Investigation on antibacterial and antifungal activity of some selected medicinal plants in Ethiopia
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Date
2018-06
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Addis Ababa Universty
Abstract
Background: Cognizant of the fact that, there has been an alarming increase in the incidences of
infectious diseases, emerging and re-emerging antibiotic resistance organisms; there is an urgent
need of novel antimicrobial compounds with new mode of action, effective and inexpensive. One
potential source for the search of such agent is medicinal plants due to the presence of wide
range secondary metabolites in their tissue.
Objectives: The aim of this study was to investigate the antimicrobial activity of 12 traditionally
used Ethiopian medicinal plants for their potency, spectrum of antibacterial, antifungal activity
and acute toxicity.
Methods: Ethnobotanical literature survey was conducted to select 12 medicinal plants.
Antimicrobial activities of 80% Ethanol extracts of all plants were investigated by agar well
diffusion techniques against 22 organisms. Agar dilution techniques were employed to determine
the Minimum Inhibitory, Bactericidal and Fungicidal Concentrations. The Oral acute toxicity
study was determined on the most active plant extract B. abyssinica.
Results: Among investigated medicinal plants, B. abyssinica, X. strumarium, R. natalensis, Z.
scabra, E. cymosa, C. abyssinica and S. abyssinica, showed strong antibacterial activity with
inhibition zone ranging from 9-27 mm; while, B. abyssinica (42 mm) and X. strumarium (48
mm) showed strong antifungal activity. The extracts of B. abyssinica showed most potent
antimicrobial activity with MIC value ranging 0.250-16 mg/ml. Staphylococcus aureus was the
most sensitive organism against B. abyssinica with MIC value of 0.25 mg/ml. Nevertheless, K.
pneumoniae and Citrobacter species were the least sensitive bacteria with 16 mg/ml MIC and
MBC value. T. mentagrophytes and T. rubrum were the most susceptible fungal organism to the
treatment of B. abyssinica, X. strumarium while, A. niger was the most resistant fungus. The LD
50 of B. abyssinica was found to be 4103.175 mg/kg.
Conclusion: The majority of the plants tested showed promising antibacterial and antifungal
potency, especially on gram positive bacteria and dermatophytes. Further studies are
recommended to explore in-vivo efficacy, mechanism of action and toxicological studies of the
most promising plant.
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Keywords
Antibacterial, Antifungal, Medicinal Plant, B. abyssinica, MIC, Acute Toxicity