The Physiological Activities of Tea Catechins

• Main Authors: David Ong, 王志偉
• Other Authors: 蔡國珍
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/71105157874479841323

碩士 === 國立臺灣海洋大學 === 食品科學系 === 93 === Abstract This study mainly reviews the antioxidative, antimicrobial and anticancer activities of the catechins, the dominant polyphenol components in tea. The scanvanging activity for hydroxy radical ranks in order as epicatechin gallate (ECG) ＞epigallocatechin gallate(EGCG)＞epicatechin（EC）＞gallic acid（GA）＞gallocatechin（GC）＞epigallocatechin（EGC）, all of which are greater than that of Vit C. The scanvanging activity of ECG and EGCT for superoxide and hydrogen peroxide is greater than that of Vit C and Vit E by 8.32 times. Catechins can inhibit the oxidation of the low density lipoproteins and accordingly, decrease the risk for arteriosclerosis. The antibacterial activity of EGCG is greater than that of EC. Both EGCG and EC have stronger effect on G（＋）bacteria than G（－）bacteria. The minimal inhibition concentration（MIC）of EGCG for S. aureus.and E.coli are 73 and 573 �慊/ml, respectively, while the MIC for EC are 183 and ＞1145 �慊/ml, respectively. The data from the action on liposome demonstrate that both EGCG and EC can damage the cell membrane and result in the leakage of the cell. The presence of the negative residues in membrane deaease the actions of EGCG and EC on the membrane. Catechins can inhibit the propogation of cancer cell by inducing the aptosis of cell and inhibiting the functions of tumor promoters, hormones, cytokines and growth factors. In the presence of 50 �慆 and 100 �慆 of EGCG the ratio for cells in G2-M phase was increased from 13.8﹪to 15.6﹪and 24.1﹪, respectively. The animal models used for the anticancer / antitumor study of catechins include: （1）N-nitrosodiethylamine injection to in A/J mice induce cancer production;（2）N-nitrosomethylbenzylamine induced the cancer of esophagus of Wistar rats;（3）treatments by 7,12-dimethylbenz[a]anthracene and 12-0-tetrade canoylphorbol-13-acetete to induce skin cancer in SENCAR rats; （4）induction of colon cancer in rats by N-ethyl-N’-nitro-N-nitroguanidine and azoxymethane.