Download Use of plants for medicine around the world

FACTSHEET 3
Use of plants for medicine around the world
The World Health Organisation estimates that up to 80 per cent of the world’s population relies
mainly on herbal medicine for primary health care. In China traditional medicine is largely
based on around 5,000 plants which are used for treating 40 per cent of urban patients and 90
per cent of rural patients. In 1991 more than 700,000 tonnes of plant material were used for the
preparation of medicines in China, of which 80 per cent were collected from the wild. In India,
where traditional health care systems are very strong, 400,000 registered traditional medical
practitioners are in practice, compared with 332,000 registered doctors (BGCI Fact Sheet).
In industrialised
countries, plants have contributed to more than 7,000 compounds produced by the
pharmaceutical industry, including ingredients in heart drugs, laxatives, anti-cancer agents,
hormones, contraceptives, diuretics, antibiotics, decongestants, analgesics, anaesthetics, ulcer
treatments and anti-parasitic compounds. Around one in four of all prescription drugs dispensed
by western pharmacists is likely to contain ingredients derived from plants (BGCI factsheet).
These include:
• Reserpine, extracted from the root of the Serpent-Root, Rauvolfia serpentina, used for
lowering blood pressure and as a tranquilliser, and in India used as a treatment for snake
bite;
Contributions of plants to the pharmaceutical industry and western medicine
•
L-Dopa, from a tropical legume Mucuna deeringiana, used for treating Parkinson’s Disease;
•
Ephedrine, a decongestant, is derived from the Chinese shrub Ephedra sinica; and
•
Picrotoxin, derived from Anamirta cocculus, a tropical climbing plant from South-east Asia,
is used as a nervous system stimulant and in cases of barbiturate poisoning.
Cultivation has replaced wild collection for the supply of some essential drugs used in modern
medicine. The Madagascar rosy periwinkle, Catharanthus roseus, is widely cultivated in Spain
and Texas for its alkaloids, vinblastine and vincristine, which are used for treating childhood
leukaemia and Hodgkin’s disease (Balick & Cox, 1996). Eucalyptol obtained from species of
Eucalyptus, found mainly in Australia, is a well-known antiseptic used in throat medicines,
cough syrups, ointments, liniments, and as an inhalant for bronchitis and asthma. Eucalyptus is
used throughout the world, and eucalyptol can be regarded as a universally-available product.
Many widely-used drugs that were first extracted from plants or inspired by research into the
active principles in plants, are now synthesised. The best-known example is probably aspirin,
chemically related to a compound that was first extracted from the leaves and bark of the willow
tree, Salix alba, and a herb, meadowsweet, Filipendula ulmaria. The anti-malarial drug quinine,
extracted from the bark of a South American tree Cinchona ledgeriana, was first brought to
Europe (where malaria was widespread) in the early 17th century by Jesuit priests (Pain 2001).
It is said that Oliver Cromwell died from malaria because he refused to be treated with a
“Jesuit” medicine. Synthetic quinine has now been developed for drug use, but the bark is still
used to treat certain heart arrythmias and, commercially, as a bitter flavouring agent well-known
in tonic water.
The bark of the yohimbe, Pausinystalia johimbe, is used extensively in traditional health care
systems in west Africa. It has become popular in Europe and the US for treating impotence,
particularly before Viagra became widely available. Under US law, yohimbe is regulated as a
dietary supplement, and yohimbine hydrochloride is an FDA-approved pharmaceutical drug for
impotence. However, Germany does not recommend yohimbe for impotence, citing mixed
clinical evidence and the potential for adverse side effects such as tremors, sleeplessness, high
blood pressure and rapid heartbeat (Tyler 1999). For these reasons, the German authorities
consider that yohimbe should only be used under the advice of a specialist.
HERBAL MEDICINE AND MARKET DEMAND
The law limits the amount of information the herbal medicine industry can give on the
therapeutic use of a particular plant (see factsheet 6: Law). In many countries, the public learns
much about herbal remedies from the media, but this is biased towards whatever popular
treatments are current. As a result, relatively few herbs may be popular at any one time because
equally effective alternative remedies are not necessarily reported. In recent years the most
popular herbal remedies in Europe and North America have been gingko, ginseng, echinacea
and garlic (Laird 1999).
The development of the herbal medicine market is a public affair in the sense that, unlike
western medicines which are purposely developed in laboratories, herbal medicines are known,
used and adopted partly because of their long record of use. While scientific testing of herbal
medicines is increasing, understanding and reporting their efficacy and possible side effects
from trials – if carried out at all – have necessarily been undertaken retrospectively. This can
make them vulnerable to negative reaction to cautionary reports and media scare stories.
Negative media attention and over-exposure have resulted in a recent decline of some of the
most popular herbal medicines such as ginseng and kava kava (Pierce 2001) – even though
ginseng (Panax spp.) is arguably not only the most revered medicinal plant in Traditional
Chinese Medicine, but it has also become one of the most popular MAPs in the West
(TRAFFIC 1998c).
