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This
page contains three separate articles on ethnobotany:

BETWEEN THE CANOPY AND
THE FOREST FLOOR:
Vision Plants and
Medicines in Peruvian Amazonia 
by Peter Gorman
It is just after dawn and already the jungle is
steaming. Mist hangs in the air, trailing the wild orchids up the tree
trunks they cling to, into the emerald canopy 100 feet overhead. The air
is thick with the mixed smells of fresh forest growth and pungent
rotting vegetation. Ten yards ahead of us, almost invisible in the thick
foliage, is my old friend Pablo, a Matses Indian headman dressed in an
old madras shirt and Adidas shorts. He is looking for medicinal plants
to give to a young Matses woman who is having problems with her
menstruation. He moves in the peculiar style of the Indians of the area,
half-walking, half-jogging, his head darting from side to side, scanning
the plants along the narrow hunting trail. When Pablo comes on one of
the plants he wants the woman to use, he pulls several broad waxen
leaves from the shrub's branches and hands them to the woman's husband,
Coi-ya, to hold. Coi-ya takes one of the leaves, examines it closely,
breaks it open and tastes the resin. The remainder he ties in a bundle
he hangs around his neck with a bit of vine. We continue for an hour,
during which Pablo points out several other plants for Coi-ya's wife to
use. I think we're finished when suddenly Pablo turns off the path and
begins to make his way up a small root-tangled hill. Though it is nearly
vertical, both he and Coi-ya climb it effortlessly; my partner and I
labor furiously to keep from sliding back to the hill's base at the
path. When we reach the hilltop Pablo points at a natural clearing in
the jungle surrounded by short trees. "Bastante remedios," he says
excitedly. "A lot of medicines here." How many? I ask. Pablo sharpens
his focus like a hunter who's heard an animal. He points to a vine. "Wangana
remedio," he says, wild boar medicine. And then he points to a small
tree: "Short-tailed parrot medicine." And then, suddenly he's flying,
pointing around him at trees and vines and shrubs and flowers and
crawlers and snapping out words like a soldier. "Macaw medicine! Dog
medicine! Ocelot medicine! Wild turkey medicine! Crocodile medicine!
Worm medicine! Large stinging ant medicine! Tarantula medicine!" We'd
evidently come on a "Diablo Chacra," a devil's garden, the name given to
a jungle clearing filled with useful plants. Like a dervish, Pablo turns
and points at the plants, naming animals he associates with the
medicines he finds in them, and when a new vine or flower or fruit
catches his eye he jumps up and down, points it out, names it, and acts
out the illness it treats. He dances madly for those that treat
nervousness and insanity; clutches his groin for venereal infections;
mimes vomiting and stomach cramps for ulcer treatments; hobbles on one
foot for snake-bite remedies. He keeps it up until he counts off more
than three dozen of his plants and the problems they treat. When he
finally stops he lets out a laugh. "Bastante remedios!" he says. "Bastante!"
And then we start back to the village. On the way he asks me how much of
his medicine I've learned. I tell him a little. He looks at me like a
disappointed teacher. He's pointed things out and showed me
characteristics, torn off leaves had had me smell or chew them for years
now, and I've only learned a little? How much more do I need? I need a
lifetime, really, though that isn't a thought I can express. I laugh and
tell him it isn't easy to learn, that he knows a lot of plants. "Miles,"
he says. "Thousands."
Modern Botany, Ancient Shamanism
Botany, the study of plants, dates back thousands
of years. But it wasn't until 1753 that Carolus Linnaeus, a Swedish
naturalist, produced the first comprehensive system of plant
classification and nomenclature in his book Species Plantarum,
thus beginning the era of modern botany. Linnaeus attempted to classify
most of the world's flora, which he estimated at 10,000 species. But in
1847, after a century of exploration and colonization of the Western
hemisphere, British botanist John Lindley recalculated the number of
species in the Plant Kingdom to be nearly 100,000. The subsequent
exploration of the flora of the world's rainforests have increased that
number by increments to today's 750,000. Of those, botanist Wade
Davis-whose book The Serpent and the Rainbow deals with
his
search for the plant compound used in Haitian Voodoo to zombify
people-estimates that about 10 percent, roughly 75,000, are considered
edible. Of those, only 150 have entered world commerce, and only 20,
mostly domesticated cereals and tubers, stand between the human race and
starvation. In addition to foods, several thousands of plants have been
used by different peoples as medicines. Those include the nearly 150
still in use today-mostly in religious or spiritual healing
contexts-which have varying degrees of hallucinogenic properties.
Natural hallucinogens are found in the flora-and in a few members of the
Animal Kingdom as well-of every continent but Antarctica. According to
famed Harvard botanist Richard Schultes, they have been used at some
point in the development of most cultures to one extent or another. In
the preface to their book
Plants of the Gods, authors Schultes
and Albert Hofmann (McGraw-Hill, New York, 1979) suggest that these
plants "have been known and employed in human experience since earliest
man's experimentation with his ambient vegetation....They have long
played an important role in the religious rites of early civilizations
and are still held in veneration and awe as sacred elements by certain
peoples who have continued to live...bound to ancient traditions and
ways of life. How could man in primitive societies better contact the
spirit world than through the use of plants with psychic effects
enabling the partaker to communicate with supernatural realms?" Our own
society's fascination with the use of these substances is fairly recent,
but many traditional societies continue to rely on the use of
hallucinogens. In Africa, Iboga, from the dogbane family, is still
widely employed in Gabon, and cannabis use remains vital throughout the
northern region of the continent. In Asia, cannabis, Datura and amanita
muscaria, the Fly Agaric mushroom (which Schultes calls "the most
spectacular Asiatic hallucinogen") continue to hold an important place
in several cultures. In southeast Asia, particularly New Guinea, a
number of plants, like the bark of a large tree called the Agara, are
utilized to produce visions. While European society has largely
abandoned psychedelic plantlore in recent centuries, in medieval times,
Thorn Apple, Mandrake, Henbane and Belladonna, all belonging to the
Nightshade family, were widely employed in witchcraft. There was some
unintentional, and often fatal hallucinogen use in Europe, when,
according to Schultes, "the fungus Ergot [from which Hofmann synthesized
LSD], a parasite on rye, frequently poisoned entire regions if
accidently milled into the flour.... The plague was called St. Anthony's
Fire." The majority of indigenous plant hallucinogen use, however,
occurs in the western hemisphere. Of the 150 or so hallucinogens still
employed, nearly 120 occur in the Americas. According to Schultes,
Mexico "represents without a doubt the world's richest area in diversity
and use of hallucinogens in aboriginal societies....Without any question
the Peyote cactus is the most important sacred hallucinogen....Of almost
equal religious importance in early Mexico and still surviving in
religious rituals are mushrooms, known to the Aztecs as Teonanacatl. At
least 24 species of these fungi are employed at the present time in
southern Mexico. Ololiuqui, the seeds of Morning Glories, represents
another hallucinogen of great importance in Aztec religion and is still
employed...." Peyote remains a vital part of the religion and medicine
of Native Americans throughout the southwest US as well. Next to Mexico,
the richest diversity of hallucinogens is found in the Andean highlands
and Amazon basin of South America. Andean cultures employ half-a-dozen
species of Brugmansias (Datura); the San Pedro and Luna cacti; some
species of Piri-Piri, a highland grass, to name but a few. Many are so
commonly used that they can be purchased at markets throughout Equador,
Peru and Bolivia. But of all the cultures which continue to employ
hallucinogens, it is for those in the remote areas of the Amazon basin
that they are the most integral to physical survival. There, in the
lowland swamps and jungles, a variety of hallucinogenic snuffs, teas,
and even animal substances are part of the daily regimen of hunters and
gatherers who rely on the visions these substances produce to
communicate with the animate spirits of the world in which they live.
Ethnobotanical Adventures in the Amazon
I was traveling through the Peruvian jungle with a
botanist from a small experimental pharmaceutical firm which hopes to
market medicines derived from natural rainforest products. Our
assignment was to collect plant medicines from the indigenous peoples of
the Yivari river, the border between Peru and Brazil. Once a center of
the western Amazon's rubber trade, the region has been largely ignored
since the demise of the rubber boom nearly a century ago. Most of the
Indians who once crowded the Yivari and its tributaries are gone: many
died during epidemics that raged during the boom, or in the enslavement
and warfare that accompanied it; others were long ago converted and
moved to the cities at the river's mouth, where they integrated into the
local mestizo-mixed blood-communities. There remain only a
dozen-and-a-half indigenous communities from three tribes spread out
over the 500-mile length of the river. Most of them are made up of fewer
than 100 people. Of the tribals who have vanished from the river, each
took with them a history, a language, and the accumulated knowledge
their people had of the jungle in which they lived. For the people of
these remote regions of the Amazon, plants have traditionally provided
housing, weapons, tools, food, means of transportation, trade goods,
medicine and spiritual aids. And though hundreds of years of irregular
contact with river traders, missionaries, rubber tappers, loggers, the
military and the odd tourist have introduced everything from shotguns
and metal tools to western clothing and an occasional outboard motor,
plants continue to directly provide the bulk of indigenous needs. The
study of those plants utilized by specific cultures is called
ethnobotany. Unlike the professionals in the field, who spend their
graduate years hitting the books and their post-doctoral years traveling
from one remote culture to another collecting and drying leaves and
plant parts for future study at universities, I stumbled upon the
science by accident. In 1984, I was in Peru with two friends, and we had
the opportunity to spend several days with a guide named Moises Torres
Vienna, a former military specialist in jungle survival who by then was
taking tourists out on unconventional trips. Among the things Moises
introduced us to were several edible plants and insects, a variety of
medicinal plants, and the hallucinogenic tea, ayahuasca. Though we took
the drug out of curiosity and psychedelic interest-and I found the
experience extraordinary-I knew nothing about it at the time. But on a
subsequent trip to the jungle the following year, I used ayahuasca
again, and learned that its primary function among the people who live
in remote regions was as a curative. Curanderos, jungle doctors, drink
ayahuasca to give them the ability to "see" (in the visionary aspect of
the word) into their patients, to discover what is ailing them and what
plant medicines they should use to treat them. The patient may or may
not also drink the ayahuasca. On that second trip to the Peruvian Amazon
I watched the curandero, Don Julio Jerena, successfully save the leg of
a man who had been repeatedly bitten by a bushmaster, the largest
venomous snake in the western hemisphere-after the well-stocked military
hospital in the city of Iquitos had said it would have to be amputated.
