Potential persistent mycobacterium inhibitors from plants and actinomycetes trageting isocitrate lyase and malate synthase in the glyoxylate shunt of Mycobacterium sp.
Multi- or extensive TB drug resistance, co-infection of HIV/TB and the burdensome persistent infection have placed tuberculosis (TB) as a global emergence that causes 2 million deaths annually. During persistency, Mycobacterium tuberculosis utilizes the glyoxylate pathway to survive, thus making pat...
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| Format: | Thesis |
| Language: | English English |
| Published: |
2013
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| Subjects: | |
| Online Access: | https://eprints.ums.edu.my/id/eprint/41628/1/24%20pages.pdf https://eprints.ums.edu.my/id/eprint/41628/2/FULLTEXT.pdf |
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| Summary: | Multi- or extensive TB drug resistance, co-infection of HIV/TB and the burdensome persistent infection have placed tuberculosis (TB) as a global emergence that causes 2 million deaths annually. During persistency, Mycobacterium tuberculosis utilizes the glyoxylate pathway to survive, thus making pathway enzymes such as isocitrate lyase (ICL) and malate synthase (MLS) valuable drug targets to improve persistent-TB control. The main objective of this study was to identify potential persistent inhibitor(s) targeting the specific enzyme (MLS) in the acetate growth of Mycobacterium sp. A total of 117 extracts prepared from the 44 local plants and 60 soil actinomycetes were screened against MLS using the non-pathogenic form of mycobacteria (M. smegmatis mc2155, H8000) in agar diffusion assay. The potential crude extracts were further analyzed using modified Resazurin Microtiter Assay (REMA), MLS enzymatic assay and Tetrazolium Microplate Assay (TEMA). Among the extracts tested, Hopea pentanarvia (plant) and H7763 (actinomycete) gave the most potent growth inhibition activity on M. smegmatis in REMA. The H7763 extract produced most promising MLS growth inhibitory effect and the Hopea pentanarvia showed potential anti-mycobacterium activity against the pathogenic strain, M. tuberculosis H37Rv. Following this, both potential extracts were selected for bioassay-guided fractionation, and yielded a number of bioactive compounds which were characterized by spectroscopic methods [UV, IR, Mass Spectrometry (MS), 1D- and HMBC NMR]. Hopea pentanarvia yielded a known resveratrol derivative which was finally proposed as cis -Upunaphenol K. H7763 gave a known nucleoside compound named guanine 7-N-oxide. In addition to these structural studies, a minimum inhibition concentration (MIC) agar diffusion assay was performed using the nucleoside and resveratrol derivative against M. smegmatis with 3-nitropropionate (a known ICL prototypic inhibitor) as positive control. This nucleoside (8.1 ± 2.3 μg/disc) gave the lowest MIC value compared to the resveratrol derivative (70.0 ± 14.1 μg/disc) and the known inhibitor (37.5 ± 3.5 μg/disc). The nucleoside may require further research on toxicity before use in the development of antitubercular drug against M. tuberculosis . |
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