Green tea extract interferes with the formation of amyloid plaques in Alzheimer’s disease

Contact: Laura J. Williams laurajw@umich.edu 734-615-4862 University of Michigan

ANN ARBOR—Researchers at the University of Michigan have found a new potential benefit of a molecule in green tea: preventing the misfolding of specific proteins in the brain.

The aggregation of these proteins, called metal-associated amyloids, is associated with Alzheimer’s disease and other neurodegenerative conditions.

A paper published recently in the Proceedings of the National Academy of Sciences explained how U-M Life Sciences Institute faculty member Mi Hee Lim and an interdisciplinary team of researchers used green tea extract to control the generation of metal-associated amyloid-β aggregates associated with Alzheimer’s disease in the lab.

The specific molecule in green tea, (—)-epigallocatechin-3-gallate, also known as EGCG, prevented aggregate formation and broke down existing aggregate structures in the proteins that contained metals—specifically copper, iron and zinc.

“A lot of people are very excited about this molecule,” said Lim, noting that the EGCG and other flavonoids in natural products have long been established as powerful antioxidants. “We used a multidisciplinary approach. This is the first example of structure-centric, multidisciplinary investigations by three principal investigators with three different areas of expertise.”

The research team included chemists, biochemists and biophysicists.

While many researchers are investigating small molecules and metal-associated amyloids, most are looking from a limited perspective, said Lim, assistant professor of chemistry and research assistant professor at the Life Sciences Institute, where her lab is located and her research is conducted.

“But we believe you have to have a lot of approaches working together, because the brain is very complex,” she said.

The PNAS paper was a starting point, Lim said, and her team’s next step is to “tweak” the molecule and then test its ability to interfere with plaque formation in fruit flies.

“We want to modify them for the brain, specifically to interfere with the plaques associated with Alzheimer’s,” she said.

Lim plans to collaborate with Bing Ye, a neurobiologist in the LSI. Together, the researchers will test the new molecule’s power to inhibit potential toxicity of aggregates containing proteins and metals in fruit flies.

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Other authors of the paper, all from U-M, are: Sanghyun Lee and Jung-Suk Choi of the Life Sciences Institute; Alaina DeToma, Suk-Joon Hyung, Akiko Kochi and Brandon Ruotoloa of the Department of Chemistry; and Jeffrey Brender, Ayyalusamy Ramamoorthy and Subramanian Vivekanandan of the Department of Chemistry and Biophysics.

The work was supported by the National Institutes of Health, Alzheimer’s Association, Alzheimer’s Art Quilt Initiative, American Heart Association, and a Graduate Research Fellowship from the National Science Foundation Study: http://www.pnas.org/content/early/2013/02/19/1220326110.abstract

Polyphenols in red wine and green tea halt prostate cancer growth

2010 study posted for filing

Contact: Cody Mooneyhan cmooneyhan@faseb.org 301-634-7104 Federation of American Societies for Experimental Biology

New report in the FASEB Journal suggests that disrupting a particular cellular signaling pathway could stop or slow the initiation, promotion, and progression of prostate cancer

In what could lead to a major advance in the treatment of prostate cancer, scientists now know exactly why polyphenols in red wine and green tea inhibit cancer growth. This new discovery, published online in The FASEB Journal (http://www.fasebj.org), explains how antioxidants in red wine and green tea produce a combined effect to disrupt an important cell signaling pathway necessary for prostate cancer growth. This finding is important because it may lead to the development of drugs that could stop or slow cancer progression, or improve current treatments.

“Not only does SphK1/S1P signaling pathway play a role in prostate cancer, but it also plays a role in other cancers, such as colon cancer, breast cancer, and gastric cancers,” said Gerald Weissmann, MD, editor-in-chief of The FASEB Journal. “Even if future studies show that drinking red wine and green tea isn’t as effective in humans as we hope, knowing that the compounds in those drinks disrupts this pathway is an important step toward developing drugs that hit the same target.”

