(In: Proceeding of the Sixth International Symposium on Traditional Medicine in Toyama, 1997, pp155-162)

2500 Hassaka-chou, Hikone, 522-8533 JAPAN

INTRODUCTION

Plants have developed various ways of protecting themselves against predation by herbivores. Production of secondary compounds is one example. They are frequently toxic or act directly to inhibit an animal's digestive process (ref.?). Humans have found medicinal value in many of these same

plants (e.g. Assi et al. 1985; Burkill 1985).

Recently, researchers have also found evidence to suggest that chimpanzees in the wild use medicinal plants during periods of high infection risk by parasites and when ill and infected by them (cf. Huffman and Wrangham 1994; Huffman et al. 1997). Two basic types of medicinal plant use in African great apes, bitter pith chewing and leaf swallowing, have thus far been discussed in detail (Hufman and Wrangham, 1994). Some of these medicinal plants used by chimpanzees in the context of self-medication are also known to be of medicinal use by traditional peoples across Africa and pharmacological analyses have supported their medicinal value (cf. Ohigashi et al. 1994). It has become clear that pharmacological analyses of plants used by primates is an important part of understanding their ecology, behavior and evolution.

Gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes troglodytes) of the Ndoki Forest, in the southern part of the Nouabale-Ndoki National Park of Congo (Brazzaville) (Kuroda et al. 1996, Moutsambote et al. 1994), have been confirmed to consume leaves of Thomandelsia laurifolia (T. Auders. ex Benth) Bail (Acanthaceae) and Manniophyton fulvum Muell. Arg. (Euphorbiaceae) respectively. Medicinal use is suspected in both cases, T. laurifolia because of its extremely bitter taste and known ethnomedicinal uses and , M. flavum because of its ethnomedicinal properties and the non-nutritional manner in which the leaves are swallowed whole like that reported for chimpanzees and gorillas at other sites (Huffman et al., 1996; Wrangham and Nishida, 1983; Wrangham, 1995).

Pygmy chimpanzees (Pan paniscus) in the Wamba Forest, in the central area of Congo (Kinshasa) were also confirmed to swallow leaves of some plants including M. fulvum.

Here, we present details of this indirect evidence in support of the possible medicinal use of plant species by chimpanzees and gorillas in the Ndoki Forest and pygmy chimpanzees in Wamba.

DESCRIPTION

1. Thomandelsia laurifolia

1.1 Life form, habitat, distribution

Three species are listed in this genus and all species are shrubs or small trees (Hutchinson et al. 1963; Burkill 1985). In the Ndoki Forest, only T.lauriforia is identified so far (Moutsambote et al. 1994), but it is possible that the other species also occur in this forest. It is locally known as "ngoka". This plant can grow to a height of 10 m with a diameter up to 5 cm at breast height. However, most individuals are shorter and thinner. The leaves are very bitter and the trunk and branches are long and straight. The bark is very hard.

T.lauriforia is commonly found along streams, swamps, or in

seasonally flooded areas, especially near swamps. They are also often found in drier primary vegetation. This species is reportedly distributed from Cameroon to Zaire (Burkill 1985; Hutchinson et al. 1963), however, it is not recorded in the Wamba Forest, in central Congo (Idani et al. 1994), where pygmy chimpanzee occur.

1.2 Medicinal use by people

T.lauriforia is called "ngoka" in Bomassa and other adjacent villages in the Central African Republic. There are 3 ethnic groups in Bomassa; Bantu (Bomassa), Aka and Baka, and all use leaves of T.lauriforia as follows.

Several raw young leaves are eaten as a treatment for diarrhea, colic, fever, and as an vermicide against intestinal parasites. Generally, leaves are not chewed well because of their extreme bitterness. Leaf decoctions are also used for the same purposes. Raw leaf sap is applied as an eye wash and sap and crumpled leaves are put on wounds and as a treatment for general skin disease.

Burkill (1985) notes that usage of T.lauriforia, is the same usage as T. hensii. The vernacular name of T. hensii by the Aka is "ngoka" (Assi et al. 1985), which is the same name used for T.lauriforia in Bomassa. Assi et al. (1985) also lists similar usage of T. hensii in the southern Central African Republic, including a root decoction enema for children.

A preliminary test of the antiparasitic activity of T.lauriforia using Schistosoma japonicum, conducted by Dr. H. Ohigashi, showed it to immobilize movement and egg laying activity of the adult cercaria.

1.3 Use by gorillas

Gorillas were verified to chew the young leaves of T.lauriforia by fresh feeding remains at or near their ground nest sites. Smaller plants were sometimes used for bed materials, along with traces of leaf-eating.

