From in vivo observations, a majority of M.
tuberculosis cells in latently infected individuals are in a dormant and probably nonculturable state, display little metabolic activity, and are phenotypically resistant to
antibiotics. Despite many attempts, no specific antimicrobials effective against
latent tuberculosis have yet been found, partly because of a lack of reliable and adequate in vitro models for screening of
drug candidates. We propose here a novel in vitro model of M.
tuberculosis dormancy that meets the important criteria of latency, namely, nonculturability of cells, considerable reduction of metabolic activity, and significant phenotypic resistance to the first-line
antibiotics rifampin and
isoniazid. Using this model, we found a new group of
2-thiopyridine derivatives that had potent antibacterial activity against both actively growing and dormant M.
tuberculosis cells. By means of the model of M.
tuberculosis nonculturability, several new
2-thiopyridine derivatives were found to have potent antitubercular activity. The compounds are effective against both active and dormant M.
tuberculosis cells. The bactericidal effects of compounds against dormant M.
tuberculosis was confirmed by using three different in vitro models of
tuberculosis dormancy. The model of nonculturability could be used as a reliable tool for screening
drug candidates, and
2-thiopyridine derivatives may be regarded as prominent compounds for further development of new drugs for curing latent M.
tuberculosis infection.