Traditional phytotherapy of some remedies used in treatment of malaria in Meru district of Kenya

In Kenya, most people especially in rural areas use traditional medicine and medicinal plants to treat many diseases including malaria. Malaria is of national concern in Kenya in view of development of resistant strains of Plasmodium falciparum to drugs especially chloroquine, which had been effective and affordable. This has led the Government to provide free antimalarial treatment because the cost of newer antimalarial drugs is unaffordable to local communities. However, traditional remedies against malaria are practised among the rural communities because of ease of availability and convenience and also due to social, psychological and cultural reasons. This paper examines the use of antimalarial plants among the Meru community of Imenti forest area and Gatunga, in Eastern Province, Kenya. Forty seven plant species belonging to 28 families were encountered during the study. Rutaceae, Compositae and Celestraceae families represented the species most commonly cited in treatment of malaria. Six plant species namely: Periploca linearifolia, Maytenus heterophylla, M. putterlickioides, Albizia amara, Teclea simplicifolia and Olea capensis are documented for the first time for treatment of malaria. © 2007 SAAB. Published by Elsevier B.V. All rights reserved.


Introduction
Plants have been used as sources of medicines since ancient times. The use of plant-derived drugs for the treatment of malaria has a long and successful tradition. Of particular interest are the plants used in popular medicine, for some of which it has been possible to confirm their traditional uses, and new biologically active molecules have been isolated such as quinine isolated from Cinchona bark and Artemisinin from Artemisia annua L., which illustrates the potential value of investigating traditionally used antimalarial plants for development of pharmaceutical antimalarial drugs (Srisilam and Veersham, 2003). The success of these drugs against resistant strains of Plasmodium falciparum has rekindled the search for novel antimalarial molecules from plants. In Kenya, several plant species including Azadirachta indica A. Juss (Meliaceae), Ajuga remota Benth. (Labiatae) and Caesalpinia volkensii Harms (Caesalpinaceae) are used in the treatment of malaria (Kuria et al., 2001). The use of traditional and herbal remedies seems to be the alternative choice of treatment in countries where malaria is endemic (Sofowora, 1982;Rasoanaivo et al., 1992;Gessler et al., 1995). The World Health Organisation (WHO) considers phytotherapy in its health programs and suggests basic procedures for the validation of drugs from plant origin in developing countries (Vulto and Smet, 1998).
Considering the importance of the traditional medicine, plant drugs must be scientifically evaluated for their alleged uses, safety and as suitable approach for development of new drugs (Calixto, 1996). The resurgent interest in drugs of plant origin is due to resistance of some infective agents to convectional drugs, and that approximately 80% of the rural population in sub Sahara Africa relies on traditional medicines for their primary health care needs (WHO, 2002). Approximately 25% of the drugs prescribed worldwide come from plants and of the drugs considered as basic and essential by WHO, 11% are exclusively of plant origin or synthetic drugs obtained from natural South African Journal of Botany 73 (2007) (Shu, 1998). The study of African medicinal plants has not been realized as fully as other traditional communities elsewhere such as India (Iwu, 1993). Consequently there is limited development of therapeutic products from African countries.
With the increase of anthropogenic activities in many African countries, deforestation is on the increase with consequent loss of important medicinal plants. In Kenya 2.9 million people live within 5 km of forest area exerting high pressure on the main forests such that out of the original closed canopy indigenous forest cover of 6.8 million hectares, only 1.2 million hectares is left (Wass, 1995). In view of the rapid loss of natural habitats, traditional community life, cultural diversity and knowledge of medicinal plants, documentation of African medicinal plants is an urgent matter (Van Wyk et al., 2002). The aim of the study was to therefore document a comprehensive list of antimalarial plants used in traditional and cultural set up of the Meru community as a first step in proposing appropriate scientific measures to identify through bioassay guided isolation of active constituents for use as markers in standardization of phytomedicines and possible antimalarial drug development. Two different agroecological zones representing communities living in fertile agricultural highlands and those in marginal lowland areas were studied reflecting different lifestyles of the Meru community as a whole.