The cure involved a diet and regular exercise prescribed by Don Julio,
treatment with a variety of plant medicines, and the regular drinking of
ayahuasca. When asked if it was his standard treatment for bushmaster
bites, Don Julio said no, it was a specific treatment for this
particular patient. He had seen it while under the influence of
ayahuasca the first time he was with the man. He had "seen" the sick man
healthy again, provided he stuck exactly to the regimen he'd also
"seen."
Where the Modern and the Ancient Meet
While everyone who lives in the Amazon has a
knowledge of the plants they need for survival, those with the most
refined knowledge of plants are those westerners call shaman-curanderos,
healers, medicine men and women. In the little mestizo river village of
Auchyako, Don Julio is the local curandero. On the tributary of the
Yivari on which most of the Matses live, Pablo and his cousin Wilfredo
are the healers. And despite never having met them, what Don Julio has
in common with Pablo and Wilfredo is that they all view plants as
sentient beings. Though a strange concept to the western mind, it is
common among plant healers throughout the world. That belief is the
point at which the science of ethnobotany meets the spiritualism of the
shaman. For Don Julio, who spent several years apprenticing to a healer,
access to the intelligence of plant life-among other things-is gained
through ayahuasca. For Pablo and Wilfredo, those portals are crossed by
dreaming. According to Wilfredo, the two of them "studied plant
medicines every day for two years with an old man at Buenas Lomas, a big
Matses village. The old man is dead now, but Pablo and I know the
plants." After their initial studies they learned to dream. According to
both, dreaming involves long hours of attention to specific plants,
learning to identify them by the insects and animals which associate
with them, learning their reproductive cycles, and finally by physically
sleeping near them until the plants allow you to dream them. Pablo and
Wilfredo say the plant gives you permission to use it as a curative by
allowing you to dream the illnesses it treats, and the method of
treatment. Once again, to westerners this is a foreign concept. With our
awareness of chemical composition and physical reaction, it's difficult
to accept that a plant that is used to treat a foot fungus in one
village by Pablo will not treat the same fungus in another village by
Wilfredo. Yet in several medicinal plant collecting trips with both of
them, I saw few of the same plants used to treat similar illnesses, a
testimony to their different dreams. Both acknowledge that the plants
themselves have the capability of treating illnesses, but say that
without the plant's expressed approval through the dream, the results
will be considerably less effective. To aid the dreaming, the Matses use
a psychoactive snuff they call nu-nu. Similar to the virola snuffs used
by indigenous peoples throughout northwestern Amazonia, nu-nu is made by
mixing the dried and pulverized leaves of an as-yet-unclassified wild
tobacco, with the ashes of the soft inner bark of a tree in the Macao
family; occasionally, other leaves are added as well. The result, a
bright green snuff, is blown with force through a hollow reed tube by
one man into the nostrils of another. On occasion, as many as 20
half-gram "blows" may be administered. When it hits, nu-nu hurts. It
feels as though it will take the back of your head off, and leads to
sometimes violent coughing and spitting up of dark green phlegm. But in
moments, a pervasive calm comes over the user, and fleeting visions of
extreme clarity occur. The visions are often of good places to hunt, or
new areas in the forest where medicines can be found. Following the
visions, the user is generally giddy for a short time, and then back to
normal. Though the Matses most often use nu-nu for hunting visions, it
is also a vital element in plant dreaming. According to Pablo, nu-nu
helps make the plants receptive to those who wish to communicate with
them. The first time the notion of plant communication was presented to
me, I didn't know what to make of it: I was out with Pablo, on the way
to making an animal trap. I had a headache, and he noticed it. Moments
later he pulled two leaves off a vine growing up a tree trunk and rubbed
them vigorously into my temples. He actually rubbed the skin raw enough
to draw a little blood, then had me hold the leaves in place there. In
minutes the headache vanished. His cure worked so well that I asked if
he had others. He laughed and said he did, and began to point things out
as we walked. As I later learned was typical for him, he would act out
the infirmity as he discussed the treatment. Aware I'd stumbled on a
great chance, I collected leaves, flowers and bark from the plants he
discussed. Back at his village after the trap was set, I laid out all of
the plants on the tree bark floor of his large hut, then got my tape
recorder and camera ready. There was a mestizo woman in the camp who
spoke Matses and agreed to act as my translator. I asked her to ask
Pablo to begin discussing the plants again, which she did. Pablo was
silent for a minute then broke into a wide grin and responded. I asked
my translator what he'd said. "He says he introduced you to the plants,
but now you have to make your own friends with them." I asked her what
he was talking about; she relayed the message. "He says you should go
sleep with them. Make friends with them and dream them. Then you won't
need him to explain what they are for."
Shamanic Vines, Psychoactive Frogs
Substances like ayahuasca and hallucinogenic
snuffs have until recently engendered less interest from the medical
community than they have from psychedelic pioneers. Neo-psychedelic guru
Terence McKenna sees hallucinogenic mushrooms as the probable basis for
the human race's self-cognition and the birth of language, and his
biologist brother Dennis views psychedelic plants as "the cognitive
representatives of the Plant Kingdom." But science often views these
plants as little more than intoxicants which produce "magico-religious"
visions for aboriginal cultures. It is simply too difficult for most
western scientists to accept that there may be other realms beyond the
world as we see it-realms in which plants communicate with man, realms
which are accessible through "plant spirit aids." Today, some scientists
are beginning to recognize that their assumptions may have to be
reconsidered. After 20 years of telling anyone he could that Ibogaine,
the hallucinogen used in initiation rites among the Bwiti in Gabon,
stopped his heroin addiction cold, Howard Lotsof finally convinced the
National Institute of Drug Abuse to begin testing it as an
addiction-interrupter. Similar studies of ayahuasca in connection with
alcoholism are currently taking place through the French government in
Peru, and the rainforest conservation group Botanical Dimensions
recently sponsored Dr. Charles Grob and Dennis McKenna's Huasca Project
in conjunction with the Brazilian Uniao de Vegetal, to study the medical
aspects of ayahuasca. One of the most unusual psychoactives currently
undergoing study in both France and the US is a substance extracted from
a small green tree frog, the phyllomedusa bicolor, which the Matses use
for a variety of reasons. Like Pablo's plant medicine, I came on it
unexpectedly. It was the morning after a hunt. I was sitting with Pablo
in the hut of one of his wives, pointing to objects and asking the
Matses word for them. I made notes, writing down the phonetic spelling
of things like bow, arrow, spear, and hammock. Pablo was bored with the
exercise until I pointed to a small leaf bag that hung over a cooking
fire. "Sapo," -toad- he said, his eyes brightening. From the bag he
pulled a piece of split bamboo, the size and shape of a doctor's tongue
depressor. It was covered with what looked like a thick coat of aging
varnish. "Sapo," he repeated, scraping a little of the material from the
stick and mixing it with saliva. When he was finished, it had the
consistency and color of green mustard. Then he pulled a smoldering twig
from the fire, grabbed my left wrist and burned the inside of my
forearm. I pulled away, but he held my wrist tightly and burned me
again. The burn marks were about the size and shape of a matchhead. He
scraped away the burned skin and dabbed a little of the sapo onto the
exposed areas. Instantly my body began to heat up. In seconds I was
burning from the inside and regretted allowing him to give me a medicine
I knew nothing about. I began to sweat. My blood began to race. My heart
pounded. I became acutely aware of every vein and artery in my body and
could feel them opening to allow for the fantastic pulse of my blood. My
stomach cramped and I vomited violently. I lost control of my bodily
functions and began to urinate and defecate. I fell to the ground. Then,
unexpectedly, I found myself growling and moving about on all fours. I
felt as though animals were passing through me, trying to express
themselves through my body. It was a fantastic feeling, but it passed
quickly and I could think of nothing but the rushing of my blood, a
sensation so intense that I thought my heart would burst. The rushing
got faster and faster. I was in agony. I gasped for breath. I wished I
could simply die to get it over with. But slowly, over the course of the
next few minutes, the pounding became more steady and rhythmic, and then
it finally receded to a normal rate. I realized I wasn't going to die. I
was overcome with exhaustion and slept where I was. When I awoke a few
hours later, I heard voices in the camp. But as I came to my senses I
realized I was alone. I looked around and saw that I had been washed off
and put into my hammock. I stood and walked to the edge of the hut's unwalled platform floor and realized that the conversation I was
overhearing was between two of Pablo's wives who were standing nearly 20
yards away. I didn't understand their dialect, but I was surprised to
even hear them at that distance. I walked over to the other side of the
platform and looked out into the jungle; it's noises too were clearer
than usual. And it wasn't just my hearing that had been improved. My
vision, my sense of smell-all my senses seemed sharper, and my body felt
immensely strong. When I found Pablo and indicated to him what I was
feeling he smiled. "Sapo. Fuerte." The toad is strong. (In fact, the
"toad" is a frog, but Pablo's command of Spanish is limited.) During the
next several days my feeling of strength
didn't diminish. I could go
whole days without being hungry or thirsty, and moved through the jungle
for hours without tiring. Every sense I possessed was heightened and in
tune with the environment, as though I was on an adrenal drip. I later
learned the Matses use sapo for both physical and spiritual reasons. It
is used to sharpen the senses and increase stamina on long hunting trips
when carrying food and water are difficult. As a medicine, it serves as
both a tonic to cleanse and strengthen the body, and as a toxin purge
for those with the grippe, or flu. Matses women say they use it to
determine whether they are pregnant, and to establish the health and sex
of a fetus. In large doses it acts as an abortive. On the spiritual
side, Pablo claims that in massive doses (certainly lethal in those not
accustomed to it), it allows him to project his spirit as an animal to
communicate with other animals. By chance, my reports of sapo reached
the hands of an Italian scientist, Vittorio Erspamer, at the University
of Rome. Erspamer had studied the phyllomedusa bicolor's
chemicals, but said there were no reports of the use of its secretions
by humans. Reapplying himself to the work with samples of the material I
was lucky enough to get, he determined that the secretions were a
powerful chemical cocktail with potential medical applications. Based on
Erspamer's work, two pharmaceutical houses have begun investigating the
material for possible use in producing painkillers, natural abortives,
adrenal gland stimulators, and heart medications. But despite these
various and important steps by a few investigators, most of the
hallucinogens in the world's pharmacopoeia continue to be ignored by
western science.
