107965-88-8Relevant articles and documents
Isolation of two new bioactive proanthocyanidins from Cistus salvifolius herb extract
Qa'dan, Fadi,Nahrstedt,Schmidt
, p. 454 - 457 (2011)
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.
Dimeric prodelphinidins from Limonium gmelinii roots. III
Zhusupova,Abil'kaeva
, p. 164 - 168 (2006)
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.
Production of theasinensins A and D, epigallocatechin gallate dimers of black tea, by oxidation-reduction dismutation of dehydrotheasinensin A
Tanaka, Takashi,Watarumi, Sayaka,Matsuo, Yosuke,Kamei, Midori,Kouno, Isao
, p. 7939 - 7947 (2003)
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.
Reaction kinetics of degradation and epimerization of epigallocatechin gallate (EGCG) in aqueous system over a wide temperature range
Wang, Rong,Zhou, Weibiao,Jiang, Xiaohui
, p. 2694 - 2701 (2008)
(-)-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.
Study on in Vitro Preparation and Taste Properties of N-Ethyl-2-Pyrrolidinone-Substituted Flavan-3-Ols
Han, Zisheng,Ho, Chi-Tang,Jiang, Zongde,Lai, Guoping,Qin, Chunyin,Wan, Xiaochun,Wen, Mingchun,Zhai, Xiaoting,Zhang, Hui,Zhang, Liang
, (2022/04/07)
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
Molecular Mechanism by Which Tea Catechins Decrease the Micellar Solubility of Cholesterol
Sakakibara, Takumi,Sawada, Yoshiharu,Wang, Jilite,Nagaoka, Satoshi,Yanase, Emiko
, (2019/07/03)
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.
