Mmushi T MSc (Microbiology).pdf

CHAPTER FOUR
DISCUSSION
Tuberculosis has always been a serious public health challenge and is still one of the
most devastating diseases of mankind. There has been no new anti-TB drug for
treatment in the past 30 years and the available drugs are ineffective against resistant
strains of M. tuberculosis hence there is a need to find new drugs for the treatment of
TB. Plants have been a source of some important drugs against certain infectious
diseases, thus the current study was aimed to investigate the possibility of discovering a
chemical compound(s) from plants which could be used as a cure for TB. To this end 15
plants species were selected based on their usage in traditional medicine and screened
for antimycobacterial activity with a hope of eventually isolating and purifying
compound(s) that could be developed into a drug for the treatment of TB.
Of the four solvents used in the study methanol was the best solvent since it extracted a
greater quantity of plant material from leaves than any of the other solvents. Hexane
extracted the least amount of material. Masoko et al. (2008) also found that methanol
was a better solvent compared to the others. The strong extractability of methanol is
expected since methanol has been shown to efficiently penetrate cell membrane of
plants, permitting the extraction of high amount endocellular components (Britton,
1991). This suggested that methanol extracts contained higher concentration of
compounds compared to the other solvents used in this study.
When the extraction from the different plant leaves are compared, the M. undata leaves
yielded almost equivalent mass from all solvents and its acetone extract was the highest
amongst all the acetone extracts from the other plants. Overall, different mass yields
were extracted from the different plants species using different solvents thus suggesting
that different plant leaves have different phytoconstituents.
Thin layer chromatography was used to analyse the phytoconstituents of the plant crude
extracts since it is a rapid and effective method to obtain the fingerprints of plant
extracts (McGaw et al., 2002). The BEA system showed a good separation for
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