The Coming Revolution in Plant Medicine
And it is not only the hallucinogens which are
being ignored. According to Roberto Root-Bernstein, a physiologist at
Michigan State University, most traditional medicines are dismissed. In
a recent issue of Omni magazine, he observes, "Our high-tech medical
establishment pooh-poohs primitive cures as superstitious nonsense." The
scope of industrial civilization's invisible genocide against indigenous
peoples is dizzying. Nearly 300 distinct cultures have been lost to
acculturation, disease, or loss of traditional lands worldwide since the
turn of the century-nearly one per year in the Amazon alone. But despite
the expansion of the western medical model and the rapid erosion of
traditional knowledge, plant medicines remain the primary form of
medical treatment for an estimated 75 percent of the world's population,
including most of Africa, Latin America and Asia. And even in our own
western pharmacopoeia, nearly half the medicines we use contain plant
material or synthetics derived from them-including aspirin, atropine,
digitalis, quinine, morphine, and the majority of our anti-tumor
medications. Outspoken pharmocognocist Norman Farnsworth, believes that
somewhere in the plant kingdom there is a remedy for every ailment known
to humanity. Unfortunately, most pharmaceutical houses don't agree with
him. Most view the medicine-plant successes already on the market as
either dumb luck or quaint anachronism, and since the 1950s have
preferred to work at purely synthetic drug development, ignoring the
vast potential of the world's flora. In fact, the World Wildlife Fund
estimates that less than two percent of the flora of the Amazon has been
investigated for potential medical use in even
the most cursory fashion.
And even as western pharmaceutical houses have started recently
reinvestigating plant materials for possible medical applications, the
screening method is generally to make large and haphazard plant
collections, rather than talking to the curanderos who use the plants.
Which doesn't mean that the large houses won't get involved when the
chance at a profit shows itself: Eli Lilly jumped on the rosy periwinkle
of Madagascar once independent consultants discovered it had promising
therapeutic potential. The result of their investigation led to the
development of vincristine, the chemotherapeutic agent now used in the
treatment of childhood leukemia. Fortunately, a few smaller companies
have recently decided that it is precisely the curanderos to whom they
should be talking. The most notable among them is the California-based
Shaman Pharmaceuticals, which has botanists and doctors working with
curanderos in dozens of countries worldwide. Their success or failure
may determine whether other companies go the same route. Aside from
Shaman, there are several small consorts working with individual plants.
Among the traditional medicines of Central and South America being
studied most closely is a plant-of which there are several
species-called the Una de Gato, the Cat's Claw, commonly used as a tonic
and blood cleanser. Scientists are studying it as a possible AIDS
treatment. For several years, the city of Iquitos, Peru's gateway to the
Amazon, has been the site of a clandestine operation involving
physicians from several countries. Deathly ill AIDS patients are flown
in secretly and whisked out to the jungle for intense Una de Gato
therapy. Though their results remain closely guarded, the very fact that
it is AIDS which is being treated has led to the marketing of dozens of
Una de Gato medicines, teas, and powders throughout western South
America. So much interest has been generated in the plant that Peru has
recently outlawed its export. The new interest in plant medicines,
however, has brought fewer scientists and ethnobotanists into the jungle
than it has psychedelic tripsters looking for an unusual high. And the
tourist presence in many areas of Amazonia has done much to corrupt what
remains of the traditional plant knowledge. Several Indian and mestizo
curanderos are regularly flown to the States, where they give ayahuasca
sessions to high-paying New Agers-to the detriment of the Amazon locals
who depend upon them. Dozens of others have left their communities to
work at tourist camps specializing in the shamanic experience.
Protecting Traditional Knowledge
With the loss of the world's rainforests, and the
push of western civilization into more and more remote areas of the
world, traditional plant knowledge becomes more endangered daily.
Relatively few of the plant healers in Amazonia have apprentices. And in
cultures which depend on an oral tradition passing knowledge from
generation to generation, that knowledge can be easily lost. Wilfredo is
one of the lucky plant healers who has an apprentice of his own to
teach. But neither Pablo nor Don Julio do. And as more and more of the
younger Indians and mestizos alike choose to forsake life in the jungle
for the river cities, fewer and fewer curanderos will find apprentices.
Fortunately, there are some groups working to save the endangered
knowledge of these people. In Belize, Rosita Arvigo founded the Ix Chel
Farm in 1987 to preserve the botanical knowledge of Don Elijio Panti, an
old Mopan Maya Indian. Since then the farm, funded by the National
Institutes of Health and the US Agency for International Development,
has identified 2,800 potentially curative plant species from several
local healers. They are slowly being catalogued by Michael Balick,
director of the Institute of Economic Botany at the New York Botanical
Garden. To ensure that the people whose medicines are being investigated
will get a cut of any eventual pharmaceutical profits, Arvigo organized
the Belize Association of Traditional Healers, and to ensure that the
plants themselves won't be lost to deforestation, BATH established the
Terra Nova Medicinal Plant Reserve on government-owned rainforest land.
Shaman Pharmaceutical is one of the backers of the Terra Nova Reserve.
Shaman already has its own program in place, The Healing Forest
Conservancy, which not only documents the knowledge of the peoples from
whom they collect, but also guarantees that a good part of any profits
they eventually realize from traditional medicines will be returned to
the peoples who contributed to their discoveries by keeping the herblore
alive through countless generations. In Ecuador, a similar project,
Plantas Medicinales del Campo, works to conserve the knowledge of the
Andean healers, and has produced a book of traditional medicines. In
southern India, the Irula Tribal Women's Society has begun collecting
and documenting the medicinal knowledge of the local healers, and
marketing some of the plant extracts. While an important element of all
of these projects is to ensure that traditional plantlore is not lost,
their most important principle is to generate continuing interest by the
peoples themselves in their own cultural heritage. One of the first to
realize the importance of such a step was ethnobotanist and author Dr.
Mark Plotkin, who set up The Shaman's Apprentice program several years
ago to return in written form to each Amazon tribe he worked with all
the plant knowledge he learned from them-in the hopes that it would
generate interest in the herblore among younger tribal members.
Morning in the Jungle
We were out with Wilfredo, his apprentice, and
several others in the the lush jungle behind his village. We had cut a
small tree into several one-meter lengths, and were rasping the bark-an
extract of which Wilfredo used as a skin medicine-onto large leaves laid
out on the ground. The work was tedious, as I needed several pounds of
the thin bark for my collection.
After he had done his share, Wilfredo handed the
machete to me and walked off into the brush. When he returned, he was
carrying the flowering top of a plant. "Pedro," he said, handing it to
me. "Do you know this plant?" I told him I didn't. "I use this for women
who can't carry babies. I make it a tea and they stop miscarrying." The
tiny red flowers looked like little bells; the green leaves were so fine
they were nearly translucent. It was a beautiful plant. "When we finish
the plants you asked for should we collect this?" I told him that we
might on the next trip, but that no one had asked me for that sort of
remedy this time. "Then tell them to send you back quickly. There are a
lot of plants you need to learn." Bastante.
© Peter
Gorman 2001

The Urgency of Ethnobotanical Research in
the Tropics
by Kelly
Simon (24 March 1997)
ABSTRACT: Historically, plants have been beneficial to the medical
community. Medicinal plant research is beginning to regain its
frequency, due to the realization that synthetic drug research my not
lead to the creation of all needed drugs. The rain forests of the
tropics contain great biodiversity, and this is where most medicinal
plant exploration takes place. A very productive method of plant
exploration is ethnobotany. Because of acculturation of indigenous
cultures and the fast-paced destruction of the tropical rain forests, it
is urgent that ethnobotanical research be conducted.
