|Traditional Medicinal Plants (Dar Es Salaam University Press - Ministry of Health - Tanzania, 1991, 391 p.)|
|PART I: USE AND PROMOTION OF TRADITIONAL MEDICINAL PLANTS IN THE AFRICAN REGION|
C.N.T.S., Rue Djetel, Dahmar, Tunisia
The industrial, technological and social developments in the world have significantly contributed to a situation whereby man has neglected the development of expanded uses of traditional medicines. However, our knowledge on the adverse side effects of some of the modern medicines, the emergence of diseases which are incurable with modern medicines, and adverse economic conditions particularly in the Third World countries, have re-activated interest on the development of traditional medicines for use in health care systems, all over the world. This trend has called for scientific verification of the efficacy and toxity of these medicines. The new advances require thorough ethnobotanical investigations on medicinal plants; on the traditional uses of the plants; and the mode of preparation of the medicines by the traditional healers. This paper discusses the Tunisian experience on the ethnobotanical survey of medicinal plants. The data obtained in these investigations, are compared with those reported in countries neighbouring Tunisia.
During the second half of the twentieth century, there has been rapid technological development in the search for new drugs. Third World laboratories have been "invaded" by newer and more efficient equipment to handle the isolation and identification of the active principles of plants. During the same period, computers have radically transformed, not only our working and living habits, but also our way of thinking.
Despite the above changes, it has been noted that there is paradoxically a trend to return to nature, and to "soft" medicine. Currently research is being carried out almost everywhere in the world, to try to rehabilitate traditional medicine.
In the developed countries, research to rehabilitate traditional medicine has mainly been a result of industrial development, which was geared towards production and consumption, but overlooked the dangers of such consumption. An awareness of the fact that the use of some drugs is dangerous, has led to a scenario whereby people want to go back to the roots, or to the use of medicinal plants.
In the Third World, economic factors have had a role to play in the use of medicinal plants. Due to the economic crisis, some countries are trying very hard to reduce the health budget, particularly the cost of drugs, by advocating the use of medicinal plants and other natural resources.
How can the resources of traditional medicine be used in a rational way? To answer this question, five steps must be followed: (a) taking stock of the resources of traditional medicine; (b) studying similarities in neighbouring countries; (c) modernizing the farming techniques of medicinal plants; (d) establishing procedures for the processing, quality control and standards of plant-derived products; and (e) testing the inocuity and efficiency of plant-derived products, including toxicological tests.
We now turn to a more detailed description of the above steps, with special reference to the experience obtained in Tunisia.
Stock-taking of the resources of traditional medicine
A research was carried out using a questionnaire which was distributed to primary and secondary school teachers all over the country. The research enabled the establishment of an inventory of about 1250 plants used in traditional medicine in Tunisia. Further field research was carried out in most of the regions in the country, and this helped to add 191 more plants to the inventory.
Similarities with neighbouring countries
The neighbouring countries selected for the study were Algeria and Morocco. In Algeria, Merabet carried out research in 1982, and in Morocco, Bellakdar edited a book on traditional medicine in Western Sahara in 1978. He came out with a list, of 250 species.
The study by the current author has managed to establish a list of 24 species which are used in the same way in the three countries, and 41 species which have; the same indications in at least two countries. The traditional use of 18 of the species in the inventory corresponds to characteristics which are already known, or which can be shown scientifically.
The second step described above is necessary, as it adds to the field research, and enables the researcher to sort out the plants listed in the inventory.
Modernization of the farming techniques of medicinal plants
The percentage of active principles found in the plant itself can be improved by genetic engineering and agricultural production of the plants. We will quote here an example of the results obtained with Solanum sodomeum L., a source of solasodine, a raw material which can be used for the semisynthesis of steroid hormones. The species was improved through farming techniques, and the percentage of solasodine was increased from 2.2% to 4.2%.
Establishing procedures for the processing, quality control and standards of plant-derived products
In order to maintain quality, rigid standards have to be set for plant-derived products. A law was passed in 1985 to govern the pharmaceutical industry and the different articles relating to the execution of the law are being worked out.
Testing the inocuity and efficiency of plant-derived products, including toxicological tests
Although an inventory of at least 18 plants (whose activity was demonstrated scientifically) was made, this is not always done for most of the plants used in traditional medicine. This motivated the author and his associates to undertake research aiming at testing the activity of some plants.
(a) Anti-bacterial and anti-fungal activity
16 plants were tested against 4 bacteria and 6 fungi species by using the technique of dilution, in a freezing solid environment. Six plants revealed an activity estimated at 5mg/ml, which can compare with the antibiotic, streptomycin, and the antifungal agent, griseofulvin. The six plants were: Pistacia lentiscus, Peganum harmala, Agave americana, Anonis natrix, rubus discolor and Ruta montana.
(b) Plants with cytotoxic activity
22 extracts were tested for their cytotoxic activity. The tests used were those which have been recognized by the C.C.N.S.C., using human cancerous cells (KB), and murine cells. The extract from Pergularia tomentosa was the only one which revealed an activity estimated at DI50 = 20 mg/ml.
(c) Algae used as vermifuge
Alsidium coralinum was tested by HPLC, and kainic acid was found to be present. This acid was isolated by Fuhrman in 1981 from another alga, Digenia simplex, and its vermifuge activity has been demonstrated.
(d) Plants with anti-inflammation activity
Calendula arvensis is used in traditional medicine in Tunisia to treat rheumatism. Several components were isolated and identified, such as amino acids, phenol acids, flavonoids and particularly saponosides. The study on anti-inflammation was carried out using the carragenine test. By measuring levels of hormones such as cortisone and haptoglobin, it was possible to isolate and identify a saponoside, arvensoside "A", which could be the source of this activity.
Discussion and conclusions
The testing of the above activities, and the search for new active principles need great human and material resources. However, we are of the opinion that the best way to carry out and implement successfully a programme which aims at studying the use of traditional cures derived from plants, is to work in an environment which has the following combination of factors:
(a) the use of plant-derived cures must be socially acceptable;
(b) there must be expertise in the agricultural and pharmaceutical fields; and
(c) there must be an industrial infrastructure, which deals with the transformation of traditional collections into scientific formulae, which can be prescribed and administered, according to recognized professional medical practice.