Antiplasmodial activity and phytochemical analysis of extracts from selected Ugandan medicinal plants.

ETHNOPHARMACOLOGICAL RELEVANCE: Resistance of the parasites to known antimalarial drugs has provided the necessity to find new drugs from natural products against malaria. The aim of the study was to evaluate the in vitro antiplasmodial activity of some plants used by Traditional Medical Practitioners (TMPs) of Prometra and Rukararwe in malaria treatment in Uganda to provide scientific proof of the efficacies claimed by these Herbalists. MATERIALS AND METHODS: The air dried samples of Clerodendrum rotundifolium (leaves), Microglossa pyrifolia (leaves), Momordica foetida (leaves) and Zanthoxylum chalybeum (stem bark) used for malaria treatment by TMPs were successively extracted with ethyl acetate, methanol and water to yield twelve extracts. The extracts were tested against the chloroquine-sensitive (NF54) and chloroquine-resistant (FCR3) Plasmodium falciparum strains in vitro using the micro Mark III test which is based on assessing the inhibition of schizont maturation. A compound A was extracted and purified from the stem bark of Z. chalybeum and its structure was identified and confirmed by spectroscopic methods. RESULTS: Most of the extracts tested (92%) showed an antiplasmodial activity with IC50<50µg/mL. In spite of successive extractions with different solvents, potent anti-plasmodial activity (IC50<5µg/mL) was observed in the ethyl acetate, methanol and aqueous extracts of M. pyrifolia and C. rotundifolium. Preferential enrichments of activity into water (IC50<15µg/mL) and Ethyl acetate (IC50<5µg/mL) were seen in the case of M. foetida and Z. chalybeum respectively. The most active extracts were from C. rotundifolium and M. pyrifolia with IC50 values less than 2µg/mL. Phytochemical analysis of the extracts revealed the presence of saponins, tannins, flavonoids, alkaloids and cardiac glycocides. Fagaramide isolated from Z. chalybeum had a higher activity (IC50 2.85µg/mL) against the chloroquine-resistant strain than against the chloroquine-senstive (IC50 16.6µg/mL) strain used in the study. CONCLUSION: The plant extracts analysed in this study presented an average antiplasmodial activity (58%). This study revealed for the first time the antiplasmodial activity of the plant C. rotundofolium. It's the first time the compound fagaramide (N-isobutyl-3-(3,4-methylene dioxyphenyl)-2E-propenamide) has been isolated from Z. chalybeum as one of the compounds that contribute to the activity of this plant against P. falciparum.

Medicinal plants used in malaria treatment by Prometra herbalists in Uganda.

ETHNOPHARMACOLOGICAL RELEVANCE: The aim of the survey was to document medicinal plants used in malaria treatment by Prometra (Promocion de la medicina tradicional amazonica) Traditional Medical Practitioners (TMPs) of Uganda and for search of new antiplasmodial herbal medicines (HMs) for further phytochemical analysis. MATERIALS AND METHODS: In this study, semi structured guided open and close ended questionnaires were used. Focus group discussions were conducted and key informants were chosen within the TMPs who helped in further discussions of how the herbal remedies where collected, prepared and administered. RESULTS: A sample size of 51 respondents was randomly selected among the TMPs with the help of their leader. 86 species distributed over 81 genera and 39 families were reportedly being used as herbal remedies in malaria treatment. The TMPs use symptoms like high temperature, shivering, among others in malaria diagnosis an indication that they understand malaria. They emphasized the use of leaves and bark in treatment because they can regenerate and therefore ensure sustainable use of plants rather than the use of roots which would be destructive. These TMPS treat and also advise their patients on preventive measures against malaria attacks like sleeping under mosquito nets, clearing bushes near homesteads, among others which is an indication that they help in the prevention and mitigation of malaria incidences and prevalence in the areas where they live. The Informant Consensus Factor (FIC) value of 0.8 demonstrated that the TMPs of Prometra-Uganda tend to agree with each other in terms of the plant species they use in malaria treatment an indication of quality control in as far as administration of the herbal remedies. Vernonia amygdalina Delile, Bidens pilosa L., Justicia betonica L. were highly cited as being used in malaria treatment with frequencies of mention of 38, 28 and 25, respectively. CONCLUSION: TMPs of Prometra-Uganda understand and treat malaria using the available plant diversity from their huge forest and the herbal gardens within Buyija forest. The healers are very keen at plant conservation which is a good practice. Species like Justica betonica may be investigated further for antiplasmodial assays to justify its efficacy.