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Biodiversity conservation and the application of Amazonian medicinal plants in the control of malaria

William Milliken

Royal Botanic Gardens, Kew
Richmond, Surrey, TW9 3AE, UK
Tel: 0181 332 5783/ Fax:0181 332 5278 / Email: W.Milliken@rbgkew.org.uk

Valuing the rainforest

The potential monetary value of rainforests, and its implications for the conservation of biodiversity, have now been discussed at length by a number of authors, some of whom have attempted to quantify this value (e.g. Peters, Gentry and Mendelsohn, 1989). These discussions were spawned by the rationale that there must be means of rainforest exploitation which are more financially viable than their conversion to short-term agricultural land or cattle pasture. This in turn responds to the assumption that unless a financially viable conservation option is presented to the developing countries in which most rainforests are found, then they will eventually be destroyed for short-term gain. The potential income generated by sustainable logging, extractivism (non-timber forest products), ecotourism and biodiversity prospecting have all been considered in this context. Of these, it is biodiversity prospecting, or more specifically the search for new pharmaceutical products, which has tended to generate the most enthusiasm and rhetoric. No rainforest conservation campaign leaflet is complete without a mention of the countless species with un-investigated pharmacological properties which are disappearing every day. On paper, at least, the proceeds of biodiversity prospecting also appear to present the highest potential financial returns from the rainforest. In spite of the relatively low 'hit rates' obtained by random pharmacological screening, the diversity of currently un-investigated species within even a small tract of rainforest, combined with the enormous profits which can eventually be generated by a successful 'hit', suggest that substantial capital values can be attached to them. Furthermore, agreements such as the Costa Rican INBIO/Merck contract indicate that in certain circumstances there might indeed be viable means of turning this potential value to good advantage for conservation.

Anti-malarial plants of Roraima

Between 1993 and 1995 a survey of the plant species used in the treatment of malaria was conducted in Roraima, the northernmost State of Brazil. Data were collected from seven indigenous groups in the region (the Yanomami, Macuxi, Maiongong, Wapixana, Taurepang, Ingaricó and Wai-Wai), and also from representatives of the non-indigenous populations. At least 99 plant species, of 82 genera and 41 families, were found to be used specifically in the treatment of malaria. Of these, only 22 appear to have been reported previously in the literature as being used to treat malaria elsewhere. Fifty-three of these species occur in terra firme or riverside forest, 17 in natural savanna vegetation, 20 in secondary vegetation or waste ground, and 18 are cultivated. The plants were taxonomically diverse: of the 41 families only eight were represented by more than 3 species. These were the Leguminosae, Rubiaceae, Apocynaceae, Compositae, Euphorbiaceae, Myrtaceae, Piperaceae and Solanaceae. Further details of these plants are to be published elsewhere (Milliken, 1996a, 1996bb). In these publications, in an effort to protect the intellectual property rights of the people who furnished the information, the plants have only been identified to the level of species in cases where the use of that plant as a malaria remedy has already been published, or where its properties are so widely known that its use could not realistically be said to be the intellectual property of any particular group of people.

The logical means of identifying novel anti-malarial compounds is to follow the leads from traditional medicine, and yet the greater part of the (comparatively little) research carried out in this field has to a large extent been based on randomly selected species. There is a very strong case for following up these ethnobotanical leads (Balick 1994, Cox 1994), which is supported by the results of the relatively few anti-malarial studies which have done so (e.g. Phillipson et al., 1987; Phillipson & Wright, 1991a; 1991b; Brandão, Botelho & Krettli, 1985; Brandão et al., 1992). At present, the results of the screening of the plants collected in Roraima are still at a preliminary stage, and do not merit analysis. However, the initial results indicate a far higher percentage incidence of anti-malarial activity in vitro than, for example, those of the massive random screening carried out by Spencer et al. (1947).