Study site and methods
The study was made at Imenti Forest Game Reserve in Meru district, Kenya, which is located at 0°07′ N latitude and 37°43′ E longitude, about 6 km from Meru town and at Gatunga, Tharaka, locality 0°07′ S latitude and 37°57′ E longitude about 40 km south east of Meru town (Fig. 1). Meru district is in Eastern Province of Kenya with headquarters at Meru town (0°07′ N, 37°39′ E; 1600 m above sea level), next to Imenti forest. The district is home of the Ameru, a Bantu ethnic tribe and located on the fertile north eastern slopes of Mt. Kenya but traverses high altitude to low altitude. It has a population of 1,409,373 (1999 census) people who are predominantly Christian in an area of 9922 km 2 . The district straddles the equator and Mt. Kenya (3000-5200 m above sea level) has influenced the natural conditions in the district leading to a wide variety of microclimates and agroecological zones. The southern slopes of Mt. Kenya receive ample rainfall, between 1250-2500 mm while the leeward and the lowlands to the north receive 380-1000 mm rainfall in two seasons. Vegetation varies from typical tropical savanna to mountain forest and grassland interspersed with shrubs and small trees. The Imenti forest is facing great pressure due to over-utilization of indigenous trees and medicinal plants may disappear before their uses are documented. However, there is increased awareness on the need to conserve natural resources and the Government of Kenya has initiated remedial measures.
Tharaka, part of the greater Meru district comprises of low hilly and marginal lowlands. The soils are sandy and stony. The Tharaka community lives, a much harsher life than most Meru.
The area has a bimodal rainfall pattern which is fairly erratic averaging 500-800 mm with frequent crop failure. Malaria is endemic in most parts of Tharaka. Most areas are remote and health facilities far apart, consequently the local population is more disposed to traditional ways of treatment because of ease of availability and cheaper cost (Koinange, 1982). In other areas  Antiplasmodial activity (Clarkson et al., 2004;Koch et al., 2005) Decoction of the root used for malaria (Kokwaro, 1993), also as a pain killer (Beentje, 1994) Asclepiadaceae  (Clarkson et al., 2004;Oketch-Rabah et al., 1999;Weenen et al., 1990) Infusion of stem bark used for malaria in Tanzania , leaf infusion used for malaria in East Africa (Arnold and Gulumian, 1984 (Gakunju et al., 1995) Dried stem bark used for fever and malaria (Gakunju et al., 1995) Celastraceae Maytenus undata (Thunb.) Blakelock (CM 053)

Mugucwa (G) Shrub RB Root bark boiled
Antiplasmodial activity (Gessler et al., 1994) Decoction of the stem bark used for malaria (Beentje, 1994 Root decoction used for malaria in Ethiopia (Asres et al., 2001) traditional medicine is preferred to modern medicine owing to social, psychological and cultural reasons (Katz and Kimani, 1982). The two study sites are fairly representative of the agroecological zones of the district.

Collection of ethnomedical information
Fieldwork to collect plant samples was carried out between October and December 2004. Permission for a sustainable plant harvesting was sought from Kenya Wildlife Services in the forest reserve, and the local community outside the forest areas. To obtain information on medicinal plants traditionally used for the management of malaria, traditional health practitioners (THP) and local people were interviewed with standardized questionnaires. Group interviews were also carried out among members of THP associations. Prior to surveys in each area, a research assistant was identified who had grown up in the area and knew the people and the local language well. Several contacts were made with THP to win their trust. A taxonomist who was conversant with the flora of the area was part of the collection team. Twenty five informants (5 women and 20 men; mean age: 55 years) were interviewed at Imenti forest while 13 informants (3 women and 10 men; mean age: 50 years) were interviewed at Gatunga, Tharaka.

Collection of plant samples
The Ameru word for malaria is the same as the English word for malaria and therefore the concept of the disease malaria was clearly understood by the local people. Traditionally the disease is treated in function of symptomatology and those plants claimed to treat malaria, fevers and joint pains as identified by the local people and THP were collected. The plants were identified by a taxonomist and voucher specimens deposited at the East Africa Herbarium, National Museums of Kenya. The information gathered included plant species, parts used, plant habit, method of preparation, posology and vernacular names.

Results
The ecological zones in the two study areas were different, but a number of species were common to both sites. Table 1 shows a documentation of plant species collected from the two areas based on traditional reputation for their use as antimalarials. In total 47 species in 37 genera and 28 families were identified as being used to treat malaria. The plant family, Rutaceae had the highest number of species mentioned in treatment of malaria followed by Compositae and Celestraceae in that order. Ten families had at least two species mentioned in the treatment of malaria. Eleven species in 11 genera and 8 families were common to both regions and these were: C. edulis, V. brachcalyx, C. articulatus, S. henningsii, R. staddo, Z. usambrense, F. angolensis, T. asiatica, S. incanum, W. somnifera and C. myricoides. The root bark was the most frequently mentioned part of the plant used in the preparation of the herbal remedies and results from the habit of the species showed that most of the antimalarial herbal remedies were obtained from trees and shrubs.
The method of preparation was mostly a decoction or a hot water infusion usually prepared just before use and filtered through a cloth. The plant material was used fresh or dried and most plants to be used as a remedy were stored for later use in the dry state, which allowed their utilization throughout the year. Posology was difficult to quantify but was indicated as drinking boiled but cold decoction half a cup twice daily for adults and half this amount for children which approximated to: a half cup~125 ml; a pinch: 5 g of powdered plant material in 250 ml (1/2 cup × 2) of water to be taken twice daily; a few leaves: 5 g wet leaves or 10 g dry leaves in 250 ml of water to be taken twice daily; and a handful: 20 g of powdered plant material, or 40 g coarse plant material in 250 ml of water to be taken twice daily. Treatment was supposed to be continued until recovery.

