Scientists have developed purple tomatoes which they hope may be able to keep cancer at bay.

The fruit are rich in an antioxidant pigment called anthocyanin which is thought to have anti-cancer properties.

A team from the John Innes Centre, Norwich, created the tomatoes by incorporating genes from the snapdragon flower, which is high in anthocyanin.

The study, published in Nature Biotechnology, found mice who ate the tomatoes lived longer.

Anthocyanins, found in particularly high levels in berries such as blackberry, cranberry and chokeberry, have been shown to help significantly slow the growth of colon cancer cells.

They are also thought to offer protection against cardiovascular disease and age-related degenerative diseases.

There is also evidence that the pigments have anti-inflammatory properties, help boost eyesight, and may help stave off obesity and diabetes.

The John Innes team is investigating ways to increase the levels of health-promoting compounds in more commonly eaten fruits and vegetables.

Tomatoes already contain high levels of beneficial antioxidant compounds, such as lycopene and flavonoids.

More benefit

Professor Cathie Martin, from the centre, said: “Most people do not eat five portions of fruits and vegetables a day, but they can get more benefit from those they do eat if common fruit and veg can be developed that are higher in bioactive compounds.”

The John Innes team took two genes from snapdragon that induce the production of anthocyanins in snapdragon flowers, and turned them on in tomato fruit.

Anthocyanins accumulated in tomatoes at higher levels than anything previously achieved in both the peel and flesh of the fruit, giving them an intense purple colour.

Tests on mice bred to be susceptible to cancer showed that animals whose diets were supplemented with the purple tomatoes had a significantly longer lifespan compared to those who received only normal red tomatoes.

Professor Martin said: “This is one of the first examples of metabolic engineering that offers the potential to promote health through diet by reducing the impact of chronic disease.

“And certainly the first example of a GMO [genetically modified organism] with a trait that really offers a potential benefit for all consumers.”

She said the the next step would be test the tomatoes on human volunteers.

Exciting

Dr Lara Bennett, of the charity Cancer Research UK, said: “It is exciting to see new techniques that could potentially make healthy foods even better for us.

“But it is too early to say whether anthocyanins obtained through diet could help to reduce the risk of cancer.

“We do know that eating a healthy, balanced diet that is rich in fibre, fruit and vegetables - and low in red and processed meat - is an important way to reduce your cancer risk.”

Dr Paul Kroon, of the Food Research Institute in Norwich, said the research was an “important study”.

“The technology offers great scope for altering colours of fruits and vegetables, and their content of potentially health-protective compounds.”

However, he said it would be wrong to assume the effects seen in mice would necessarily occur in humans.

Anna Denny, a nutrition scientist for the British Nutrition Foundation, stressed there was no “magic bullet” against diseases such as cancer and heart disease.

“Fruit and veg with higher levels of health-promoting compounds should not been seen as a replacement for eating a healthy balanced diet.”

Story from BBC NEWS:
http://news.bbc.co.uk/go/pr/fr/-/2/hi/health/7688310.stm

Published: 2008/10/26 15:52:22 GMT

© BBC MMVIII

ScienceDaily (Oct. 24, 2008) — The leading cause of death in all cancer patients continues to be the resistance of tumor cells to chemotherapy, a form of treatment in which chemicals are used to kill cells.

Now a study by UC Riverside biochemists that focuses on cancer cells reports that ingesting apigenin – a naturally occurring dietary agent found in vegetables and fruit – improves cancer cells’ response to chemotherapy.

Xuan Liu, a professor of biochemistry, and Xin Cai, a postdoctoral researcher working in her lab, found that apigenin localizes tumor suppressor p53, a protein, in the cell nucleus – a necessary step for killing the cell that results in some tumor cells responding to chemotherapy.

The study, published in the online early edition of the Proceedings of the National Academy of Sciences, provides a novel approach to conquer tumor resistance to chemotherapy, and suggests an avenue for developing safe chemotherapy via naturally occurring agents.

Normally, cells have low levels of p53 diffused in their cytoplasm and nucleus. When DNA in the nucleus is damaged, p53 moves to the nucleus where it activates genes that stop cell growth and cause cell death. In this way, p53 ensures that cells with damaged DNA are killed.

In many cancers, p53 is rendered inactive by a process called cytoplasmic sequestration. Apigenin is able to activate p53 and transport it into the nucleus, resulting in a stop to cell growth and cell death.

“In therapy you want to kill cancer cells,” explained Cai, the first author of the research paper. “But to stop cell growth and to kill the cell, p53 first needs to be moved to the cell’s nucleus to function. Apigenin is very effective in localizing p53 this way.”

Apigenin is mainly found in fruit (including apples, cherries, grapes), vegetables (including parsley, artichoke, basil, celery), nuts and plant-derived beverages (including tea and wine). It has been shown by researchers to have growth inhibitory properties in several cancer lines, including breast, colon, skin, thyroid and leukemia cells. It has also been shown to inhibit pancreatic cancer cell proliferation.

“Our study advocates the inclusion of vegetables and fruit in our daily diet to help prevent cancer,” said Liu, the research paper’s coauthor.

The National Institutes of Health supported the five-year study.

Next in their research Liu and Cai plan to design therapies for cancer by finding compounds that are like, but perform better than, apigenin.

Adapted from materials provided by University of California - Riverside

ScienceDaily (Jun. 28, 2007) — They’ve been said to stall aging, ward off disease and wage internal war against the harmful free radicals that pummel our bodies every day. But just how well do antioxidants—those all-powerful compounds often found in richly colored fruits and vegetables, such as blueberries, blackberries and red cabbage—actually perform inside the human body?

Nutritionists with the Agricultural Research Service (ARS), the U.S. Department of Agriculture’s chief scientific research agency, recently tackled this question. Their findings appear in the current issue of the Journal of the American College of Nutrition.

Led by Ronald Prior, an ARS chemist who works at the Arkansas Children’s Nutrition Center in Little Rock, the researchers investigated how the consumption of different fruits affected volunteers’ antioxidant status.

They did this by measuring the plasma (blood) antioxidant capacity (AOC) of volunteers who’d just ingested blueberries, cherries, dried plums, dried-plum juice, grapes, kiwis or strawberries.

The series of ARS studies confirmed what many antioxidant experts have long suspected: that the free-radical-busting compounds found in foods are quite complex, with some apparently being easier to absorb and utilize than others.

For instance, the researchers found that despite their high antioxidant content, plums did not raise plasma AOC levels in volunteers. According to Prior, one of the major phytochemicals in plums is chlorogenic acid, a compound not readily absorbed by humans.

As for the wild blueberry, a larger-than-average serving of this much-heralded antioxidant source was needed to boost plasma AOC levels. A noticeable climb in AOC wasn’t detected until volunteers consumed at least a half-cup serving of the berries.

The volunteers’ consumption of grapes and kiwifruit both led to noticeable spikes in plasma AOC. But it’s not clear yet which compounds were responsible for the increased levels.

Alternatively, when volunteers were asked to consume a shake containing protein, carbohydrates and fat, with no antioxidants, their blood antioxidant levels dropped.

While additional research is needed to determine if elevated plasma AOC levels translate to a lower risk for chronic degenerative disease, the current ARS study is an important first step in efforts to establish recommendations for antioxidants in the diet.

USDA/Agricultural Research Service (2007, June 28). Not All Antioxidants Are Created Equal. ScienceDaily. Retrieved December 4, 2007, from http://www.sciencedaily.com