The number of species used in the treatment of this one disease, solely within a relatively small part of the Amazon, is on the face of it remarkable. It emphasizes not only how little we (the outsiders) still know about the medicinal properties of Amazonian plant species, and of the true scope of existing indigenous knowledge of those properties, but also of the enormous potential which still genuinely seems to exist for the discovery of new and viable remedies for major diseases among those plants. In the case of malaria, there is an urgent global need for such new and effective medicines, as resistance to 'traditional' quinine-based compounds continues to develop in the most serious form of the disease, cerebral malaria (Plasmodium falciparum), at an alarming rate.

However exciting the implications of the results of this research may be, at present the search for new anti-malarials and its potential rewards do not immediately appear to be a particularly good advertisement for the conservation benefits of biodiversity prospecting. Malaria, being a disease primarily restricted to the poorer countries of the world, cannot compete with the diseases which preoccupy the developed world in terms of being a potential pharmaceutical gold-mine. As a consequence, the amount of commercial-sector research being conducted in this field is minimal. However, if the climatic changes which are predicted as a result of global warming actually take place, this situation could change significantly. Martin and Lefebvre (1995) estimate that this process could increase the range of malaria by up to 28%, by expanding the area in which the ambient temperature and climatic conditions are suitable - at least for part of the year - for its transmission. The areas where malaria transmission is seasonal, and thus most likely to provoke severe epidemics on account of the lower resistance in local populations, may increase by as much as 55%.

Unless one subscribes to the belief that the medicinal properties of plants are the result of divine providence, there is no reason to believe that remedies for diseases which are not endemic to rainforest regions should be any less abundant among their plants than remedies for those which are. There really may be cures for AIDS, cancer, asthma and heart disease amongst them. The capacities of the people of these regions or countries to investigate and exploit this potential is, in many cases, limited by a lack of resources and expertise. As a result, if anybody is likely to exploit and profit from the biodiversity of the rainforest, it will be the multi-national pharmaceutical giants. The percentage return to the country of origin, if any, will depend upon the care with which an agreement has been worked out in advance, and on the level of honesty and selflessness of the people involved. Whatever happens, the percentage will inevitably be low. Will this small return be judged by those countries to have justified the 'investment' which it has made in the conservation of rainforest for biodiversity prospecting?

This discussion is missing one crucial point, and one which tends to be missed or dismissed with frightening frequency by developers, national authorities and conservationists alike. The point is that we are discussing rainforests as if they were nothing more than a series of spectacular biodiversity reservoirs, and ignoring the fact that in general they are somebody else's lands over which we (including the national authorities of the countries in which the rainforests occur) do not have the right to make decisions. The resources belong to the indigenous peoples who inhabit these forests, and who rely upon them for their livelihoods.

Anti-malarial plants and conservation

The potential for influencing biodiversity conservation, if there is one, played no part in the conception of this project nor in its execution. What, though, might be the role of research into these northern Amazonian anti-malarials in the promotion of biodiversity conservation? Almost certainly not as a means of identifying a source of funds sufficiently great to guarantee preservation of the rainforests of the region. This has already been discussed. But as a means of helping to support the indigenous peoples who inhabit those forests, and thereby supporting the most careful and effective custodians of their biodiversity? Perhaps. If a commercial anti-malarial product were to be developed from one of the plants collected during this survey, then the percentage of the profits which would theoretically (and rightfully) return to the people who provided the information could potentially bring them significant benefits. At present the greatest need of many of these peoples is for guaranteed rights to their traditional lands, and a source of income could conceivably help them to secure these rights.

One uncomfortable but nonetheless valid consideration is the potentially negative effect which a more effective system of malaria control, whether through the application of new plant products or the use of local plants themselves, might have on the conservation of biodiversity. Malaria, which generally speaking coincides in its geographical range with the areas of greatest global biodiversity, is estimated by the World Health Organization to cause between one and two million deaths per year (principally in Africa). Effective control of the disease would inevitably place a greater population pressure on the natural resources in these areas.

