Anti-Mycobacterial Activity Of Labisia Pumila Benth. & Hook. F. And Its Bioactive Constituents Against Surrogate Tuberculosis Organisms
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Date
2016-07
Authors
Jamaludin, Nur Liyana
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Abstract
The development of multidrug resistant tuberculosis (TB) strains becomes a
major factor contributing to the rise of global TB incidence. Therefore, the urgent
need of effective, safe and inexpensive anti-TB drugs has geared many researches
towards natural products including plants. Partitions from Labisia pumila were
investigated to evaluate their anti-mycobacterial potential against Mycobacterium
tuberculosis surrogate organisms (M. smegmatis, M. fortuitum, and M. kansasii)
using tetrazolium microdilution assay. The most active partitions were produced by
n-hexane of stem-root and leaf parts against M. kansasii with minimum inhibitory
concentrations (MICs) of 50 - 200 μg/mL. These partitions were selected for
bioassay guided fractionation process using column chromatographic techniques,
which produced 20 different fractions. These fractions were screened against
M. kansasii and fractions R2, R6, and L7 exhibited the most promising activity
(MIC: 25 – 50 μg/mL). Further screening of these active fractions was carried out
against M. tuberculosis H37Ra strain and the MIC values produced were 12.5, 50
and 100, μg/mL, respectively. Phytochemical analysis of the most active R2 fraction
using gas chromatography-mass spectrometry resulted in the identification of three
major compounds; vaccenic acid, octadecanoic acid, and 10-heptadecenoic acid. The
activity of these compounds against M. tuberculosis H37Ra exhibited MIC values
100 - 400 μg/mL, displaying lower activity compared to their original fraction R2
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(MIC: 12.5 μg/mL). Interaction study of R2 fraction with first-line anti-TB drugs
against M. kansasii and M. tuberculosis H37Ra using checkerboard method produced
one synergistic interaction with rifampicin against M. tuberculosis H37Ra, with
fractional inhibitory concentration index (FICI) value of 0.375, increasing the
individual activity of fraction and drug by eight and four folds, respectively. This
synergistic interaction was further verified using time-kill assay and produced an
additive interaction of 94.46 % killing rate at the end of the study period. The
observation of M. tuberculosis H37Ra cells treated with R2 fraction using
transmission electron microscopy (TEM) showed the breakage of the outer cell
structure and deformation of the tubercle cells. Cytotoxicity study of R2 fraction
against nasopharyngeal epithelial cell line, NP69 revealed that it was highly
cytotoxic with IC50 value of 7.57 ± 1.75 (mean ± SD) μg/mL. In conclusion, the
promising anti-mycobacterial activity of L. pumila indicates its potential as a source
of remedy for the treatment of TB.
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Keywords
The development of multidrug resistant tuberculosis , contributing to the rise of global TB incidence.