Scientists conducted in vitro experiments which showed that the inhibition of the sphingosine kinase-1/sphingosine 1-phosphate (SphK1/S1P) pathway was essential for green tea and wine polyphenols to kill prostate cancer cells. Next, mice genetically altered to develop a human prostate cancer tumor were either treated or not treated with green tea and wine polyphenols. The treated mice showed reduced tumor growth as a result of the inhibited SphK1/S1P pathway. To mimic the preventive effects of polyphenols, another experiment used three groups of mice given drinking water, drinking water with a green tea compound known as EGCg, or drinking water with a different green tea compound, polyphenon E. Human prostate cancer cells were implanted in the mice and results showed a dramatic decrease in tumor size in the mice drinking the EGCg or polyphenon E mixtures.

“The profound impact that the antioxidants in red wine and green tea have on our bodies is more than anyone would have dreamt just 25 years ago,” Weissmann added. “As long as they are taken in moderation, all signs show that red wine and green tea may be ranked among the most potent ‘health foods’ we know.”

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Receive monthly highlights from The FASEB Journal by e-mail. Sign up at http://www.faseb.org/fjupdate.aspx. The FASEB Journal (http://www.fasebj.org) is published by the Federation of the American Societies for Experimental Biology (FASEB). The journal has been recognized by the Special Libraries Association as one of the top 100 most influential biomedical journals of the past century and is the most cited biology journal worldwide according to the Institute for Scientific Information.

FASEB comprises 23 societies with more than 100,000 members, making it the largest coalition of biomedical research associations in the United States. FASEB enhances the ability of scientists and engineers to improve—through their research—the health, well-being and productivity of all people. FASEB’s mission is to advance health and welfare by promoting progress and education in biological and biomedical sciences through service to our member societies and collaborative advocacy.

Details: Leyre Brizuela, Audrey Dayon, Nicolas Doumerc, Isabelle Ader, Muriel Golzio, Jean-Claude Izard, Yukihiko Hara, Bernard Malavaud, and Olivier Cuvillier. The sphingosine kinase-1 survival pathway is a molecular target for the tumor-suppressive tea and wine polyphenols in prostate cancer. doi:10.1096/fj.10-160838 ; http://www.fasebj.org/cgi/content/abstract/fj.10-160838v1

New evidence that green tea may help fight glaucoma and other eye diseases

2010 study posted for filing

Contact: Michael Bernstein
m_bernstein@acs.org
202-872-6042
American Chemical Society

This release is available in Chinese.

Scientists have confirmed that the healthful substances found in green tea — renowned for their powerful antioxidant and disease-fighting properties — do penetrate into tissues of the eye. Their new report, the first documenting how the lens, retina, and other eye tissues absorb these substances, raises the possibility that green tea may protect against glaucoma and other common eye diseases. It appears in ACS’s bi-weekly Journal of Agricultural and Food Chemistry.

Chi Pui Pang and colleagues point out that so-called green tea “catechins” have been among a number of antioxidants thought capable of protecting the eye. Those include vitamin C, vitamin E, lutein, and zeaxanthin. Until now, however, nobody knew if the catechins in green tea actually passed from the stomach and gastrointestinal tract into the tissues of the eye.

Pang and his colleagues resolved that uncertainty in experiments with laboratory rats that drank green tea. Analysis of eye tissues showed beyond a doubt that eye structures absorbed significant amounts of individual catechins. The retina, for example, absorbed the highest levels of gallocatechin, while the aqueous humor tended to absorb epigallocatechin. The effects of green tea catechins in reducing harmful oxidative stress in the eye lasted for up to 20 hours. “Our results indicate that green tea consumption could benefit the eye against oxidative stress,” the report concludes.

 

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ARTICLE FOR IMMEDIATE RELEASE
“Green Tea Catechins and Their Oxidative Protection in the Rat Eye”

DOWNLOAD FULL TEXT ARTICLE
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/jf9032602

CONTACT:
Chi Pui Pang, Ph.D.
Department of Ophthalmology and Visual Sciences
The Chinese University of Hong Kong
Hong Kong Eye Hospital
Kowloon, Hong Kong
Phone: 852 27623169
Fax: 852 27159490
Email: cppang@cuhk.edu.hk

New evidence that green tea may help improve bone health

20009 study posted for filing

Contact: Michael Woods
m_woods@acs.org
202-872-6293
American Chemical Society

Researchers in Hong Kong are reporting new evidence that green tea — one of the most popular beverages consumed worldwide and now available as a dietary supplement — may help improve bone health. They found that the tea contains a group of chemicals that can stimulate bone formation and help slow its breakdown. Their findings are in ACS’ Journal of Agricultural and Food Chemistry, a bi-weekly publication. The beverage has the potential to help in the prevention and treatment of osteoporosis and other bone diseases that affect million worldwide, the researchers suggest.

