Biological and Mechanistic Characterization of Novel Prodrugs of Green Tea Polyphenol Epigallocatechin Gallate Analogs in Human Leiomyoma Cell Lines

2016 ◽  
Vol 117 (10) ◽  
pp. 2357-2369 ◽  
Author(s):  
Reda Saber Ibrahim Ahmed ◽  
Gang Liu ◽  
Andrea Renzetti ◽  
Pershang Farshi ◽  
Huanjie Yang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Tea Polyphenol ◽  
Green Tea Polyphenol

The Green Tea Polyphenol Epigallocatechin Gallate (EGCG) Antagonizes the Inhibitory Effect of Bortezomib on Myeloma Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4794-4794
Author(s):  
Renate Burger ◽  
Hanna Czekalla ◽  
Tanja Ahrens ◽  
Kathrin Richter ◽  
Andreas Guenther ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Cell Lines ◽  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Chemotherapeutic Agents ◽  
Dependent Manner ◽  
Tea Polyphenol ◽  
Myeloma Cells ◽  
Green Tea Polyphenol ◽  
Dose Dependent

Abstract Dietary plant polyphenols are known to have antitumor, antiinflammatory, and antioxidant activity and as such may sensitize tumor cells to chemotherapeutic agents. We have evaluated the effects of the green tea polyphenol epigallocatechin gallate (EGCG) alone and in combination with other drugs on human myeloma cells. The compound is currently under investigation in several phase I/II clinical trials including for treatment of patients with early stage chronic lymphocytic leukemia. EGCG inhibited the in vitro growth of human myeloma cell lines in a time and dose-dependent manner. IC50 concentrations were between 12.5 μM and 50 μM as measured in a colorimetric tetrazolium (MTS) based assay and by trypan blue exclusion. Excess amounts of IL-6, bone marrow stromal cells, or overexpression of Mcl-1 and Bcl-xL could not protect from EGCG induced cytotoxicity. Pretreatment of INA-6 cells with EGCG resulted in a dose-dependent inhibition of IL-6 induced STAT3 tyrosine phosphorylation. In accordance with the essential role of STAT3 for INA-6 cell survival, EGCG induced apoptosis as determined by flow cytometry upon 7-amino-actinomycin D/annexin-V staining. In cell lines not dependent on exogenous IL-6, EGCG induced growth inhibition was abolished by pretreating the cells with 200 U/ml catalase, an enzyme which reduces reactive oxygen species (ROS). The combination of EGCG with doxorubicin, dexamethason, or rapamycin did not result in increased growth inhibition. In contrast, growth inhibition by bortezomib was antagonized with EGCG at concentrations that were not inhibitory when used alone (1–10 μM). In conclusion, EGCG exerts its effects on myeloma cells through several mechanisms including inhibition of IL-6 mediated signalling pathways via STAT3 and induction of oxidative stress. Notably, at pharmacologically achievable concentrations, EGCG antagonized bortezomib activity. Thus, the intake of natural polyphenols (high consumption of green tea or taking green tea extracts) may be critical during therapy with bortezomib.

The Acid-Promoted Reaction of the Green Tea Polyphenol Epigallocatechin Gallate with Nitrite Ions

2005 ◽  
Vol 18 (4) ◽  
pp. 722-729 ◽  
Author(s):  
Lucia Panzella ◽  
Paola Manini ◽  
Alessandra Napolitano ◽  
Marco d'Ischia
Keyword(s):  
Green Tea ◽  
Epigallocatechin Gallate ◽  
Tea Polyphenol ◽  
Green Tea Polyphenol

The green tea polyphenol (−)-epigallocatechin gallate attenuates β-amyloid-induced neurotoxicity in cultured hippocampal neurons

Life Sciences ◽  
2001 ◽  
Vol 70 (5) ◽  
pp. 603-614 ◽  
Author(s):  
Young-Taeg Choi ◽  
Chul-Ho Jung ◽  
Seong-Ryong Lee ◽  
Jae-Hoon Bae ◽  
Won-Ki Baek ◽  
...  
Keyword(s):  
Green Tea ◽  
Hippocampal Neurons ◽  
Epigallocatechin Gallate ◽  
Tea Polyphenol ◽  
Green Tea Polyphenol ◽  
Β Amyloid ◽  
Cultured Hippocampal Neurons
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