green tea catechins
TRANSCRIPT
Pharmacological mechanisms & Clinical Applications Of Catechins From Green Tea
Guided ByDr. VGM Naidu
Presented By Anjana Sharma PC/2014/201
04/15/2023 2
Contents
1. Introduction2.Catechins3.What causes Cancer4.Cellular signalling in Cancer5.Mechanism Of action of EGCG6.EGCG as Anticancer agent7. Role of EGCG in Arthritis8. Role of EGCG in Obesity9.Role of EGCG in Diabetic Nephropathy10.Conclusion11.References
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Introduction
Botanical Name-Camellia sinensis Origin –ChinaChemical Constituents-Catechins,Caffeine,vitamin E and C,Fluoride and Potassium
Companies producing green tea in india1.Assamica Agro2.Tetley Green Tea
The secret of green tea lies in the fact that it is rich in catechins particularly EGCG(epigallocatechin)
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Catechins
▪ Catechins are a type of antioxidant found in the greatest abundance in the leaves of the tea plant Camellia sinensis
Types of Catechins found in Green tea1.Epicatechin2.Epigallocatechin3.Epicatechin gallate4.Epigallocatechin -3-gallate
EGCG consists of more than 40 % of total catechins found in green tea and is a very powerful antioxidant.
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What Causes CANCER
▪ Tumorigenesis is a multistep process that can be activated by any of various environmental carcinogens,tumor promoters and inflammatory agents.
▪ Cancer promoting agents modulate the transcription factors (NFκB,AP-1) ,antiapoptotic proteins, proapoptotic proteins,protein kinases,cell cycle proteins etc.
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Cellular Signalling In Cancer
Exposure of cells specially DNA with carcinogen leads to genotoxic damage
• INITIATION
Actively proliferating abnormal cells persists and replicates
• PROMOTION
An uncontrolled growth of
cells,gradual conversion of pre
malignant to malignant
cells.metastasis and angiogenesis
• PROGRESSION
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Action Of EGCG
▪ Anticarcinogenic Activity
EGCG inhibits cancer-associated stages and exert an inhibitory effect on DNA methylation via blocking performance of DNMTs, strong free radical scavenging and antioxidant activities
EGCG exhibits the highest protection against DNA scissions, mutations, and in non-enzymatic interception of superoxide anions.
EGCG has antiproliferative activities on tumor cells through the blockage of growth factor binding to the receptor and the suppression of mitogenic signal transduction
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Inhibition of tumorigenesis and possible mechanism:Molecular targets
1. Antioxidant PotentialThe antioxidant activities of EGCG are due to the presence of phenolic groups that are sensitive to oxidation and can generate quinone.
Inhibition of oxidative damage constitutes the first line of defense system against carcinogenic insults and can be considered as most effective way for preventing cancer.
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2. Induction of Apoptosis and Cell Cycle Arrest
At molecular basis apoptosis can be mediated by two pathwaysExtrinisic Pathway• At the plasma membrane upon ligation of
the death receptor
Intrinsic Pathway• At the mitochondria
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Contd….
NFκB in cancer cells appears to involve regulation of cell proliferation, control of apoptosis, promotion of angiogenesis, and stimulation of invasion/metastasis
EGCG-induced apoptosis in tumor cells may be mediated through NFκB inactivation
This inactivation is associated with the enhancement phosphorylation dependent degradation of IkBα, subsequent increases in nuclear translocation of p65 protein and inhibition of IKK activity
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Inhibition of epigenetic modifications
▪ Epigenetics refers to heritable changes that are not encoded in the DNA sequence itself, but play an important role in the control of gene expression. In mammals, epigenetic mechanisms include changes in DNA methylation, histone modifications and non-coding RNAs.
Hypermethylation often limits the accessibility of transcription factors to promoters, promote the methyl-CpG binding domain (MBD) binding, which results in recruitment of additional silencing-associated proteins, and ultimately, gene silencing.
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Conclusion
Epigallocatechin-3-gallate (EGCG) is a potent antioxidant, antiinflammatory, antiangiogenic, and antioncogenic compound derived from green tea.
Most modern medicines currently available for treating cancers are very expensive, toxic, and less effective in treating the disease.Thus, one must investigate further in detail the EGCG derived from green tea, described traditionally, for the prevention and treatment of cancer and other diseases.
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References
1. Singh, Brahma N., Sharmila Shankar, and Rakesh K. Srivastava. "Green tea catechin, epigallocatechin-3-gallate (EGCG): mechanisms, perspectives and clinical applications." Biochemical pharmacology 82.12 (2011): 1807-1821.
2. Xu, Yan, et al. "The anti-obesity effect of green tea polysaccharides, polyphenols and caffeine in rats fed with a high-fat diet." Food & function 6.1 (2015): 296-303.
3. Yoon, Sang Pil, et al. "Protective effects of epigallocatechin gallate (EGCG) on streptozotocin-induced diabetic nephropathy in mice." Acta histochemica 116.8 (2014): 1210-1215.
4. Gu, Jian-Wei, et al. "EGCG, a major green tea catechin suppresses breast tumor angiogenesis and growth via inhibiting the activation of HIF-1α and NFκB, and VEGF expression." Vasc Cell 5.1 (2013):
5. Shimizu, Masahito, et al. "Chemopreventive Potential of Green Tea Catechins in Hepatocellular Carcinoma." International journal of molecular sciences 16.3 (2015): 6124-6139.