Characterization of n-Hexane sub-fraction of Bridelia micrantha (Berth) and its antimycobacterium activity
1 AIDS Virus Research Laboratory, Department of Microbiology, University of Venda, Thohoyandou 0950, South Africa
2 Department of Biochemistry and Microbiology, University of Fort Hare, Private Bag X1314, Alice 5700, South Africa
3 Research and Academic Directorate, Walter Sisulu University, Mthatha, South Africa
4 Department of Biochemistry and Microbiology, University of Buea, Cameroon
BMC Complementary and Alternative Medicine 2011, 11:28 doi:10.1186/1472-6882-11-28Published: 11 April 2011
Tuberculosis, caused by Mycobacterium tuberculosis (MTB), is the most notified disease in the world. Development of resistance to first line drugs by MTB is a public health concern. As a result, there is the search for new and novel sources of antimycobacterial drugs for example from medicinal plants. In this study we determined the in vitro antimycobacterial activity of n-Hexane sub-fraction from Bridelia micrantha (Berth) against MTB H37Ra and a clinical isolate resistant to all five first-line antituberculosis drugs.
The antimycobacterial activity of the n-Hexane sub-fraction of ethyl acetate fractions from acetone extracts of B. micrantha barks was evaluated using the resazurin microplate assay against two MTB isolates. Bioassay-guided fractionation of the ethyl acetate fraction was performed using 100% n-Hexane and Chloroform/Methanol (99:1) as solvents in order of increasing polarity by column chromatography and Resazurin microtiter plate assay for susceptibility tests.
The n-Hexane fraction showed 20% inhibition of MTB H37Ra and almost 35% inhibition of an MTB isolate resistant to all first-line drugs at 10 μg/mL. GC/MS analysis of the fraction resulted in the identification of twenty-four constituents representing 60.5% of the fraction. Some of the 24 compounds detected included Benzene, 1.3-bis (3-phenoxyphenoxy (13.51%), 2-pinen-4-one (10.03%), N(b)-benzyl-14-(carboxymethyl) (6.35%) and the least detected compound was linalool (0.2%).
The results show that the n-Hexane fraction of B. micrantha has antimycobacterial activity.