Kava kava (Piper methysticum) has been the subject of negative publicity after a period of
burgeoning sales (See Kava factsheet). Its safety is being investigated after six reported cases of
liver failure and one death in Europe were attributed to the over-use of standardised kava
extracts (Laird 1999).
A traditional medicine for which demand is greater than the potential for supply is the African
tree Pygeum (Prunus africana factheet). The bark is a very popular natural remedy for prostate
disorders in some European countries such as Spain – but it is harvested from wild trees
growing in the montane forests of Africa and Madagascar and is unsustainable under current
practices (see box below). While the bark can be harvested sustainably, harvesters either cut too
much, which results in the death of the trees, or they fell whole trees. The International Centre
for Research in Agroforestry (ICRAF) and others are working in Africa to establish sustainable
sources of Prunus africana through conservation of wild tree populations and assistance to
smallholders to grow the tree – something that will help increase farmers’ incomes. ICRAF is
also working on a breeding programme to select varieties which will take less time to reach
harvestable age (Ekola et al. 2000).
Silphion: a lost medicinal plant
Silphion was a multi-use weedy plant revered by the Ancient Greeks and used to such an
extent that it became extinct. Botanists can no longer find the species, which has been
identified on coins minted between 570 and 250 BC in Cyrene, a city in what is now
eastern Libya.
The perennial roots and strongly ribbed annual stems of the Silphion plant were eaten in
their fresh state, being regarded as a perfume, flavouring agent and spice. The juice was
used medicinally to treat a wide range of symptoms and diseases, especially
gynaecological ailments. It was also an effective contraceptive.
It appears that Silphion was found only in the dry hinterlands of the Middle East. Attempts
to cultivate it appear to have failed, and wild plants remained the only source of supply. It is
not known why it disappeared, although over-harvesting is considered to have been a
contributing factor.
From Lambert et al. 1997:7
Devil’s Claw, Harpagophytum procumbens, is another popular remedy that is unsustainably
harvested (See Devil’s Claw factsheet) and may become extinct in the wild under current
practices (Laird 1999). Devil’s Claw is produced in southern Africa including Namibia, the
biggest exporter in the region. Just under 200 tonnes were exported from Namibia between
January and August 2000 (Cole and Lombard 2000). Between 10,000 and 15,000 harvesters rely
on sales from its collection as their only source of cash. However, current prices are not a true
reflection of the real value of their work: indeed, over the last the 24 years the price has dropped
by as much as 85 per cent in US dollar terms. In 1998, a sustainably harvested Devil’s Claw
project was set up on one resettlement farm in Namibia and has rapidly expanded. The
following year, 10,210kg of certified organic Devil’s Claw was produced, providing local
people with a sustainable product at a guaranteed and fair price (see Factsheet 2: ‘Cultivation
versus wild harvest’). This could be the way forward, provided that users of Devil’s Claw
demand that suppliers stock only certified products (see Factsheet 5: ‘What can the consumer
do?’).
Herbal medicines are an essential and growing part of the international pharmacopeia.
Knowledge of their medicinal properties is growing as a result of research and testing, which
will make them an increasingly safe alternative or a preferred option to western medicine.
However, much of the market relies on unsustainable sourcing by underpaid collectors – a
precarious foundation for any industry. Customers need to know what they are buying and to
understand how they can influence the security of their supplies.
REFERENCES
Balick, M. J. & Cox, P.A. (1996) Plants, People and Culture: the science of ethnobotany. The
Scientific American Library, New York.
BGCI Fact Sheet. ‘Plants as medicine’. Botanic Gardens Conservation International/ British
Airways/ International Centre for Conservation Education.
Cole, D., and Lombard, C. (2000). ‘The sustainably harvested Devil’s Claw project in Namibia:
some primary producer issues’. The Centre for Research Information and Action in Africa,
Windhoek.
Ekola, A., Sutherland, J., and Wilson, E. (2000). Ancient medicinal tree threatened with
extinction: tree is leading remedy for prostate disorders worldwide. . Future Harvest.
www.futureharvest.org/news/prunusrelease.shtml
Foster, S. (2001) Vietnamese ginseng: a rare species of Panax. HerbalGram 52: 50-54.
Laird, S. A. (1999). The botanical medicine industry. In ‘The commercial use of biodiversity:
access to genetic resources and benefit-sharing’ (K. ten Kate and S. A. Laird, eds.), pp. 78-116.
Earthscan, London.
Lambert, J., Srivastava, J., and Vietmeyer, N. (1997). ‘Medicinal plants: rescuing a global
heritage,’ The World Bank, Washington, DC.
Pain, S. (2001). The Countess and the cure. New Scientist, 15 September 2001.
TRAFFIC (1998c). ‘American ginseng: the root of North America’s medicinal herb trade executive summary’. TRAFFIC International, Cambridge.
Tyler, V. (1999). Six man-loving herbs that really work. Prevention, April.