A new concept for anti-tuberculosis drug discovery

Tuberculosis remains one of the major causes of death throughout the world. The rise of multi- and extensive- drug resistant Mycobacterium tuberculosis strains and TB-HIV co-infection has escalated the need for new anti-TB drugs. As commonly employed in drug discovery, classical bioassay guided isolation lacks information about structural identity until the very last step of the procedure. A novel methodology (HP)TLC-Bioautography-MS/NMR was developed to address this deficiency. This 3-D set-up that aligns modern microbiological, chromatographic and spectroscopic methods enables detection and determination of the structure of potential anti-TB lead compounds at an early fractionation stage. With the information at hand, a targeted and economically feasible isolation procedure using counter current chromatography can be performed, which shortens the isolation time, avoids isolation of unwanted compounds, including those active only due to synergy, and facilitates the detection of otherwise overlooked active minor constituents. The method was optimized and its specificity and versatility was demonstrated using established drugs, as well as for extracts of several anti-TB active actinomycete strains. Various examples will be presented which demonstrate the usefulness of this novel approach. This project is supported by R21 grant 5 R21 AI093919 – 02.