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The 4th International symposium on Green Tea, Sept. 3, 1997, Seoul, Korea
1. The effect of catechin on Alzheimer's disease
2. Effect of green tea on peroxidative damage and expression of genes related
with antioxidative defense system in rat liver exposed to microwaves
3. Inhibition of tobacco carcinogen-induced lung tumorigenesis in A/J mice by
green tea and its major polyphenol as antioxidants
4. Protective effects of green tea polyphenols on the ultraviolet-induced
dermal extracellular damage
5. Protection against Cancer risk by Green Tea and Antibacterial activity of
Tea Catechin against Helicobactor pylori
6. Studies on Analysis and Synthetic Extraction of Pharmaceutical Components
in green tea on Curing Diabetes.
7. Biochemical studies on tumor non-promoting effect of green tea extract in
DMH-treated rats.
8. Utilization of Tea Extracts and The Prospect of Catechins as Anticancer
Agents
9. Protective effects of green tea against oxidative damage in rats treated
with acute ethanol.
Title
Effect of green tea on peroxidative damage and expression of genes related
with antioxidative defense system in rat liver exposed to microwaves
Speaker
Soon-Jae Rhee
Dept. of Food Science and Nutrition, Catholic University of Taegu-Hyosung,
Korea
Abstract
The damage of tissues on account of the exposure to the microwaves and
defense effect of the damage by the administration of green tea were observed on
rats.
The rats were divided into two groups : control group and green tea (GT)
group which was administrated the distilled water and MW green tea extracts for
14 days before the irradiation of microwave. The rats were irradiated with
microwave at frequency of 2.45GHz for 15 min, and then the change pattern of MFO
system, antioxidative defense system, peroxidative damage of tissues and
gene expression in the damaged tissues were investigated for 16 days to compared
with the normal group which was not irradiated and administrated the green tea.
The activity of cytochrome P450 in the liver was gradually increased to the
level of normal group at 16 days after irradiation with microwaves, and that of
GT group was similar to the normal group. The activity of NADPH-cytochrome P450
reduced in GT group became less than that of MW group at 4 and 6 days after the
irradiation.
The activity of superoxidase dismutase (SOD) in both group of MW and GT was
similar to that of the normal group even though the activity in both groups was
apt to be increased. The activity of glutathione peroxidase (GSH-px) in MW group
was lower than the normal group at 4 and 6 days after the irradiation, but
increased to the level of normal group at 16 days. The activity of GT group was
the same levels as the normal group, but was higher than the normal group from 8
days after the irradiation with microwave. The activity of glutathione S-transferase
(GST) in MW group was generally decreased at first, but reached to the level of
normal group after the irradiation. The activity of GST in GT group was similar
to the normal group during the irradiation. The content of thiobarbituric acid
reactive substances (TBARS) in liver of MW group was increased to 1.6, 1.5, 1.7
and 1.3 fold of the normal group at 2, 4, 6 and 8 days after the irradiation
respectively, but recovered to the level of normal group at 16 days. The content
of TBARS in liver of GT group was increased to 1.3 fold of the normal group at 2
and 4 days but recovered to the level of normal group at 8 days after the
irradiation. The level of SOD gene expression in MW group was lower than the
normal group within 6 days, but that of GT group was higher than MW group. The
GSH-Px gene was expressed a little bit lower than the normal group, but that of
GT group was expressed to higher level than MW group from 4 days after the
irradiation. It was suggested that the damage of liver tissues were alleviated
and rapidly recovered to the normal level by the contribution to the
normalization of imbalances in antioxidative system with the administration of
green tea extract.
Title
Inhibitions of tobacco carcinogen-induced lung tumorigenesis in A/J mice by
green tea and its major polyphenol as antioxidants
- Speaker
- Fung-Lung Chung
- American Health foundation
Abstract
In this study we examined the effects of green tea, its major components (-)-epigallocatechin
gallate (EGCG), and caffeine on the tobacco-specific nitrosamine
4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induced lung tumorigenesis
in A/J mice. We also studied the effects of green tea and EGCG on
O6-methylguanine (O6-mG) and 8-hydroxydeoxyguanosine (8-OH-dG) formation in
lungs caused by NNK treatment. Mice were given 2% tea infusion, 560ppm EGCG, or
1120ppm caffeine solution as drinking water 13 weeks. During this time, NNK
(11.65mg/kg b.w.) was administered by gavage 3 times weekly for 10 weeks from
weeks 3 to 12. The bioassay was terminated 6 weeks after the last NNK treatment.
