SCIENCE / MEDICINE : Rain Forest and Its Medical Secrets Shrinking Fast
Out there in the tropical rain forests, known only to primitive tribes and perhaps not even to them, is a shrub or a vine that can save men’s lives--if it survives their depredations.
The green canopies that cover the heart of Africa, the Amazon Basin and southern Asia have yielded medicinal secrets since the dawn of man.
Quinine, extracted from the bark of the cinchona tree, quells the fever of malaria. And the leaves of the rosy periwinkle, native to Madagascar and a familiar blossom in Los Angeles gardens, contain alkaloids that are used to treat childhood leukemia, Hodgkin’s disease and other cancers.
Scientists cannot say what other remedies remain hidden in the rain forests, but they can document the disappearance of nature’s great storehouse of biological diversity.
Vanishing Rain Forests
About 7% of the Earth’s land surface remains under the canopy, more than half in the tropical belt of the Americas. With the intrusion of man--dams, timbering, roads, farming and ranching--more than 40% of the rain forests disappeared in the decades between 1940 and 1980 alone, according to accepted estimates.
Growing population and economic ventures are putting pressure on the remaining forests, and on the 120,000 plant species they nourish in incredible diversity.
Disappearing with the rain forests are the tribal cultures that have unlocked the power of these plants. As the species become extinct, so do the medicine men and their healing arts. The loss can be measured by the story of a scientist deep in the Amazon who asked a primitive medicine man what he prescribed for headaches. “Take an aspirin,” the shaman replied.
Now, concurrent with aesthetic, economic and moral movements for preservation of the rain forests and the animals and plants that live within them, scientists are mounting a race to save their medical secrets from extinction. Experts in the field met here in northern Thailand recently to map strategy.
‘Nature a Better Pharmacist’
Almost all agreed with Norman R. Farnsworth of the University of Illinois at Chicago, a tough-talking professor of pharmacognosy (the study of natural drug products) who insists that “Mother Nature is a better pharmacist. She is a producer of what a researcher of synthetic drugs would never dream up.”
For six days, the world’s leading botanists, ethnobotanists, conservationists, pharmacognocists and experts in traditional medicines wrestled with what can and should be done. They produced what they called--”a bit gloriously,” a British participant conceded--the Chiang Mai Declaration, which proclaims “the urgent need for international cooperation and coordination to establish programs for conservation of medicinal plants to ensure that adequate quantities are available for future generations.”
Held under the auspices of the World Health Organization, the International Union for the Conservation of Nature and the World Wildlife Fund, the conference of mixed disciplines jelled around the need to rise above differences between industrialized and developing countries over exploitation of medicinal resources and over strategies. None of the participants was overly sanguine about the prospects, but together they identified problems and goals.
The discussions centered around three areas--how to find new medicinal plants, how to conserve them and others already known, and how to promote and finance the programs.
Mark J. Plotkin, an ethnobotanist of the Harvard Botanical Museum in Boston, infused what might have been a dry, scientific conference with a sense of adventure and challenge. The 32-year-old Louisianian, whose childhood hero was Frank (Bring ‘Em Back Alive) Buck, says the best way to find medicinal plants is to ask the man who uses them.
Shamans Are Disappearing
“Talking plants with a shaman is like having Larry Bird ask you to shoot baskets with him,” Plotkin said, describing his field work in the far reaches of the Amazon.
But the shamans are disappearing, victims of the encroaching modern world.
“In countless films,” Plotkin noted, “he has often been portrayed in a grass skirt with a bone through his nose, waving rubber snakes and shouting gibberish. . . .
“(But) these medicine men usually have a profound knowledge of tropical plants. . . . A single shaman of the Wayana tribe in the northeast Amazon, for example, may use over 100 different species for medicinal purposes alone.
“A great many of the remedies are effective. Fungus infections of the skin are a common affliction in the tropics, and modern medicine can only suppress, not cure, serious cases. On more than one occasion, I have had serious infections successfully treated by shamans using jungle plants.”
Plotkin noted, however, that none of the shamans he encountered had an apprentice.
Like Losing a Library
“The oral traditions of these medicine men are not being passed on,” he said. “When a shaman dies, it’s like a library being burned.
“Unless we act now, thousands and thousands of years of accumulated knowledge of how to use rain forest plants is going to disappear before the turn of the century.”
Farnsworth, the University of Illinois researcher, made the same point on oral traditions.
“Folk or ethnomedical uses represent leads that may shortcut the discovery of modern therapeutic drugs, either directly from the plants or from their synthetic analogs,” he explained. “Although some skeptics regard such uses as mere ‘old wives’ tales,’ the fact remains that many important modern plant drugs have been discovered by following leads from folk uses.”
Among others, he mentioned digitalis, derived from the foxglove plant and used to treat heart disorders. According to Farnsworth, three-quarters of the plant-derived compounds used in medicinal drugs were discovered by researchers pursuing “old wives’ tales.”
