The chemotherapeutic effectiveness of five Nigerian plants used in treating malaria

Malaria continues to be one of the greatest health challenges in Africa especially in Nigeria. Resistance of parasites to already existing drugs is leading to unacceptable levels of therapeutic failures globally. There is a growing realization that combination therapy is vital to the optimal control of malaria in developing countries [1]. It has great advantages and latent potentials to be explored over monotherapy. WHO 2001 recommendations of the Artemisinin combination therapy (Acts') is a proven example. The present work focused on the antiplasmodial and cytotoxic effects of five plants commonly used in Nigerian folk medicine either singly (monotherapy) or combined to treat malaria. Ethyl acetate and dichloromethane extracts of two plants exhibited significant activity against chloroquine sensitive and chloroquine resistant strains of Plasmodium falciparum and no significant toxicity against Chinese Hamster Ovarian cell lines. A combination of the extracts of two plants showed a significant enhancement of the activity. A bioassay guided fractionation using solid phase extraction and high performance liquid chromatography revealed three compounds. Two known compounds, linoleic and linolenic acid have been structurally elucidated and characterized using NMR and GC-MS spectrometry methods. These compounds exhibited a good selectivity index against the sensitive and resistant strains of the Plasmodium falciparum parasite. No significant in vitro toxicity was observed with the compounds. The extract tested in vivo at 800mg/kg was not toxic. Further in vivo work of the most active extract and the bioavailability studies of the compounds are in progress.

Acknowledgements: Funding from the University of Cape Town, and the Medical Research Council of South Africa.

References: [1] Guerin, P.J. et al. (2002) Lancet Infect. Dis. 2:564–573.