Gallocatechin gallate

J Agric Food Chem. 2003 Dec 3;51(25):7303-7.

Heat-epimerized tea catechins rich in gallocatechin gallate and catechin gallate are more effective to inhibit cholesterol absorption than tea catechins rich in epigallocatechin gallate and epicatechin gallate.[Pubmed: 14640575 ]

It has been known that tea catechins, (-)-epicatechin (1), (-)-epigallocatechin (2), (-)-epicatechin gallate (3), and (-)-epiGallocatechin gallate (4) are epimerized to(-)-catechin (5), (-)-gallocatechin (6), (-)-catechin gallate (7), and (-)-Gallocatechin gallate (8), respectively, during retort pasteurization. We previously reported that tea catechins, mainly composed of 3 and 4, effectively inhibit cholesterol absorption in rats.
METHODS AND RESULTS:
In this study, the effect of heat-epimerized catechins on cholesterol absorption was compared with tea catechins. Both tea catechins and heat-epimerized catechins lowered lymphatic recovery of cholesterol in rats cannulated in the thoracic duct and epimerized catechins were more effective than tea catechins. The effect of purified catechins on micellar solubility of cholesterol was examined in an in vitro study. The addition of gallate esters of catechins reduced micellar solubility of cholesterol by precipitating cholesterol from bile salt micelles. Compounds 7 and 8 were more effective to precipitate cholesterol than 3 and 4, respectively.
CONCLUSIONS:
These observations strongly suggest that heat-epimerized catechins may be more hypocholesterolemic than tea catechins.

Nippon Shokuhin Kagaku Kogaku Kaishi, 2000, 47(2):120-9.

Relationship between antioxidative activity estimated by XYZ-dish method and catechin concentration in commercially available tea drinks.[Reference: WebLink]

A relationship between antioxidative activity and catechin concentration was investigated for estimating antioxidative potency of commercially available tea drinks by using the XYZ-dish method.
METHODS AND RESULTS:
Antioxidative activity of canned drinks determined by the XYZ-dish method increased in the following order : other teasGallocatechin gallate (EGCg), Gallocatechin gallate and epigallocatechin (EGC) were found to have stronger antioxidative activities. It was suggested that the presence a hydroxyl group at 5′-position of B ring and the total number of aromatic hydroxyl groups contributed to the increase in activity. The concentration of catechin compounds in tea drinks showed different levels among the tea samples examined, particularly it was markedly higher in the tea infusions than in canned tea drinks. High contents of EGCg and EGC were detected in most of the tea drinks with stronger antioxidative activities, suggesting that the two catechins mainly affected the antioxidative activity of tea drinks. Furthermore, it was confirmed that the antioxidative activity was dependent on the catechin concentration, because a significant high correlation was found between the activities and the total concentration of eight catechins in the tea drinks.
CONCLUSIONS:
These results demonstrated that the XYZ-dish method was useful as an antioxidative assay of tea drinks containing polyphenolic antioxidant activity.

Medicinal Chemistry Research, 2013, 22(7):3372-8.

Epimerization of epigallocatechin gallate to gallocatechin gallate and its anti-diabetic activity.[Reference: WebLink]

Compared with epiGallocatechin gallate (EGCG), its epimer Gallocatechin gallate (GCG) is more stable and more bioactive, even when least contained in green tea.
METHODS AND RESULTS:
In this study, EGCG can be selectively epimerized into GCG catalyzed by a phosphate buffer (pH 5.8) at 60 °C for 2 h with the highest yield of 65.6 %. A plausible mechanism for this conversion was also presented. To evaluate the anti-diabetic activity of GCG, we had investigated an oral glucose tolerance test and determined the plasma levels of glucose, insulin, triglyceride, and free fatty acid in a streptozotocin-induced diabetic rat model system.
CONCLUSIONS:
The results suggested that both GCG and EGCG might have anti-diabetic effects by increasing sensitivity of insulin, and GCG is more active than EGCG.

Journal of Functional Foods, 2017, 30:159-67.

Gallocatechin gallate (GCG) inhibits 3T3-L1 differentiation and lipopolysaccharide induced inflammation through MAPK and NF-κB signaling[Reference: WebLink]

Gallocatechin gallate (GCG), as the epimer of EpiGallocatechin gallate (EGCG), the content is low in traditional tea made from Camellia sinensis and C. assamica. However, previous studies found that the content of GCG was almost the same as EGCG in canned and bottled tea drinks. Accumulating evidences indicated that GCG possessed multiple biological activities, but the anti-obesity study of GCG is poorly reported.
METHODS AND RESULTS:
In this study, the anti-adipogenic activities of GCG were investigated. The results showed that as EGCG, GCG significantly reduced the intracellular lipid droplets and expressions of major adipogenic transcription factors, such as PPAR γ, SREBP-1c and C/EBP α. Further study revealed that the expressions of FAS, ACC, FAT and SCD-1 were decreased in 3T3-L1 cells treated with GCG. GCG treatment also dose-dependently decreased the intracellular ROS level, attenuated MAPK pathway activation in 3T3-L1 differentiations. Additionally, GCG decreased the activation of NF-κB, and down-regulated the production of IL-6 and MCP-1 induced by LPS.

J Agric Food Chem. 2009 Aug 26;57(16):7293-7.

Effects of tea catechins, epigallocatechin, gallocatechin, and gallocatechin gallate, on bone metabolism.[Pubmed: 19653629 ]

In this study, three tea catechins, epigallocatechin (EGC), gallocatechin (GC), and Gallocatechin gallate (GCG), were investigated for their effects on bone metabolism.
METHODS AND RESULTS:
The effects of the tea catechins on bone formation were evaluated using cultured rat osteoblast-like osteosarcoma cell line UMR-106. EGC stimulated alkaline phosphatase activity significantly at concentrations of 10 and 20 microM. The amount of mineralization also increased significantly with EGC. On another cell culture platform, EGC significantly inhibited osteoclast formations from RAW 264.7 cells upon receptor activation of nuclear factor-kappaB ligand induction on the fourth day of treatment, at a concentration of 10 microM. EGC also dose-dependently inhibited the mRNA expression of tatrate-resistant acid phosphatase. GC and GCG could decrease osteoclastogenesis at 20 microM.
CONCLUSIONS:
The present study illustrated that the tea catechins, EGC in particular, had positive effects on bone metabolism through a double process of promoting osteoblastic activity and inhibiting osteoclast differentiations.