Focusing on the potential for further discoveries, particularly in the rain forests, Farnsworth said 40 species of flowering plants yielded prescription drugs sold in the United States in 1980, and half of them came from the tropics. And the diversity of rain forest plant life--the pool for potential discovery--remains unique.
Notes Plotkin: “A hectare (2.47 acres) of forest in the northeastern region of the United States typically contains about 20 species of trees, whereas a similar plot in western Amazonia may contain more than 300.”
‘Back-Yard Pharmacies’
According to the World Health Organization, at least 75% of the world’s population relies on plant-based traditional medicine for primary health care. In Indonesia, jamu women pass door to door selling herbal concoctions in old Johnnie Walker bottles, and jamu companies are big business. Many Indonesian families tend small plots of medicinal plants--”back-yard pharmacies,” Paul Wachtel of the World Wildlife Fund called them.
China boasts a highly organized system of traditional medicine, and in Sri Lanka and India, ayurvedic, a natural, holistic medicine, is considered by its practitioners a better alternative to Western practices.
Scientists from developing countries represented at Chiang Mai were quick to defend their medicines in comparisons with Western pharmaceuticals.
“Quackery is not exclusive to any system of medicine,” said Olayiwoke Akerele, who heads WHO’s traditional medicine program. But Akerele, a Nigerian, also sees the threat of changing times. When he was a boy in Lagos, he said, tribesmen from the north would bring herbal remedies to the capital when they drove their cattle to town. Now the cattle come by train.
To preserve plant-based medicines, learning the secrets of the shamans is only the first step. the scientists at Chiang Mai vigorously debated the next step. Should more medicinal plants be cultivated, and, if so, what is the optimal size of a plot and where should it be established? What should be the role of the world’s botanical gardens, the vast majority in the developed world.
Need for a Plan Stressed
“We’re rather good at growing plants,” noted V. H. Heywood of England’s botanical Kew Gardens, pitching the expertise of his profession.
Selling a plan of action to governments, foundations and other sources of the money it will take to preserve the rain forests and exploit their medicinal plants was an overriding concern here.
“We’ve got to quantify,” Heywood insisted in an early session. “How many ethnobotanists do we need, and in how many areas? Preserving the world’s plants and animals is too big a brief to sell.”
Heavy financial support from Western pharmaceutical giants seems unlikely. Synthetic drugs make up the bulk of their product line, and investment in full-scale research into medicinal plants is a financial long shot.
“The big companies are run by business elements,” observed James D. McChesney of the University of Mississippi School of Pharmacy. “They have quarterly balance sheets and stockholders.”
Peter P. Principe of the U.S. Environmental Protection Agency, outlining the economic problems, told the participants that research into plant-based drugs reached its peak from 1953 to 1960. By 1980, when the industrywide research budget was $2 billion, plant-research funding was less than one-tenth of 1%.
Pressure for Fast Results
“The pharmaceutical industry operates with a development horizon of 15 years or less, meaning that a drug has to be developed, tested, approved by government agencies, and marketed successfully within that period. . . ,” according to Principe’s report. “There is considerable pressure on the development stage to produce new drugs as quickly as possible.”
The result, he said, is that big companies have generally abandoned direct screening of plants for potential use, and even trial-and-error hypothesizing of new compounds in favor of modifying proven drugs.
Still, many plant compounds cannot be synthesized, and tens of thousands of tons of raw plant material are imported by Western countries each year for drug production. In 1980, the worldwide price of imports was $551 million.
Several conference participants from developing countries described export demand that has nearly wiped out some species. Villagers have scoured their lands for valuable export plants with no concern for conservation. With most medicinal plants growing in the tropics and other underdeveloped areas, strategies such as taxing schemes, on-site cultivation and domestic pharmaceutical industries were weighed at Chiang Mai to recompense the exporting countries.
“The Earth is on the verge of experiencing an extinction of species unparalleled in human experience,” Principe said. “Ecologists and botanists generally believe that approximately 10% or more of the high plant species that currently exist will become extinct before the end of this century.”
THE GLOBAL IMPORTANCE OF TROPICAL FORESTS Tropical rain forests (Shown in black) Torpical rain forests cover just 7% of the world’s land surface, but contain about half of its known plant and animal species. Each year, man’s encroachment reduces the size of tropical forests by 44,000 square miles, or about the size of the state of Louisiana. The five countries hardest hit by deforestation include Brazil, Colombia, Indonesia, Mexico and Nigeria.
Foxglove (Digitalis pupurea) A native of western Europe and the Mediterranean, it is the source of the drug Digitalis, used in the treatment of heart disorders.
Quinine (Cinchona Pubescens) The bark of the cinchona tree, of this tropical species, native to South America, yields quinine, used for decades to treat malaria. Demand nearly led to extinction so cinchona plantations were cultivated in India, Java, Ceylon and Australia.
Rosy Periwinkle (Canthyrus Rosea) This colorful plant, native to Madagascar, contains alkaloids used in the treatment of childhood leukemia, Hodgkin’s disease and other cancers.
