In vivo Anti-plasmodial Activity of Crude Extracts of Three Medicinal Plants Used Traditionally for Malaria Treatment in Kenya

The aim of the study was to determine the in vivo anti-plasmodial activity of three plants Rhamnus prinoides, Rubus keniensis and Garcinia buchananii which are used for malaria treatment by indigenous communities in Kenya. This work was done at the Department of Biological and Preclinical studies, Institute of Traditional Medicine, Muhimbili University of Health & Allied Sciences in October 2016 to August 2017. Male and female albino mice were infected with Plasmodium berghei (ANKA) in the Peter’s four day suppression test. Five groups of mice; Group 1 (solvent: 5 mL/kg body weight of 1% carboxymethyl cellulose), Group 5 (10 mg/kg body weight chloroquine), Groups 2, 3 and 4 were given 200, 400 and 800 mg/kg body weight of plant extracts. The results showed that 5% aqueous methanol extracts of R. prinoides, G. buchananii and R. keniensis exhibited higher anti-plasmodial activity than the 1:1 dichloromethane: methanol extracts in the preliminary testing. The doses showing 50% parasite suppression (EC50) were 139.2, 169.4 and 245.1 mg/kg body weight for R. prinoides, G. buchananii and R. keniensis, respectively. In vivo anti-plasmodial activity of the three plants has supported the traditional use of extracts of Rhamnus prinoides, Rubus keniensis and Garcinia buchananii for treatment of malaria. Isolation of compounds from these plants is in progress.

Evaluation of the cytotoxic activity of extracts from medicinal plants used for the treatment of malaria in Kagera and Lindi regions, Tanzania.

A number of medicinal plants used for treatment of malaria in Tanzania have been documented, but information on their safety and efficacy is still based on traditional knowledge accumulated over years and not on pre-clinical and clinical evaluation. The present study aimed to assess the cytotoxic activity of extracts of selected plant species used for treatment of malaria in Tanzania. Ethanol extracts were evaluated for cytoxicity by using MTT assay on LLC-MK2 cells and by brine shrimp lethality assay. Forty five (93.75%) out of 48 crude extracts assessed using LLC-MK2 cells were non-cytotoxic while three extracts (6.25%) were cytotoxic with CC50 <30 μg/mL (cut-off point). In the brine shrimp assay 30 (65.2%) out of 46 extracts tested were non-toxic while 16 extracts (34.8%) were toxic (LC50 <100 μg/mL). Antiaris toxicaria stem bark extract was the most cytotoxic to mammalian cells. This study demonstrates that, most of the antimalarial plants tested were non-toxic. These observations corroborate with traditional healers’ claims that the herbal medicines used in their areas are safe. However, further studies using different toxicity models are suggested to further confirm their claims.

Anti-Mycobacterial and Toxicity Activities of Some Priority Medicinal Plants from Lake Victoria Basin, Tanzania.

Aims: This study has evaluated ethanol extracts from five medicinal plants selected through ethnobotanical study from Lake Victoria basin, Tanzania for their in vitro antimycobacterial activity against two Mycobacterium species and cytotoxicity against brine shrimp larvae. Study Design: Laboratory experimental tests. Place and Duration of Study: Institute of Traditional Medicine, Muhimbili University of Health and Allied Sciences, P.O. Box 65001, Dar es Salaam, Tanzania, between July 2010 and July 2011. Methodology: Five medicinal plants were selected from the priority list obtained from Lake Victoria basin, Tanzanian side. Collection, processing and drying of plant samples were done in the field with the assistance of a botanist while extraction and concentration of plant samples to obtain crude extracts were done in the laboratory following standard procedures. The plants included in this study are Antidesma membranaceum, Crassocephalum manii, Entada abyssinica, Croton dichogamus and Rubia cordifolia. The two fold microdilution method was used to determine the MIC values of extracts against two Mycobacterium marker strains (Mycobacterium indicus pranii and Mycobacterium madagascariense). The cytotoxicity of plant extract was evaluated against brine shrimp larvae. Furthermore, the extracts were screened phytochemicaly to establish the group of compounds responsible for the activity. Results: Among the tested extracts, the stem bark of A. membranaceum and C. manii showed moderate to mild activity against M. indicus pranii (MIC = 0.3125 mg/ml) and M. madagascariense (MIC = 0.625 mg/ml) respectively. Furthermore, A. membranaceum exhibited significant toxicity activity with LC50 value of 36.134 μg/ml against brine shrimp larvae. Other plants were moderately active when tested in vitro against the above organisms. Phytochemical screening of extracts indicated the presence of different classes of compounds. Conclusion: This study has shown the potential of the priority medicinal plant extracts to be the source of possible lead compounds and anti‐TB drug candidates needed for the management of Tuberculosis. Isolation of active principles from active fractions will be further undertaken.