Preliminary antimycobacterial study on selected Turkish plants (Lamiaceae) against Mycobacterium tuberculosis and search for some phenolic constituents

Background: The global resurgence of tuberculosis is a significant threat. Lamiaceae members have been used in folk remedies for centuries. This study was designed to assess the in-vitro antimycobacterial activity of eighteen crude extracts from six plants (Lamiaceae) and to characterize their phenolic and flavonoid compounds. Methods: Six Turkish medicinal plants of the family Lamiaceae (Stachys tmolea Boiss., Stachys thirkei C. Koch, Ballota acetabulosa (L.) Benth., Thymus sipthorpii Benth., Satureja aintabensis P.H. Davis, and Micromeria juliana (L.) Benth. ex Reich.) were collected in 2009 - 2010. Dried and crushed plant samples were subjected to sequential extraction with petroleum ether, ethyl acetate, and methanol in order of increasing polarity. A broth microdilution method was employed to screen extracts against four mycobacterial strains of Mycobacterium tuberculosis. Phenolic and flavonoid compounds were characterized by liquid chromatography-mass spectrometry. Results: S. aintabensis, T. sibthorpii, and M. juliana were found to develop considerable activity against the four strains of M. tuberculosis with the minimal inhibitory concentrations value of 12.5-100 mu g/ml. S. aintabensis and T. sibthorpii extracts killed M. tuberculosis with the minimum bactericidal concentration value of 50-800 mu g/ml. On the basis of these prominent antimycobacterial activity, we suggest that they could be a source of natural anti-tuberculosis agents. Conclusion: S. aintabensis and T. sibthorpii showed activity by killing Mycobacteria strains. The major phenolic compound was rosmarinic for T. sibthorpii and S. aintabensis. Flavonoids might be "a modal" for the drug design.