Health
In Amazon, a frustrated search for cancer cures
(Agencies)
Updated: 2009-11-17 11:34
JIGSAW PUZZLE
Among the natural products being used to fight cancer today is Taxol, a chemotherapy drug that comes from the bark of the Pacific yew tree.
David Newman, head of the Natural Products Branch of the U.S. National Cancer Institute, said several promising cancer drugs derived from natural sources as varied as a deep-water sponges and microbes are currently going through clinical trials. Often the natural compounds are tweaked or mimicked to better fight cancer cells.
"It's a detective story and a jigsaw puzzle, but you don't know how many pieces there are or what the picture looks like," he said. "In one teaspoon of soil from the Amazon, you find over a thousand microbes that have never been isolated."
Out of an estimated 80,000 species of flower-bearing plants in the Amazon, only about a fifth have been identified.
Newman said progress in Brazil has been greatly hampered by the inability of companies to patent a natural product under legislation passed in the 1990s, leaving no incentive to invest in research.
He cited the example of a Brazilian viper snake whose venom proved vital to the development of blood pressure drug captopril in the 1970s, a find that might not have happened under today's laws.
Further analysis of the promising compounds found by Varella's team has been held up while the university waits for access to a nuclear-magnetic resonance machine that can isolate the active elements.
"We're still a long way from discovering an actual medicine that could cure a type of cancer but we have strong signs that some plants have substances that inhibit the growth of tumors," said Mateus Paciencia, a bearded 34-year-old botanist.
Their main hope is that growing concern over the environment and increasing government efforts to slow the destruction of the Amazon by ranchers and loggers will turn the tide in favor of sustainable forest industries, of which they say their work is a prime example.
"There is nothing more sustainable than this," said Paciencia. "We take a kilogram worth of samples from a tree that weighs a ton and get an extract that lasts 10 years."
As he hung from a tree trunk, Ferreira said his relationship with the forest had been transformed by his job. He used to cut down trees with a chainsaw and sell the lumber in the city of Manaus, about 80 km (50 miles) down river from the research site.
"I think we'll find a medicine, and it won't take too long," he said. "If I deforest, I'm killing not just one plant but destroying a lot of other plants as well. So the job we're doing here is much better."
