SCIENTISTS LOOK TO WEEDS IN WAR ON DISEASE

Don't tread on that dandelion as you pass by - it might one day save your
life.

Scientists are taking a fresh look at weeds and common plants as a
potential source for valuable new drugs and chemical compounds. The search
is already under way both by private industry and public laboratories,
according to Dr Robert Nash of the UK's Institute of Grassland and
Environmental Research. Dr Nash was addressing a session yesterday at the
British Association Festival of Science in Sheffield.

Many people were familiar with the idea that the Amazonian rain forest
harboured plants that could provide important drugs, but few were aware
that potentially useful chemicals were also available from common or garden
weeds, trees and vegetables.

Advanced chemical analysis techniques were making it easier to find,
identify and extract substances which could be useful in the fight against
diseases, he said.

Even something as common as a potato could give us something new. "You can
find there are chemicals in there that people didn't know about," he said.
Researchers in Britain were finding thousands of promising new compounds
every year, potential drugs such as taxol, the anti-cancer drug which was
originally derived from the yew tree. The search was helped by folklore and
old knowledge about the treatment of illness using plants, he said.

Carnations and bluebells were both once used in treatments for
tuberculosis, he said, and both were now being analysed for active chemical
agents that might help fight the disease. "There are a lot of chemicals in
there and no one has tested them," he said.

Bluebells are also thought to contain potential anti-viral and anti-cancer
chemicals. Such chemicals might provide alternative medicines that could be
used against organisms that had become resistant to today's treatments.

The approach was an effort to "go back to nature to look for new
medicines", stated Dr Maria Ines Chicarelli-Robinson, of Molecular Nature
Ltd, a company hunting for new compounds. Plants had been used as medicines
in China for 4,000 years, she said. "It is not something that hasn't been
done before." Of the world's top 20 drugs, eight originally came from
plants and are worth an estimated $10 billion annually. Of the top 100
drugs, about half come from plants, Dr Chicarelli-Robinson said. "In our
back yard in weeds in Wales we are finding very interesting chemicals."

Harmless plant viruses may one day be harnessed to help produce vaccines,
drugs and chemicals inside plants. Prof Michael Wilson of Horticultural
Research International described a new technique which involves taking a
piece of a common plant virus and combining it with a gene that is able to
make a useful chemical.

This is used to infect a plant and the plant in turn begins to produce the
chemical. "You can see that as a factory, a sunlight and water-driven
factory," Prof Wilson said. The plant itself did not have to be genetically
modified, and when harvested up to half its total weight was made up of the
target chemical, well above what any genetically modified plant could
deliver.