In Vitro Evaluation of the Anti-mycobacterial Activity of Selected Medicinal Plants in Ethiopia on Mycobacterium tuberculosis and Mycobacterium bovis Strains
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Date
2020-02
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Addis Ababa University
Abstract
Background: Tuberculosis (TB) is a major global health problem causing ill-health in millions
of the world’s population each year. The emergence of drug resistant strains is a major challenge
to the TB control program. Hence, there is an urgent need for the development of new drugs and
in this regard, herbs could be potential sources of anti-TB drugs due to their special attribute as a
large source of therapeutic phytochemicals that may lead to novel drugs development.
Objective: The objective of this study was to investigate the in vitro anti-mycobacterial activity
of the 80% methanol extracts of Euphorbia candelabrum (E. candelabrum) latex, Rumex
abyssinicus (R. abyssinicus) root, Otostegia integrifolia (O. integrifolia) leaf and Erythrina
brucei (E. brucei) stem bark, the chloroform extract of Vernonia amygdalina (V. amygdalina)
leaf and the oil of O. integrifolia leaf on Mycobacterium tuberculosis and Mycobacterium bovis
strains. Additionally, to test the anti-oxidant activity of E. candelabrum extract and to carry out a
preliminary phytochemical screening for the plant extracts.
Methods: The 80% methanol extracts were obtained through cold maceration technique, the
chloroform extract of V. amygdalina was obtained through successive soxhlet extraction and the
oil was obtained by employing hydrodistillation extraction technique. Macro-dilution technique
was used for determining the minimum inhibitory concentration (MIC). The free radical
scavenging ability of E. candelabrum was tested by using 2, 2-diphenyl-1-picrylhydrazyl assay.
Statistical Package for Social Sciences software was used for data analysis. One way analysis of
variance followed by Tukey’s post hoc test was employed to test significance.
Results: The MIC of the chloroform extract of V. amygdalina leaf was 10mg/ml against the
mycobacterial strains. The 80% methanol extracts of E. brucei, O. integrifolia and R. abyssinicus
were effective against only M. bovis with MIC ranging from 12.5 - 25mg/ml. The oil from O.
integrifolia leaf was inactive. Although E. candelabrum did not show anti-mycobacterial
activity, it showed an anti-oxidant activity with a half maximal inhibitory concentration (IC50) of
281μg/ml.
Conclusion: There may be a possibility to develop new compounds from V. amygdalina against
mycobacterial strains. E. brucei, O. integrifolia and R. abyssinicus showed mycobacterial growth
inhibition against M. bovis strain. Hence, these plants should be further evaluated for the
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development of anti-tuberculosis drugs. E. candelabrum may aid in TB treatment through other
host directed therapeutic mechanisms rather than direct mycobacterial growth inhibition.
Description
Keywords
Tuberculosis, Mycobacteria, Vernonia amygdalina, Euphorbia candelabrum, Otostegia integrifolia, Rumex abyssinicus, Erythrina brucei, anti-mycobacterial activity, resazurin, anti-oxidant activity.