino, Nobuyoshi,Yanase, Emiko,Nakatsuka, Shin-Ichi
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scheme or table
p. 875 - 877
(2011/07/30)
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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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- Composition for Topical Use
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The use, as a dermatological or cosmetic medicament, of compounds capable of transiently interacting with the AhR receptor (aryl hydrocarbon receptor) as agents for modulating skin functions such as sebaceous function, skin healing, skin atrophy termed “dermatoporosis”, estrogen deprivation and defense against infection, without inducing other toxic effects of the TCDD type. The compounds that interact with the AhR receptor are chosen in that they have a metabolism favorable to the dissociation of these effects, in particular by virtue of in situ production from a precursor and/or metabolization modulated in situ.
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- ACTIVE COMPONENT FRACTION OF HIGH ANTIVIRAL ACTIVITY
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A method of producing active component fractions from dried and ground root material of a species of the rheum family by extraction with ethanol, removal of lipophilic minor components and methanol, followed by shaking in ethyl acetate and separating the combined ethyl acetate phase into a limited number of fractions by columnar chromatography in the presence of an eluant.
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- MANUFACTURING METHOD OF GALLOCATECHIN GALLATE BY EPIMERIZATION OF EPIGALLOCATECHIN-3-GALLATE
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The present invention relates to a method for the preparation of gallocatechin gallate through epimerization of epigallocatechin-3-gallate by heat. In particular, the solubility of epigallocatechin-3-gallate is increased using organic solvent and the pH of the solvent is controlled, and then heated. The present invention enables production of gallocatechin gallate for industry by increasing its conversion rate.
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Page/Page column 6-10
(2008/06/13)
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- Reaction kinetics of degradation and epimerization of epigallocatechin gallate (EGCG) in aqueous system over a wide temperature range
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(-)-Epigallocatechin gallate (EGCG) is the most abundant catechin in green tea, which has been linked with many health benefits. To ensure the conceivable health benefits from thermally processed products, a kinetic study on the stability of (-)-EGCG in aqueous system was carried out using a HPLC-UV system and Matlab programming. Simultaneous degradation and epimerization of (-)-EGCG were characterized during isothermal reactions at low temperatures (25-100°C) combined with previously conducted experimental results at high temperature (100-165°C); the degradation and epimerization complied with first-order reaction and their rate constants followed Arrhenius equation. Mathematical models for the stability of (-)-EGCG were established and validated by the reactions at 70°C and with varied concentrations from different catechin sources. Two specific temperature points in the reaction kinetics were identified, at 44 and 98°C, respectively. Below 44°C, the degradation was more profound. Above 44°C, the epimerization from (-)-gallocatechin gallate (GCG) to (-)-EGCG was faster than degradation. When temperature increased to 98°C and above, the epimerization from (-)-GCG to (-)-EGCG became prominent. Our results also indicated that the turning point of 82°C reported in the literature for the reaction kinetics of catechins would need to be re-examined.
- Wang, Rong,Zhou, Weibiao,Jiang, Xiaohui
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experimental part
p. 2694 - 2701
(2010/08/04)
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- EPIGALLOCATECHIN-3-GALLATE CRYSTAL COMPOSITIONS
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Crystalline epigallocatechin-3-gallate compositions and methods of use.
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Page/Page column 25-27
(2009/01/24)
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- METHODS OF SEPARATING CATECHINS FROM GREEN TEA LEAVES
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There have been a number of reports on the isolation of (-)-EGCG from green tea. However, the presence of many components with their similar water solubility and the structural similarities of the catechins make the isolation of pure (-)-EGCG difficult. The absence of a simple, efficient and inexpensive method of obtaining pure (-)-EGCG has hampered the evaluations of (-)-EGCG in animal and human clinical studies. This invention provides a method of isolating catechins, including (-)-EGCG, by first converting the catechins to their respective ester forms. The esterified catechins are then separated by chromatography, and converted back to catechins. The method of this invention is relatively simple, and a substantial amount of catechins may be obtained.