In fact, this project was not aimed at finding new anti-malarial products for world-wide use, but at identifying the most effective locally available medicines for local use. Malaria arrived relatively recently among many of the indigenous communities of Roraima, on the heels of the disastrous gold-rush which swept through the region at the end of the 1980s and the beginning of the 1990s. Lack of previous experience of malaria on an epidemic scale left the more isolated of these communities, such as the Yanomami, in a very precarious situation, some of them having little or no knowledge of how to treat it with locally available resources. Many people died. Suitable resources evidently do appear to exist, however, as demonstrated by the results of this survey, and it is hoped that by identifying the most effective regional anti-malarial plants, and by disseminating information on how they are used, it will be possible to diminish the dependence which some of these indigenous communities have developed on external medical support.

Theoretically, any development which supports the autonomy of indigenous people should strengthen their ability to remain as custodians of their own territories, thereby (incidentally) assisting in the conservation of biodiversity. It would be naive and unrealistic, however, to imagine that such developments are of any great consequence in the face of the greater issues which govern whether or not indigenous peoples are to be able to retain their traditional ways of life and their lands. Northern Amazonian Brazil is a prime example of this conflict of interests. One could promote and encourage the use of locally available medicines and the sustainable use of forest resources until blue in the face, but in truth all of this is fairly irrelevant when viewed in the context of gold-mining, ranching, logging and the lack of sincerety among local and national politicians who support these activities on the lands of indigenous peoples and who consistently and deliberately fail to recognize their rights.

References

Balick, M.J. 1994. Ethnobotany, drug development and biodiversity conservation - exploring the linkages. In: Prance, G.T., Chadwick, D.J. & Marsh, J. (eds) Ethnobotany and the Search for New Drugs. Ciba Foundation Symposium 185. New York, USA; John Wiley & Sons. pp. 4-24.

Brandão, M.G.L., Botelho, M.G.A. & Krettli, A.U. 1985. Quimoterapia experimental antimalárica com produtos naturais: uma abordagem mais racional?. Ciência e Cultura 37: (7) 1152-1163.

Brandão, M.G.L., Grandi, T.S.M., Rocha, E.M.M., Sawyer, D.R. & Krettli, A.U. 1992. Survey of medicinal plants used as antimalarials in the Amazon. Journal of Ethnopharmacology 36: 175-182.

Cox, P.A. 1994. The ethnobotanical approach to drug discovery: strengths and limitations. In: Prance, G.T., Chadwick, D.J. & Marsh, J. (eds) Ethnobotany and the Search for New Drugs. Ciba Foundation Symposium 185. New York, USA; John Wiley & Sons. pp. 25-41.

Martin, P.H. & Lefebvre, M.G. 1995. Malaria and climate: sensitivity of malaria potential transmission to climate. Ambio 24: (4) 200-207.

Milliken, W. 1996a. Malaria and anti-malarial plants in Roraima, Brazil. Tropical Doctor (in press).

Milliken, W. 1996b. Traditional anti-malarial medicine in Roraima, Brazil. Economic Botany (in press).

Peters, C.M., Gentry, A.H. & Mendelsohn, R.O. 1989. Valuation of an Amazonian forest. Nature 339: 655-656.

Phillipson, J.D. & Wright, C.W. 1991a. Antiprotozoal agents from plant sources. Planta Medica 57 (suppl.): 53-59.

Phillipson, J.D. & Wright, C.W. 1991b. Can ethnopharmacology contribute to the development of antimalarial agents? Journal of Ethnopharmacology 32: 155-165.

Phillipson, J.D., O'Neill, M.J., Wright, C.W., Bray, D.H. & Warhurst, D.C. 1987. Plants as sources of antimalarial and amoebicidal compounds. In: Leeuwenberg, A.J.M. (compilers). Medicinal and Poisonous Plants of the Tropics. Wageningen, Netherlands; Centre for Agricultural Publishing and Documentation. pp.70-79.

Spencer, C.F., Koniuszy, F.R. Rogers, E.F. Jr, Shavel, J., Easton, N.R., Kaczka, E.A. Jr, Kuehl, F.A., Phillips, R.F., Walti, A., Folkers, K., Malanga, C. & Seeler, A.O. 1947. Survey of plants for antimalarial activity. Lloydia 10: 145-174.

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