Discussion
The aim of the ethnomedical survey and documentation was to catalogue the plants used traditionally against malaria. The results of this study show that a large number of medicinal plants are traditionally used in treatment of malaria among the communities in the two study areas. Eleven plant species were common in both study sites. This may confirm the effectiveness of traditional herbal remedies prepared from these species in the two communities. Studies from other regions of Africa indicate Rubiaceae to have many species used in the management of malaria in different countries (Iwu, 1994 (Beentje, 1994;Kokwaro, 1993) Verbenaceae Clerodendrum myricoides (Hochst.) Vatke (CM 086)

Munjugu (I/G) Shrub RB Roots boiled in water
Antiplasmodial activity (Muregi et al., 2004, Gessler et al., 1994 Root decoction used for malaria and venereal diseases (Beentje, 1994) RB = root bark, SB = stem bark, W/p = whole plant, L = leaves, I = Imenti forest game reserve, G = Gatunga. Rutaceae was reported to have more species than Rubiaceae, and nine other families were reported to have a similar and or greater frequency on the number of species cited as sources of antimalarial remedies as Rubiaceae, which would indicate the importance of these families as possible sources of antimalarial plants. The information on the frequently utilized antimalarial plant species is also an important lead to the species that can be targeted for antiplasmodial tests and phytochemical analysis.
Since there is no safer, effective and cheaper antimalarial remedies than chloroquine in the treatment of malaria, development of new antimalarial drugs from plant sources may be the way forward in dealing with global drug resistant problems of malaria (Gessler, 1995). Natural products and their derivatives represent over 50% of all the drugs in clinical use in the world (Van Wyk et al., 2002). The root bark was the most commonly used part of the plant and this was found to be destructive where in some cases the whole plant had to be uprooted. This calls for conservation and harvesting strategies to facilitate sustainable utilization of these plant resources (Cunningham, 2001). Among African medicines, indigenous plants play an important role in the treatment of a variety of diseases (Phillipson, 1995) and are often used by healers to treat diseases identified as malaria (Sofowora, 1980;Omulokoli et al., 1997). They are commonly used in East Africa (Kokwaro, 1993;Chhabra et al., 1993), in South Africa (Watt and Breyer-Brandwijk, 1962) and in West Africa (Oliver-Bever, 1986). The practice of traditional medicine is widespread in China, Japan, Sri Lanka, Pakistan and Thailand. In China and India pharmaceutical companies produce and market galenicals (Norman et al., 1985).

are some of specific examples.
A. indica is the third most commonly used herbal medicine to treat malaria in Kenya after A. remota and C. volkensii (Kuria et al., 2001). As Sofowora (1982) noted, many people in several African countries take a decoction of A. indica (neem tree) for malaria fever. Their reasons for doing so include reaction to chloroquine, a dislike for synthetic drugs, and the expense and unavailability of synthetic antimalarials. The lack of standardization and quality control is one of the main disadvantages of traditional medicine (Evans-Anfom, 1986;Sofowora, 1982). Isolation and characterization of active constituents need to be undertaken for use as markers in standardization of the extracts, thus minimizing the risk of overdoses.
Most of the plants were collected within Imenti forest, the latter is facing great pressure due to over-utilization of indigenous trees and medicinal plants may disappear before their uses are documented. Kenya's strategy for conservation of forests involves intensification of timber and other non-wood products outside forest areas (Njuguna et al., 2000). Consideration of plants of medicinal value for such conservation activities is lacking in part due to lack of knowledge of their value. Documentation of medicinal plants traditionally used in treatment of malaria will lead to their recognition and conservation. It is also important that the entire ethnoflora of the study areas be documented as a measure of conservation strategies for target species that could support the health and economy of the communities concerned. Some plant resource users in other developing countries have realized that community forestry is not a question of trees but should include on-farm non-timber forest products for subsistence as well as commercial purposes (Byron, 1995).

Conclusion
Many plant species reported in this study have been investigated for their phytoconstituents and pharmacological activities, and the latter are in agreement with the ethnomedical uses reported in this paper. The plants studied were selected from an ethnopharmacological inquiry during an ethnobotanical survey for medicinal plants traditionally used for treatment of malaria in Meru district. Six plant species are documented for the first time for treatment of malaria.
The study allowed the recovery of a rich patrimony of empirical knowledge regarding the traditional uses of plants, which is handed on orally and thus inevitably destined to get lost over the years; it also permitted the singling out of new medicinal plants. Chemotaxonomy, bioactivity and isolation of principles may lead to other uses of the plant apart from its traditional use. And besides allowing the recovery of empirical knowledge linked to medical and other uses, ethnobotany also permits the preservation and handing down of anecdotes, proverbs, rhymes and rituals regarding plants. For example in Meru a sick person with mumps would go round several times the tree Croton macrostachyus and sing: Mutuntu twaria mbucu Nani gutwarie ntuntu (C. macrostachyus help me carry my mumps and I assist you carry your seeds).
The sick person would leave confident that he has left behind the illness afflicting him and that he would feel well gradually.
C. macrostachyus is also a medicinal plant whose decoction from root bark is drunk for malaria and venereal diseases.