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Page/Page column 8; 9
(2008/06/13)
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- Dimeric prodelphinidins from Limonium gmelinii roots. III
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Two dimeric proanthocyanidines identified as 2R,3R,4R-(-)-epigallocatechin- (4β→ 8)-2R,3R-(-)-epigallocatechin-3-O-gallate and 2R,3R,4R-(-)-epigallocatechin-(4β→8)-(-)-2R,3R,3,5,7,3′, 4′,6′-hexahydroxyflavan were isolated by adsorption chromatography over polyamide of the ethylacetate fraction of the aqueous alcohol extract of Limonium gmelinii roots. The former proanthocyanidine was isolated for the first time from sea lavender whereas the latter is new. 2006 Springer Science+Business Media, Inc.
- Zhusupova,Abil'kaeva
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p. 164 - 168
(2008/02/01)
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- (-)-EPIGALLOCATECHIN GALLATE DERIVATIVES FOR INHIBITING PROTEASOME
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(-)-EGCG, the most abundant catechin, was found to be chemopreventive and anticancer agent. However, (-)-EGCG has at least one limitation: it gives poor bioavailability. This invention provides compounds of generally formula 10, wherein R1 is selected from the group of--H and C1 to C6 acyl group; R2, R3, and R4 are each independently selected from the group of--H,--OH, and C1 to C6 acyloxyl group; and at least one of R2, R3, or R4 is--H. The derivatives of (-)-EGCG that is at least as potent as (-)-EGCG. The carboxylate protected forms of (-)-EGCG and its derivatives are found to be more stable than the unprotected forms, which can be used as proteasome inhibitors to reduce tumor cell growth.
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Page/Page column 5; 6
(2008/06/13)
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- A structure-activity study for the inhibition of metalloproteinase-9 activity and gene expression by analogues of gallocatechin-3-gallate
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Catechins are able to modulate the gelatinolytic activity of matrix metalloproteinase-9 (MMP-9) by reducing its release from macrophages. Gallocatechins decrease MMP-9 secretion by lowering MMP-9 promoter activity and mRNA levels. The effect appears to be dependent on some structural and stereochemical requirements. In this study, the relationship between chemical structure and activity was studied by testing the effect of analogues of (±)-gallocatechin-3-gallate (±)-GCG, selectively deprived of hydroxyl groups, on MMP-9 activity, transcription, and secretion. Our results indicate that (±)-GCG and (±)-catechin-3-gallate are characterized by a substitution pattern compatible with direct inhibition of MMP-9 activity. Conversely, when transcription was the target, (±)-trans-3-flavanol-3- benzoate, lacking all the hydroxyl groups, was the most effective both in lowering MMP-9 promoter activity and consequently protein secretion, and in inhibiting nuclear-factor-κB-driven transcription. Our results suggest that the structural requirements for enzyme inhibition are different from those necessary for targeting gene expression. Birkhaeuser Verlag, 2005.
- Dell'Agli,Bellosta,Rizzi,Galli,Canavesi,Rota,Parente,Bosisio,Romeo
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p. 2896 - 2903
(2007/10/03)
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- The structural variation in the incubation products of (-)-epigallocatechin gallate in neutral solution suggests its breakdown pathways
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Three new compounds, in addition to previously reported compounds, were isolated from a product mixture obtained on incubating (-)-epigallocatechin gallate (EGCG) in neutral solution. The products were two monomeric (EGCG-MOx-M3 and EGCG-MOx-M4) and one dimeric (EGCG-MOx-D4) structure involving the flavan skeleton. Possible oxidation-reduction pathways producing drastic changes in the structure of EGCG were presented based on the structures of the breakdown products.