In the new study, Ping Chung Leung and colleagues note that many scientific studies have linked tea to beneficial effects in preventing cancer, heart disease, and other conditions. Recent studies in humans and cell cultures suggest that tea may also benefit bone health. But few scientific studies have explored the exact chemicals in tea that might be responsible for this effect.

The scientists exposed a group of cultured bone-forming cells (osteoblasts) to three major green tea components — epigallocatechin (EGC), gallocatechin (GC), and gallocatechin gallate (GCG) — for several days. They found that one in particular, EGC, boosted the activity of a key enzyme that promotes bone growth by up to 79 percent. EGC also significantly boosted levels of bone mineralization in the cells, which strengthens bones. The scientists also showed that high concentrations of ECG blocked the activity of a type of cell (osteoclast) that breaks down or weakens bones. The green tea components did not cause any toxic effects to the bone cells, they note.

 

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ARTICLE #3 FOR IMMEDIATE RELEASE “Effects of Tea Catechins, Epigallocatechin, Gallocatechin, and Gallocatechin Gallate, on Bone Metabolism”

DOWNLOAD FULL TEXT ARTICLE http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/jf901545u

CONTACT:
Ping Chung Leung, Ph.D.
Institute of Chinese Medicine
The Chinese University of Hong Kong
Shatin, Hong Kong
People’s Republic of China
Phone: 852-22528868
Fax: 852-2632441
Email: pingcleung@cuhk.edu.hk

Green tea component may help preserve stored platelets, tissues

2009 study posted for filing

Contact: Suong-Hyu Hyon, Ph.D. biogen@frontier.kyoto-u.ac.jpCell Transplantation Center of Excellence for Aging and Brain Repair

Tampa, Fla. (September 14th, 2009) – In two separate studies, a major component in green tea, epigallocatechin-3-O-gallate (EGCG), has been found to help prolong the preservation of both stored blood platelets and cryopreserved skin tissues. Published in the current double issue of Cell Transplantation (18:5/6), now freely available on-line at http://www.ingentaconnect.com/content/cog/ct, devoted to organ preservation and transplantation studies from Japan, the two complimentary studies have shown that EGCG, known to have strong anti-oxidative activity, can prolong platelet cell “shelf life” via anti-apoptosis (programmed cell death) properties and preserve skin tissues by controlling cell division.

Dr. Suong-Hyn Hyon, lead author on both studies and associate professor in the Institute for Frontier Medical Sciences in Kyoto, Japan, says that EGCG, a green tea polyphenol, is a known anti-oxidation and anti-proliferation agent, yet the exact mechanism by which EGCG works is not yet known. However, some of the activity of EGCG is likely to be related to its surface binding ability.

Enhanced platelet preservation

Using standard blood banking procedures, the storage duration for platelet cells (PCs) is limited to five days internationally or three days in Japan. During storage, PCs undergo biochemical, structural and functional changes, and PCs may lose membrane integrity and haemostatic functions, such as aggregability and affinity for surface receptors. Thus, PC shortages often occur. When EGCG was added to blood platelet concentrates, aggregation and coagulation functions were better-maintained after six days, perhaps due to EGCG’s anti-oxidative ability. Researchers suggested that EGCG inhibited the activation of platelet functions and protected the surface proteins and lipids from oxidation.

“Functions were restored by the maintained surface molecules with the detachment of ECGC by washing,” noted Dr. Hyon. “EGCG may lead to an inhibition of platelet apoptosis and lower rates of cell death, offering a potentially novel and useful method to prolong platelet storage period.”

EGCG enhances life of cryopreserved skin grafts

Another team of Japanese researchers studied the effects of using EGCG on frozen, stored skin tissues. As with platelet storage, the storage of skin tissue for grafting presents problems of availability and limitations on the duration of storage.

