Ethnobotany and ethnopharmacy

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Chapter 5 Ethnobotany and ethnopharmacy

Many drugs that are commonly used today (e.g. aspirin, ephedrine, ergometrine, tubocurarine, digoxin, reserpine, atropine) came into use through the study of indigenous (including European) remedies – that is, through the bioscientific investigation of plants used by people throughout the world. Table 5.1 lists just a few of the many examples of drugs derived from plants. As can be seen, most plant-derived pharmaceuticals and phytomedicines currently in use were (and often still are) used by native people around the world. Accordingly, our information is derived from local knowledge as it was and is practised throughout the world, although European and Mediterranean traditions have had a particular impact on these developments. The historical development of this knowledge is discussed in Chapter 2. This chapter is devoted to traditions as old as, or older than the written records but which have been passed on orally from one generation to the next. Some of this information, however, may have not been documented in codices or studied scientifically until very recently.

Table 5.1 Botanical drugs used in indigenous medicine and of importance in the development of modern drugs

Ethnobotany and ethnopharmacology are interdisciplinary fields of research that look specifically at the empirical knowledge of indigenous peoples concerning medicinal substances and their potential health benefits, and (as with all drugs) the potential toxicological risks associated with such remedies. Empirical knowledge was sometimes recorded in herbals and other texts on materia medica (examples are given in Chapter 12). Written traditions are obviously better documented and easier to access, but both written and oral forms of indigenous phytotherapy are important factors influencing the use of medicinal plants in the Western world. Each year new plants become popular with some sections of the population (and often are as quickly forgotten again). Only a few are sufficiently well-studied scientifically and can be recommended on the basis of bioscientific and/or clinical evidence.

Ethnobotany

Shortly before the start of the 20th century (1896), the American botanist William Harshberger coined the term ‘ethnobotany’ – the study of plant use by humans.

Ethnobotany studies the relationship between humans and plants in all its complexity, and is generally based on a detailed observation and study of the use a society makes of plants, including all the beliefs and cultural practices associated with this use.

It is usual for ethnobotanists to live with indigenous people, to share the everyday life of their community and, of course, to respect the underlying cultures. Ethnobotanists have a responsibility both to the scientific community and to the indigenous cultures. According to the above definition, ethnobotany focuses not only on medicinal plants, but also on other natural products derived from nature, such as:

• plants used in rituals

• colouring agents

• fibre plants

• fertilizers

• building materials for houses, household items, boats, etc.

• ornamentals

• oil plants.

This broad definition is still used today, but modern ethnobotanists face a multitude of other tasks and challenges (see below). Medicinal plants have always been one of the main research interests of ethnobotany and the study of these resources has also made significant contributions to the theoretical development of the field (Berlin 1992); however, the more anthropologically oriented fields of research are beyond the scope of this introductory chapter.

Ethnopharmacology

Ethnopharmacology as a specifically designated field of research has had a relatively short history. The term was first used in 1967 in the title of a book on hallucinogens (see Efron et al 1970). The field is nowadays much more broadly defined.

The observation, identification, description and experimental investigation of the ingredients, and of the effects of the ingredients, and the effects of such indigenous drugs, is a truly interdisciplinary field of research which is very important in the study of traditional medicine. Ethnopharmacology is here defined as ‘the interdisciplinary scientific exploration of biologically active agents traditionally employed or observed by man’ (Bruhn & Holmstedt 1981: 405–406).

This definition draws attention to the bioscientific study of indigenous drugs but does not explicitly address the issue of searching for new drugs. Medicinal plants are an important element of indigenous medical systems in many parts of the world, and these resources are usually regarded as part of the traditional knowledge of a culture. Europe has for many years profited from the exchange of ideas with other continents, and many of the natural products and phytomedicines used today are derived from plants used in indigenous cultures. Examples of 18th century explorers who described indigenous plant use in detail are Richard Spruce (British), Hipolito Ruiz (Spanish) and Alexander von Humboldt (German), who co-discovered curare.

The story of curare

An interesting example of an early ethnopharmacological approach is provided by the study of the botanical origin of the arrow poison curare, its physiological effects and the compound responsible for these effects. Curare was used by certain, wild, tribes in South America for poisoning their arrows and many early explorers documented this usage. The historical aspects of the scientific investigation of curare by Bernard (1966) are outlined in Chapter 2, but the detailed descriptions made by Alexander von Humboldt in 1800, of the process used to prepare poisoned arrows in Esmeralda on the Orinoco River, are equally interesting. von Humboldt had met a group of native people who were celebrating their return from an expedition to gather the raw material for making the poison and he described the ‘chemical laboratory’ used to prepare the poison (Humboldt 1997:88, from the original text published 1800):

He [an old Indian] was the chemist of the community. With him we saw large boilers (Siedekessel) made out of clay, to be used for boiling the plant sap; plainer containers, which speed up the evaporation process because of their large surface; banana leaves, rolled to form a cone-shaped bag [and] used to filter the liquid which may contain varying amounts of fibres. This hut transformed into a laboratory was very tidy and clean.

The botanical source of curare was eventually identified as the climbing vine Chondrodendron tomentosum Ruiz and Pavón; other species of the Menispermaceae (Curarea spp. and Abuta spp.) and Loganiaceae (Strychnos spp.) are also used in the production of curares of varying types (Bisset 1991). von Humboldt then eloquently described one of the classical problems of ethnopharmacology:

We are unable to make a botanical identification because this tree [which produces the raw material for the production of curare] only grows at quite some distance from Esmeralda and because [it] did not have flowers and fruit. I had mentioned this type of misfortune previously, that the most noteworthy plants cannot be examined by the traveller, while others whose chemical activities are not known [i.e. which are not used ethnobotanically] are found covered with thousands of flowers and fruit.

The role of the ethnobotanist

The role of the ethnobotanist in the search for new drugs was important until the second half of the 20th century, when other approaches became more ‘fashionable’. More recently, the study of ethnobotany has again received considerable interest in the media and in some segments of the scientific community. Also the ‘Western’ use of such information has come under increasing scrutiny, and the national and indigenous rights of these resources have become acknowledged by most academic and industrial researchers. These developments result in a considerable challenge to (and increasing responsibilities for) ethnobotanists and ethnopharmacologists. Simultaneously, the need for basic scientific investigation of plants used in indigenous medical systems is becoming ever more relevant. The public availability of research results is as essential for further developing and ‘upgrading’ indigenous and traditional medicine as it is for any other medical or pharmaceutical system.

Ethnopharmacology and the convention on biological diversity (convention of RIO)

None of the studies discussed so far took the benefits for the providers (the states and their people) into account. This has changed in recent years. Ethnopharmacological and related research using the biological resources of a country are today based on agreements and permits, which in turn are based on international and bilateral treaties. The most important of these is the Convention of Rio or the Convention on Biological Diversity (see http://www.biodiv.org/chm/conv.htm), which looks in particular at the rights and responsibilities associated with biodiversity on an international level:

The objectives of this Convention, to be pursued in accordance with its relevant provisions, are the conservation of biological diversity, the sustainable use of its components and the fair and equitable sharing of the benefits arising out of the utilization of genetic resources, including by appropriate access to genetic resources and by appropriate transfer of relevant technologies, taking into account all rights over those resources and to technologies, and by appropriate funding.

The basic principles of access are regulated in article 5:

States have, in accordance with the Charter of the United Nations and the principles of international law, the sovereign right to exploit their own resources pursuant to their own environmental policies, and the responsibility to ensure that activities within their jurisdiction or control do not cause damage to the environment of other States or of areas beyond the limits of national jurisdiction.

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