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DOI: 10.1055/s-2007-986948
Evaluation of the anti-TB potential of bryophytes
With more than 1.5 million casualties a year and one third of the world's population latently infected, tuberculosis (TB), together with HIV, represents one of the most menacing diseases of mankind [1, 2]. The contemporary TB treatment regimen requires the combination of at least 4 different antibiotics for 6–9 months. This situation and the increasing number of multi-drug resistant strains (MDR) of Mycobacterium tuberculosis indicate an urgent need for new antimycobacterial compounds and treatment strategies [2, 3].
Hitherto, many plants were found to exhibit antimycobacterial activities [4, 5]. However, bryophytes have hardly been investigated in this respect. We therefore conducted a bioassay-guided evaluation strategy on 13 North American bryophytes in order to evaluate their potential antimycobacterial activities against virulent M. tuberculosis (H37Rv) in an Alamar Blue assay (MABA). Our preliminary data showed significant inhibition (≥90%) of M. tuberculosis (H37Rv) in the crude petrol-ether and dichloromethane extracts of Thuidum recognitum Hedw. (Thuidaceae), and Leucobryum glaucum (Hedw.) Angst. (Leucobryaceae). Applying fast centrifugal partition chromatography (FCPC), and high-speed current counter chromatography (HSCCC), sub-fractions exhibiting ≥90% inhibition at 64 ug/ml could be obtained from both plants and will be analyzed further. With regard to potential lead structures, two active diterpenes, namely ent-3β-acetoxy-trachyloban-18-al (MIC: 59.34µg/ml) and ent-trachyloban-17-all (MIC: 24.36µg/ml) could be isolated from lipophilic extracts of Jungermannia exsertifolia Steph. (Jungermanniaceae). Our results suggest that bryophytes are a remarkable group of plants that deserve further attention in the search of lead structures for new anti-tubercular drugs.
Acknowledgements: Austrian Science Fund (FWF), Vienna, Austria.
References: [1] http://www.who.int/mediacentre/news/releases/2007/pr08/en/index.html, [2] Chakrabarti, B. et al. (2007) Future Microbiology 2: 51–61. [3] American Thoracic Society et.al. (2003) Am J Respir Crit Care Med 167: 603–62. [4] Newton, S. et. al. (2002) Phytother Res 17: 303–22, Cantrell, L et. al. (2001) Planta Med. 67: 685–94.