United Kingdom
October 22, 2008
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Purple tomatoes high in anthocyanins |
Scientists have expressed genes
from snapdragon in tomatoes to grow purple tomatoes high in
health-protecting anthocyanins.
Anthocyanins are naturally occurring pigments found at
particularly high levels in berries such as blackberry,
cranberry and chokeberry. Scientists are investigating ways to
increase the levels of health-promoting compounds in more
commonly eaten fruits and vegetables.
“Most people do not eat 5 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,“ says Prof Cathie Martin from the
John Innes Centre.
Anthocyanins offer protection against certain cancers,
cardiovascular disease and age-related degenerative diseases.
There is evidence that anthocyanins also have anti-inflammatory
activity, promote visual acuity and hinder obesity and diabetes.
Tomatoes already contain high levels of the antioxidant
lycopene. Highly processed tomatoes are the best source, or
tomatoes cooked in a little oil, which helps to release the
lycopene from cells. Flavonoids meanwhile are soluble in water,
and foods containing both water soluble and fat-dissolved
antioxidants are considered to offer the best protection against
disease.
In this study the scientists expressed two genes from snapdragon
that induce the production of anthocyanins in snapdragon
flowers. The genes were turned on in tomato fruit. Anthocyanins
accumulated in tomatoes at higher levels than anything
previously reported for metabolic engineering in both the peel
and flesh of the fruit. The fruit are an intense purple colour.
The scientists tested whether these elevated levels actually had
an effect on health. In a pilot test, the lifespan of
cancer-susceptible mice was significantly extended when their
diet was supplemented with the purple tomatoes compared to
supplementation with normal red tomatoes.
"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," says Professor Cathie Martin.
“And certainly the first example of a GMO with a trait that
really offers a potential benefit for all consumers. The next
step will be to take the preclinical data forward to human
studies with volunteers to see if we can promote health through
dietary preventive medicine strategies.”
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High anthocyanin purple tomato and red wild-type
tomato |
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