107965-88-8Relevant academic research and scientific papers
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.
Study of the release of gallic acid from (-)-epigallocatechin gallate in old oolong tea by mass spectrometry
Lee, Ren-Jye,Lee, Viola S. Y.,Tzen, Jason T. C.,Lee, Maw-Rong
, p. 851 - 858 (2010)
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.
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.
Stability of tea polyphenol (-)-epigallocatechin-3-gallate and formation of dimers and epimers under common experimental conditions
Sang, Shengmin,Lee, Mao-Jung,Hou, Zhe,Ho, Chi-Tang,Yang, Chung S.
, p. 9478 - 9484 (2005)
(-)-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.
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.
Oligomerization mechanism of tea catechins during tea roasting
Morikawa, Hitomi,Okuda, Keita,Kunihira, Yuji,Inada, Aoi,Miyagi, Chika,Matsuo, Yosuke,Saito, Yoshinori,Tanaka, Takashi
, p. 252 - 259 (2019)
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.
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.
Theasinensin A, a Tea Polyphenol Formed from (-)-Epigallocatechin Gallate, Suppresses Antibiotic Resistance of Methicillin-Resistant Staphylococcus aureus
Hatano, Tsutomu,Kusuda, Miwako,Hori, Mami,Shiota, Sumiko,Tsuchiya, Tomofusa,Yoshida, Takashi
, p. 984 - 989 (2003)
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.
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
The oxidation of (-)-epigallocatechin-3-gallate inhibits T-cell acute lymphoblastic leukemia cell line HPB-ALL: Via the regulation of Notch1 expression
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
, p. 1679 - 1684 (2020/01/28)
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.
