Mother Nature's Cauldron of Cures
by Jennifer A. Biser
Few people debate the need to preserve tropical habitats. One of the best-known concerns is the potential loss of some two-thirds (about 167,000) of the world's flowering plant species--all possible sources of medicinal compounds for humans. These botanicals provide substances required for drugs that otherwise couldn't be synthesized, and they give pharmacologists ideas for developing new ones. Some are also sold directly to consumers in nearly natural forms such as extracts, tinctures, or tablets. All told, tropical plants supply more than one-quarter of our modern prescription drugs. Yet scientists have investigated a mere one percent of the total species available. The reason? As Cornell University phytochemist Eloy Rodriguez explains, "The process of drug discovery by random screening is a laborious task requiring hundreds of hours of effort by highly trained scientists."
At the current rate of forest depletion, however, we'll run low on plant species to analyze before we've brought many more drugs to market. Perhaps the best way through the maze of so many plant species is to interview traditional healers who have used the forest as a pharmacy for hundreds of years. After all, according to Norman Farnsworth, director of the program for collaborative pharmaceutical science research at the University of Illinois, Chicago, 90 of 121 common prescriptions used worldwide originated from folklore claims. Here are some examples of human medicines derived from plants:
allicin - Used to fight fungal infections and eliminate intestinal parasites, from garlic (Allium sativum); more than 100 derivatives of this compound have other medicinal uses such as to lower blood cholesterol and promote circulation.
aspirin - Headache remedy and heart attack preventative, from willow (Salix alba); used in folk medicine to ease headaches.
atropine - Antispasmodic and pupil dilator, from belladonna (Atripa belladonna); used by women in medieval European courts to dilate their eyes.
digitalis - Treatment for congestive heart failure, from foxglove (Digitalis purpurea); used as a popular folk remedy for stimulating the heart.
emetine - Treatment for amoebic dysentery from Cephaelis ipecacuanha; ipecac syrup, which induces vomiting, is prepared from the dried roots of this plant.
ephedrine - Active ingredient in decongestants, from the stem of a Chinese shrub (Mahuang); used to relieve colds and asthma attacks. iron and vitamin C - Found in shoots of stinging nettle (Urtica dioica); the broth makes a good tonic for anemics; freeze-dried nettle leaves are used to treat hay fever symptoms.
menthol - In spearmint (Mentha spicata), used to soothe muscle lining of digestive tract; in peppermint (Mentha piperata) oil, used to treat migraines and topically treat muscle aches; menthol oil in steam is a good decongestant.
morphine - Painkiller from opium poppy (Papaver somniferum); used by Romans and Greeks as a sedative/sleep aid.
physostigmine - Treatment for glaucoma and poison antidote, from Calabar bean (Physostigma venenosum); a deadly legume given to accused criminals during rituals in Africa.
picrotoxin - Treatment for convulsions from dried fruit of Anamirta paniculate; used as an antidote for morphine poisoning in India and Sri Lanka.
quinine - Drug of choice, from the dried bark of Cinchona calisaya, to treat malaria until 1942, when chloroquinine took over; the disease has evolved resistance to chloroquinine in some areas, and quinine is still one of the best available malaria treatments.
reserpine - Tranquilizer and hypertension drug, from snakeroot (Rauvolfia serpentina); used in India to calm anxiety.
thymol - Tea brewed from the leaves of thyme (Thymus vulgaris) is an expectorant prescribed for coughs; thyme is also used as a digestive tonic, to promote sleep, and to decrease fever and headaches.
tubocurarine - Surgical anesthetic from the Amazonian curare vine (Chondodendrom tomentosum); used to make an arrow poison.
vinblastin, vincristine - Treatments for cancer from cultivated roots of the Madagascar periwinkle (Catharanthus roseus); found in Madagascar and India.
Some medicinal knowledge has come from observing animals. (See Really Wild Remedies) For example, people in India, as well as Native Americans, consider the bear a "great physician of the woods." By noting which plants bears ate, Indians developed a medicinal concoction called karadi panchamritham, which in Sanskrit means "bear delicacy made of five ingredients." Native American tribes also use the word "bear" to describe many natural healing plants that treat a wide variety of ailments. How and why bears and other animals, such as primates, choose particular plants remains the bigger mystery. They may be attracted to foliage with a specific scent or taste, especially if ill. Scientists have noted emphasis on these botanical qualities in medicinal plant selection among the Tzeltal Mayans of Mexico. Ailing animals may also be drawn to certain plants by fellow members of their species, emphasizing the role that social interaction might play in the plant selection process. Young animals may observe their parents using particular species when they are ill, and might learn the association between sickness, plants, and healing. However animals seem to cure what ails them, many fascinating "discoveries" await diligent scientists willing to carefully study these natural healers.
(ZooGoer 27(1) 1998. Copyright 1998 Friends of the National Zoo. All rights reserved.)