Throughout history, humans have looked to plants
as their primary medicinal source. In fact, "[b]otany..
was traditionally regarded as a branch of medicine," and it wasn't until
the mid-1800s that botany was recognized as its own distinct science
(Raven, Evert, and Eichhorn 707). Even today, many important drugs are
botanically derived. The "most widely used pharmaceutical in the world"
is aspirin, which was originally derived from the Queen-of-the-Meadow
plant (Filipendula ulmaria) (Wilson 283; Wyman 381). Ephedrine, which
is derived from the species Ephedra sinica, is presently used as a
bronchodilator (Balick and Cox 34). Several drugs come from the opium
poppy (Papaver somniferum), including morphine, an analgesic, and
papaverine, an antispasmodic (Wyman 779; Balick and Cox 35). The rosy
periwinkle (Catharanthus roseus) has given the medical community two
very important drugs: vinblastine, a treatment for Hodgkin's disease,
and vincristine, a treatment for pediatric leukemia (Balick and Cox
33,35).
Pharmaceutical companies looked to nature for
medicine up until the 1960's when computers prompted the turn towards
synthetic drugs, which now comprise nearly 75% of all the prescriptions
in this country (Newman 482; Sears 92). For nearly thirty years,
synthetic drug research dominated the pharmaceutical industry, until
natural drug research began to make a comeback around 1990, when it was
realized that even with the advanced computerized technology that
exists today, scientists cannot abandon nature as a source for drugs.
This is because "tropical plants contain powerful chemical defenses,
many of which are too complex to be accurately replicated in a lab.
Additionally, scientists have already synthesized many of the substances
which are [in fact] reproducible" (Newman 83). As Monroe Wall, an
organic chemist from North Carolina's Research Triangle Institute,
states, "Scientists may be able to make any molecule they can imagine on
a computer, but Mother Nature--over the course of millions of years--is
an infinitely more ingenious and exciting chemist" (qtd. in Sears 93).
Indeed, millions of years of evolution in the
plant kingdom has resulted in an array of chemically diverse
botanicals. This chemical complexity and diversity, which is probably
due to the building of defense mechanisms to ward off enemies in nature,
has made plants a "rich source of medicines" (Cox and Balick 82).
Despite this, less than 1,325 of the world's 265,000 flowering plant
species have been thoroughly tested for their medicinal potential (83).
Since plants are such good sources of medicine, and since it is not
currently possible to create all necessary drugs synthetically, it seems
that greater emphasis should once again be placed upon the exploration
and testing of medicinal plants, at least as long as nature holds
information unknown to us. Some pharmaceutical companies, including
Shaman Pharmaceuticals and Merck & Company, have done just that, in the
tropical rain forest.
The tropical rain forest is the primary area of
focus for those searching for medicinal plants, due to its rich
biodiversity: "Nature reaches its fullest expression in the tropical
forest, whether measured by sheer numbers of species or by the
complexity of their interactions" (Terborgh 3). In fact, approximately
one half of the world's flowering plants reside in tropical forests
(Cheng). Plants living in tropical forests "have had to develop complex
chemical arsenals to survive against a myriad [of] attackers: other
insects, fungi, viruses, and bacteria," making them prime sources for
medicinal research (qtd. in Newman 481). The vast majority of these
plants are yet to be reviewed by botanists, and there may be several
potentially life saving drugs in the rain forest just waiting to be
discovered. Dr. Michael Balick, director of the New York Botanical
Garden's Institute of Economic Botany, along with Dr. Robert Mendelsohn,
economist at Yale University, have roughly estimated that there are 328
drugs in the rain forests that have not yet been found (Cheng). While
this figure has been disputed, notably by Dr. Jim Miller of the Missouri
Botanical Garden, few dispute that the rain forests are potentially
significant sources for new medicines (Cheng).
To tap into the medicine cabinet of the tropical
rain forests, more and more pharmaceutical companies are increasing
funding for medicinal plant exploration in the tropics. There are many
different methods being used by researchers to find plants that may turn
out to be useful drugs. One of these methods involves randomly
collecting plants and then mechanically screening them for useful
medicinal properties. The National Cancer Institute successfully used
this method of plant exploration to uncover the drug taxol, which turned
out to be a useful treatment for ovarian cancer and certain forms of
breast cancer (Cox and Balick 83). However, the
method of random plant exploration of the tropics up to this point has
been relatively unproductive, uncovering a very small percentage of
plants which display pharmacological activity. Other methods of
exploring the rain forests for medicine take a more focused approach.
In some of these methods, the selection of plants for medical testing is
based on the ecology of a certain area; in other methods, the selection
of plants is based on taxonomic or chemical relationships between plants
(Cox and Balick 84; Lewis and Elvin-Lewis 16). Another method is
ethnobotany, a multi-disciplinary "study of the relationships between
plants and people" (Balick and Cox 3). Using the ethnobotanical method
of plant exploration, researchers obtain information from native healers
which guides them in their selection of plants to be tested for
medicinal properties. Many common drugs are the direct results of
ethnobotanical research, including aspirin, caffeine (a stimulant),
ephedrine, cocaine (an ophthalmologic anesthetic), and morphine (Cox and
Balick 34,35). According to Walter H. Lewis and Memory P. Elvin-Lewis,
authors of "Medicinal Plants as Sources of New Therapeutics," about
three-quarters of the biologically active plant-derived compounds
presently in use worldwide have been discovered through follow-up
research to verify the authenticity of data from. . . ethnomedicinal
uses, [so] it is reasonable to conduct ethnobotanically directed
research in order to optimize the search for novel pharmaceuticals.
(16) In their article "The Ethnobotanical Approach to Drug Discovery,"
Paul Alan Cox and Michael J. Balick state, "[t]he history of drug
discovery implies that the ethnobotanical approach is the most
productive of the plant surveying methods" (84). The primary reason
ethnobotany is so productive is that it incorporates the use of
medicinal knowledge of indigenous societies living in the tropics into
plant exploration and drug discovery.
The ethnobotanical process is a long and complex
one, and it begins by choosing a group of people to study. To an
ethnobotanist, a group of people native to a particular location is a
better candidate for an ethnobotanical study than an immigrant
population because it is assumed that indigenous people are more
knowledgeable of their habitat, as they have had considerably more time
to experiment with the surrounding resources. The degree of
biodiversity of the habitat in which the indigenous society lives and
the method of transmission of medicinal knowledge within the culture are
also important considerations in choosing society to work with in an
ethnobotanical study (Cox and Balick 84). Thus, a society native to an
area with great biodiversity, such as a tropical rain forest, that
passes down medicinal knowledge orally from generation to generation
would be a likely candidate for an ethnobotanical study.
Once a society has been chosen for study, an
ethnobotanist immerses himself or herself in the indigenous culture,
often learning the language and becoming accustomed to the traditions of
the culture. It is important that a trusting relationship be built
between the ethnobotanist and the culture's native healer in order to
ensure cooperation in the transfer of botanical and medicinal knowledge.
According to the personal experiences of Richard Evans Schultes, an
ethnobotanist who studied cultures in the Amazon for nearly fifty years,
indigenous people are "extremely friendly and cooperative," and an
ethnobotanist is "usually immediately accepted [by the
culture] and may even. . . [encounter] excessive collaborative
attention" (Schultes 27). If an ethnobotanist feels that a plant used
in traditional medicine has drug-producing potential, that plant may
undergo a series of tests to determine if it contains chemicals that
combat diseases. If the plant leads to the manufacture of a marketable
drug, the indigenous society and/or the country in which it is located
will often be compensated in some way. As with the Samoan people whose
knowledge of the tree species Homalanthus nutans led to the derivation
of prostratin, a "drug candidate for the treatment of AIDS, " the
compensation may be in the form of royalties from the sale of a drug
derived from a plant uncovered with the help of an indigenous culture (Balick
and Cox 55). However, with peoples who have no concept of money in
their culture, royalties from the sale of a drug are meaningless; "[f]or
many indigenous peoples, the right to live unmolested and undisturbed on
their ancestral lands is the greatest value" (60-61). To compensate
these people, "nature preserves [are created to] protect both
biodiversity and indigenous cultures" (61). In Samoa, the Falealupo
Rain Forest Reserve has been established in the location of the
prostratin-producing trees (60).
Over many generations, experimentation with the
resources in an indigenous society's habitat takes place, and the
results of medicinal experimentation accumulates as the wisdom is
carried on from generation to generation. Since the primary goal of
researchers is to gain greater knowledge about the enormous collection
of unfamiliar plants in the tropical rain forests, indigenous people who
have lived with and used these plants for hundreds, or perhaps
thousands, of years are excellent sources to look to for medicinal
information. Balick and Cox pointed out that "[c]onsistent application
of a given species for an ailment over millennia generates information
rather analogous to that produced by large scale clinical trials. Such
repetitive, long term use of
botanical species [by indigenous peoples] can be expected to have
identified both the most effective medicinal plants and those that are
too toxic for use (84)."
Thus, the ethnobotanist has much to gain by
observing the medicinal uses of plants by the native healer of an
indigenous society. The ethnobotanical approach to plant exploration
provides a more focused view of the tropical plant collection and, in
turn, leads to more productive results than other methods.
