Ethnobotany and the medicinal plants of the Korup rainforest project area, Cameroon

A. ABONDO,* F. MBENKUM,* and D. THOMAS**

* Institute of Medical Research
& the Study of Medicinal Plants
P.O. Box I.M.P.M. Yaounde, Cameroon

**Missouri Botanical Garden
P.O. Box 299, St. Louis
Missouri 63166 - 0299, U.S.A.

ABSTRACT

The Korup Rainforest of Southwestern Cameroon poses the twin challenges of high botanical and high ethnic diversity. Using innovative techniques, we have identified plants used in traditional medicine, that are a basis for both regional primary health care and raw material for pharmaceutical products.

Introduction

Project Background

The Korup Project in Southwestern Cameroon is a joint Cameroon World Wide Fund For Nature (WWF) venture that is aimed at combining rural development with nature conservation on one of Africa's most genetically diverse forests (WWF, 1987).

Two sites constitute the project area (Figure 1). The first is the 126,000 hectare, Korup National Park, where uses are limited to the protection and observation of the forest ecosystem, and the second is a 300,000 hectare area surrounding the park, where an integrated rural development activity takes place. In the second area a spatial approach has been adopted where the land is zoned for different classes of land use.

The project that has been operating since 1987 is very complex and uses a multi-disciplinary approach to attain its goal. The operations are grouped into Natural Resources Management projects and Support Activities that are concerned basically with infrastructural development. Natural Resources Management includes sustainable agricultural systems for the various ecological zones, appropriate agroforestry systems to meet the socio-economic and environmental needs of the area, and the investigation of the potential for sustainable harvesting of the diverse products of the forest, such as, medicinal plants, natural herbicides and pesticides, dyes, gums, resins, leaf proteins, nuts and fruits.

Ethnobotanical Background

In the past, tropical forests were commercially exploited for products, principally timber and little attention was given to the secondary products, though they provided the local people with food, medicines and materials for crafts and construction purposes (Thomas et al., 1989).

The ethnobotanical study that we have undertaken is part of the inventory needed for sound forest management and rural development. The two background components to the study of ethnobotany, especially medicinal plants, are a knowledge of the vegetation, and an understanding of the culture.

Botanical Background

The plant species of the Korup Project area are fairly well known through the botanical inventory carried out by Duncan Thomas with the Missouri Botanical Garden and the Cameroon National Herbarium. The forest is thought to be richer in plants and animal species, perhaps than any other African forest.

This area is dominated by a closed canopy lowland forest with high alpha-diversity, and relatively low beta- diversity. Letouzey (1985) has divided the forest into two associations. The first is made of the Atlantic-Biafran forest, occurring on sandy clays at low attitude of up to 300 m. This is a species rich association, with many gregarious species of the Caesalpinioideae, like Guilbertiodendron. Also, Oubanguia alata, Dichostemma glaucescens and Cola spp. are abundant, especially C. semecarpophylla. The second is the Atlantic-Northwestern association, found on clay soils at higher altitudes 300- 700 m. It has fewer Caesalpinoideae, while Terminalia and Entandrophragma species and Anonidium manii are common. This is the most species - rich association in Cameroon and is also rich in endemics like Medusandra mpomiana. Forest on steep hill sides and ravines are distinctive. Unlike the two associations described above, they are relatively species - poor, but rich in gregarious Cluciaceae such as Garcinia conrauna and G. nobilis. The species Grossera macrantha as well as the rare endemic Nopoleonea equertonii are restricted to these hillside forests.

Ethnocultural Background

Much of the background information on the culture of the area has been drawn from the study of the Northern villages of Korup by Di Nola (1988), a forestry and agricultural visit by Ramshaw (1988) food survey of Mundemba town and Ndian Estate by Malleson (1987), forestry survey in the Korup project by Synnott (1989), a survey on the people of Korup by Devitt (1988), and from being familiar with most prevalent illness of the area and some treatments.

The Korup Project area is ethnically diverse since the boundary between the Bantu people of the Cameroon-Congo group and Semi-Bantu people of the Nigeria - Cameroon Cross River area runs through it (Figure 2). The main ethnic groups of the Cross River area are the Ekoi, the Ejagham, the Ibibio and the Korup, while those of the Cameroon-Congo Bantu Sector are the Uroko and Mbo tribes, to the east of the project area.

Methods

Data collection was preceded by extensive preliminary studies, so as to be familiar with all parts of the project area and design the field work around a viable timetable.

We defined a sampling site as a village. A minimum of two villages were sampled for each ethnic group in the area of study. The four major ethnic groups are the Ejagham, the Upper Balong, the Korup and the Okoko.

Two formal data sets were required for this study, together with a large quantity of information obtained in informal discussions. The data sets were collected in May, June and December 1988, and February to May 1989.

Show-and-tell methods

This was a method used for comparative ethnobotany study to obtain comparative information on plant names and uses.

A standard herbarium that could be examined by villagers as the centre piece of the study was collected from a wide range of habitats in the area. The herbarium contained 260 plant specimens, chosen to test a number of hypotheses concerning plant use in Korup. It enabled us to show all the important structures of plants, such as leaves, flowers and fruits.

By using a fixed set of species instead of a stochastic sub-set of the total flora, direct comparisons were made between data sets. Furthermore, by using an empirical approach where the same specimens were shown in each village, we obtained replicate data sets and built up an overall picture of the names and uses of each species and could easily spot in consistent results.