“To provide best outcomes, skin grafts must be processed and stored in a manner that maintains their viability and structural integrity until they are needed for transplantation,” explained Dr. Hyon. “Transplant dysfunction often occurs as the result of oxidation. A better storage solution could prevent this.”

It is known that polyphenols in green tea promote the preservation of tissues, such as blood vessels, cornea, islet cells, articular cartilage and myocardium at room temperature. Also, it is known that ECGC has stronger anti-oxidant activities than vitamin C because of its sterochemical structure and is reported to play an important role in preventing cancer and cardiovascular diseases.

This study examined how EGCG might help extend the preservation duration of frozen rat skin tissues and found that skin grafts could be protected from freeze-thaw injuries when EGCG was absorbed into various membrane lipids and proteins. Results of the study showed that EGCG enhanced the viability and stored duration of skin grafts up to seven weeks at 4 degrees C.

“The storage time of skin grafts was extended to 24 weeks by cryopreservation using EGCG and the survival rate was almost 100 percent,” noted Dr. Hyon.”

“These studies highlight the benefits of using natural compounds such as ECGC to enhance the preservation of stored tissues, possibly due to their anti-oxidative properties” said Dr. Naoya Kobayashi, guest editor of this double issue of Cell Transplantation.

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Contact: Suong-Hyu Hyon, PhD, associate professor, Research Center for Nano Medical Engineering, Institute for Frontier Medical Sciences, Kyoto University, 53 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507 Japan. Tel: +81 75 751 4125, Email: biogen@frontier.kyoto-u.ac.jp

The editorial offices for CELL TRANSPLANTATION are at the Center of Excellence for Aging and Brain Repair, College of Medicine, the University of South Florida and the Diabetes Research Institute, University of Miami Miller School of Medicine. Contact, David Eve, PhD. at celltransplantation@gmail.com or Camillo Ricordi, MD at ricordi@miami.edu

News Release by Randolph Fillmore, Florida Science Communications.

Cream with green tea extract hinders HIV transmission: study

2009 study posted for filing

(AFP)–May 19, 2009

WASHINGTON (AFP) – A chemical found in green tea helps inhibit sexual transmission of the virus which causes AIDS, said a study Tuesday that recommends using the compound in vaginal creams to supplement antiretrovirals.

Medical experts at Germany’s University of Heidelberg said the compound could be a low-cost arrow in the quiver of medical weapons to fight the spread of HIV in research-poor countries.

The researchers said they determined that the green tea polyphenol, or vegetable tannin, called epigallocatechin-3-gallate (EGCG) is capable of neutralizing a protein in sperm which serves as a vector for viral transmission during sex.

EGCG degrades what is known as a semen-derived enhancer of virus infection, or SEVI, described in the study as “an important infectivity factor of HIV.”

Writing in the online edition of the Proceedings of the National Academy of Sciences, the researchers said they “recently identified a peptide fraction in human semen that consistently enhanced HIV-1 infection.”

SEVIs capture viral elements and attach them to the surface of target cells, enhancing cell fusion and decreasing a cell’s ability to repel viral threats.

EGCG “targets SEVI for degradation” and “abrogates semen-mediated enhancement of HIV-1 infection in the absence of cellular toxicity,” said the researchers, some of whom work at the university’s Heinrich-Pette-Institute for Experimental Virology and Immunology.

Because of its effects on semen-based HIV transmission threats, the study’s authors said “EGCG appears to be a promising supplement to antiretroviral microbicides to reduce sexual transmission of HIV-1.”

With the vast majority of the world’s 33 million people with HIV infected through heterosexual sex, and as 96 percent of new infections occur in poor and developing nations, researchers said the use of green tea EGCG in topical creams would “provide a simple and affordable prevention method” to guard against HIV transmission.

Green tea, which originated in China and is widely consumed in Asia, the Middle East and growing numbers of western countries, is already popular for its antioxidant qualities.

Study reveals how green tea boosts brain cell production to aid memory

Contact: Ben Norman
Sciencenewsroom@wiley.com
44-012-437-70375
Wiley

Brainy beverage: Study reveals how green tea boosts brain cell production to aid memory

It has long been believed that drinking green tea is good for the memory. Now researchers have discovered how the chemical properties of China’s favorite drink affect the generation of brain cells, providing benefits for memory and spatial learning. The research is published in Molecular Nutrition & Food Research.