Shaman Pharmaceuticals Inc. (see below) , located
in San Carlos, California, employs only ethnobotany as a means for
discovering new drugs (Hamilton). Ethnobotanists from Shaman
Pharmaceuticals travel to tropical areas like Latin America in search of
medicinal knowledge to be obtained from native healers and use this
knowledge to collect certain plants that will be brought back to the
United States to be screened for medicinal qualities (Hamilton). Being
a small company, only about seventy-five plants are screened per year by
Shaman pharmaceuticals, but, in comparison to larger companies that use
random plant selection to screen thousands more plants each year, Shaman
is doing quite well: "Shaman comes up with an initial 'hit' [during the
screening process] about half the time, vs. a minuscule fraction of that
in random screening programs" (Hamilton). In its first four years,
Shaman has discovered two promising drugs--one to treat respiratory
infections and one to treat herpes simplex virus infections (Cox and
Balick 86).
With the great potential that possibly hundreds of
plant derived drugs lie hidden in the jungles of the tropics, and with
the relative successes of the ethnobotanical approach to medicinal plant
exploration, why aren't more ethnobotanists in the tropical rain forests
searching for these drugs? Funding seems to be a major obstacle that is
preventing companies from conducting ethnobotanical research.
Pharmaceutical companies do not seem to be willing to spend much money
on tropical plant exploration unless they can be assured that they will
profit from it. While the fruits of ethnobotany have created
considerable profit for pharmaceutical companies (the sale of
vinblastine and vincristine alone brings in $180 million per year),
monetary gain is realized only after years of research and
experimentation. In the beginning, Shaman Pharmaceuticals received all
of its research funding from a larger pharmaceutical company, Eli Lilly,
but this funding was cut off in 1994, and now Shaman's future depends on
whether a marketable drug is produced in the near future (Newman 496).
However, even though Shaman has two possible drugs currently being
tested, it may be several years before a drug is actually sold and
profit is made, and the company may run out of funding before then.
One problem even more serious and more detrimental
to ethnobotanical research than lack of funding is the modernization of
indigenous cultures. As greater numbers of indigenous societies come in
contact with people from more industrialized nations, there is a
tendency for the younger generations of indigenous societies to leave
behind the traditions and customs of their own society in order to grasp
those of the "modern" world. Richard Evans Schultes, professor of
biology and director of the Harvard Botanical Museum, addresses the
issue: "What we in the developed world call civilization is rapidly
encroaching on indigenous communities, just as it is encroaching on the
plants, and native botanical lore is usually an early casualty. In
only one generation, acculturation can lead to the disappearance of
botanical knowledge acquired over millennia (26)." When the medicinal
knowledge of native healers is not passed down to apprentices, it will
only live as long as the healer.
As fewer young people desire to become
apprentices, the threat is great that this knowledge will be lost. This
already happened in Samoa, where two healers who worked with
ethnobotanist Paul Alan Cox to discover the drug prostratin died in
1993, taking with them many years of medicinal knowledge that was not
passed down to an apprentice (Cox and Balick 87). One thing that can be
done to prevent this is to increase the magnitude of ethnobotanical
research in the tropics to ensure that as much medicinal knowledge as
possible is recorded before the native healer's lips are silenced
forever.
As the numbers of native healers dwindle
because of acculturation, the ability to explore the rain forests
through ethnobotanical research becomes increasingly limited. In
addition, the mass destruction of the tropical rain forests throughout
the world is severely limiting the amount of biological diversity that
the ethnobotanist, or any other plant explorer, has available to him or
her for searching for botanical medicines. Between twenty-seven million
acres and fifty million acres of tropical forests are destroyed every
year; at the current rate of deforestation, every acre of rain forest
would be destroyed by the year 2024 (Newman 485). As the deforestation
of tropical rain forests continues, so does the extinction of half of
the world's plant species. An unfortunate example of the loss of
medicinal plants due to deforestation occurred in the late 1980s to
early 1990s. A small sample from a gum tree in Malaysia was taken by
scientists in 1987 for the purposes of testing it for medicinal
properties (482). This testing took place in 1991 with promising
results: a compound found in the Malaysian gum tree "blocked the spread
of the HIV-1 virus in [a] human immune cell" (qtd. in Newman 482).
However, when scientists returned to Malaysia to gather more samples
from the gum tree, they discovered not only that the tree had been cut
down, but also that there were no other trees like it that could be
found (Newman 482). Although the compound was far from being called a
cure for AIDS, "the results looked promising in the possible eradication
of the virus" (482). As deforestation continues, this loss of potential
drugs due to plant extinction may become a common occurrence. At the
current rate, it has been estimated that between 1994 and 2004,
twenty-five plant-derived drugs will not be discovered, due to
extinction caused by deforestation (487). Therefore, "[w]ith the
continual extinction of an unknown number of these potentially valuable
species, the likelihood of finding a cure for cancer and, similarly,
many other as-yet incurable diseases, also diminishes" (487).
Mass deforestation of the tropical rain forests is
undoubtedly the work of human hands. Usually, it is the lure of
"short-term cash generation" that prompts nations in these tropical
areas to utilize the rain forests for profit (Newman 488). However,
this utilization, which includes "timber extraction, cattle ranching,
crop production, mining, [and] road construction," results in the
destruction of tropical rain forests (488). The most common practice
that results in deforestation is slash-and-burn agriculture (488). In
this farming method, the trees in the area to be used for cultivation or
grazing are cut down (slash), and then they are set on fire (burn).
This produces a nutrient-rich layer of ash which sits on top of the
existing soil, making the area a prime location for crop production
(488). However, "[w]ithout the tropical canopy to protect the ground,
...frequent and heavy rains leach nutrients from the soil, rendering the
land virtually worthless" (489). Because of this, farmers move to a new
area every few years to begin anew the cycle of slash-and-burn, thus
perpetuating the deforestation of tropical rain forests.
Since the main causes of deforestation stem from
economic need, a way to eliminate deforestation is to eliminate the
economic need of indigenous societies. In order to ensure the cessation
of deforestation, those responsible must become convinced that they will
profit from conserving the tropical rain forest (Newman 495).
Ethnobotany offers one way to do this: through agreements between
ethnobotanists (along with the pharmaceutical companies they work for)
and indigenous societies, those who aid in the search for plant-derived
drugs will receive monetary compensation for their contributions to the
drug-seeking and conservation efforts (496). Further, royalties from
any drug manufactured through the help of an indigenous society will
benefit the society either monetarily or through increased conservation
of the tropical rain forest in which they live (496). Shaman
Pharmaceuticals is one company devoted to preventing deforestation: "By
enabling the locals to make a living collecting samples, Shaman hopes to
create the necessary economic alternative to deforestation" (496).
Although Shaman Pharmaceuticals neglects compensation of the government
of the country in which the ethnobotanical plant exploration takes
place, this aspect must not be ignored because "[w]ithout financial
benefit for the government, . . . [there is] little deterrence for the
impoverished governments to continue exploiting their nations' natural
resources" (496). Therefore, if it is more profitable to cooperate with
ethnobotanical research than it is to practice logging, slash-and-burn
agriculture, or other forest-depleting practices, then deforestation may
be halted and conservation can begin.
As it is the most productive of all the plant
exploration methods currently being used, ethnobotany can be used as a
tool for both acquiring the extensive medicinal knowledge of the
indigenous peoples and exploring the vast biodiversity of the tropical
rain forests in which they live, as well as discovering botanically
derived drugs. However, as acculturation takes place among the younger
generations of indigenous cultures, the threat of the loss of medicinal
knowledge compiled over many generations is great because fewer young
people want to participate in traditional medicine by becoming
apprentices to the culture's medicinal healer. If there is no
apprentice to carry on the medicinal knowledge to the next generation,
this knowledge will die with the native healer. Furthermore, as
deforestation of the tropical rain forests continues, more and more
potentially life-saving botanical drugs will be lost forever, due to
extinction. Thus, as the legacy of indigenous medicine will survive
only a few more generations, and as deforestation threatens to destroy
the indigenous healers' medicine cabinet, there is great urgency that
plant exploration be conducted through ethnobotanical research. The
only way to preserve the wisdom of the native healers, and, similarly,
the only way to ensure that as few drugs as possible are lost to
deforestation is to make sure that extensive, large-scale ethnobotanical
research is conducted throughout the tropical regions of the world.
Since we use the knowledge from these dying healers to find potentially
life-saving drugs, which are located in the rapidly deforested tropical
rain forests, future human life may depend on the urgency of
ethnobotanical research in the tropics.
Works Cited
Balick,
Michael J. and Paul Alan Cox. Plants, People, and Culture: The
Science of Ethnobotany. New York: Scientific American Library, 1996.
Cheng, Vicki. "328 Useful Drugs Are Said to Lie Hidden in Tropical
Forests." 27 June 1995. New York Times. Online 15 Feb. 1997.
Cox, Paul Alan and Michael J. Balick. "The Ethnobotanical Approach to
Drug Discovery." Scientific American. June 1994: 82-87.
Hamilton, Joan. "The Medicine Man Will See You Now." Business Week
1 Mar. 1993.
Lewis, Walter H. and Memory P. Elvin Lewis. "Medicinal Plants as
Sources of New Therapeutics." Annals of the Missouri Botanical Garden 82 (1995): 16-24.
Newman, Erin B. "Earth's Vanishing Medicine Cabinet: Rain Forest
Destruction and Its Impact on the Pharmaceutical Industry." American Journal of Law and
Medicine 20 (1994): 479-501.
Raven, Peter H., Ray F. Evert, and Susan E. Eichhorn. "Plants and
People." Biology of Plants. 5th ed. New York: Worth, 1992.
Schultes, Richard Evans. "Burning the Library of Amazonia." The
Sciences Mar.-Apr. 1994: 24-30.
Sears, Cathy. "Jungle Potions." Handbook Science Annual: A Modern
Science Anthology for the Family. Ed. Joseph M. Castagno. Southwestern Company, 1993.