Mice treated with NNK developed 22.5 lung adenomas per mouse, whereas NNK
treated mice that drank green tea or EGCG as drinking water developed only 12.2
and 16.1 tumors per mouse. Mice that drank green tea or caffeine solution showed
lowered body weight gains, although little difference in water and diet
consumption was noted in these groups. While green tea and EGCG exerted little
effect on the formation of O6-mG, both treatments suppressed the increase of
8-OH-dG levels in mouse lung DNA. The inhibition of 8-OH-dG formation in lung
DNA by green tea and EGCG is consistent with their ability to inhibit lung
tumorigenesis by NNK. Because 8-OH-dG is a DNA lesion caused by oxidative
damage, these results suggest that the mechanism of inhibition by green tea and
EGCG in NNK-induced lung tumorigenesis is due at least partly to their
antioxidant properties.
Protective effects of green tea polyphenol on the ultraviolet-induced dermal
extracellular damage
- Speaker
- Kyu-Hwan Yang
- Dept. of biological Science, Korea Advanced Institute of Science and
Technology
Abstract
UV-irradiation has been known to lead skin photoaging including skin cancer
and the wrinkle formation. The reactive oxygen intermediates produced in the
UV-irradiated skin induced various matrix metalloproteinases (MMPs) such as
collagenase, stromelysin and gelatinase, etc. which degrade extracellular
matrix. UV irradiation also reported to upregulate the transcription factors,
NF-¥ÊB and AP-1, which are known to be stimulators of MMP genes. Meanwhile, it
has been known that green tea and its components possess significant
chemopreventive effects against chemical carcinogens- and photo-caused skin
tumor formation. In this study, protective effects of green tea polyphenols (GTP)
on the UV-induced skin damage (photoaging) were studied. DPPH
(1,1-diphenyl-2-picryl-hydrazyl) was used for the free radical scavenging
experiments. UV-induced erythma was measured by the colorimetric evaluation of
Chromameter, and TBA method was used for the lipid peroxidation test. The
inhibition of collagenase mRNA and protein synthesis was assayed by the Northern
blot assay and ELISA NF-¥ÊB and AP-1 binding activity were measured using
electrophoretic mobility shift assay.
Among several GTP tested, (-)-epigallocatechin 3-O-gallate (EGCG) showed the
maximum protective effects against UV-induced skin damage. The 50% scavenging
dose (SC50) of EGCG was 3.3 ¥ìg/ml, while that of vitamin E was 16.5 ¥ìg/ml. The
erythma relative index of the control and the EGCG treated group was 268¡¾88 and
159¡¾53, respectively. The lipid peroxidation was significantly reduced in the
EGCG treated group. EGCG decreased collagenase both in protein and mRNA level.
The nuclear transcription factor, NF-¥ÊB and AP-1 binding activity was also
inhibited by the EGCG treatment. These results indicated that EGCG might protect
against UV-induced skin damage through the regulation of cellular redox state.
Protection against cancer risk by green tea and antibacterial activity of
tea catechin against Helicobactor pylori
- Speaker
- Itaro Oguni
- Dept. of Food and Nutrition, University of Shizuoka, Japan
Abstract
Cancer mortality statistics on Japanese people indicated that the death rate
from cancer of both males and females in Shizuoka prefecture located in the
central Japan is much lower than the average of Japanese people. We further
investigated this phenomenon epidemiologically and experimentally. Also
recently, Helicobactor pylori (H. pylori) was strongly suggested to play a role
in gastric carcinogenesis. We investigated the effect of tea catechin against H.
pylori. The results were as follows.
(1) In the Midwest areas of Shizuoka pref. where green tea is the staple
product, the standardized mortality ratios (SMRs) for cancer of all sites and
stomach cancer were much lower than the average ratio of Japanese people in both
sexes.
(2) The survey analysis of green tea intake indicated that the inhabitants in
the areas with low SMR due to stomach cancer seemed to have been much more
habitual in drinking green tea compared with those of the areas with high SMR.
(3) Oral administration of crude extracts of green tea inhibited the growth
of mouse sarcoma 180 inoculated into mice.
(4) Oral administration of crude extracts of green tea inhibited the
incidences of the carcinoma in both esophagus and forestomach in mice induced by
in vitro formation of nitrososarcosine from its precursors, sarcosine (a
secondary amine) and sodium nitrite.
(5) Tea catechin had an antibacterial activity against H. pylori.
These results strongly suggested that green tea played a role in protecting
against cancer risk.