- Hatano, Tsutomu,Ohyabu, Takayo,Yoshida, Takashi
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p. 303 - 310
(2007/10/03)
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- Stability of tea polyphenol (-)-epigallocatechin-3-gallate and formation of dimers and epimers under common experimental conditions
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(-)-Epigallocatechin-3-gallate (EGCG), the most abundant and biologically active compound in tea, has been extensively studied for its activities related to disease prevention in animal models and in vitro. However, its stability under different experimental conditions has not been well-characterized. In the present study, the stability of EGCG in animal drinking fluid and under cell culture conditions and the factors that affect its stability under these conditions were investigated. Our results demonstrated that auto-oxidation and epimerization are the two major reactions causing the instability of EGCG. The structures of the major oxidation products, EGCG dimers, were identified. The rates of these reactions were affected by the temperature, pH, the partial pressure of oxygen, the level of antioxidants, the concentration of EGCG, and other components of tea. In future studies with EGCG, its stability should be considered in order to avoid possible artifacts.
- Sang, Shengmin,Lee, Mao-Jung,Hou, Zhe,Ho, Chi-Tang,Yang, Chung S.
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p. 9478 - 9484
(2007/10/03)
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- Polyphenol proteasome inhibitors, synthesis, and methods of use
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The present invention relates to synthetic green tea derived polyphenolic compounds, their modes of syntheses, and their use in inhibiting proteasomal activity and in treating cancers. The present invention is also directed to pharmaceutical compositions useful in methods of inhibiting proteasomes and of treating cancers.
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Page/Page column 12
(2008/06/13)
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- Production of theasinensins A and D, epigallocatechin gallate dimers of black tea, by oxidation-reduction dismutation of dehydrotheasinensin A
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Theasinensins A and D are B,B′-linked dimers of (-)-epigallocatechin 3-O-gallate connected through R and S biphenyl bonds, respectively, and are major constituents of black tea. Enzymatic oxidation of epigallocatechin 3-O-gallate produced dehydrotheasinensin A, and the structure was shown to be equivalent to an o-quinone of theasinensin A. When the aqueous solution of dehydrotheasinensin A was heated, theasinensin D was produced along with galloyl oolongtheanin. On the other hand, dehydrotheasinensin A was converted to theasinensins A and D along with oxidation products in phosphate buffer at pH 6.8 at room temperature. The results strongly suggested that theasinensins in black tea were produced by oxidation-reduction dismutation of dehydrotheasinensin.
- Tanaka, Takashi,Watarumi, Sayaka,Matsuo, Yosuke,Kamei, Midori,Kouno, Isao
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p. 7939 - 7947
(2007/10/03)
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- Theasinensin A, a Tea Polyphenol Formed from (-)-Epigallocatechin Gallate, Suppresses Antibiotic Resistance of Methicillin-Resistant Staphylococcus aureus
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When (-)-epigallocatechin gallate (EGCG), the main constituent of tea polyphenols, was kept in a neutral buffer, it decomposed rapidly to give theasinensin A as the major product. Theasinensin A suppressed the oxacillin resistance of methidllin-resistant Stphylcoccus aureus (MRSA). In the presence of theasinensin A (3.5 × 10-5 M), the minimum inhibitory concentrations (MICs) of oxacillin decreased from 256 or 64 μg/mL to 4 μg/mL for the MRSA strains used. The presence of this compound (3.5 × M-5) also decreased the MIC of other β-lactam (penicillin G, from 32 μg/ mL to 0.125-0.5 μg/mL; ampicillin, from 16-32 μg/ml to 0.5-1 μg/mL) and aminoglycoside (streptomycin, from 4- 16 μg/mL to 0.125 -4 μg/mL) antibiotics for the MRSA strains.
- Hatano, Tsutomu,Kusuda, Miwako,Hori, Mami,Shiota, Sumiko,Tsuchiya, Tomofusa,Yoshida, Takashi
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p. 984 - 989
(2007/10/03)
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- Enantioselective synthesis of epigallocatechin-3-gallate (EGCG), the active polyphenol component from green tea.
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[reaction: see text]. Enantioselective synthesis of epigallocatechin-3-gallate (EGCG, 3b), the active polyphenol component from green tea, has been achieved by using a stereospecific cyclization of the Sharpless asymmetric dihydroxylation product 7c as the key step.