Terborgh, John. Diversity and the Tropical Rain Forest.
New York: Scientific American Library, 1992.
Wyman, Donald. Wyman's Gardening Encyclopedia. New York:
Macmillan, 1986.

Case Study: Shaman
Pharmaceuticals
Integrating Indigenous
Knowledge, Tropical Medicinal Plants, Medicine, Modern Science and
Reciprocity into a Novel Drug Discovery Approach
Shaman Pharmaceuticals,
Inc.
213 East Grand Ave.
South San Francisco, CA 94080
Introduction
Tropical
forest plant species have served as a source of medicines for people of
the tropics for millennia. Many medical practitioners with training in
pharmacology and/or pharmacognosy are well aware of the number of modern
therapeutic agents that have been derived from tropical forest species.
In fact, over 120 pharmaceutical products currently in use are
plant-derived, and some 75% of these were discovered by examining the
use of these plants in traditional medicine(1). Of these, as
shown in Table I,
a large portion have come from tropical forest species. Yet while many
modern medicines are plant-derived, the origins of these pharmaceutical
agents and their relationship to the knowledge of the indigenous people
in the tropical forests is usually omitted.
Today,
five centuries after the Old World and the New World first collided, it
is no longer a question of whether indigenous peoples should benefit
from products that have been developed on the basis of their knowledge.
Individual ethnobiologists and organizations such as the Society of
Economic Botany, the International Society of Ethnobiology, and the
American Anthropological Association have emphatically stated the
importance of ethical reciprocal conduct by all parties who perform
research with indigenous peoples(2-6). The most challenging
issues which remain are: How do indigenous and local peoples,
themselves, define benefits, and through what mechanisms can individuals
and organizations working with these groups provide such benefits? These
are questions which one pioneering pharmaceutical company, Shaman
Pharmaceuticals, addresses as part of its ethical obligation of doing
business.
Shaman
Pharmaceuticals, Inc. is a South San Francisco-based pharmaceutical
company that focuses on isolating bioactive compounds from tropical
plants that have a history of medicinal use. Shaman is working to
promote the conservation of tropical forests and bridge the gap between
the biomedical needs of both indigenous cultures and the rest of the
global population. Eschewing the mass screening approach typically done
by many pharmaceutical companies, Shaman has pioneered a novel approach
to drug discovery, integrating traditional plant natural products
chemistry, the science of ethnobotany, medicine, and medicinal chemistry
while maintaining a commitment of reciprocity to the indigenous
cultures.
The Rainforest as a Source For New Pharmaceuticals
Until the
early 1970's, there was a strong interest in looking at plants as
sources of new pharmaceutical agents. In fact, many modern
pharmaceutical companies can trace their origins to products originating
from plants. However, advances in molecular biology, genetic
engineering, and computational chemistry in the late 1970's and 1980's
and, even more recently, advances in combinatorial chemistry(7,8)
created much promise within the pharmaceutical industry without the need
to explore nature's chemical diversity.
Natural
product chemists and phytochemists recognize that plant species contain
a bewildering diversity of secondary metabolites. Individual plant
species often contain over 1,000 unique chemical entities (or the
enzymatic machinery needed to produce compounds upon the proper
stimulus). One of the most compelling explanations for this vast array
of chemical diversity, which resides within the biological diversity of
tropical plant species, is the science of chemical ecology. Plants
living in tropical forest habitats have had to develop and survive under
intense competition for resources and nutrients. They have also had to
develop an extraordinary array of defenses, most of them chemical, to
protect themselves from viral diseases, fungal pathogens, insects and
mammalian predators. The biodiversity of tropical forest plant species,
coupled with the chemical diversity found within each plant, leads one
to the conclusion that tropical plants are perhaps the most valuable
source of new bioactive chemical entities.
The
enormous chemical diversity of the tropical rain forest can be best
appreciated if one considers the relative abundance and diversity of
plants on earth. It is estimated that there are roughly 500,000 higher
flowering plant species occupying terrestrial habitats. Of these 500,000
species, many await discovery description by scientists. A large number
of species has only been very superficially examined for their
pharmacological and medical application. Less than 1% of these species
has been thoroughly investigated for their potential use as novel
therapeutic agents.
The
development of robotics for high-throughput, random screening in the
1980's and an ability to handle large numbers of samples, coupled with
the need to find new bioactive chemical entities has renewed interest in
looking once again at novel tropical plant species, and has stimulated a
long overdue renaissance of activities in the areas of plant natural
product chemistry, pharmacognosy, and ethnomedical research. One
approach that this renewed interest in plant natural product chemistry
has taken involves a return to the classic random collection of plants
that are incorporated into high throughput screening programs with a
variety of mechanism-based assays with specific applications to numerous
therapeutic areas. This methodology is well-suited to the infrastructure
and philosophical approach to drug discovery of traditional yet highly
successful pharmaceutical firms.
A more
integrated approach involves a highly-focused collective program for
medicinal plants with a primary emphasis on the use of plants by
indigenous people in the tropical regions of the world. This latter
methodology is the one utilized by Shaman Pharmaceuticals since its
inception, and the approach has been highly effective. As depicted in
Figure 1,
the ethnomedically driven approach to drug discovery differs from other
drug discovery processes by beginning and ending in humans.
Shaman
relies extensively and intensively on the primary fieldwork of
internationally recognized ethnobotanists who work closely with their
indigenous colleagues and shamans (traditional doctors in cultures) in
tropical regions of Asia, Africa and Latin America. This approach
requires a great deal of research well before any plant material is
collected and brought into the company for investigation, and involves
examining all the known information regarding the use of plants by
people in any given tropical forest habitats to treat a variety of
illnesses. Before any research expedition is undertaken, we prepare a
full regional study on the epidemiology, traditional medicine, culture
and ecology of the people and the environment in which they live.
Information on the plants known to be utilized in any given area is
assembled by searching several international databases on ethnomedicine,
medicinal activities of plants and any known chemistry of plants with
such activity. We also search for data from international and national
hospitals in remote areas and treatment programs that work with local
and native people. All of this information is synthesized and integrated
into our field research program.
Shaman
Pharmaceutical's field research teams are then sent to selected tropical
regions to collect indigenous information and witness first-hand the use
of plant medicines to treat various illnesses. These field research
teams are comprised of ethnobotanists, western trained medical doctors,
local botanical collaborators and indigenous healers and herbalists.
This combination of expertise allows for a highly focused selection of
plant candidates for screening and subsequent development.
Since all
of the tropical plant species collected by Shaman have a history of
ethnomedical use in humans (Figure 1), the need to screen tens of
thousands of plant species and plant species extracts is unnecessary. In
essence, the rainforest, its associated ethnomedical history, and the
field research prioritization serves as the initial biological screen.
Instead, the in vivo laboratory screening serves as a
confirmatory screen. The most promising plant leads are then subjected
to fractionation campaigns, whereby natural product chemists use
state-of-the-art chemical separation techniques to separate the chemical
entity responsible for the observed activity from its inactive
components. Modern spectroscopic techniques are then used to elucidate
the chemical structure of the active compound.
Shaman
Pharmaceutical's operations began in 1990. Utilizing the ethnobotanical-ethnomedical
approach to collecting tropical medicinal plant species, Shaman has been
successful in bringing two products into clinical trials within 24
months of that time. This focused approach is currently being used in
Shaman's antidiabetic discovery program. Since the inception of the
diabetes program two years ago, Shaman has discovered multiple new
chemical leads from plant sources and, to date, patents have been filed
on five of them. Each of these chemical leads is currently undergoing
preclinical evaluation.
The
Rainforest as a Source For Medicinal Chemistry Leads
Three
years ago, Shaman decided to augment its drug discovery effort using
medicinal chemistry. One of medicinal chemistry's missions is to provide
synthetic support for natural product leads in the event that the
isolated natural product is available in a low yield and/or the plant
source is not amenable to sustainable harvesting. In this situation,
when feasible, a synthetic approach to the natural product is
considered. An equally important medicinal chemistry mission is to use
the isolated natural product as a template for further structural
modification to reduce toxicity and/or improve potency. As a result of
this process, new chemical leads can be generated from the initial
orally active natural product lead. The medicinal chemistry program has
been highly successful: Two total syntheses originating from an
antifungal natural product isolated from Irlbachia alata and
Anthocleista djalonensis were completed and have been
published,(9,10) and a structural modification study
originating from a natural product isolated from Ambrosia
chamissonis resulted in four patents and has recently been
published.(11) More recently in the antidiabetic discovery
area, the advantage of the Shaman Pharmaceutical process -- beginning
with an orally active natural product lead as the template -- has led,
through further synthetic modification, to the discovery of two new
orally active synthetic leads. A patent has been filed on one of these
with the second patent soon to follow, and both are currently undergoing
preclinical evaluation.
Shaman's Reciprocity Strategies
The idea
of compensating indigenous people for the use of knowledge about
biological diversity is one based on fairness and equity. A logical
means of compensating indigenous peoples for their role in a drug
discovery process would be to accord them a share of the profits from
the drug, once it is commercialized. However, because of the long period
of time needed for commercial drug discovery and development, often ten
years or more, such a mechanism for reciprocity requires a long waiting
period before any benefit is realized by the indigenous peoples.
Furthermore, in most instances, the indigenous knowledge gathered would
not lead to a commercial product and thus, no benefit of any kind would
come to the local people.
