Out of the Amazon

The Amerindians of the Amazon Basin have for centuries been reaping medicinal benefits from the region’s rainforests. "The natives were the first to carry out clinical testing, to experiment with new plants, to combine natural substances; they have always been alchemists," says Gordon Cragg, an expert in indigenous medicine at the U.S. National Cancer Institute.

The Amazon has contributed dozens of substances to Western medicine. Among the best known are curare, an essential component of modern anesthetics, and quinine, used to treat one of the world’s most important diseases, malaria.

Quinine is extracted from the bark of the cinchona tree and was used for centuries by native Amazonians to reduce fever. In 1820 two French pharmacists isolated it chemically, and in 1944 it was reproduced in the laboratory. "Traditional medicine was the inspiration and the foundation of drugs against [malaria]," says Cragg. "Although today you find case resistance to quinine-based medicines in many places, for a long time it was essential."

A Washingtonian, Richard Gill, discovered the properties of curare and was a pioneer in bridging Amazonian and Western medicine. After graduating from college, he traveled in 1929 to Ecuador, where he struck up a friendship with the natives and began to unravel the "pharmacopoeia" of the jungle. When in 1934 he was diagnosed with multiple sclerosis, he thought that the powerful poison used by the natives on the tips of their arrows might be an alternative therapy. Curare acts by blocking certain chemical receptors so nerve impulses cannot reach the muscles. Thus, Gill reasoned, a medication based on curare might be useful in treating MS or Parkinson’s disease.

He organized an expedition with more than 100 members that penetrated deep into the forest and succeeded in extracting the secret of producing curare. He also discovered 75 other botanical species potentially useful for medical treatments. He recalled his experiences in an expedition film and book titled White Water and Black Magic. Although curare did not prove useful in treating MS, its relaxant qualities were useful in the development of anesthetics. Since Gill’s findings, neuromuscular blocking has been an essential part of anesthesia.

More recent examples of Amazonian medicinal contributions include chanca piedra ("shatterstone"), use by native peoples to cleanse the internal organs and treat kidney stones; manaca, an anti-inflammatory used to treat endocrine system problems; and iporuru, the plant base for a number of remedies for muscular and joint pain.

"Potentially, there are many medications that could be extracted from tropical plants, and the strange thing is that different species often produce the same substance," says Cragg. He adds that many rainforest substances stimulate the immune system, which makes them a useful complementary therapy to other treatments.

Besides the Amazon, other regions in the Americas have made important contributions to modern medicine. An Aztec medicine extracted from the ñame (a type of yam) is now used as a steroid hormone in birth control. The main ingredient in Taxol, used in the treatment of breast cancer, is extracted from the Pacific yew tree, which grows in the western U.S. states of Oregon and Washington.

"What is fundamental is to provide the appropriate formula and to know the correct dose for each intervention. Nature is wise, and the indigenous inhabitants knew just what to take and in what quantity. Westerners should learn from them," says Cragg.

—Paula Andaló