Threat to medicines from plant extinctions

Paul Eccleston, The Telegraph 18 Jan 08;

Millions of lives could be at risk because the plants which provide the basis of more than half of all prescription drugs face extinction, a new report warns.

The loss of plants and trees which provide natural medicines could provoke a global healthcare crisis, says Botanic Gardens Conservation International (BGCI).

Potential cures for some of the world's deadliest diseases - including currently untreatable cancer - may be lost if the problem is not checked.

In its report London-based BGCI, which links botanic gardens in 120 countries, calls for urgent action to help secure the future of health care across the world.

It says 70 per cent of all newly-developed drugs in the United States, the world's largest and wealthiest pharmaceuticals market, are derived from natural sources and despite major scientific advances, human health is still overwhelmingly dependent on the plant kingdom.

Sara Oldfield, Secretary General of BGCI, said: "We are using up a wide range of the world's natural medicines and squandering the potential to develop new remedies. And yet it is perfectly possible to prevent plant extinctions".

Scientists had predicted that biochemistry would allow most drugs to be produced synthetically in the laboratory but in many cases it has proved impossible to reproduce the beneficial compounds found in plants.

The report cites as an example the world's most widely-used cancer drug, Paclitaxel, which is derived from the bark of several species of yew tree. Its complex chemical structure and biological function has so far made it impossible to produce artificially.
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Until recently it took an average of 6 trees to produce a single dose resulting in the decimation of wild yew populations across the world. In China's Yunnan Province, once famous for its yew forests, 80 per cent were destroyed within a three year period.

"The dramatic decline in a range of yew species, highlights the global extinction crisis that is facing medicinal plant species." said Sara Oldfield.

Poorer countries will be particularly hard-hit if trees and plants continue to be destroyed at the current rate. The World Health Organisation estimates that 5.3 billion people - 80 per cent of the global population - rely on traditional plant-based medicine as their primary form of healthcare, and in many cases collection and sales of these plants provide their only form of livelihood.

But the report says it is in the poorer rural areas where trees and plants are most threatened.

The report's author Belinda Hawkins said: "The loss of the world's medicinal plants may not always be at the forefront of the public consciousness, however it is not an overstatement to say that if the precipitous decline of these species is not halted, it could destabilise the future of global healthcare, putting many millions of lives at risk."

The BGCI has drawn on the work of some of the world's leading botanists, conservationists, healthcare professionals and traditional healers to identify which medicinal plant species are most at risk and what steps are needed to save them.

"Our report calls for co-ordinated global conservation efforts to save medicinal plants working with local communities and drawing on the skills and expertise of botanic gardens that have been involved in medicinal plant study since their first establishment 500 years ago." said Sara Oldfield.

Some of the plants at risk

Hoodia - (Hoodia gordonii)
Origin: Namibia
• Used for centuries by the San Bushmen of Namibia to stave off hunger on long hunting trips.
• The plant has sparked interest for its perceived ability to suppress appetite and is under investigation as a key weapon in the fight against obesity.
• Britney Spears famously took this in the form of lollipops as part of her efforts to loose weight.

With pharmaceutical giants such as Pfizer having expressed an interest into the plant's appetite suppressing properties, there has been an explosion of speculation into its use as a 'miracle' weight loss drug.

As a result vast quantities of the plant have been ripped from the wild, decimating entire populations. The catch 22 is that until its properties are proven few will invest in planting the species as a commercial crop, but scientists fear that by the time this is established for sure the plants may be on the verge of extinction.

Hou Po - (Magnolia officinalis)
Origin: South West China
• Contains Honokiol, a chemical that has been proven to be effective in treating previously untreatable cancers.
• Honokiol also helps soften blood vessels, thereby stemming the onset of major cardiovascular disease.
• Also used to treat senile dementia, by improving blood flow to the brain.

One of the most ancient flowering plants, dinosaurs once walked amongst groves of magnolias. Yet despite often held up as the species from which all today's flowers evolved, half of the world's magnolias are now threatened with extinction.

Bark from several different species has been used in traditional Chinese medicine for up to 5,000 years, where it is considered one of the most important therapeutic herbs. It's antioxidant effect, 1,000 times more potent than Vitamin E, has been proven to successfully reverse cardiovascular disease, slow the onset of senile dementia, and even hold promise to treat a variety of previously untreatable cancers.

Magnolia bark extract also has powerful anti-bacterial effects, and when added to chewing gum kills 63 per cent of the bacteria that cause bad breath, in comparison to the traditionally used peppermint oil, which kills just 3.5 per cent.

Caterpillar fungus - (Cordyceps sinensis)
Origin: China and Bhutan
• One of the most important species in traditional Chinese medicine, Cordyceps extracts have been demonstrated to raise the oxygen-carrying capacity of the blood.
• This has been used to dramatically reduce the times of Chinese long distance runners, so much so that they attracted suspicions of drug use.
• This same ability has been shown to slow down the decline in aerobic fitness and energy levels that is associated with old age.

Cordyceps is a parasitic fungus that grows in the bodies of various species of insect and insect larvae in the tundra of the Tibetan Plateau. Once infected by the fungal spores, the insect's body becomes slowly filled by the branching fungus. The fruiting body then explodes out of its head, like something from a science fiction film, to distribute its spores into new hosts.

Over collection has drastically reduced Cordyceps populations in the Tibetan Plateau, with its effects increasingly visible on the landscape of this fragile ecosystem.

Autumn Crocus (Colchicum autumnale)
Origin: Europe and North Africa
• Used as an assassin's poison in Ancient Greece.
• Vital to many plant breeding efforts, bearing the ability to make sterile hybrids fertile.
• Recorded as successfully curing leukaemia.
• One of the few effective natural treatments for gout.

In mid September park lawns across the country become dotted with delicate pink flowers, as the Autumn Crocus comes into bloom.

Yet few would recognise it as one of the most deadly poisons of the ancient world. The Ottomans, Romans and Greeks all used an extract of the roots as an animal poison, with some sources citing its widespread use in warfare - for example poisoning wells. In smaller doses it has a variety of therapeutic uses, including the treatment of gout and leukaemia.

Perhaps its most surprising secret is that it is key to many modern plant breeding efforts. The same substance responsible for its toxicity also has the remarkable ability to render highly-manipulated sterile hybrids fertile again, working by doubling the chromosome number.

However the stunning petals of the Autumn crocus may prove its undoing, as it is under grave threat from over-harvest for the horticultural trade and habitat loss.

Chinese Yew (Taxus wallichiana)
Origin: South West China
• The source of the world's most popular anti-cancer drug.
• Sacred to the Celts, as the tree of eternal life.
• Paradoxically all parts of the tree are also deadly poisonous.
• Shakespeare, Keats, Wordsworth, Tolkein, Agatha Christie and JK Rowling have all sung its praises.

The Ancient Celts planted yew in graveyards and buried its branches with their dead, believing that it had the power to grant eternal life. Many of these trees still exist in the churchyards that were built directly on top of ancient Celtic sites, and are now counted as some of the oldest trees in Europe, with a lower estimate of 2,000 years.

It is a compound extracted from yew that is leading the fight against breast, ovarian and lung cancer. Taxol, found in the leaves and bark of yew trees is the key constituent in many chemotherapy regimes, used in the world's number one selling breast cancer drug.

However since the discovery of this action in the 1960's, there has been a precipitous decline in several yew species. With the bark of 6 trees needed for just a single dose of the drug, the global clear cut felling of these trees for their medicinal properties has left many teetering on the verge of extinction.