From its
inception, Shaman has been committed to the concept of reciprocal
benefits: to developing new therapeutic agents by working with
indigenous and local peoples of the tropical rainforests and, in the
process, contributing to the conservation of biological and cultural
diversity, or "biocultural diversity".(12-14) The kind and
type of reciprocity is driven by the expressed needs of the people
themselves. We place a high value on the knowledge that we receive from
our collaborators, and for this reason, feel it absolutely necessary to
reciprocate the contribution to our drug development process. Inherent
in our commitment is a direct acknowledgment, in both ethical and
financial terms, of the intellectual property rights of the indigenous
people with whom we work. In our opinion, their traditional knowledge is
an irreplaceable cultural resource. Thus, we believe that our company
has the dual obligation to provide compensation for that knowledge and
to help our collaborators maintain it.
The needs
of the indigenous people with whom we work are often immediate. Shaman
considers it unacceptable to delay compensation to the indigenous
peoples until a product is developed and generating a profit on the
market. Our approach to appropriate reciprocity was developed in part to
address the needs of the indigenous peoples and to address a potential
conflict between our company's recognized obligations and the nature of
the pharmaceutical industry. Thus, Shaman's approach to reciprocity
instead involves three timeframes -- immediate, medium-term, and
long-term. A number of articles describing specific aspects of our
biocultural diversity and reciprocity programs has been published, and
those interested should consult these articles.(15,16) Here,
only a brief overview of our reciprocity program is offered.
Short-term
reciprocity can take many forms, but the underlying theme is that it
addresses the immediate needs of the community. While short-term
reciprocity is a novel concept amongst the pharmaceutical industry, it
really is quite simple. We ask the local people with whom we collaborate
to identify compensation options. Some examples of short-term
compensation have included building an airstrip extension in the
Ecuadorian Amazon, organizing community-based public health workshops
and forest conservation workshops, and offering direct medical care to
our partner communities. One example of the latter involved a request by
the Yanomami Indians in the Northern Brazilian Amazon. Their people were
dying from a chloroquinine-resistant strain of malaria which was
introduced by the gold miners. Shaman subsequently contacted Hoffman
LaRoche, Inc., the manufacturer of Lariam, a synthetic compound which is
effective against chloroquinine-resistant malaria. Hoffman LaRoche
responded with a donation of Lariam. We forwarded the medication to the
Commission for the Creation of a Yanomami Preserve in São Paulo, which
delivered it to the Yanomami for use among the most critical cases. A
second example involved a Papua New Guinea collaborator who had been
poked in the eye with a thorn while doing his field botanical work six
months prior to our visit. Subsequently, the man had developed a
cataract which made him blind. Upon our medical evaluation of this man,
we determined that his sight could be restored with routine cataract
surgery and an intraocular lens implant. Since this man did not have the
money to pay for the surgery, Shaman paid for all of his surgery and
travel fees. Shaman has also provided and completed two clean drinking
water systems to communities in Ecuador and Indonesia.
Medium-term reciprocity focuses on providing benefits that may not be
immediately apparent, but that will nonetheless provide benefit to the
community before profit sharing might. One method used is to enhance the
communities scientific and research capability. Specific examples of
this have included providing chemical reagents, high pressure liquid
chromatography equipment, scientific software, books, and other
resources used for training the local country scientists. Another method
used has been to provide scholarships and fellowships to scientists
working on traditional medicine. Shaman also has an ongoing exchange
program, whereby local scientists have come to Shaman for a period of
1-9 months to learn new scientific technology. Another form of
medium-term reciprocity has included the commissioning of sustainable
harvesting studies of plant species that are important for local
traditional medicine and also are of interest to Shaman.
The
long-term reciprocity involves returning a portion of the profits to the
indigenous communities once a commercial product is realized. However,
Shaman does not advocate only compensating the community or communities
directly responsible for the commercial product. Instead, Shaman will
provide a portion of the profits of any and all products to all of the
communities and countries in which we have worked.
An
important aspect of this long-term strategy is the mechanism that will
be used to distribute the compensation. At the same time that Shaman was
incorporated as a for-profit company, it founded the Healing Forest
Conservancy as a nonprofit organization with an independent board of
directors and advisors. The Healing Forest Conservancy is dedicated to
conserve cultural and biological diversity and to sustain the
development and management of the natural and biocultural resources that
are a part of the heritage of native populations. The Conservancy was
founded because no governmental organization existed to provide a formal
and consistent process to compensate countries and communities for
ethnobotanical leads which subsequently are developed into commercial
product. The Conservancy ensures a mechanism for the species-rich
tropical countries and the small-scale indigenous communities in
tropical forests to be equitably compensated for their participation in
the development of therapeutic agents. A number of pilot programs have
been initiated and described in recent publications.(14,17,18)
Conclusion
It is a
fact that the tropical rainforest regions of the world are disappearing
due to a multitude of commercial interests. With this destruction comes
the loss of cultural habitat and indigenous knowledge which has been
gained and utilized for millennia. As part of our drug discovery effort,
we work with indigenous cultures to provide alternative
income-generating activities, such as sustainable harvesting and
extraction industries, to large-scale logging or clearing of the land
for livestock.(14) Such sustainable harvesting activities can
contribute to the conservation of the biological and cultural diversity
of the region. Our novel reciprocity programs demonstrate the value we
place on indigenous knowledge. To preserve the rainforest without
preservation of shamanic knowledge of the plants in the forest would be
to cut ourselves off from the cures for present and future diseases. In
order to preserve that knowledge, we must ensure that it is passed on
from generation to generation by promoting cultural diversity. In
contrast to most pharmaceutical drug discovery efforts, Shaman has
developed a pioneering technology platform, integrating the sciences of
ethnobotany, ethnomedicine, medicine, modern separation science,
medicinal chemistry, and primary in vivo screening. The
process has led to the discovery of multiple orally active
antihyperglycemic leads in our diabetes drug discovery program that are
currently undergoing preclinical evaluation. We are currently entering
Phase II clinical trials with ProvirTM, an oral product for
the treatment of secretory diarrhea, beginning a pivotal Phase III
clinical study on Virend®, a topical
antiviral for the treatment of herpes, and plan to file in 1996 an
Investigational New Drug application (IND) to begin Phase I testing on
Nikkomycin Z, an oral antifungal for the treatment of endemic mycoses.
ACKNOWLEDGMENTS
The
authors would like to acknowledge the contributions of Lisa Conte,
Shaman's Scientific Strategy Team, outside investigators and the entire
research, development and administration teams of Shaman
Pharmaceuticals. Special thanks are due to all of the indigenous and
local scientists with whom we work in the tropics of Asia, Africa and
Latin America, especially Coweña, Huepe, Coba, Tiro, Coba and César
Gualinga.
References
(1)
Farnsworth, N. R.; Akerele, O.; Bingel, A. S. Bull. World Health
Org., 1985, 63, 965-981.
(2) Anon.
The Manila Declaration Concerning the Ethical Utilization of Asian
Biological Resources. UNESCO Regional Network for the Chemistry of
Natural Products in Southeast Asia, Selangor, Malaysia: 1992.
(3) Boom,
B. Ethics in Ethnopharmacology. In Proceedings of the First Congress
of Ethnobiology; Elizabetsky, E., ed.; Museu Paraense Emilio Goeldi:
Belem, Brazil, 1990; Vol. 2, Part F, 147-153.
(4) Boom,
B. Garden, 1990, 14, 28-31.
(5)
Cunningham, A. B. Cultural Survival Quarterly (summer),
1991, 15, 1-4.
(6) Cox,
P. A.; Balick, M. J. Scientific American, 1994,
270, 82-87.
(7) Borman,
S. Chemical & Engineering News, February 12, 1996, 74(7),
29-54.
(8) Baum,
R. Chemical & Engineering News, February 12, 1996, 74(7),
28, and references cited therein.
(9) Bierer,
D. E.; Dubenko, L. G.; Gerber, R. E.; Litvak, J.; Chu, J.; Thai, D. L.;
Tempesta, M. S.; Truong, T. V. J. Org. Chem., 1995,
60, 7646.
(10)
Bierer, D. E.; Gerber, R. E.; Jolad, S. D.; Ubillas, R. P.; Randle, J.;
Nauka, E.; LaTour, J.; Dener, J. M.; Fort, D. M.; Kuo, J. E.; Inman, W.
D.; Dubenko, L. G.; Ayala, F.; Ozioko, A.; Obialor, C.; Elisabetsky, E.;
Carlson, T.; Truong, T. V.; Bruening, R. C. J. Org. Chem.,
1995, 60, 7022.
(11)
Bierer, D. E.; Dener, J. M.; Dubenko, L. G.; Gerber, R. E.; Litvak, J.;
Peterli, S.; Peterli-Roth, P.; Truong, T. V.; Mao, G.; Bauer, B. E.
J. Med. Chem., 1995, 38, 2628.
(12) King,
S. R. Cultural Survival Quarterly, 1991,
15(3), 19-22.
(13) King,
S. R. Conservation and Tropical Medicinal Plant Research. In
Medicinal Resources of the Tropical Forest; Balick, M. J.;
Elisabetsky, E.; Laird, S. A., eds.; Columbia University Press: New
York, 1996; pp 63-74.
(14)
Moran, K. Ethnobiology and US Policy. In Sustainable
Harvest and Marketing of Rainforest Products, Plotkin, M. Famolare,
L., eds.; Island Press: Washington, D. C., 1992; Chapter 5.
(15) King,
S. R.; Carlson, T. J. Intersciencia, 1995,
20 (3), 134-139.