“Green tea is a popular beverage across the world,” said Professor Yun Bai from the Third Military Medical University, Chongqing, China. “There has been plenty of scientific attention on its use in helping prevent cardiovascular diseases, but now there is emerging evidence that its chemical properties may impact cellular mechanisms in the brain.”

Professor Bai’s team focused on the organic chemical EGCG, (epigallocatechin-3 gallate) a key property of green tea. While EGCG is a known anti-oxidant, the team believed it can also have a beneficial effect against age-related degenerative diseases.

“We proposed that EGCG can improve cognitive function by impacting the generation of neuron cells, a process known as neurogenesis,” said Bai. “We focused our research on the hippocampus, the part of the brain which processes information from short-term to long-term memory.”

The team found that ECGC boosts the production of neural progenitor cells, which like stem cells can adapt, or differentiate, into various types of cells. The team then used laboratory mice to discover if this increased cell production gave an advantage to memory or spatial learning.

“We ran tests on two groups of mice, one which had imbibed ECGC and a control group,” said Bai. “First the mice were trained for three days to find a visible platform in their maze. Then they were trained for seven days to find a hidden platform.”

The team found that the ECGC treated mice required less time to find the hidden platform. Overall the results revealed that EGCG enhances learning and memory by improving object recognition and spatial memory.

“We have shown that the organic chemical EGCG acts directly to increase the production of neural progenitor cells, both in glass tests and in mice,” concluded Bai. “This helps us to understand the potential for EGCG, and green tea which contains it, to help combat degenerative diseases and memory loss.”

This paper is published as part of a collection of articles bringing together high quality research on the theme of food science and technology with particular relevance to China. Browse free articles from Wiley’s food science and technology publications including the Journal of Food Science, Journal of the Science of Food and Agriculture and Molecular Nutrition & Food Research

Ingredient found in green tea significantly inhibits breast cancer growth in female mice: EGCG decreases in TCSA (66%), tumor weight (68%) 5 weeks

Repost from 2008

Contact: Donna Krupa dkrupa@the-aps.org 703-967-2751 American Physiological Society

SAN DIEGO, CA — Green tea is high in the antioxidant EGCG (epigallocatechin-3- gallate) which helps prevent the body’s cells from becoming damaged and prematurely aged. Studies have suggested that the combination of green tea and EGCG may also be beneficial by providing protection against certain types of cancers, including breast cancer. A new study conducted by researchers at the University of Mississippi researchers now finds that consuming EGCG significantly inhibits breast tumor growth in female mice. These results bring us one step closer to better understanding the disease and potentially new and naturally occurring therapies.

The study was conducted by Jian-Wei Gu, Emily Young, Jordan Covington, James Wes Johnson, and Wei Tan, all of the Department of Physiology & Biophysics, University of Mississippi Medical Center, Jackson, MS. Dr. Gu will present his team’s findings, entitled, Oral Administration of EGCG, an Antioxidant Found in Green Tea, Inhibits Tumor Angiogenesis and Growth of Breast Cancer in Female Mice, at the  121st Annual Meeting of the American Physiological Society (APS; www.the-APS.org/press), part of the Experimental Biology 2008 scientific conference.

The Study

Epidemiological studies suggest that green tea and its major constituent, EGCG, can provide some protection against cancer. Because these studies were very limited, the anti-cancer mechanism of green tea and EGCG was not clear. As a result, the researchers examined whether drinking EGCG (just the antioxidant infused in water) inhibited the following: expression of VEGF (vascular endothelial growth factor, which is found in variety of breast cancer types); tumor angiogenesis (thought to help tumors to expand by supplying them with nutrients); and the growth of breast cancer in female mice.

Seven week old female mice were given EGCG (25 mg/50 ml) in drinking water for five weeks (approximately 50-100 mg/kg/day.) The control mice received regular drinking water. In the second week of the study mouse breast cancer cells were injected in the left fourth mammary glands of the mice. Tumor size was monitored by measuring the tumor cross section area (TCSA). Tumors were eventually isolated and measured for tumor weight, intratumoral microvessel (IM) density (using staining), and VEGF protein levels (using ELISA).

