|Arch Microbiol. 2014 Oct;196(10):681-95. |
|Isolation and characterization of rat intestinal bacteria involved in biotransformation of (-)-epigallocatechin.[Pubmed: 24947740]|
|Two intestinal bacterial strains MT4s-5 and MT42 involved in the degradation of (-)-Epigallocatechin(EGC) were isolated from rat feces. |
METHODS AND RESULTS:
Strain MT4s-5 was tentatively identified as Adlercreutzia equolifaciens. This strain converted (-)-Epigallocatechin(EGC) into not only 1-(3, 4, 5-trihydroxyphenyl)-3-(2, 4, 6-trihydroxyphenyl)propan-2-ol (1), but also 1-(3, 5-dihydroxyphenyl)-3-(2, 4, 6-trihydroxyphenyl)propan-2-ol (2), and 4'-dehydroxylated (-)-Epigallocatechin(EGC) (7). Type strain (JCM 9979) of Eggerthella lenta was also found to convert (-)-Epigallocatechin(EGC) into 1. Strain MT42 was identified as Flavonifractor plautii and converted 1 into 4-hydroxy-5-(3, 4, 5-trihydroxyphenyl)valeric acid (3) and 5-(3, 4, 5-trihydroxyphenyl)-γ-valerolactone (4) simultaneously. Strain MT42 also converted 2 into 4-hydroxy-5-(3, 5-dihydroxyphenyl)valeric acid (5), and 5-(3, 5-dihydroxyphenyl)-γ-valerolactone (6). Furthermore, F. plautii strains ATCC 29863 and ATCC 49531 were found to catalyze the same reactions as strain MT42. Interestingly, formation of 2 from (-)-Epigallocatechin(EGC) by strain MT4s-5 occurred rapidly in the presence of hydrogen supplied by syntrophic bacteria. Strain JCM 9979 also formed 2 in the presence of the hydrogen or formate. Strain MT4s-5 converted 1, 3, and 4 to 2, 5, and 6, respectively, and the conversion was stimulated by hydrogen, whereas strain JCM 9979 could catalyze the conversion only in the presence of hydrogen or formate.
On the basis of the above results together with previous reports, the principal metabolic pathway of (-)-Epigallocatechin(EGC) and EGCg by catechin-degrading bacteria in gut tract is proposed.
|Febs Letters, 1997, 401(2-3):230-234. |
|Green tea catechins suh α(–)-epicatechin and (–)-epigallocatechin accelerate Cu2+-induced low density lipoprotein in propagation phase[Reference: WebLink]|
METHODS AND RESULTS:
Effects of (-)-epicatechin (EC) and (-)-Epigallocatechin(EGC) on Cu2+-induced low density lipoprotein (LDL) oxidation were studied in initiation and propagation phases. When 1.5 microM EC or EGC was added to the mixture of isolated human LDL and Cu2+ in the initiation phase, the oxidation of LDL was inhibited in agreement with previous findings. In contrast, in the propagation phase, 1.5 microM of EC or EGC worked as an accelerator of the oxidation, and acceleration ratios (maximum about 6 times) were modified depending on the concentrations of catechin used and the oxidation process in the propagation phase. The evidence was obtained from formation of thiobarbituric acid reactive substances (TBARS), detecting conjugated diene measured by absorbance at 234 nm and investigating fragmentation of apoprotein B (apo B) in LDL. Even in the propagation phase of LDL oxidation, the elevated concentrations of EC or EGC worked as inhibitors: after 40 min incubation of LDL with Cu2+, 10.0 microM EC or 2.0 microM EGC inhibited LDL oxidation. Yet, nitric oxide (NO) released from 5 microM zwitterionic polyamine/NO adducts had an inhibitory in all phases of LDL oxidation.
These results indicate that catechins such as EC and EGC can act as free radical terminators (reducing agents) or accelerators (oxidizing agents) under oxidation circumstances, which is a different character from NO. From the above evidence, further investigations are needed on many natural flavonoids, the most potent antioxidative compounds in foods.
|Biosci Biotechnol Biochem. 1999 Sep;63(9):1654-6. |
|DNA cleavage activities of (-)-epigallocatechin, (-)-epicatechin, (+)-catechin, and (-)-epigallocatechin gallate with various kinds of metal ions.[Pubmed: 10610127]|
|The DNA cleavage activities of (+)-catechin (C), (-)-epicatechin (EC), (-)-Epigallocatechin(EGC), and (-)-epigallocatechin gallate (EGCg) were examined with 16 different metal ions. Cu(2+) with all the catechins facilitated DNA cleavage, while Ag+ with EGC and EC showed a strong repressive effect. The other metal ions examined showed little effect.|
|Food Funct. 2013 Oct;4(10):1521-5. |
|Blood anticoagulation and antiplatelet activity of green tea (-)-epigallocatechin (EGC) in mice.[Pubmed: 24056410]|
|(-)-Epigallocatechin(EGC) was prepared from green tea polyphenols through column chromatography of a polyamide (3.6 × 40 cm). |
METHODS AND RESULTS:
Three dosages of EGC (0.25, 0.5, 1.0 g kg(-1) d(-1)) were ingested respectively by ICR mice via gavage. Compared with the control group, group (-)-Epigallocatechin(EGC) 0.5 (dosage, 0. 5 g kg(-1) d(-1)) and group (-)-Epigallocatechin(EGC) 1.0 (dosage, 1.0 g kg(-1) d(-1)) presented significant inhibition on platelet aggregation in mice accompanied by 18.4 and 25.6% of inhibition ratio, respectively. The bleeding times (BT) of mice in group (-)-Epigallocatechin(EGC) 0.5 and group EGC1.0 were significantly prolonged (P < 0.01) as well as blood clotting time (BCT) in group (-)-Epigallocatechin(EGC) 1.0 (P < 0.05). All three dosages of EGC prolonged activated partial thromboplastin time (APTT) significantly (P < 0.01), but had no prominent effect on prothrombin time (PT) and fibrinogen level which indicated that the anticoagulation of (-)-Epigallocatechin(EGC) could not be attributed to the level decrease of coagulation factor such as fibrinogen.
The results demonstrated that EGC had prominent antiplatelet activity and blood anticoagulation in a dose-dependent manner.