The manner of eating leaves is peculiar in comparison with plant species used. Firstly, the young leaves are far bitterer than any of the more than 100 other gorilla plant foods tasted. Secondly, gorillas ate only the tips of about 10-20 leaves, but many young leaves remained untouched. Normally, with other plants, they ate the whole leaf and many more leaves were eaten at one time. For example, gorillas usually stripped an entire vine of its leaves when feeding on Cissus spp. and Rubiaceae ground vines.

Thus, it is suggested that gorillas take leaves of T.lauriforia may be

taken not only for food but perhaps also as a form of self-medication.

Some intestinal parasites have been found in gorilla feces, such as the proglottids of tapeworms (Yamagiwa, pers. comm.) and possibly nematodes. However, we have not data yet available to test the relation between T.lauriforia ingestion and parasite infection in gorillas at the time of use.

1.4 Use by chimpanzees

We have no evidence of T.lauriforia leaf-eating by chimpanzees. Broken branch with feeding remains were often found in the forest, but we could not determine the feeder. Chimpanzees perforate termite mound with straight and hard twigs of T.lauriforia when termite-fishing (Kuroda 1992; Suzuki et al. 1995), but we never found leaf-eating remains at such sites.

2. Manniophyton fulvum

2.1 Life form, habitat, distribution

Manniophyton fulvum is a small sized woody vine with coarse skin,

it is distributed widely throughout tropical African forest areas (Dalziel et al.

1963). The local name in Ndoki and many parts of Zaire is "kusa" or

"lo-kusa". This is well known to people because they make hunting and fishing net from its strong inner bark. Leaves are covered fine spines. This species is common in the open forest, including secondary forests and gap areas, but is often also found in closed primary forest and swamp areas.

2.2 Medicinal use by people

The leaf does not taste bitter, but is rather astringent as leaves of some other species so, but it differs from them in making the tongue feel a little numb. In some regions of DRC, leaves are used as a treatment for diarrhea by people (D.N. Mwanza pers. comm., quoted by Huffman et al. 1994). In Ghana, a decoction and/or sap of root and/or leaves is used for gonorrhoea, stomach problems, skin disease, parasites, and bronchial trouble (Abbiw 1990). Neither in Bomassa nor in Wamba, was medicinal usage of this plant noted. Dr. H. Ohigashi (unpublished data) detected weak antimalaria activity in crude extracts from the leaves.

2.3 Use by gorillas

Gorillas were confirmed to eat young leaves and pith from fresh feeding trace, but piece of non-chewed leaves has not been found in their feces. It is difficult to say whether gorillas use of this plant for medical purpose or not.

2.4 Use by chimpanzees and pygmy chimpanzees

Undigested large parts of young leaves were found in chimpanzee (N=1) and pygmy chimpanzee (N=3) feces. It was clear that the leaf was swallowed without being chewing. The same behavior has bee recorded in other study sites (Huffman, 1993; Huffman, in press). There was no other direct/indirect record in chimpanzees of the Ndoki Forest.

In Wamba, a female pygmy chimpanzee (bonobos) was observed to swallow one young leaf after which her daughter begged and was given a piece off. The female did not seem to have physical problem. Chimpanzees in Tai National Park, Ivory Coast also swallow the leaves of this and a number of other species (Boesch, 1995).

Non-chewed leaves of Palisota brachythirsa (N=3) and Ctenitis sp. (Fougere) (M=1) were found in feces of pygmy chimpanzees in Wamba. Those leaves are covered with fine fur and small prickles respectively. Huffman argued that coarse surface or fur of leaves may trap small intestinal parasites weaken by chemical compounds of leaves. It may also possible that such leaf may make strong intestinal perstaltic movement which help to excrete parasites.

CONCLUSION

The peculiar ingestive habits of medicinal plants by gorillas and chimpanzees in the Ndoki Forest and pygmy chimpanzees in Wamba Forest were described here. These suggest the possibility that they use medicinal plants in the context of self-medication. To examine this hypothesis, further studies are needed on behaivor, plant pharmacology, stool examination, and parasitological analysis to test for the association between parasite infection and plant use.

It is also noteworthy that such pharmacological studies help to revaluate the traditional knowledge of natural plant medicines, which is rapidly disappearing.

ACKNOWLEDGMENTS

I wish to give our sincerest gratitude to the Ministry of Science and Technology, and the Ministry of Forestry Economy of the Republic of Congo for their long-term corporation. I also thank Drs. J. Dinga-Reassi, A. Dinga-Makanda, and M. Onanga for supporting our project, Drs. J-M. Moutsambote, R. Oko, T. Nishihara, S. Shigeru for cooperating in the field, Dr. M. Fay and other staff of the Wildlife Conservation Society in Brazzaville for their kind help and cooperation. This study was financed by a grant from the Monbusho International Scientific Research Program and Toyota Foundation.

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