At the end of the five week period the researchers found that oral consumption of EGCG  caused significant decreases in TCSA (66%), tumor weight (68%), IM density 155±6 vs.111±20 IM#mm^2) and VEGF protein levels (59.0±3.7 vs. 45.7±1.4 pg/mg) in the  breast tumors vs. the control mice, respectively (N=8; P<0.01).  Further, VEGF plasma levels were lower in EGCG mice than in control mice (40.8±3.5 vs. 26.5±3.8 pg/ml P< 0.01).

Dr. Gu, the senior researcher for the study, hypothesized that the reason for the link between EGCG and the reductions in the cancer data was because EGCG directly targets both tumor blood vessels and tumor cells of breast cancer for suppressing the new blood vessels formation in breast tumor, the proliferation and migration of breast cancer cells.

Gu concluded by saying, “In this study we have demonstrated that the frequent ingestion of EGCG significantly inhibits breast tumor growth, VEGF expression and tumor angiogenesis in mice. We believe our findings will help lead to new therapies for the prevention and treatment of breast cancer in women.”

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Physiology is the study of how molecules, cells, tissues and organs  function to create health or disease. The American Physiological Society (APS; www.The-APS.org/press) has been an integral part of this  discovery process since it was established in 1887.

NOTE TO EDITORS: The APS annual meeting is part of the Experimental Biology 2008 (EB ’08) gathering and will be held April 5-9, 2008 at the San Diego, CA Convention Center. To schedule an interview with Dr. Gu please contact Donna Krupa at 301.634.7209 (office), 703.967.2751 (cell) or DKrupa@the-APS.org.

Green tea extract ‘eradicates cancer tumours’

Powerful new anti-cancer drugs based on green tea could soon be developed   after scientists found an extract from the beverage could make almost half   of tumours vanish.

By , Medical Correspondent 6:05PM BST 21 Aug 2012

The University of Strathclyde team made 40 per cent of human skin cancer   tumours disappear using the compound, in a laboratory study.

Green tea has long been suspected of having anti-cancer properties and the   extract, called epigallocatechin gallate, has been investigated before.

However, this is the first time researchers have managed to make it effective   at shrinking tumours.

Previous attempts to capitalise on its cancer-fighting properties have failed   because scientists used intravenous drips, which failed to deliver enough of   the extract to the tumours themselves.

So, the Strathclyde team devised a “targeted delivery system”, piggy-backing   the extract on proteins that carry iron molecules, which cancer tumours   Hoover up.

The lab test on one type of human skin cancer showed 40 per cent of tumours   disappeared after a month of treatment, while an additional 30 per cent   shrank.

Dr Christine Dufès, a senior lecturer at the Strathclyde Institute of Pharmacy   and Biomedical Sciences, who led the research, said: “These are very   encouraging results which we hope could pave the way for new and effective   cancer treatments.

“When we used our method, the green tea extract reduced the size of many of   the tumours every day, in some cases removing them altogether.

“By contrast, the extract had no effect at all when it was delivered by other   means, as every one of these tumours continued to grow.

“This research could open doors to new treatments for what is still one of the   biggest killer diseases in many countries.”

She added: “I was expecting good results, but not as strong as these.”

Dr Dufès said population studies had previously indicated that green tea had   anti-cancer properties, and scientists had since identified the active   compound as epigallocatechin gallate.

But the Strathclyde researchers were the first to delivery it in high enough   doses to tumours to have an effect.

She explained: “The problems with this extract is that when it’s administered   intravenously, it goes everywhere in the body, so when it gets to the   tumours it’s too diluted.

“With the targeted delivery system, it’s taken straight to the tumours without   any effect on normal tissue.”

Cancer scientists are increasingly using targeted delivery to improve results,   relying on the many different ‘receptors’ that tumours have for different   biological substances.

In this instance, the scientists used the fact that tumours have receptors for   transferrin, a plasma protein which transports iron through the blood.

The results have been published in the journal Nanomedicine.

The “ultimate objective” was a clinical trial in humans – but Dr Dufès said   that was some way off.

http://www.telegraph.co.uk/health/healthnews/9490733/Green-tea-extract-eradicates-cancer-tumours.html

Green tea boosts production of detox enzymes, rendering cancerous chemicals harmless

Contact: Greg Lester lester@aacr.org 267-646-0554 American Association for Cancer Research

PHILADELPHIA − Concentrated chemicals derived from green tea dramatically boosted production of a group of key detoxification enzymes in people with low levels of these beneficial proteins, according to researchers at Arizona Cancer Center.