Studies on analysis and synthetic extraction of pharmaceutical components in
green tea on curing diabetes
- Speaker
- Wang Dongfeng
- Department of tea science, Anhui agricultural university, China
Abstract
There is very popular folk remedy of using green tea to cure diabetes in
China and Japan. According to the analysis of the content of main pharmaceutical
components in green tea, it was found that the lower tea grade was, the less the
content of polyphenols, catechin and caffeine contained. However the content of
crude tea polysaccharide (CTPS) was on the contrary. CTPS had effect on reducing
blood sugar and enhancing immunity of the mice. CTPS was composed of
polysaccharide, protein, ash and other components etc. Polysaccharide was made
up of five monosaccharides, its molecular weight was about 107000. Protein in
CTPS was about composed of 13 amino acids. About 1.6% caffeine, 4.0% tea
polyphenols (TP) and 2.3% CTPS could be extracted from green tea by a new
synthetic extraction method studied by authors. Green tea resource is very in
China and other countries. It is very valuable to exploit CTPS in coarse tea and
to be used in food and medicine.
Biochemical studies on tumor non-promoting effect of green tea extract in
DMH-treated rats
- Speaker
- Hyun-Suh Park
- Dept. Food & Nutrition, Kyunghee University, Korea
Abstract
This study was designed to observe the effect of green tea on colon
carcinogenesis in 1,2-dimethylhydrazine (DMH) treated rats. Males Sprague Dawley
rats, at 7 weeks old, were divided into 4 groups, i.e. control group : distilled
water supplied as drinking water for 20 weeks ; green tea group (GT) : green tea
extract (2.5% w/v water) supplied for experimental period ; third group (GT-I) :
green tea extract supplied for the first part of 10 weeks and then water for 10
weeks, and forth group (GT-II) : water for the first part of 10 weeks and then
green tea extract supplied for 10 weeks. All rats were fed the same experimental
diet and injected i.m. with DMH (180mg/kg).
Tumor incidence was lower in GT group (39%) than control (47%). Crypt length
and proliferative zone in colonic mucosa were significantly decreased by green
tea when supplied throughout the experimental period. However, there was no
significant effect by green tea when supplied for 10 weeks (GT-I and GT-II). The
levels of PGE2 and TXA2 in colonic mucosa were lower in GT group than control
(p<0.0001). Content of C20:4 and the preformed level of PGE2 and TXA2 in tumor
tissues were higher than normal mucosa. Green tea significantly increased fecal
excretion of total bile acid but not secondary bile acid.
These results suggest that green tea could have preventive effect against
colon cancer when consumed daily by influencing on antioxidant effect and the
metabolism of arachidonic acid.
Title
Utilization of tea extracts and the prospect of catechins as anticancer
agents
- Speaker
- Du Qizhen
- Tea Research Institute, Chinese Academy of Agricultural Sciences, China)
Abstract
In recent ten years, much attention has been paid to the research and
development of tea extracts, and tea extracts has been extensively being used in
daily chemical products, food, health care, medical products and other products.
This paper summarizes 49 patent uses of tea extracts and some nonpatent uses
such as using tea polyphenols and tea pigments as food antioxidants and
therapeutic medicines of heart and brain vessel diseases. The 49 patents include
15 in daily chemical products, 21 in health care and medical products, 8 in
foods and 5 in other products.
The research results of recent ten years showed catechins, especially EGCG,
have prevention effects on cancers and can also repress the growth of cancer
cells. Based on the results we expect that catechins can be used as cancer
prevention agents and medicines for cancer therapy in the near future.
Protective effects of green tea against oxidative damage in rats treated
with acute ethanol.
- Speaker
- Yong-Ku Han
- Pacific R&D Center Institute of Skin Biology Safety, Efficacy,
Microbiology team, Korea
Abstract
Ethanol has been known to produce membrane damage through increased lipid
peroxidation leading to impairment of various tissues. Especially, growing
evidence suggests that free radical mechanisms have been contributed to
ethanol-induced liver injury. An increased generation oxygen species such as
superoxide (O2-) and H2O2 has been observed in liver microsomes through the
intervention of the ethanol-inducible cytochrome P450.
In this study, to investigate the effect of green tea on ethanol metabolism
and ethanol-induced oxidative stress, we estimated ethanol blood concentration
and antioxidant system such as superoxide dismutase (SOD) activity and
glutathione content in rats. Rats were fed on commercial food with 1%(v/v) green
tea solution as drinking liquid for one month and ethanol administration as a
50% solution in I.P. injection.
Total superoxide dismutase activity, vitamin E and glutathione content in
ethanol-treated rats were in general reduced in comparison to that of their
matched controls. Oral application of green tea resulted in significant
reduction against ethanol-induced oxidative damage, and ethanol blood
concentration.
Some of the cellular damages observed following ethanol challenges could be
attributed to the reduced level of these antioxidative systems. Our study
suggests that green tea may be useful against oxidative damage caused by
ethanol.
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