Views:3 Author:Site Editor Publish Time: 2015-11-13 Origin:Site
Medicinal plants play a critical role in the healthcare provision of much of the world's population. Whether they are used to make a decoction in rural Africa, to extract an alkaloid in Switzerland or as a health food supplement in the United States, demand is increasing. This paper attempts to examine the trade in medicinal plants; determine the volume of medicinal plant material that is traded and identify the main sources of demand and supply. In so doing the paper addresses the conservation implications arising from the trade and considers some possible solutions.
Medicinal plant demand
Before considering the sources of medicinal plants and mechanics of the trade, an understanding of where the demand for medicinal plants comes from is needed.
Medicinal plant material is used by a large number of industries. This paper attempts to focus mainly on demand from industries which use these plants for their medicinal or health giving properties as explained below. The problem lies in the fact that statistical data do not usually differentiate between these groups and other users such as manufacturers of: cosmetics, detergents, dyes, insecticides, foods, paints etc.
This sector uses medicinal plants:
- for the isolation of single purified drugs, e.g. digitoxin extracted from digitalis and vincristine fromCatharanthus roseus.
- in advanced extract form where the extract is highly standardised in terms of the active constituents it contains. In many cases, these are in admixtures with other ingredients, e.g. senna extract from Cassia senna.
- as starting material for the production of other semi-synthetic pharmacologically active substances. For example, plant saponins can be extracted and altered chemically to produce sapogenins required to manufacture steroids.
Demand for medicinal plants from this group alone is significant with an estimated 25% of prescription drugs in the US containing plant extracts or active principles prepared from higher plants (Farnsworth and Soejarto, 1985).
In some countries (e.g. Germany), there is little distinction between pharmaceutical and phytopharmaceutical companies as both may sell products made from standardised extracts of plant material. However, in other countries where the licensing criteria for plant extracts are very different from those for medicines, there is more of a distinction.
Phytopharmaceutical companies not only use plant extracts but also raw plant material for example to make tinctures, teas or in capsule form.
Health Product Companies
Examples of some of the more important health products are garlic, ginseng, propolis, royal jelly, tonics, guarana and herbal drinks for which there has been a growing demand recently.
There is also a fine line of distinction between health products and phytopharmaceuticals as many health products are being marketed as such in order to avoid the need to license a product as a medicine (a costly and complex process).
Although traditional medicines could equally be covered under phytopharmaceuticals, a distinction is made here in order to highlight their importance in the medicinal plants trade. The WHO estimated that 80% of the population of developing countries rely on traditional medicines (primarily plant drugs) for their primary healthcare needs.
The most renowned traditional systems are Ayurvedic, Unani and traditional Chinese medicine (TCM). In addition, there are many less well documented systems of traditional medicine which have been handed down from one generation to the next by word of mouth and practised in many parts of the world. In the Côte d’Ivoire, a market survey of 800 households found that traditional medicines were not just used in rural areas but increasingly in urban areas as well (Bodeker, 1997).
In addition to the traditional medicine practitioners in developing countries, there are an increasing number of alternative practitioners of natural medicine in the developed world.
Demand for medicinal plants is undoubtedly increasing in all the above sectors (with the possible exception of their use as pure chemical isolates) and this growth is fuelling an increase in both the number of species and volume of plant material being traded. What we now need to consider is from what sources this demand is being met.
Medicinal Plant Species
It is estimated that some 10,000 plant species are used medicinally, most of these are used in traditional systems of medicine. However, only a relatively small number of species are used in any significant volume. For example, in TCM, 9,905 botanical materials are used but only an estimated 500 are commonly used. (Natural Medicine Marketing, 1996).
A study undertaken by the International Trade Centre (ITC) in 1982 suggested that 400 species were used in Europe (ITC-UNCTAD GATT, 1982). More recent findings suggest that the number could be closer to 1,500 including those used in homeopathy (Lange, 1996). There are no reliable data on the number of plant species that are currently traded in high volume; indeed, such a list is badly needed.
An analysis of plant derived materials used in prescription drugs during 1980 found that only 40 species of higher plants are used as sources of drugs. (Farnsworth et al., 1986).