- Li,Chan
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p. 739 - 741
(2007/10/03)
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- Oligomeric proanthocyanidin glycosides of Clementsia semenovii and their biological activity. III
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The structures of two oligomeric proanthocyanidins isolated from roots of Clementsia semenovii have been established using chemical and spectral data. Animal studies showed that these compounds possess hypocholesterinemic, hypolipidemic, and anti-inflammatory activities.
- Kuliev,Kim,Vdovin,Abdullaev,Khushbaktova,Syrov
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- Oligomeric proanthocyanidin glycosides of Clementsia semenovii
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Five new proanthocyanidins have been isolated from the roots of Clementsia semenovii A. Bor. The structures of two of these compounds have been established by various chemical and physical methods: 7-0-[6-0-galloyl-β-D-Glcp →6 O-βD-Glcp →6O-β-D-Glcp → 6O-β-D-Glcp]-(+)-gallocatechin-(4α-8)-(+)-gallocatechin- (4α-8)-(-)-epigallocatechin-(4β-8)-(-)-epigallocatechin-(4β-8)- (-) -epigallocatechin-(4β-8)-(+)-catechin - CS-1 and 3-O-galloyl-7-O-(β-D-Glcp → 6O-β-D-Glcp)-(-)-epigallocatechin-(4β-8)-[3-O-galloyl-(-)- epigallocatechin]-(4β-8)-[3-O-galloyl-(-)-epigallocatechin]-(4β-8)-[3- O-galloyl-5-O-(6-O-galloyl-O-β-D-Glcp)]-(-)-epicatechin - CS-2.
- Matamarova,Kuliev,Vdovin,Abdullaev,Murzubraimov
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p. 676 - 682
(2007/10/03)
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- Chemical Evidence for the De-astrigency (insolubilization of Tannins) of Persimmon Fruit
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After artificial removal of the astringency from persimmon fruit by treatment with ethanol, thiol-promoted degradation of the insolubilized proanthocyanidin polymers with 2-sulfanylethanol yielded 4β-(2-hydroxyethylsulfanyl)-6- and -8-flavan-3-ols 9-14.Furthermore, when deuteriated ethanol was used for de-astringency, the deuterium atoms were incorporated into the C2 unit attached to the A-ring of these compounds.These findings evidently show that acetaldehyde formed in situ from ethanol plays an important role in polymerization (insolubilization) of water-soluble proanthocyanidins, causing the loss of astringency.
- Tanaka, Takashi,Takahashi, Ryuji,Kouno, Isao,Nonaka, Gen-ichiro
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p. 3013 - 3022
(2007/10/02)
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- PROANTHOCYANIDINS OF Rhodiola semenovii
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The structures of two compounds previously isolated from Rhodiola semenovii, rhodokhinoside (I) and rhodikhim (II), have been established.
- Khi, Kim Khvan,Kuliev, Z. A.,Vdovin, A. D.,Yagudaev, M. R.,Malikov, V. M.
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p. 681 - 685
(2007/10/02)
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- Tannins and Related Compounds. LXXVII. Novel Chalcan-flavan Dimers, Assamicains A, B and C, and a New Flavan-3-ol and Proanthocyanidins from the Fresh Leaves of Camellia sinensis L. var. assamica KITAMURA
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Three novel chalcan-flavan dimers, assamicains A (1), B (2) and C (3), and a new flavan-3-ol (14) and proanthocyanidins (19,20) have been isolated, together with the known flavan-3-ols (4-13), proanthocyanidins (15-18,21), theasinensins (22-24) and hydrolyzable tannins (25,26), from the fresh leaves of Camellia sinensis var. assamica (Camelliaceae), and their structures have been established on the basis of spectroscopic evidence in conjunction with thiolytic degradation and enzymatic hydrolysis. - Keywords: Camellia sinensis var. assamica; Camelliaceae; polyphenol; assamicain; chalcan-flavan dimer; proanthocyanidin; theasinensin; flavan-3-ol; hydrolyzable tannin; black tea
- Hashimoto, Fumio,Nonaka, Gen-ichiro,Nishioka, Itsuo
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