Antiplasmodial potential of traditional phytotherapy of some remedies used in treatment of malaria in Meru-Tharaka Nithi County of Kenya.

ETHNOPHARMACOLOGICAL RELEVANCE: Medicinal plants play a major role in many communities across the world, in the treatment and prevention of disease and the promotion of general health. The aim of the study was to escalate documentation from an earlier study of medicinal plants, traditionally used to combat malaria by the Ameru community of Imenti Forest area and Gatunga in Eastern Region of Kenya, and validate their ethnopharmacological claims by evaluating their antiplasmodial efficacies. MATERIALS AND METHODS: The study was carried out in Meru County at Imenti Forest Game Reserve and in Tharaka Nithi County at Gatunga. Traditional health practitioners (THP) were interviewed with a standard questionnaire to obtain information on medicinal plants traditionally used for management of malaria. Group interviews were also held among THPs and members of the community. The antiplasmodial activities of the crude extracts against chloroquine sensitive (D6) and resistant (W2) Plasmodium falciparum were determined using the semi-automated micro-dilution technique that measures the ability of the extracts to inhibit the incorporation of (G-3H) hypoxanthine into the malaria parasite. RESULTS: Ninety nine (99) species in eighty one (81) genera and forty five (45) families were documented and evaluated for in vitro antiplasmodial activity. Compositae, Fabaceae, Meliceae, Rubiaceae, Rutaceae and Verbenaceae had the highest number of species mentioned in treatment of malaria in Meru/Tharaka Nithi study area. Twenty four (24.2%) species showed antiplasmodial efficacy of IC50 ≤ 5 µg/ml and were considered to have potential for isolation of antimalarial compounds. Eight plant (8) species with moderate antiplasmodial activity namely; Cordia africana, Commiphora africana, Elaeodendron buchananii, Gomphocarpus semilunatus, Tarena graveolens, Plectranthus igniarius, Acacia senegal and Ziziphus abyssinica were documented from this region for the first time for the treatment of malaria. The antiplasmodial activity of MeOH root bark extract of Maytenus obtusifolia was very promising (IC50 < 1.9 µg/ml) and this is the first report on traditional use of M. obtusifolia for treatment of malaria and antimalarial activity. CONCLUSIONS: The results seem to indicate that ethnopharmacological inquiry used in search for new herbal remedies as predictive and could be used as the basis for search of new active principles. Eight plant (8) species are documented from this region for the first time for the treatment of malaria. This is the first report on traditional use of M. obtusifolia for treatment of malaria and evaluation of its antiplasmodial activity.

Antiplasmodial potential of traditional antimalarial phytotherapy remedies used by the Kwale community of the Kenyan Coast.

ETHNOPHARMACOLOGICAL RELEVANCE: In Kenya, 22 million people are at risk of malaria, 70% of them are in rural areas and most of these people use traditional plant based medicines to treat malaria. The aim of the study was to escalate documentation, from an earlier study of medicinal plants, traditionally used to treat malaria by the Digo community of Kwale County, taking cognizance of their pharmacological information by evaluating their antiplasmodial efficacies. MATERIALS AND METHODS: The study was carried out in Kwale County at Shimba Hills Game Reserve and adjoining part of Kinango. Traditional health practitioners (THP) were interviewed with a standard questionnaire to obtain information on medicinal plants traditionally used for management of malaria. Group interviews were also held among THPs and members of the community. The plant samples collected were tested for antiplasmodial activity against chloroquine sensitive (D6) and resistant (W2) Plasmodium falciparum using the ability of extracts, prepared from the plant species, to inhibit the incorporation of [G-3H] hypoxanthine into the malaria parasites. RESULTS: Fifty seven (57) species in forty eight (48) genera and thirty (30) families were documented and evaluated for in vitro antiplasmodial activity. Apocynaceae, Euphorbiaceae, and Rubiaceae families had each about 12% of the plant species reported as antimalarial remedy and represented the species that are most commonly used. Twelve species (21.1%) showed antiplasmodial efficacy of IC50<5µg/ml and these were Boscia salicifolia, Cissampelos mucronata, Clerodendrum myricoides, Commiphora schimperi, Flueggea virosa, Maytenus undata, Maytenus senegalensis, Maytenus putterlickioides, Vernonia amygdalina, Warburgia stuhlmannii, Zanthoxylum chalybeum and Tabernaemontana pachysiphon. CONCLUSIONS: These results seem to indicate that ethnopharmacological inquiry used in search for new herbal remedies as predictive and could form the basis of an ethnopharmacopoeia and search for new active principles. This is the first report on traditional use of T. pachysiphon for malaria and its antiplasmodial activity.

Plasmodium berghei ANKA: selection of resistance to piperaquine and lumefantrine in a mouse model.

We have selected piperaquine (PQ) and lumefantrine (LM) resistant Plasmodium berghei ANKA parasite lines in mice by drug pressure. Effective doses that reduce parasitaemia by 90% (ED(90)) of PQ and LM against the parent line were 3.52 and 3.93 mg/kg, respectively. After drug pressure (more than 27 passages), the selected parasite lines had PQ and LM resistance indexes (I(90)) [ED(90) of resistant line/ED(90) of parent line] of 68.86 and 63.55, respectively. After growing them in the absence of drug for 10 passages and cryo-preserving them at -80 degrees C for at least 2 months, the resistance phenotypes remained stable. Cross-resistance studies showed that the PQ-resistant line was highly resistant to LM, while the LM-resistant line remained sensitive to PQ. Thus, if the mechanism of resistance is similar in P. berghei and Plasmodium falciparum, the use of LM (as part of Coartem) should not select for PQ resistance.