US meeting acknowledges tribal healers

The interests of tribal healers and university researchers meet when it comes to natural medicines. Substances recovered from plants, bacteria and fungi represent an important resource when it comes to tackling disease.

"Nature is the ultimate molecular architect," said Dr Gordon Cragg, of the National Cancer Institute within the US Health Institutes, during a weekend session on natural medicines at the American Association meeting in Washington.

"In my opinion, nature is still going to be the best source of new treatments," he said. A fungus delivered antibiotics to the world and fungi and bacteria were "a tremendous resource for drug discoveries". Many modern pathogens are becoming resistant to the existing range of drugs, and plants are a rich source of new compounds.

Many new drugs from nature are first identified by learning from traditional healers, explained Prof Mahabir Gupta of the University of Panama. Of the drugs derived from natural origins, 76 per cent were found by following up "ethno-botanical leads" from healers, he said. His university has joined with almost 20 institutions across Latin America in the search for promising pharmaceuticals derived from nature.

"The biodiversity of the region is very rich," he said, and there was an active programme to collect plants, produce extracts and screen them for biological activity.

Plants were "very attractive" chemical factories producing thousands of novel substances, said Prof Kurt Hostettmann of the University of Lausanne. The search for natural drugs should be hastened, however, "because the traditional knowledge of the healers is disappearing".

He described one very promising anti-fungal compound discovered in the outer bark of roots recovered from a tree in Africa. It had already been shown in tests to be "much more active" than existing anti-fungal agents, he said, and had been proved effective against 200 different fungal species. He thought the drug might come on to the market within two years as an oral treatment for AIDS patients who are highly susceptible to fungal infections.

Another substance, an anti-viral agent, had been discovered in an extract derived from a tree in Argentina, Prof Gupta said. It had shown "very remarkable anti-HIV activity" and was undergoing further testing. Care was necessary, he added, because highly active agents might also be found to be highly toxic.

Not all compounds found in nature and holding promise as a drug were benign, Prof Hostettmann said. "We have to fight against the idea that what is natural is inherently good." He described a new disorder seen since 1986 in ageing male elephants known as "floppy trunk disease".

Elephants grazing near the margins of some water sources were ingesting an unknown plant that contained a powerful neuro-toxin strong enough to paralyse the elephant's trunk. Without its trunk it could not eat or drink, and many animals had died from the disorder. The search was on to find the plant and hopefully a way to overcome the disease.