Walk-in-the woods method

Before the comparative study was carried out, information on plant names and uses was collected by walking around the village and nearby area with our traditional experts and guides. This exercise was known as the "walk in the woods".

This is a standard ethnobotany method used to obtain information through the study of living plants. This approach helped establish the credentials of our informants, identify any useful plants of the area not included in the comparative study, and improved the quality of the comparative data, by obtaining some names in advance that assisted identification of the herbarium specimens.

Traditional treatment and primary health care

Role and Tiers

In developing countries, a large number of people, especially children, die daily of preventable or curable diseases because of lack of simple health care. In most cases this is due to limited resources, poor communication, vast distances, poverty, lack of education etc. (Sofowora, 1982).

As a result of this, traditional medicine has become more accessible to most of the people in rural parts of Africa, where some 80 per cent of the population rely on indigenous forms of medicine. In Korup, where traditional skills exist and where natural resources and phytochemicals are extensively used, it is possible to achieve rural development objectives in the area of primary health care. For example, filaria is widespread in the project area, including both river blindness and loa-loa. The Simulium, whose secondary host is the black fly, is common in all fast -flowing, unshaded streams. Ayong village is situated on the bank of a large stream and with abundant simulian host in the village. According to the villagers, blindness was not a serious problem and that worms in the eye were destroyed using eye drops from Scleria boivinii.

Two tiers of indigenous medicine have been identified in the Korup area. One is traditional medicine proper, that uses specialised skills in diagnosing, preventing or eliminating physical, social and mental diseases. The other, known as "folk" medicine, need not involve a specific medical system, but relates rather to use by traditional remedies by villagers, who do not derive their income from this source.

Although the two tiers are not very distinct and overlap to a considerable extent, folk medicine is regarded as part of the first tier of health care system. For serious illnesses, the patient may seek treatment in the second tier: a traditional practitioner, or a hospital.

Preparation of Herbal Remedies

We cannot adequately assess the importance of drug preparation and other aspects of treatment in Korup because our investigation was botanically oriented.

Although the preparation of individual medicines has not been studied in detail, many customs govern the preparation and administration of each remedy, and these vary from one village to another. Some preparation customs however, appear to be important, such as the condition and time of collection of the material, dose and method or form of administration.

The common forms of preparation are aqueous infusions or decoctions and pastes. The whole plants or plant parts are generally steeped in cold or hot water, or occasionally in cold palm wine or palm gin, locally known as "Afofo". Decoctions are usually prepared with boiling water. In the case of ointments and orally administered medicines, the plants are often ground to a paste with palm oil, and other ingredients like Aframomum melegueta seeds are added.

Infusions and decoctions are frequently drunk or used as enemas, while pastes are eaten, or used as poultices or as ointments. They may even be rubbed on, or put into shallow cuts in the skin, often seven in number. In some cases, medicines are first chewed, and then spat into wounds or incisions. The treatment of fevers is often accompanied by steam baths.

Treatment using plants

The term medicinal plants, when interpreted broadly, includes all plants whose usefulness is derived from specific phytochemicals produced as secondary derivatives of major metabolic pathways (Thomas and Mbenkum, 1987).

Classifications of medicinal plants are frequently based on the type of chemical action involved. We have not used this approach because the study involved neither chemical analysis nor an extensive literature search. Another approach involves the listing of plants under the illnesses or symptoms treated. We have tried to follow this plant as far as possible, despite confusion over what disease or problem the plant was actually treating. We have listed those plants used in traditional medicine, which are quite distinct from ceremonial and magical plants that we have left out.

Conclusion

Traditional medicine is very widely practised in the Korup area, where all villages have at least one traditional practitioner with considerable knowledge, while some remedies are known by most villagers. These treatments are most useful for primary health care and represent the equivalent of non- prescription drugs in orthodox medicine.

Research and extension work are the keys to integrating folk medicine into modern primary health care. The major objective should be to match safe, effective remedies to common illnesses, using local medicinal plants. The problem is that very little is known about fold medicine and traditional medicine proper, and it is impossible to say how effective they are without a lot more research.

In order to accomplish this integration, inventories of medicinal plants and the flora of the various regions must be carried out. This should be followed by consultations between medical doctors, pharmacologists and ethnobotanists, aimed at listing the diseases the villagers can identify and treat, along with the plants to be considered for treating them. Meanwhile, additional phytochemical and pharmacological research should be carried out on important medicinal plants to determine their chemical composition, biological activity, toxic effects and optimal doses. These studies could identify plants which could be used to manufacture medicines for the treatment of numerous common ailments of both humans and animals. These medicines could be used to reduce dependance on imports, and their manufacture would provide a domestic pharmaceutical industry, leading to the development of much local expertise in this field.

Preliminary studies by WWF and Cameroon scientists, have shown that many of the Korup forest plants contain useful chemicals that include fungicides, pesticides, dyes, and even natural contraceptives and aphrodisiac compounds. So far, over 90 substances have been isolated - 38 new to science, with potential commercial use in industry and medicine. Furthermore, one or two species we have identified, contain phytochemicals with anti-viral properties and could be researched as a possible treatment or control of AIDS. It is likely that more will be discovered since much of the flora has not yet been researched.

TREATMENT USING PLANTS OF KORUP