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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
Antimicrobial Activity and Probable Mechanisms of Action of Medicinal Plants of Kenya: Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus
PLoS ONE, Volume 8, No. 6, Article e65619, Year 2013
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Description
Withania somnifera, Warbugia ugandensis, Prunus africana and Plectrunthus barbatus are used traditionally in Kenya for treatment of microbial infections and cancer. Information on their use is available, but scientific data on their bioactivity, safety and mechanisms of action is still scanty. A study was conducted on the effect of organic extracts of these plants on both bacterial and fungal strains, and their mechanisms of action. Extracts were evaluated through the disc diffusion assay. Bacteria and yeast test strains were cultured on Mueller-Hinton agar and on Sabouraud dextrose agar for the filamentous fungi. A 0.5 McFarland standard suspension was prepared. Sterile paper discs 6 mm in diameter impregnated with 10 μl of the test extract (100 mg/ml) were aseptically placed onto the surface of the inoculated media. Chloramphenicol (30 μg) and fluconazole (25 μg) were used as standards. Discs impregnated with dissolution medium were used as controls. Activity of the extracts was expressed according to zone of inhibition diameter. MIC was determined at 0.78-100 mg/ml. Safety studies were carried using Cell Counting Kit 8 cell proliferation assay protocol. To evaluate extracts mechanisms of action, IEC-6 cells and RT-PCR technique was employed in vitro to evaluate Interleukin 7 cytokine. Investigated plants extracts have both bactericidal and fungicidal activity. W. ugandensis is cytotoxic at IC50<50 μg/ml with MIC values of less than 0.78 mg/ml. Prunus africana shuts down expression of IL 7 mRNA at 50 μg/ml. W. somnifera has the best antimicrobial (1.5625 mg/ml), immunopotentiation (2 times IL 7 mRNA expression) and safety level (IC50>200 μg/ml). Fractions from W. ugandensis and W. somnifera too demonstrated antimicrobial activity. Mechanisms of action can largely be attributed to cytotoxicity, Gene silencing and immunopotentiation. Use of medicinal plants in traditional medicine has been justified and possible mechanisms of action demonstrated. Studies to isolate and characterize the bioactive constituents continue. © 2013 Mwitari et al.
Authors & Co-Authors
Mwitari, Peter Githaiga
Kenya, Nairobi
Kenya Medical Research Institute
China, Tianjin
Tianjin University of Traditional Chinese Medicine
Ayeka, Peter Amwoga
China, Tianjin
Tianjin University of Traditional Chinese Medicine
Kenya, Njoro
Egerton University
Ondicho, Joyce M.
Kenya, Nairobi
Kenya Medical Research Institute
Matu, Esther N.
Kenya, Nairobi
Kenya Medical Research Institute
Bii, Christine C.
Kenya, Nairobi
Kenya Medical Research Institute
Statistics
Citations: 108
Authors: 5
Affiliations: 3
Identifiers
Doi:
10.1371/journal.pone.0065619
e-ISSN:
19326203
Research Areas
Cancer
Genetics And Genomics
Health System And Policy
Study Locations
Kenya