These findings, published in the August issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, suggest that a green tea concentrate might help some people strengthen their metabolic defense against toxins capable of causing cancer.

In a study of 42 people, the concentrate − composed of chemicals known as green tea catechins in amounts equal to that found in 8-16 cups of green tea − boosted production of the enzymes, which belong to the glutathione S-transferase (GST) family, by as much as 80 percent in some participants.

GST enzymes are believed to be crucial to the body’s defense against cancer-causing chemicals and other toxins, according to the study’s lead investigator, H.-H. Sherry Chow, Ph.D., a research associate professor at the University of Arizona. They modify the cancer-causing molecules that would otherwise damage cellular DNA, thus rendering them inert.

“They actually convert known carcinogens to non-toxic chemicals, and studies have shown a correlation between deficient expression of these enzymes and increased risk of developing some cancers,” Chow said.

“Expression of this enzyme varies dramatically in people due to genetic variation and environmental factors,” Chow added. “Green tea catechins somehow increase gene expression of these enzymes, which can be an advantage to people with low levels to start with.”

Green tea has long been of interest to researchers given studies that have shown populations in which it is often consumed, such as the Chinese and Japanese, generally have lower rates of cancer. To find out if green tea can protect against cancer, the NCI has sponsored a number of rigorous scientific studies testing capsules of the extract, Polyphenon E, that have been prepared in Japan to meet exact specifications. These pills contain epigallocatechin gallate (EGCG), a catechin known for its potent antioxidant activity, and are currently being tested against a variety of cancers in clinical trials.

This study was designed to see if green tea catechin concentrate had any effect on the levels of GST enzymes in healthy individuals − research that could explain the tea’s anti-cancer properties. Healthy volunteers were asked to abstain from consuming any tea or tea-related products for four weeks. At the end of this “washout period,” blood was drawn and baseline GST enzyme levels were determined for each participant. Then, the volunteers were asked to take four Polyphenon E capsules, for a total of 800 milligrams of EGCG, each morning on an empty stomach for four weeks and to abstain from drinking tea or eating many cruciferous vegetables, which contain other beneficial chemicals. Another blood sample was taken after four weeks, and GST activity was determined.

Researchers found that use of Polyphenon E enhanced GST activity when data from all participants were included for analysis. But it had its most significant effect in volunteers whose baseline blood measurements showed low GST activity − an 80 percent increase compared to baseline GST activity. Activity did not change in volunteers with medium GST expression, or in those with the highest levels, GST seemed to decrease slightly although researchers believe that decline was due to random variation.

“This is the first clinical study to show proof that chemicals in green tea can increase detoxification enzymes in humans,” Chow said. “There may be other mechanism in play by which green tea may protect against cancer development, but this is a good place to start.”

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The NCI supported the study and researchers from NCI also participated in conducting the study.

The mission of the American Association for Cancer Research is to prevent and cure cancer. Founded in 1907, AACR is the world’s oldest and largest professional organization dedicated to advancing cancer research. The membership includes nearly 26,000 basic, translational, and clinical researchers; health care professionals; and cancer survivors and advocates in the United States and more than 70 other countries. AACR marshals the full spectrum of expertise from the cancer community to accelerate progress in the prevention, diagnosis and treatment of cancer through high-quality scientific and educational programs. It funds innovative, meritorious research grants. The AACR Annual Meeting attracts more than 17,000 participants who share the latest discoveries and developments in the field. Special Conferences throughout the year present novel data across a wide variety of topics in cancer research, treatment, and patient care. AACR publishes five major peer-reviewed journals: Cancer Research; Clinical Cancer Research; Molecular Cancer Therapeutics; Molecular Cancer Research; and Cancer Epidemiology, Biomarkers & Prevention. Its most recent publication, CR, is a magazine for cancer survivors, patient advocates, their families, physicians, and scientists. It provides a forum for sharing essential, evidence-based information and perspectives on progress in cancer research, survivorship, and advocacy

*Reposted for Filing