(16) King,
S. R.; Carlson, T. J.; Moran, K. Biological Diversity, Indigenous
Knowledge, Drug Discovery, and Intellectual Property Rights. In
Valuing Local Knowledge: Indigenous People and Intellectual Property
Rights; Brush, S.; Stabinsky, D., eds.: Island Press: Washington,
D. C., 1996; Chapter 8, pp 167-185.
(17)
Moran, K. Biocultural Diversity Conservation Through the Healing
Forest Conservancy. In Intellectual Property Rights for
Indigenous Peoples, A Source Book; Greaves, T., ed.; Society for
Applied Anthropology: Oklahoma City, OK, 1994; pp 101-109.
(18) King,
S. R.; Carlson, T. J.; Moran, K. J. Ethnopharm., 1996,
51, 45-57.
About the Authors
Dr. Donald
E Bierer is Group Leader of Medicinal Chemistry for Shaman
Pharmaceuticals, Inc. Previously, Dr. Bierer was a scientist with
Procter & Gamble Pharmaceuticals in Norwich, NY, and prior to that, was
a postdoctoral research associate with Professor Henry Rapoport at the
University of California, Berkeley. He received his Ph.D. in organic
chemistry in 1988 from the University of Tennessee and his B.S. degree
in chemistry and pre-law from Indiana University of Pennsylvania.
Address: Shaman Pharmaceuticals, Inc. 213 East Grand Ave. South San
Francisco, CA 94080; fax: 415-873-8377;
e-mail:
dbierer@shaman.com
Dr. Thomas
J. Carlson is Senior Director of Ethnobotanical Field Research for
Shaman Pharmaceuticals, Inc. Dr. Carlson develops and coordinates the
medical and public health components of the ethnobotanical expeditions
at Shaman Pharmaceuticals, is a medical advisor to the Healing Forest
Conservancy and is also an Assistant Clinical Professor at Stanford
University Medical Center. He received his M.D. degree at Michigan State
University and received his B.S and M.S. degrees in botany from the
University of Michigan. Address: Shaman Pharmaceuticals, Inc. 213 East
Grand Ave. South San Francisco, CA 94080; fax: 415-873-8367;
e-mail:
tcarlson@shaman.com
Dr. Steven
R. King is Senior Vice-President for Ethnobotany and Conservation for
Shaman Pharmaceuticals, Inc. Formerly the chief botanist for Latin
America at Arlington Virginia's Nature Conservancy, Dr. King has also
worked as a research associate for the Committee on Managing Global
Genetic Resources at the National Academy of Sciences, and was a
doctoral fellow at The New York Botanical Garden's Institute of Economic
Botany. His Ph.D. and M.S. degrees were earned from City University of
New York, and his research experience covers such countries as Papua New
Guinea, Paraguay, Indonesia, Mexico, Columbia, Ecuador, Peru, Bolivia,
and Guatemala. Dr. King helped found Shaman Pharmaceuticals in 1990.
Address: Shaman Pharmaceuticals, Inc. 213 East Grand Ave. South San
Francisco, CA 94080; fax: 415-873-8367;
e-mail: sking@shaman.com
CLINICALLY USEFUL DRUGS FROM TROPICAL RAIN FOREST PLANTS
|
Compound Name |
Plant Source |
Therapeutic Category |
|
in Medical Sciences |
|
Ajmalicine |
Rauvolfia serpentina (L.) Benth. ex Kurz |
Circulatory stimulant |
|
(Apocynaceae)
(Indian snakeroot) |
|
Andrographolide |
Andrographis paniculata Nees (Acanthaceae) |
Antibacterial |
|
(Karyat) |
|
Arecoline |
Areca
catechu L. (Palmae) (Betek-nut palm) |
Anthelmintic |
|
Asiaticoside |
Centella asiatica (L.) Urban |
Vulnerary |
|
(Umbelliferae)
(Indian pennywort) |
|
*Atropine |
Duboisia myoporoides R.Br. (Solanaceae) |
Anticholinergic |
|
(Australian cork tree) |
|
*Bromelain |
Ananas comosus (L.) Merrill (Bromeliaceae) |
Antiinflammatory; |
|
(Pineapple) |
Proteolytic |
|
*Camphor |
Cinnamomum camphora (L.) Nees & Eberm. |
Rubefacient |
|
(Lauraceae)
(Camphor tree) |
|
*Chymopapain |
Carica papaya L. (Caricaceae) (Papaya) |
Proteolytic; |
|
Mucolytic |
|
*Cocaine |
Erythroxylum coca Lam. (Erythroxylaceae) |
Local anesthetic |
|
(Coca) |
|
Curcumin |
Curcuma longa L. (Zingiberaceae) (Turmeric) |
Choleretic |
|
*Deserpidine |
Rauvolfia tetraphylla L. (Apocynaceae) |
Antihypertensive; |
|
(Snakeroot) |
Tranquilizer |
|
*L-Dopaa |
Mucuna deeringiana (Bort.) Merrill |
Antiparkinsonism |
|
(Leguminosae)
(Velvet Bean) |
|
*Emetine |
Cephaelis ipecacuanha (Brot.) A. Richard |
Amebicide; |
|
(Rubiaceae)
(Ipecac) |
Emetic |
|
Glaucarubin |
Simarouba glauca DC. (Simaroubaceae) |
Amebicide |
|
(Paradise tree) |
|
Glaziovine |
Ocotea glaziovii Mez (lauraceae) |
Antidepressant |
|
(Yellow cinnamon) |
|
Gossypol |
Gossypium spp. (Malvaceae) (Cotton) |
Male
contraceptive |
|
*Hyoscyamine |
Duboisia Myoporoides R.Br. (Solanaceae) |
Anticholinergic |
|
(Australian cork tree) |
|
Kawaina |
Piper
methysticum Forst. f. (Piperaceae) |
Tranquilizer |
|
(Kava-kava) |
|
Monocrotaline |
Crotalaria spectabilis Roth (Leguminosae) |
Antitumor agent |
|
(Rattlebox) |
(topical) |
|
Neoandrographolide |
Andrographis paniculata Nees (Acanthaceae) |
Dysentery |
|
Nicotine |
Nicotiana tabacum L. (Solanaceae) |
Insecticide |
|
(Tabacco) |
|
*Ouabain |
Strophanthus gratus (Hook.) Baill. |
Cardiotonic |
|
(Apocynaceae)
(Twisted flower) |
|
*Papain |
Carica papaya L. (Caricaceae) (Papaya) |
Proteolytic; Mucolytic |
|
*Physostigmine |
Physostigma venenosum Balf. (Leguminosae) |
Anticholinesterase |
|
(Ordeal Bean) |
|
Picrotoxin |
Anamirta cocculus (L.) Wright & Arn. |
Analeptic |
|
(Fish
berry) |
|
*Pilocarpine |
Pilocarpus jaborandi Holmes (Rutaceae) |
Parasympathomimetic |
|
(Jaborandi) |
|
*Quinidine |
Cinchona ledgeriana Moens ex Trimen |
Antiarrhytmic |
|
(Rubiaceae)
(Yellow cinchona) |
|
*Quinine |
Cinchona ledgeriana Moens ex Trimen |
Antimalarial; |
|
(Rubiaceae)
(Yellow cinchona) |
Antipyretic |
|
Quisqualic acid |
Quisqualis indica L. (Combretaceae) |
Anthelminthic |
|
(Rangoon creeper) |
|
*Rescinnami |
Rauvolfia serpentina (L.) Benth. ex Kurz |
Anthypertensive; |
|
(Apocynaceae)
(Indian snakeroot) |
Tranquilizer |
|
*Reserpine |
Rauvolfia serpentina (L.) Benth. ex Kurz |
Antihypertensive; |
|
(Apocynaceae)
(Indian snakeroot) |
Tranquilizer |
|
Rorifone |
Rorippa indica (L.) Hiern (Cruciferae) |
Antitussive |
|
(Nasturtium) |
|
Rotenone |
Lonchocarpus nicou (Aubl.) DC. |
Piscicide |
|
(Leguminosae)
(Cube root) |
|
*Scopolamine |
Datura metel L. (Solanaceae) |
Sedative |
|
(Recurved
thorapple) |
|
Stevioside |
Stevia rebaudiana Hemsley (Compositae) |
Sweetener |
|
(Sweet herb; Ka'a He'e) |
|
Strychnine |
Strychnos nux-vomica L. Loganiaceae |
CNS stimulant |
|
(Nux
vomica) |
|
Theobromine |
Theobroma cacao L. (Sterculiaceae) |
Diuretic; Vasodilator |
|
(Cocoa, cacao) |
|
*Tubocurarine |
Chondrodendron tomentosum R. & P. |
Skeletal muscle |
|
(Menispermaceae)
(Curare) |
|
Vasicine (Peganine) |
Adhatoda vasica Nees (Acanthaceae) |
Oxytocic |
|
(Malabar nut) |
|
*Vinblastine |
Catharanthus roseus (L.) G.Don |
Antitumor agent |
|
(Apocynaceae)
(Madagascan periwinkle) |
|
Yohimbine |
Pausinystalia yohimba (K.Schum.) Pierre |
Adrenergic blocker; |
|
ex
Beille (Rubiaceae) |
Aphrodisiac |
* Currently used in the
United States.
a Now
also synthesized commercially.
Source:
(1) Farnsworth, N. R Screening Plants for New Medicines. In
Biodiversity; Wilson, E. O., ed.; National Academy Press:
Washington, D. C., 1988; pp 83-97.
(2) Soejarto, D. D.; Farnsworth, N. R. Perspect. Biol. Med.,
1989, 32, 244-256.
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