Ripe Fruit Preferred

A team led by Bernhard Kräutler at the University of Innsbruck (Austria) has now determined that the breakdown of chlorophyll in ripening apples and pears produces the same decomposition products as those in brightly colored leaves. As the researchers report in the journal Angewandte Chemie, these colorless decomposition products, called nonfluorescing chlorophyll catabolytes (NCC), are highly active antioxidants—making them potentially very healthy.

The beautifully colored leaves of fall are a sign of leaf senescence, the programmed cell death in plants. This process causes the disappearance of chlorophyll, which is what gives leaves their green color. For a long time, no one really knew just what happens to the chlorophyll in this process.

In recent years, Kräutler and his team, working with the Zurich botanists Philippe Matile and Stefan Hörtensteiner, have been able to identify the first decomposition products: colorless, polar NCCs that contain four pyrrole rings—like chlorophyll and heme.

Now the Innsbruck researchers have examined the peels of apples and pears. Unripe fruits are green because of their chlorphyll. In ripe fruits, NCCs have replaced the chlorophyll, especially in the peel and the flesh immediately below it. These catabolytes are the same for apples and pears, and are also the same as those found in the leaves of the fruit trees. “There is clearly one biochemical pathway for chlorophyll decomposition in leaf senescence and fruit ripening,” concludes Kräutler.

When chlorophyll is released from its protein complexes in the decomposition process, it has a phototoxic effect: When irradiated with light, it absorbs energy and can transfer it to other substances. For example, it can transform oxygen into a highly reactive, destructive form. As the researchers were able to demonstrate, the NCCs have an opposite effect: They are powerful antioxidants and can thus play an important physiological role for the plant.

It then became apparent that NCCs are components of the diets of humans and other higher animals, and that they could thus also play a role in their systems. Other previously identified important antioxidants in the peels of fruits include the flavonoids. Thus, the saying, “an apple a day keeps the doctor away” seems to be true, according to Kräutler.

Citation: Bernhard Kräutler, Colorless Tetrapyrrolic Chlorophyll Catabolites in Ripening Fruit Are Effective Antioxidants, Angewandte Chemie International Edition 2007, 46, No. 45, 8699–8702, doi: 10.1002/anie.200703587

Source: Angewandte Chemie

Autumn colours may be a safety mechanism for trees, say researchers
(PhysOrg.com) -- One sign of autumn is the leaves turning colour, but why do some turn red? This question has baffled biologists for decades, and many ideas have been put forward to explain leaf colour change in autumn. Now, Dr Thomas Döring, a visiting post-doc in the Division of Biology at Imperial College London, has come up with a new possible explanation.
Using everyday language to explain scientific concepts could help students learn, study finds
(PhysOrg.com) -- To talk about photosynthesis, you need to know a little Latin, a bit of French, some Greek, a word coined by a pair of French chemists in the 19th century, and a word of ancient origin that has been adopted and adapted by scientists around the world.
Substantial improvement in essential cheap solar cell process
A cheap alternative to silicon solar cells can be found in dye-sensitised solar cells. This type of cell imitates the natural conversion of sunlight into energy by, for instance, plants and light-sensitive bacteria. Annemarie Huijser has succeeded in substantially improving a process in this type of solar cell, which is similar to Grätzel cells. Huijser will receive her PhD on this subject from TU Delft on Tuesday 25 March.
New animal and plant species found in Vietnam
World Wildlife Fund scientists said today that the discovery of 11 new animal and plant species in a remote area in central Vietnam underscores the importance of conservation efforts in the ancient tropical forests of the region.
How green is my planet?
Scientists from Bournemouth University and the University of Southampton have devised a new method of examining how much of the earth's surface is covered by vegetation and assessing the state of health of the foliage. The European Space Agency (ESA) has recognised the value of this information which is likely to be a vital tool for researchers examining models of terrestrial productivity, gas exchange and climate change.
A Field Of Beams
By firing rapid pulses of polarized light at corn, spinach and other crops, researchers have uncovered a picture of plant health that is invisible to the naked eye. Using a portable light source and detector technology, the researchers can differentiate minute differences in leaf colors - indicators of over- or under-fertilization, crop-nutrient levels and perhaps even disease.
Key Molecule in Plant Photo-Protection Identified
Another important piece to the photosynthesis puzzle is now in place. Researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley have identified one of the key molecules that help protect plants from oxidation damage as the result of absorbing too much light.
The researchers determined that when chlorophyll molecules in green plants take in more solar energy than they are able to immediately use, molecules of zeaxanthin, a member of the carotenoid family of pigment molecules, carry away the excess energy.
Scientists use remote satellite imaging to predict outbreaks of infectious disease
Scientists in the USA have established a way to predict outbreaks of cholera, making it easier to control. This finding could provide a model to predict and potentially control outbreaks of other important infectious diseases.

Ripe Fruit Preferred

Related stories:

News discussion: