Harvesting the Secrets of Bush Doctors
THE FIRST THING Rosita Arvigo does when I step onto her porch by a patch of tropical forest near Belize's Macal River is jump up to get me a glass of "jungle juice"--her own refreshing blend of extracts from gumbo limbo bark and hibiscus flowers. "See how red it is? It's a blood builder and good for the heart," she says, noting my tousled appearance after a bumpy dirt-road detour. She should know. She's been studying medicinal plants from the jungles of Belize since the early 1980s. That's when she first encountered Don Elijio Panti, a local Mayan healer--or bush doctor--who died in 1996 at age 103.
It took her a year to convince Panti to take an American under his wing, but her persistence paid off. After gaining his trust, she spent years making a written record of every plant remedy in his repertory. Then in the 1990s, under a National Cancer Institute (NCI) program collecting plants from around the world in a search for cancer cures, she served as NCI's field supervisor in Belize. Some 3,000 plants with potential medicinal qualities were collected--75 percent of the 4,000 plants estimated to grow in Belize. "That was the fascinating bit of information that nobody knew," says Arvigo, who holds a doctorate in naprapathy from the University of Chicago. "If we extrapolated that to other countries, it could mean that more than half the plants in the world have health benefits and we just don't know it yet."
In our sophisticated world of sterile hospitals and white coats, it's still hard to imagine that, according to the World Health Organization, at least 75 percent of the world's six billion people rely on plant-based traditional medicine as their primary health care. "Over millions of years plants, animals and microorganisms have developed sophisticated chemistry that protects them from being eaten," says Gordon Cragg, chief of NCI's natural products branch in Frederick, Maryland. "The chemist at the bench can't hope to compete with nature."
Although Cragg admits that the chances for isolating a medically useful compound from any given plant are slim, the discoveries are worth the effort. "Some of our best drugs have come from plants," he says, citing aspirin, from the bark of the willow tree, morphine, extracted from poppies, and ephedrine, an anti-asthma drug derived from a plant long used in traditional Chinese medicine. Others include quinine from the bark of South America's cinchona tree used to treat malaria, and digitalis from foxglove used to treat heart disorders.
At the NCI repository for tens of thousands of plants collected from some 25 countries, scientists have been working for decades to extract and test chemical compounds.
Between 1960 and 1982, NCI collected 35,000 plant samples and tested 114,000 extracts. From those, only three cancer-fighting drugs emerged. "But one of them was taxol, an important drug in the war against breast and ovarian cancer," says Cragg. Taxol comes from the bark and needles of Pacific yew trees traditionally used by many North American tribes.
From 1986 to 1996, a second collection program included plants from Belize. Cragg says that although the Belize samples haven't shown any meaningful anti-cancer activity, the plants could still yield treatments for other ailments.
Because finding a promising drug among hundreds of thousands of plants truly is like looking for a needle in a haystack, Arvigo is adamant about working with traditional healers, whose knowledge of medicinal plants has passed down through generations for at least 1,000 years. "Native healers in Belize know that the dried leaves of the tres puntas plant can be used to treat salmonella poisoning, intestinal parasites and skin infections, and I've personally collected 21 different plants that people can take for diabetes," she says. "Most people think the world has gotten more sophisticated, but in this case, that's just not true. People--scientists included--have always searched the hills for compounds, and they've never stopped."
And in an era where infectious diseases such as tuberculosis and malaria are rapidly becoming resistant to drugs, there's even more reason to look to nature for cures, says Cragg.
Arvigo couldn't agree more. "Nature is indeed a free pharmacy," she says, sending me on my way with a parcel of jungle juice and instructions on how long to steep the concoction--just in case I feel tired after the hike back to my hammock near the river.
Heidi Ridgley is an associate editor.